Aspen MUSE ReferenceGuide

Aspen MUSE Reference Guide

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Copyright Version Number: 2004

Copyright 1981 - 2004 Aspen Technology, Inc. All rights reserved.

Aspen ACOL™, Aspen ACX™, Aspen APLE™, Aspen Adsim™, Aspen Aerotran™, Aspen CatRef®, Aspen Chromatography®, Aspen Custom Modeler®, Aspen Decision Analyzer™, Aspen Dynamics®, Aspen Enterprise Engineering™, Aspen FCC®, Aspen Hetran™, Aspen Hydrocracker®, Aspen Hydrotreater™, Aspen Icarus Process Evaluator™, Aspen Icarus Project Manager™, Aspen Kbase™, Aspen Plus®, Aspen Plus® HTRI®, Aspen OLI™, Aspen OnLine®, Aspen PEP Process Library™, Aspen Plus BatchFrac™, Aspen Plus Optimizer™, Aspen Plus RateFrac™, Aspen Plus SPYRO®, Aspen Plus TSWEET®, Aspen Split™, Aspen WebModels™, Aspen Pinch®, Aspen Properties™, Aspen SEM™, Aspen Teams™, Aspen Utilities™, Aspen Water™, Aspen Zyqad™, COMThermo®, COMThermo TRC Database™, Aspen DISTIL™, Aspen DISTIL Complex Columns Module™, Aspen FIHR™, Aspen FLARENET™, Aspen FRAN™, Aspen HX-Net®, Aspen HX-Net Assisted Design Module™, Aspen Hyprotech Server™, Aspen HYSYS®, Aspen HYSYS Optimizer™, ACM Model Export™, Aspen HYSYS Amines™, Aspen HYSYS Crude Module™, Aspen HYSYS Data Rec™, Aspen HYSYS DMC+ Link™, Aspen HYSYS Dynamics™, Aspen HYSYS Electrolytes™, Aspen HYSYS Lumper™, Aspen HYSYS Neural Net™, Aspen HYSYS Olga Transient™, Aspen HYSYS OLGAS 3-Phase™, Aspen HYSYS OLGAS™, Aspen HYSYS PIPESIM Link™, Aspen HYSYS Pipesim Net™, Aspen HYSYS PIPESYS™, Aspen HYSYS RTO™, Aspen HYSYS Sizing™, Aspen HYSYS Synetix Reactor Models™, Aspen HYSYS Tacite™, Aspen HYSYS Upstream™, Aspen HYSYS for Ammonia Plants™, Aspen MUSE™, Aspen PIPE™, Aspen Polymers ®, Aspen Process Manuals™, Aspen BatchSEP™, Aspen Process Tools™, Aspen ProFES 2P Tran™, Aspen ProFES 2P Wax™, Aspen ProFES 3P Tran™, Aspen ProFES Tranflo™, Aspen STX™, Aspen TASC-Thermal™, Aspen TASC-Mechanical™, the aspen leaf logo and Enterprise Optimization are trademarks or registered trademarks of Aspen Technology, Inc., Cambridge, MA.

All other brand and product names are trademarks or registered trademarks of their respective companies.

This document is intended as a guide to using AspenTech's software. This documentation contains AspenTech proprietary and confidential information and may not be disclosed, used, or copied without the prior consent of AspenTech or as set forth in the applicable license agreement. Users are solely responsible for the proper use of the software and the application of the results obtained.

Although AspenTech has tested the software and reviewed the documentation, the sole warranty for the software may be found in the applicable license agreement between AspenTech and the user. ASPENTECH MAKES NO WARRANTY OR REPRESENTATION, EITHER EXPRESSED OR IMPLIED, WITH RESPECT TO THIS DOCUMENTATION, ITS QUALITY, PERFORMANCE, MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE.

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Corporate

Aspen Technology, Inc. Ten Canal Park Cambridge, MA 02141-2201 USA Phone: (1) (617) 949-1000 Toll Free: (1) (888) 996-7001 Fax: (1) (617) 949-1030 URL: http://www.aspentech.com/

Related Documentation In addition to online help systems available via the product applications, a number of printable documents are provided to help users learn and use the HTFS family of products:

Title Content

HTFS Installation Guide.pdf Describes the installation routine

HTFS User Guide.pdf Provides an overview of the HTFS family of products

ACOL Reference Guide.pdf

ACOL Getting Started Guide.pdf

User instructions for the ACOL product

APLE Reference Guide.pdf

APLE Getting Started Guide.pdf

User instructions for the APLE product

MUSE Reference Guide.pdf

MUSE Getting Started Guide.pdf

User instructions for the MUSE product

FIHR Reference Guide.pdf

FIHR Getting Started Guide.pdf

User instructions for the FIHR product

FRAN Reference Guide.pdf

FRAN Getting Started Guide.pdf

User instructions for the FRAN product

PIPE Reference Guide.pdf

PIPE Getting Started Guide.pdf

User instructions for the PIPE product

TASC Thermal Reference Guide.pdf

TASC Thermal Getting Started Guide.pdf

User instructions for the TASC Thermal product

TASC Mechanical Reference Guide.pdf

TASC Mechanical Getting Started Guide.pdf

User instructions for the TASC Mechanical product

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Table of Contents

1 Introduction................................................................1-1

1.1 Overview..............................................................................1-3

1.2 MUSE, MULE, MUSC and PFIN .........................................1-4

1.3 Exchanger Geometries........................................................1-5

1.4 Design Calculations.............................................................1-6

1.5 Heat Transfer and Pressure Drop .......................................1-6

1.6 Property Data Sources ........................................................1-7

1.7 Thermosyphons...................................................................1-7

1.8 Output Options ....................................................................1-8

1.9 Documentation ....................................................................1-8

2 Using MUSE................................................................2-1

2.1 Overview..............................................................................2-3

2.2 The Start up View ................................................................2-5

2.3 Running MUSE....................................................................2-6

2.4 MUSE Icons.........................................................................2-7

3 Data Input...................................................................3-1

3.1 Overview..............................................................................3-3

3.2 Input Views ..........................................................................3-4

3.3 Process Data Input ..............................................................3-6

3.4 Geometry Data Input ...........................................................3-7

3.5 Other Data Input ..................................................................3-8

3.6 Input Units ...........................................................................3-8

3.7 Using Help .........................................................................3-10

3.8 Finding Input Items ............................................................3-11

3.9 The Input File.....................................................................3-12

3.10 Default Input Data File.......................................................3-13

3.11 Input Errors and Warnings.................................................3-14

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4 Output.........................................................................4-1

4.1 Overview..............................................................................4-3

4.2 Output Views .......................................................................4-3

4.3 Output Files .........................................................................4-6

4.4 Error / Warning Message Log..............................................4-8

4.5 Other Output........................................................................4-8

5 Physical Properties ....................................................5-1

5.1 Overview..............................................................................5-3

5.2 Properties Input ...................................................................5-6

5.3 Properties Data Input (Old Style).......................................5-10

5.4 Mixture Calculations (Old Style) ........................................5-14

5.5 Property Databanks...........................................................5-17

5.6 Importing Properties & Process Data ................................5-19

5.7 Importing from HYSYS ......................................................5-21

5.8 Importing from a Properties Package ................................5-23

5.9 Properties Output ..............................................................5-24

5.10 Pressure Dependence.......................................................5-25

6 Other Facilities...........................................................6-1

6.1 Overview..............................................................................6-3

6.2 User Fin Databank...............................................................6-3

6.3 Project File Structure ...........................................................6-4

7 Examples ....................................................................7-1

7.1 Overview..............................................................................7-3

7.2 Case 1 Design .....................................................................7-4

7.3 Case 1 Simulation .............................................................7-11

7.4 Case 1, Layer by Layer Calculations (MULE) ...................7-17

7.5 The Zig-zag .......................................................................7-22

Index............................................................................I-1

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Introduction 1-1

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1 Introduction

1-1

1.1 Overview...........................................................................................3

1.2 MUSE, MULE, MUSC and PFIN .......................................................4

1.3 Exchanger Geometries....................................................................5

1.4 Design Calculations ........................................................................6

1.5 Heat Transfer and Pressure Drop...................................................6

1.6 Property Data Sources ....................................................................7

1.7 Thermosyphons...............................................................................7

1.8 Output Options ................................................................................8

1.9 Documentation.................................................................................8

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1-2 Introduction

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1.1 OverviewMUSE can perform a range of calculations on plate-fin heat exchangers, either simple two-stream exchangers, or complex ones with multiple streams. The basic calculation options are:

MUSE’s User Interface presents a structured approach to data input. The software can run at various levels of detail, and is extensively supported by Help Text. A range of outputs are produced, in both tabular and graphical form. There is an Exchanger Diagram, available in the input for performance calculations, so that you can check that the data you have provided is correct, or in the output from design calculations.

MUSE Calculation Modes

Simulation This determines the heat load, pressure changes, and outlet conditions for each stream in the exchanger, based on an exchanger you specify, and given stream inlet conditions.

Layer by Layer Simulation

Same as normal simulation, but on a layer by layer rather than stream by stream basis. This option lets you assess the stacking pattern in which layers of the various streams are arranged.

Thermosyphon This determines the performance of an exchanger, with a geometry you specify, with one stream operating as a thermosyphon. The exchanger can either be internal to the column or outside it and connected via pipework. You can specify either the head of liquid driving the thermosyphon flow, or the thermosyphon stream flowrate, leaving the program to calculate the one you do not specify.

Design This will produce a “first shot” design of a heat exchanger to meet a heat load duty and pressure drop limits, which you specify for each stream. This should be a useful indication of what a specialist manufacturer would provide. A final design of a plate-fin exchanger must, however, come from a manufacturer, who can use proprietary finning and specialist design and manufacturing techniques.

Crossflow Exchanger For single or multi-pass, or thermosyphon.

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1.2 MUSE, MULE, MUSC and PFINHistorically HTFS has had four separate programs for plate fin heat exchangers.

These programs are now termed Calculation Engines and are gathered together under the generic title MUSE, which is used throughout this manual. There is one User Interface, with the individual programs appearing as calculation options. The input data required for these options varies slightly, but there are no incompatibilities. The output formats are all very similar. The initial release of MUSE for Windows (1997) contained only the original MUSE. The design option (PFIN) and layer-by-layer option (MULE) were incorporated in version 3.00, the first release with this User Guide. The crossflow option (MUSC) was incorporated in version 3.10.

The Help Text for MUSE often refers to individual program names. For example it refers to “the design option (PFIN)”, or “crossflow exchangers (MUSC)” to help distinguish between the various calculation options.

Program Use

MUSE For general purpose performance simulation and thermosyphons.

MULE For general purpose performance simulation and thermosyphons.

MUSC For simulating special crossflow designs of plate fin exchangers (including crossflow reboilers).

PFIN For ‘first-shot’ design.

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1.3 Exchanger Geometries MUSE allows for the following aspects of plate-fin exchanger geometry:

Exchanger Geometries

Overall Geometry

Stream entry and exit at any point along the exchanger.

Inlet and outlet distributors.

Internal re-distribution into otherwise empty layers.

Partial draw-off of a stream.

Nozzles.

Change of main fin type at points along the exchanger length.

Exchangers in parallel.

Exchangers in series (in Design, if needed).

Internal and external thermosyphon reboilers.

Layer patterns, including allowance for double or triple banking.

Empty layers.

Performance evaluation with some streams switched off.

Distributors End entry/exit - Full end, central end, at side.

Side entry/exit - Diagonal, mitred, indirect.

Hardway.

Single- or twin-headed distributors.

Finning Plain.

Perforated.

Serrated (lanced or multi-entry).

Wavy (herringbone).

Unfinned.

Correlations for fin performance.

Option to supply manufacturer’s performance data.

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1.4 Design CalculationsThe PFIN calculation engine in MUSE offers a ‘first shot’ design capability. It will produce a design based purely on the required inlet and outlet process conditions for each stream, or you can specify certain aspects of the exchanger, for example the fins or distributors to be used, and leave the program to complete the design.

While this ‘first shot’ approach should in many cases give a reasonable approximation to what a plate fin manufacturer might suggest, you should be aware that sometimes there may be significant differences. For a more realistic design, you would need to select proprietary fins and use proprietary fin performance data from a manufacturer. For complex multi-stream exchangers, specifying the distributor types and constraining the number of layers for certain streams can also lead to improvements on the design produced by PFIN unaided.

1.5 Heat Transfer and Pressure DropMUSE can perform heat transfer and pressure drop calculations on single or two-phase streams, involving sensible heating or cooling, boiling or condensation, or any combination of these. Streams can be either pure components, or multi-component mixtures.

Facilities are provided whereby you can modify the heat transfer coefficients and pressure gradients calculated by MUSE, either by scaling them, or replacing them with specified values.

MUSE calculates fin efficiencies, allowing for local thermal conduction along the fin metal to the parting sheet. It can also allow for longitudinal thermal conduction in the parting sheets and sidebars, transferring heat from the hot to the cold end of the exchanger.

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1.6 Property Data Sources MUSE offers a range of options for providing the physical property information needed for heat transfer and pressure drop calculations. If you have stream property information available, this can be input directly, or imported provided it is in the correct format. If the stream is a mixture of known composition, MUSE can perform vapour liquid equilibrium and mixture calculations to determine the stream properties. This can be done using the COMThermo package which has data for over 1000 components, or the smaller NEL40 package.

See Chapter 5 - Physical Properties for more information on the various properties options and methods.

1.7 ThermosyphonsFor thermosyphons, MUSE has methods for calculating both frictional and gravitational pressure changes in the inlet and outlet pipework connecting the exchanger to the column. You can simplify each line to an equivalent length, allowing for bends, diameter changes, and generalised flow restrictions.

MUSE will either determine the thermosyphon stream flowrate, consistent with the driving pressure head you specify, or evaluate the head needed to drive a particular flowrate. It will tabulate the pressure changes in all the components of the circuit, as well as provide full information about exchanger performance.

For the condensing stream in a thermosyphon, you can specify a number of options, with either its flow, inlet pressure, or exit quality (vapour mass fraction) adjusting to conform to the calculated heat load. In a cryogenic flow driven by a turbine, the condensing stream operating pressure usually adjusts itself to give complete condensation in supplying the required heat load.

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1.8 Output OptionsMUSE produces a number of different types of output information. Some are in the form of output views, consist of information that can be tabulated, plotted, and printed out. Other information is available as output files, which you can examine via the User Interface. The Find facility helps to locate text within these files. You can control the amount of information they contain using flags in the program input.

MUSE also includes an extensive set of error and warning messages, to provide clear information on what is required, if you omit vital data, or provide unusual or inconsistent input.

Chapter 4 - Output gives more detailed information on the program output.

1.9 DocumentationHTFS supplies the following manuals on the Software CD:

• HTFS User Guide• HTFS Installation Guide

(these two are generic to all programs)• MUSE Getting Started• MUSE Reference Guide

This Reference Guide provides basic information on using the program, its capabilities, the required input data (see Chapter 3 - Data Input), and the results (see Chapter 4 - Output). Chapter 5 - Physical Properties covers the range of options for providing the information needed to run the program.

Also contained in this manual is a set of standard examples (see Chapter 7 - Examples) for you to work through. These examples illustrate a range of exchanger calculations that can be performed using MUSE, and show you the various methods of inputting the relevant data.

When appropriate, this manual includes the MUSE input and output views to help with explanations. Since MUSE is being continuously developed, there may be minor discrepancies between what you see on

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your computer, and the views shown in this manual. The discrepancies may relate to layout, or to numerical values, but should not be taken as indicating any problem.

See the MUSE Getting Started for information on the set of QA data that is included with the program. The QA data are input data sets to help ensure that MUSE is functioning properly. These sets should be run in MUSE and then checked that the results are the same (within the limits of computer accuracy) as the corresponding output files, which are also provided.

The Help Text is the most extensive documentation available for MUSE. It is available whenever you are running the program, or can be loaded separately. There are direct links to appropriate Help topics for every input item, and from many other places in the program.

The technical methods used in MUSE are proprietary, and full details are available only to companies who are members of HTFS. These methods are described in HTFS Design Reports DR50, DR62 and in a range of HTFS Research Reports. These are produced each year, and compare method predictions with the results of the continuing HTFS experimental program on plate-fin heat exchangers.

To load the Help Text when you are not running MUSE, double-click on MUSE.HLP in the main MUSE directory.

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Using MUSE 2-1

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2 Using MUSE

2-1

2.1 Overview...........................................................................................3

2.2 The Start up View.............................................................................5

2.3 Running MUSE.................................................................................6

2.4 MUSE Icons......................................................................................7


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2-2 Using MUSE

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Using MUSE 2-3

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2.1 OverviewThe normal procedure when running MUSE is to set up input data representing a particular case, to run the case, and to examine the results. If you come back to a case, which you have run previously, you can examine the results without needing to run the program again. You can very easily make changes to a case and re-run it. After making changes, you can decide whether to save them for future reference, or simply to Run the changed case, see what the results are, and then decide whether to save it. You can also save a case part way through providing input, so you can come back later and complete it.

Facilities are provided for you to provide a descriptive title for each run, to number a run, and to add a number of lines of comments giving further information.

Further information on the data input is provided in Chapter 3 - Data Input of this guide, and on output in Chapter 4 - Output. Extensive Help Text is available when running the program. This covers not only the details of input and output, but also the use of the User Interface and on plate-fin exchangers in general.

Figure 2.1

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The Welcome view appears, which contains a list of recently used input files, and gives you the option of opening an Existing file, or starting a New one. Select the New button, and you will be taken to the Start up view where you can begin inputting data for a new example.

You can save an example at any point during data input, or after you have run it. When you next start MUSE, you will see it in the list of recently used files, and can double-click on it to select it. If you want to find a previous input file which does not appear in the recently used list, click on Open. When you open an input file, MUSE will also open all the associated output files, if any, produced by a previous run.

When you have your MUSE file loaded, you can start a (different) new case, using the New command under the File menu. Selecting New will clear any existing data and set up default data. Return to a different existing case by using the Open command under the File menu.

Regardless of the method you choose to begin a new case, the view available is the Start up view, shown in Figure 2.2. You can return to that view at any point by selecting Start up under the Input menu.

When you start an existing case, you will not be taken to the Start up view, but for a simulation case you will be shown the Exchanger Diagram, (Geometry Preview view), if available, while for a design case you will be shown the Process Data input views. You will also see the Run Title, to remind you of the case you have selected. The Exchanger Diagram can also be access at any time from the View menu or by clicking on the appropriate toolbar icon. For the diagram to be available, you must have provided the basic information on where each stream enters and leaves the exchanger. It will also show information on main fin number and distributor and nozzle layout, provided you have supplied the relevant input information.

You can also use the key SHIFT F1 to return to the Start up view.

View Geometry Diagram icon

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2.2 The Start up View

The Start up view is important because it ensures that you are shown a set of input options consistent with what you want to do. You must set the items on the Start up view, or accept the defaults, and click on OK before you can enter any other data.

The most important item is the Calculation Mode. The default is Simulation - MUSE, but you can reset it to Design - PFIN or Thermosyphon - MUSE, or Layer-by-Layer - MULE, or Crossflow - MUSC. As with all input items, press F1 to see the Help Text, if you are not sure what the options mean or what you should do.

It is always important to specify the number of streams in the exchanger.

The Number of Fins to be Directly Input should be set if you are going to provide information on fin geometry or performance in the input. It can be left blank if you are doing a simple design (when MUSE will select all the fin information), or if you are going to get all your fin data from a fin databank.

Basic Input Mode is a facility which limits the number of input items you can see. If you are a new user, setting it may help you get an overview of the most important items and options in the MUSE input. If

Figure 2.2

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you set it, you can return to the Start up view at any time and unset it, to gain access to the full range of input. If you save your data while using Basic Mode and then reopen the case later, it will again be displayed in Basic Mode.

The Equipment Item Number and the Job Title are optional input, but it is recommended that you provide them for future reference.

Click on OK to gain access to the input views for your new case.

2.3 Running MUSEWhen you have prepared your data input (see Chapter 3 - Data Input) you must Run one of the calculation engines to generate results. You can run the calculation engine corresponding to the calculation type you specified either by:

• Clicking on the Run icon.• Selecting Calculate All under the Run menu.• Pressing F4 on the keyboard.

The Run menu also lets you run calculation engines other than the one you specified under Calculation Mode on the Start up view. You will be asked for confirmation first.

A view will appear detailing the progress made as the calculation is run. See Figure 2.3.

Figure 2.3

Run icon

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Sometimes this will be too rapid to follow in detail, but it can be useful for MUSE cases that take more than a few seconds to run. A message appears when the calculation is complete, and the Results Summary view, and/or the Error/Warning Log appears. See the Chapter 4 - Output for more details.

The Run Progress view records the file that is being run. If the extension is .MUI, you are running the case you just opened, without having made any changes to it. If the file extension is .MUA, you are running the edited copy of your original input file, having made changes to it.

2.4 MUSE Icons

MUSE has a toolbar containing a number of icons, which can be clicked on as short-cuts to the frequently performed program operations. The meaning of each icon appears as a ToolTip after the cursor has been left positioned on it for a second or two. When toolbar icons are referenced in this manual, an image of the icon will often appear in the margin adjacent to the relevant paragraph. The following table gives a brief description of each of the available icons.

MUSE 3.30 and subsequent releases will work with Windows 2000 and XP.

Figure 2.4

Name Icon Function

New Create a new case.

Open Locate and open an existing case.

Save Save the active case.

Preview Input File

View the input data file.

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2-8 MUSE Icons

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The Help Text provides more information on all the operations described above.

Find Input Item Open the Find Item view.

Geometry Open the Geometry input form.

Advanced Geometry

Open the Advanced Geometry input form.

Process Open the Process Data input form.

Fins Opens the Fin Geometry and Performance Data input form. Only accessible if Numbers of Fins specified on the Start up view is greater than zero.

Options Opens the Options input form.

Physical Properties

Open the Physical Properties input form.

Run Run the MUSE calculations.

View Geometry Diagram

View the Geometry Diagram.

Help Open the MUSE Help Text.

Exit Exit MUSE.

Name Icon Function

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3 Data Input

3-1

3.1 Overview...........................................................................................3

3.2 Input Views.......................................................................................4

3.3 Process Data Input ..........................................................................6

3.4 Geometry Data Input .......................................................................7

3.5 Other Data Input...............................................................................8

3.6 Input Units ........................................................................................8

3.7 Using Help ......................................................................................10

3.8 Finding Input Items........................................................................11

3.9 The Input File .................................................................................12

3.10 Default Input Data File.................................................................13

3.11 Input Errors and Warnings..........................................................14


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3-2 Data Input

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3.1 OverviewMUSE has a number of data input forms (views), each comprising several tabbed pages. These are found under the Input menu. The contents of each page vary slightly according to the Calculation Type (Design, Simulation or Thermosyphon etc.) you have specified.

Data is input either by typing in values, or selecting from a drop-down list. You do not need to fill in all the data input items, only those that sufficiently describe the case under consideration. If you are only interested in thermal performance, you can omit information on distributors and nozzles, but you should remember that the calculated pressure drop will not then allow for these items. All the items controlling the details of the calculation, or outputs can be omitted. Program defaults will then be used.

If you are unsure what a data item means, position the cursor on that item and press F1. You will be shown the Help Text on that item, which can show diagrams, define defaults, and let you explore other relevant information. It can point you to assumptions made by the program, and to what use is made of an input item during MUSE calculations.

For a full description of each item, and a listing of all possible items, use the Help Text. For more information on Physical Properties, both input and output, see Chapter 5 - Physical Properties.

Some input items have checks on them to prevent you from inputting inappropriate values. For simulation cases, use the Exchanger Diagram (View menu) to ensure you have specified the exchanger layout correctly. A complete and systematic check on input is made when you run MUSE calculations. You will be shown a list of any errors and warnings produced.

An asterisk (*) adjacent to an input item indicates that it is normally necessary to supply this item.

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3.2 Input ViewsUnder the Input menu you will see a list of input views, each of which consists of a set of tabbed pages. The views and their tabbed pages are as follows.

Views Tabbed Pages

Geometry Basic Geometry.

Layer Pattern.

Layer Definition.

Thermosyphons.

Stream Geometry.

Distributors and Nozzles.

Pass Lengths.

Advanced Geometry Extra Main Fins.

Redistributors.

Substreams.

Layer Flow Distribution.

Inter-pass Details.

Process Process.

Process Constraints.

Process - Exchanger.

Fins Fin Geometry.

Fin Performance.

Options Comments to go on Output.

Output Options.

Calculation Options.

Physical Properties These views have a different layout from the other views, and are described in Chapter 5 - Physical Properties.

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Figure 3.1 shows a typical example of an input view.

Some views/tabbed pages are only used for certain Calculation Modes. They sometimes have a different set of items on them, depending on the Calculation Mode. In the Basic Input option, a reduced set of views, with a reduced set of input items on them appears. This may make it easier for you to find your way around the input, if you are unfamiliar with the program.

Figure 3.1

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3.3 Process Data InputSome information on the Process tabbed pages must always be provided, but many of the items on the forms may be optional or alternatives. In Design Mode, MUSE needs sufficient information to be able to work out both inlet and required outlet conditions for each stream. In performance modes, only the inlet conditions are needed, but it is valuable also to supply estimated outlet conditions, since the program can then compare calculated outlet conditions with your expectations.

An example of alternative inputs might be the inlet conditions for a multi-component stream with two phase entry. These can be defined either by the inlet temperature, or by the inlet quality (vapour mass fraction). Other alternatives apply primarily in Design mode. Stream heat loads can either be supplied explicitly, or derived from the mass flowrate and inlet and outlet conditions. In Design mode, if you provide more data than necessary for a stream, MUSE will undertake consistency checks, and warn you of any discrepancies.

Discrepancies tend to arise when the sources of your process and property data are different. For example, if you get your properties data from NEL40, then there may be minor discrepancies from values for the

Figure 3.2

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same substance from other sources. This applies particularly to T-h-x (temperature-enthalpy-quality) properties data. Though the discrepancies are often equivalent to less than a degree in temperature, this may be comparable with stream to stream temperature differences, and can significantly affect predicted exchanger performance. Discrepancies may sometimes be circumvented by appropriate input. For example, for a stream which must condense completely, it may be best to specify the Outlet Quality (= 0.0) rather than the outlet temperature, which may not correspond exactly to the bubble point temperature from internal VLE and NEL40 calculations.

The best method of preventing discrepancies is to obtain process and properties data from the same source.

The Process Constraints and Process - Exchanger views only need input if you want to make special modifications to the calculations performed.

3.4 Geometry Data InputA significant number of input views relate to the geometric configuration of the exchanger and related equipment. Several are only required in special circumstances. The Thermosyphon view is only required for thermosyphon calculations. Distributor information is usually only needed in performance modes if you want distributor pressure losses to be calculated.

Layer pattern information must be supplied for Layer by Layer simulations (MULE), but is optional for Stream by Stream simulations (MUSE, etc.), and is not used in Design (PFIN) calculations.

The main difference in geometry input is between Design mode calculation, and the other modes. In the other modes, you should generally specify as much information as you have available to describe the exchanger, both its size and layout.

In Design mode, all the geometry information can be omitted. You can, however, supply partial geometry information, and the program will determine the remainder, consistent with the part you have supplied. For example, you could specify distributor types and orientations, leaving the program to determine their size and location. You could

Process data can also be imported, along with Properties data, from a PSF file. See Chapter 5 - Physical Properties.

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specify that certain fin types be used (plain, serrated etc.) or even that certain specific fins be used, for some or all of the streams.

3.5 Other Data InputProperties information must always be provided. This is described in Chapter 5 - Physical Properties.

Options input can normally be left set to default values, unless you want to modify the basis of the calculations, or suppress or switch on certain outputs. A special option in Design mode lets you ignore some or all of the geometry data input. This can be useful if you have an exchanger geometry defined, but want to explore the effects of a redesign to new process conditions

3.6 Input UnitsThe various parts of MUSE input can each be in one of five sets of units. The three basic ones are:

• SI (mm, °C, kJ/kg etc.)• British/US customary (inches, °F, BTU/lb etc.)• Metric (mm, °C, kCal/kg etc.)

There are then variants on the SI and Metric sets, in which absolute temperatures (K) are used instead of °C.

The units can be defined separately for the Geometry, Process and Fin data. Properties data can be defined separately for every individual stream.

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When a new file is created, it uses a single unit set for all data, which you can preset (the default setting is SI units). You can change the units via the Preferences option under the File menu. Alternatively, you can click on the Units field at the bottom of any input view, to get to the Preferences (Units) view. If you click on the Change Input Units Together checkbox, a single change sets the units of all components of the input to a consistent set. There is also an option to define the Default units for any New file you subsequently initiate.

When you change the units, you can decide whether or not any values you have already input should have their units converted to the new system. None of the pre-set input defaults have units, so you do not need to select the Convert option if you have not yet supplied any data. If you are using a default input file set up by your company, however, this may contain pre-set values which need converting, should you change the units.

The units of the program output will be deduced from the input units, though you can explicitly specify one of the various sets under the Options input.

Figure 3.3

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3-10

3.7 Using HelpThe Help Text in MUSE is the definitive source of information on Program Input, and on other aspects of the program. The Help Text is kept fully up to date with every release.

MUSE Help can be access at any point using the Help menu, or during input, you can press F1 to go directly to help on the item where the cursor currently points.

The Help Text provides information on data input, how to use the User Interface, the program output, and on errors and warnings. There is also general information on plate-fin heat exchangers, and the reasons for choosing particular design features.

Manuals, as supplied on the Software CD, give an overview of facilities and options, and full information on installation. For specific information on how to use the program facilities, use the Help text.

Figure 3.4


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You will also find information on MUSE capabilities, new features in the latest version, and contact points for user support.

3.8 Finding Input ItemsIf you need to specify information on some aspect of a MUSE case, and do not know where to find the relevant input view, then look up the item in the Help Text index using the Search facility. Try alternative descriptions if you cannot at first find what you expect.

When you have found the Help Text relevant to the particular input item, you will see that there is an input item identifier at the bottom of the Help view. This takes the form of a Line number and Item number in the input file. For example Inlet Temperature is 204.1, meaning item 1 one line 204 (there can be up to 6 items on a line). See Figure 3.5

To find a particular item, use the Find Item command under the View menu. When you type in a line number, you will be shown the list of items on that line. If you click on a particular item, you will either be taken to the input view where it occurs, or get an indication that it is only visible with some other Calculation Type setting. For Physical Properties input, you will just be taken to the main properties view, and may need to investigate subsidiary views yourself.

Some Error and Warning messages give line and item numbers. You can use the Find Item facility to identify the item more fully, and go to the input view where you can amend it.

Figure 3.5

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3.9 The Input FileWhen you provide MUSE input, it is used to generate an input file, which has a simple layout, and contains all the information you have provided. The file consists of a set of lines, each identified by a number occupying the first three characters, and followed by up to six items of data. When only some of the items on a line are present, asterisks (*) are used to indicate omitted items.

The data lines are gathered together into ‘blocks’, with a related set of line numbers. The following table lists the data type and their respective number ranges.

The first line in each block identifies the block, and the units of the input data. Some data blocks are repeated, for example there is a Process block, and at least one Properties block, for each stream.

A full listing of all possible input data items is given in the Help Text. The Help Text on individual items indicates the line number (and position on the line).

You can preview the Input data file, before it is run, under the View menu.

The User Interface normally holds an internal version of the input file, which is modified in response to changes you make in the input, and which is used when you ask for MUSE calculations to be Run. You have the option of saving this internal version of the input file, at any stage. You will be explicitly offered the option of saving it, for example on Exit from the program. If you do not save it, any initial version of your input file will be left unaltered.

Data Type Range

Program Options 001-099

Geometry 101-199

Process 201-299

Stream Properties 301-399

Component Properties 401-499

Fin 701-799

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Both the saved input file and the current internal version may contain data which is not relevant to the current calculation mode. No data are lost when you change the Calculation Mode.

3.10 Default Input Data FileYou can set up a default input data file, which is called up whenever you ask for a New input data file. This can contain any amount of pre-set input data. You can set up several such files, and have the option of selecting from among them when you run MUSE.

To set up such a default file, create a partial input data file in the usual way, and save it with an appropriate name. Then select Preferences, under the File menu, and select the Files tabbed page. Select your default file under the Default File option.

When you use such a default input file, you should be careful to do a Save As (under the File menu) to give an appropriate name to your new datafile, different from the name of your default file. To select a different default input data file, go the File menu, then Preferences and Files and make your selection. Then select File menu, then New, to initiate a new data file based on your new default.

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3.11 Input Errors and WarningsIf some mal-operation occurs when you are using the MUSE User Interface, or if you have provided data, which the Interface cannot interpret, then an information message view will appear. You will need to click on this, and take appropriate action before you can continue.

In some circumstances, some of these input warnings from the User Interface may appear to be repeated, as you make use of various different parts of the User Interface. This can be annoying, if the message relates to something you judge not to be relevant, or to something you plan to correct shortly. To prevent such warnings being displayed, select the File menu, then Preferences, and choose the General tabbed page. This lets you switch off various categories of warning messages from the Interface. See Figure 3.6.

It should be emphasised that this facility does not affect the more stringent checks performed when you Run the MUSE calculations. Error and Warning messages on running cannot be suppressed, and are always sent to a special message log, as well as being incorporated in the main lineprinter output. Chapter 4 - Output.

Figure 3.6

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4 Output

4-1

4.1 Overview...........................................................................................3

4.2 Output Views....................................................................................3

4.3 Output Files......................................................................................6

4.4 Error / Warning Message Log .........................................................8

4.5 Other Output ....................................................................................8


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4-2 Output

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4.1 OverviewRunning the MUSE calculations produces a number of different types of output. These can be viewed using the Output menu. When you stop working on an example, all the key output files remain in place, so you can view the output again, once you re-enter a case you have previously worked on.

This chapter gives an overview of the various outputs you can inspect, to help you find particular details you may be interested in. A more detailed description of all the outputs is available in the Help Text. See Output in the Help Text contents view.

4.2 Output ViewsYou can select from a set of output views, which contain the main results and information used to generate them.

• Results Summary.• Full Results.• Specified Duty.• Temperature Profiles.• Other Profiles.• Stream Details.• Thermosyphon Details.• Geometry - Overall.• Geometry - Streams.• Geometry - Distributors.• Exchanger Diagram.• Zig-zag Diagram.• Fin Geometry.• Fin Performance.• Alternative Designs.

Not all these outputs will be available. For example the Zig-zag is only produced if you have supplied a layer pattern input, Alternative Designs and Specified Duty are only shown in Design mode.

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There are also views where you can review, in tabular or graphical form, the physical property data used for each stream.

• Stream Properties.• T-h-x.• Stream Compositions.

Figure 4.1 shows the Results Summary view, which appears automatically at the end of a run, providing that the initial input checking has been successful.

If any warning or related messages have been produced, the Error/Message Log will be written on top of the Results Summary, so you should read this first, to check that there are no problems with the data used to generate the Results.

The contents of the Results Summary view depend on the calculation mode. In Design mode, this is geometric information on the best design found. In Simulation and Thermosyphon modes, the key results are process data, particularly the calculated outlet conditions, and for Thermosyphons, the flowrates.

The Results Summary view also records the number of error and warning messages, and most importantly, whether a design met various design constraints, or whether a simulation calculation converged.

Figure 4.1

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The Full Results output uses Internet Explorer, or your equivalent HTML viewer, and has Topic Headings to give you direct access to various parts of the results. The information shown is that in the Lineprinter output file, the most comprehensive output.

Figure 4.2

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4.3 Output FilesSome of the MUSE output is directed to files. The User Interface has a File View facility when you select these outputs under the Output menu. This applies to the following files.

• The Brief Output.• The Lineprinter Output.• The 80-column Output.• The Physical Properties Output.

The Lineprinter output is the most comprehensive set of results from MUSE. It is up to 132 characters wide. When you run the MUSE calculations from the User Interface, by default all the possible components of the Lineprinter output are produced. See Figure 4.3 for an example of this output.

Figure 4.3

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If you would like a more limited version, go to the Input menu, then Options, then Output Options to switch off any parts you do not want. Then re-run the program to generate the reduced file.

In some cases, there are also Output Options for various output tables to be extended, or repeated, but these are rarely of interest after a successful run.

The 80-column output is usually a more restricted version of the Lineprinter output, but after design calculations, it can contain a record of why various design choices were made. The Brief Output contains similar information to the Results Summary view.

For each of the above, you will see an option for printing out the file. You can also select part of a file - click and drag with the mouse - and then copy this to the clipboard. You can paste the clipboard contents into a text viewer/editor such as Notepad, or a word processor application, and then print the selected text from there.

One of the most useful features of the File View facility is a Find button. If you want more information on some aspect of an exchanger, for example, nozzles, vibration checks, clearances, baffles, just click on Find, then type the relevant word. Use Find Next if the first occurrence is not what you want. The Find is not case sensitive.

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4.4 Error / Warning Message LogWhen you run MUSE calculations, an extensive set of checks is performed on the data you have provided, and then further checks are made as the program continues its operation. These checks result in Error and Warning messages, which are collected together in a file and which also appear in the main record of the run, the Lineprinter output. The messages file will often be the first thing you see when you have run MUSE.

Errors are normally fatal, in that MUSE has identified some fundamental inconsistency in your data, or a lack of vital data, which means that it cannot continue further with its calculations.

Warnings occur if a value you have supplied is outside an expected range. For example an Inlet Temperature of 20K, which is not impossible, but unlikely. Warnings also occur if there is an inconsistency in your data, for example if you specify an inlet quality, which is different from that deduced from your inlet temperature. They also occur if your exchanger has some unexpected feature, such as triple banking in the layer pattern.

With any such warnings, you should check the input data, to confirm that it is as you intended, and amend it if necessary.

4.5 Other OutputWhen MUSE calculations are run, a file called the INTOUT file is produced. Its extension is .MUF and it contains all the data needed by the Output views. You can’t view this file from the Interface, or suppress its output.

After a Design calculation, you can go to the File menu, and click on Create Simulation Case, to be given the option of creating a MUSE input file for a Stream-by Stream Simulation. You will be asked for a name for the new file (by default based on the current name, but terminating in ‘s’) and have the option of selecting from the Alternative Designs table for the design of interest.

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5 Physical Properties

5-1

5.1 Overview...........................................................................................3

5.1.1 Properties Data Input ...............................................................45.1.2 Properties Used .......................................................................5

5.2 Properties Input ...............................................................................6

5.2.1 Setting a Data Source ..............................................................75.2.2 Get Properties ..........................................................................85.2.3 Rules for Direct Property Input .................................................9

5.3 Properties Data Input (Old Style) .................................................10

5.3.1 Input Directly ..........................................................................115.3.2 User Databank .......................................................................125.3.3 Single Component Stream from NEL40 .................................135.3.4 Components: Calculation of the Properties of a Mixture........13

5.4 Mixture Calculations (Old Style)...................................................14

5.5 Property Databanks.......................................................................17

5.6 Importing Properties & Process Data ..........................................19

5.6.1 Importing PSF Files................................................................19

5.7 Importing from HYSYS..................................................................21

5.8 Importing from a Properties Package..........................................23

5.9 Properties Output ..........................................................................24

5.10 Pressure Dependence.................................................................25


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5.1 OverviewA wide range of options are provided for providing the physical property data needed by this program. The user interface contains the HTFS COMThermo package, which contains data for over 1000 substances and a range of methods for determining vapour liquid equilibrium and mixture properties, and can be used to set up tables of property data for each stream.

The calculation engine contains the HTFS Physical Properties Package (PPP), which contains facilities for checking and interpolating the tables of property data. PPP also contains a small properties databank (NEL40), and methods for setting up property data tables as the calculation is run. This facility is useful for pure components, but for mixtures, use of the COMThermo package is more flexible.

Physical Properties Options are common to most HTFS programs. Examples in this section are based on a two stream heat exchanger, but the description applies also to HTFS programs where the number of streams is one (e.g. PIPE) or more than two (e.g. MUSE, FIHR).

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5.1.1 Properties Data Input There are two separate properties options under the Input menu:

Physical PropertiesThis lets you define a stream data source (components and methods) for the COMThermo databank, and then calculate a table of stream properties, which can be used as program input. It also lets you directly input property data tables, or modify those just calculated. Section 5.2 - Properties Input gives more details.

Physical Properties (Old Style)This gives you access to all the facilities which were in HTFS programs before the COMThermo databank was included. These include a second facility to directly input data tables, an option to import pre-set data from a databank at run time, and options to specify streams as single or multiple components from the NEL40 databank, or elsewhere. Section 5.3 - Properties Data Input (Old Style) gives more details.

Use of the newer style input, with the COMThermo package gives you more control. This lets you set up, check and if necessary revise properties data before running the program. Except for the special case when you provide direct input, the old style input only sets up the properties data tables data when the program is run.

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5.1.2 Properties UsedA set of Property Data comprises liquid properties, vapour properties and T-h-x data as appropriate. The data required are as follows:

Sets of 1-24 liquid data points, 1-24 vapour data points and 2-26 T-h-x points are used. Although separate sets of temperatures can in principle be used for each of the three subsets, when COMThermo is used the liquid and vapour temperatures are identical with the relevant ones for T-h-x.

Property Data

Liquid Temperature for liquid properties.

Liquid Density.

Liquid Specific Heat.

Liquid Viscosity.

Liquid Thermal Conductivity.

Surface Tension (for two-phase streams, optional).

Vapour Temperature for vapour properties.

Vapour Density.

Vapour Specific Heat.

Vapour Viscosity.

Vapour Thermal Conductivity.

T-h-x Data Temperature for T-h-x.

Specific Enthalpy [h].

Quality (vapour mass fraction) [x].

The properties need not relate explicitly to the process conditions in the equipment through which the system flows in any way. Data can be extrapolated as well as interpolated if necessary. It is, however, clearly sensible that the properties cover a broadly similar temperature range to that in the equipment, as major extrapolations are likely to be less accurate than interpolations.

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5.2 Properties InputProperties input using COMThermo normally involves:

• Setting up one or more data Sources.• Selecting a data source for each stream, then defining the

composition, temperatures and pressures for the properties data tables.

• Generating the property data tables, using Get Properties.

There are, however, four special data sources also provided:

• Direct Input - you type the numbers in yourself, copy them from a spreadsheet, or modify values already calculated by COMThermo.

• Not set here - meaning that one of the options under Physical Properties (old style) is used.

• Air or Water from NEL40 - a special setting under which air or water data are obtained from the NEL40 package at run time. No further settings for the stream are necessary.

The data source options, and calculated property tables are shown in the main Physical properties view.

Figure 5.1

See Section 5.2.1 - Setting a Data Source below.

See Section 5.3 - Properties Data Input (Old Style).

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5.2.1 Setting a Data SourceA Data Source defines the components in a stream, and the VLE and properties methods to be used. For a new case you will normally first click on Add to set up a new Data Source. You can then select a set of components from the master list, and add them to the list for the Data Source. A Search facility lets you find components in the list more easily, searching on either name or formula. Many components can be identified under a variety of synonyms. The form ‘*abc’ can be searched on, to find the string ‘abc’ preceded by other characters.

To define a data source, it is necessary to select property calculation methods, (the Property Package) as well as a set of components.

If you selected a Stream Type on the main properties input form, then a default Property Package will be selected. You can, however, change the package used, from a selection including Peng Robinson, SRK, NRTL, and variants on these. A brief description of each is given on screen.

Figure 5.2

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When both components and Property Package are set, the status bar at the bottom right turns green and reads Ready. You can then close this view, and on the main Properties input view, the new Data Source is available to be selected for any stream.

5.2.2 Get PropertiesGet Properties calculates properties at one or more pressure levels, using a set of temperature points. Using the Options facility lets you either define a temperature range and a number of points (from which the temperature points are determined automatically) or you can choose to specify the temperatures to be used explicitly. A temperature range and set of pressures are initialised from any process information you provide where possible.

Get Properties causes the spreadsheet of property data to be filled in automatically. If a stream is two phase within or near the range of defined temperatures, property data at the bubble and dew point are added in.

After properties have been calculated you can delete individual data points (data columns). You can explore the effect of changing the Property Package, used using Edit to revise the Data Source.

Once data has been generated, you can change the Data Source to Direct Input and edit individual property values, though this is not recommended.

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5.2.3 Rules for Direct Property InputData for Two Phase streams must always contain the dew and bubble points, if these points are within the range of data you supply. If they are outside the range of data provided, they will be estimated by extrapolation of T-h-x data. When data are provided, the highest Enthalpy point with Quality 0 is assumed to be the bubble point, and the lowest Enthalpy point with Quality 1 is assumed to be the dew point. Points need not be provided in any particular order, but are sorted into order of increasing enthalpy by the PPP when the calculation is Run.

The facility to supply the specific enthalpy and molecular weight of individual phases is available via the Show Phase Enthalpies and Molecular Weights checkbox, on the Options view. These are always optional inputs.

For Single Phase streams data need only be input for one phase. Specific enthalpy data are optional, as they can be found by integrating specific heats.

A set of Stream Properties data you specify should all relate to the same pressure, typically some mean pressure within the exchanger. You can supply a second set of stream data at a different pressure, permitting the program to allow for the pressure dependence of properties. Such dependence is sometimes significant, particularly for thermosyphons, or if there is a very close temperature approach between streams. For the PIPE program, pressure dependence is mandatory. See Section 5.10 - Pressure Dependence for more information.

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5.3 Properties Data Input (Old Style)

The Old Style physical properties input gives access to all the facilities that were present before HTFS programs included the COMThermo. Many of these facilities are associated with the fact that, unlike COMThermo options, with many old-style options you cannot see the properties until you have run the Calculation Engine.

The master view for old style input is shown in Figure 5.3. Using this, Physical Property information can be supplied in a number of ways.

You can:

• Input Stream Properties directly. You can either type them, or import them from a PSF file. See Section 5.6 - Importing Properties & Process Data.

• Identify data from a User Databank. The calculation engine will read data from this databank when it runs.

• For a single component stream, get the data directly from the NEL40 Databank supplied with the program.

• Tell the program the stream components and composition, and get it to calculate the properties.

Figure 5.3

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The Data Source item on the main Physical Properties input view allows you to select the various options. You should also set the Phase before supplying further data. A two-phase stream means that it can be either single phase or two phase, depending on the temperature.

If you have previously set up properties data using COMThermo, or the corresponding direct input (see Section 5.2 - Properties Input), you will see the Data Source set to Approximately. You can change the Data Source to Direct Input, and view and edit the properties data, but you will not be able to access it again using the main Properties Input.

5.3.1 Input DirectlyIf you set the Data Source to Input Directly, you can then click on the Property Table button to open a view, shown in Figure 5.4, where you can enter the properties.

If you have previously imported data from a PSF file, you will be able to see what you have imported.

Figure 5.4

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5-12 Properties Data Input (Old Style)

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You need to specify the properties indicated above for one or both phases. For Two-phase streams you also supply T-h-x data. Although you can supply data at up to 24 temperature points, this is potentially tedious if you are typing the data in, and you are most likely to use this method when you have only one or two data points available, for example at an exchanger inlet and outlet.

You can use different sets of temperatures for the Liquid, Two-phase (Enthalpy + Quality) and Vapour Properties. You should normally fill in the data tables from the left, without leaving gaps, though this is not strictly necessary.

For Single Phase streams, T-h-x data are not usually input, as they can be found by integrating specific heats. If, however, you do want to input Enthalpies for a Single Phase stream, click on Show T-h-x, and that T-h-x part of the input table will become available.

Heat Load data, rather than Specific Enthalpies, can be specified. If you supply a heat load, you must also specify the flowrate to which it relates.

You can supply Compressibilities instead of Vapour densities. Use the radio button to specify this option.

The rules for direct property input are as defined in Section 5.2.3 - Rules for Direct Property Input. The additional facilities available under Old Style input are as follows.

5.3.2 User DatabankIf you have previously set up data in a user databank, then when you set Data Source to User Databank, you will see a list of the datasets in this bank under the Code drop-down list. All you need to do is select which of them you want. See Section 5.5 - Property Databanks.

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5.3.3 Single Component Stream from NEL40HTFS programs come with a 40-component databank called NEL40. If your stream is a single component in this bank, all you have to do is identify the component in the Code drop-down list. For more information on NEL40, see Section 5.5 - Property Databanks.

5.3.4 Components: Calculation of the Properties of a Mixture

You must specify the Mixture Composition (mass or molar) and identify the Components. The program will calculate a full set of Stream Properties. The methods used are not as advanced as in Process Simulators or specialist properties software packages. See Section 5.4 - Mixture Calculations (Old Style) for more information.

In summary, when using Old Style input:

• If the stream is a pure Component: use the NEL40 databank if possible.

• If someone has prepared the properties in electronic form (PSF File or User Databank), use that.

• If the properties have been calculated, input the data.• Failing any of these, if you know the Composition, get the

program to calculate the Properties of the mixture.

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5.4 Mixture Calculations (Old Style)Mixture calculations determine the properties of a stream given its components and composition. If the stream is two phase, then VLE (vapour liquid equilibrium) calculations must be performed to determine the bubble and dew point temperatures and the compositions of the individual phases at intermediate temperatures. Given the phase compositions, mixing rules can be applied to determine each stream property from the corresponding component properties.

With the Old Style input, mixture calculations are performed when the calculation engines run.

From the main Properties input view, set the Data Source for the stream concerned to Components, and then click on the Specify Mixture button. The Specify Mixture view, Figure 5.7, lets you define the temperature range over which mixture properties should be calculated, or amend the calculation methods or results.

Figure 5.5

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For a Two Phase stream, you can select the method to be used for VLE calculations, SRK or Ideal. There is also a facility called T-h-x Override, whereby you can control the results of the VLE calculations. At the basic level, you can simply specify all the temperatures at which you want the calculations performed. You can also request that any calculated bubble and dew points (temperatures and optionally enthalpies), be modified to conform to pre-set values. More information on all these options is given in the Help Text, accessible by using the Help button at the bottom of the page.

All the inputs on the Specify Mixture view are optional, but you must use it to access the Define Components and Define Compositions views, via the appropriate buttons.

From the Define Components view, Figure 5.6, you can identify each component, and where data for it is to be obtained. Click on Add Component until the correct number are identified. The number should be the total number of components in all such mixtures. If the same component occurs in more than one stream, it need only be counted once. There is no need to include those components which only occur in pure component streams.

Figure 5.6

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If your components are in NEL40, select this as the component Data Source, and identify the component in the Code drop-down list. If you have the DIPPR databank, you can select from this similarly.

You can also select from a User Databank of component data (if you have set one up previously), or you can choose to Input Directly. Selecting Input Directly as the Data Source enables the Property Table button. If clicked the view for direct input of component properties is opened. The properties needed for each component are similar to those required for a stream, but the Liquid Properties are saturation line values, and the Vapour Properties are ideal gas values, that is values in the low pressure limit.

Each component can be identified as Liquid only, Vapour only, or Two Phase. It is normally safe to leave the components set to Two Phase, but if a stream is Single Phase, you can obviate the need for VLE calculations by specifying all the components to be Single Phase as well. For a Two Phase stream you can specify some of the components (incondensibles) as Vapour-only, but not as Liquid-only. With the SRK method, (see later) it is best to leave all components set as Two Phase.

When you have defined components, click on the Specify Composition button on the Define Components view or back on the Specify Mixture view. On the Compositions view, see Figure 5.7, enter the compositions, as fractions, flows or percentages. Identify whether you are supplying Mass or Molar values.

Figure 5.7

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5.5 Property DatabanksThe program contains two databanks for physical properties COMThermo and NEL40.

The COMThermo databank contains data for over 1000 substances, and is accessible via the User Interface to set up tables of Physical Properties data as part of the program input. To see the list of substances in COMThermo, go to the Physical Properties input view, and click on Add in the Data Source box.

The NEL40 databank contains data for 40 commonly used compounds, and is part of the calculation engine. The input file used by the calculation engine is given the stream components and composition, but properties are not generated until the calculation engine is run. To see the list of substances in NEL40, go to the Physical Properties (old style) input view, set the Data Source to single component from NEL40 and look in the Code drop-down list.

The COMThermo databank includes software for performing vapour liquid equilibrium (VLE) and mixture calculations, using a variety of methods. This includes interaction parameters appropriate to each of the methods offered. In principle the COMThermo package can be linked to a variety of Properties databanks, but as supplied with HTFS programs, only the Hyprotech databank is available.

The NEL40 databank does not in itself contain any methods for VLE calculations, though it does do mixture calculations when phase compositions are known. A VLE facility for use with NEL40 is provided within the HTFS Physical Properties Package (PPP), but it is not as extensive as the facilities offered with COMThermo.

Properties from COMThermo will depend on the equation of state used in the properties method selected, even for pure components. Differences in properties of a few percent may be found between COMThermo and NEL40 in comparisons for compounds which are in both. This may reflect uncertainties in known values of properties, or differences in the equations of state used.

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For viscosities and thermal conductivities NEL40 can be more accurate for pure components. For two phase mixtures this advantage may be offset with the superior phase composition accuracy achievable with COMThermo.

One case where NEL40 may be more reliable than COMThermo is for water, since NEL40 contains an accurate water/steam package. Differences are only likely to be significant at high pressures. The HTFS interface to COMThermo therefore contains a facility for Water from NEL40, which may be used instead of setting a Data Source for water from COMThermo itself.

There is a similar facility for air, which appears in NEL40, but is not conveniently available in COMThermo.

The DIPPR databank (which you may have purchased separately) contains the properties of over 1000 substances. It does not contain mixing rules. It can be used for components, which are liquids or vapours. It contains data on some solids as well, but the available HTFS mixing rules cannot predict the properties of solutions of these solids.

You can set up a User Databank with the properties of any components, which you may frequently need to access, but which are not in NEL40. The structure of the databank is very similar to that of the Component blocks of an Input file. The Help Text gives full details.

You can also set up a User Databank containing the properties of streams. The User Interface lets you add the properties of any stream to such a databank. Use the Output to Databank checkbox on the Properties Output Options view (via the main Properties input view). You are advised to run the program first without this checkbox set, to ensure that the stream properties produced are acceptable. Then re-run the program with the checkbox set. Make sure that the stream has a meaningful name you will recognise in future. When you have put one or more sets of stream data in the userbank, on subsequent runs you can select User Databank as the Data Source on the main Properties input view using the Code drop-down list, select from among the previously established data.

The User Databanks of stream and component data are files. Specify their location by selecting Preferences, under the File menu on the Files tab, specify the appropriate tab.

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5.6 Importing Properties & Process Data

There are three ways you can import properties and process data into the case you are running:

• Import a PSF file (set up by a Process Simulator).• Import from HYSYS (if this is available).• Generate and Import a PSF setup using your company’s own

physical properties software while you are using this HTFS program (if an interface has been written).

5.6.1 Importing PSF FilesPSF files are files containing process and/or property information for one or more streams. They can be generated by Process Simulators, and have the file extension .PSF. It is normally best to import PSF data before entering any other process or properties data.

The data from a PSF file go directly into your input file. The import facility can be access via either the Input or the File menus. The first step is to identify the particular PSF file from which you want to import data. You will then be taken to the Import PSF Data view.

Figure 5.8

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If the PSF file has been prepared specifically for the exchanger you are interested in, you may simply be able to click on OK. You can, however, use the Import PSF Data view to direct only part of the information from a PSF file into the input file.

You can:

• View the stream Names, Number and Inlet/Outlet Temperatures in the file.

• Import data for some streams but not others.• Import Process data, or only Property data, or both.• Import data at any selection of pressure levels (PSF files often

contain properties data at the Inlet, Outlet and Mean Pressures in the exchanger).

• Change the stream Number when you import data.

The Import facility shows you the stream names and inlet/outlet temperatures in the PSF file. The temperature units of the display can be reset by clicking on the Units field in the top right corner.

The Import To column shows the Stream Number to which data will be imported. This is initially set to the Stream Number from the PSF file, but you can reset it to a different number if you want, or if it is necessary for the program. You can set it to ignore, enabling you to import data for only one stream (or fewer than all the streams for multi-stream exchangers). You cannot set two stream numbers to be the same.

The Use Properties column lets you select which pressure levels in a PSF file to use for Properties data. If there are data for three pressure levels, you can select two (upper and lower), one (middle level), or you can opt for a special selection.

If you want to import the properties data but not the process data, click on Separate Process and Properties, and you will see that the Import To column is divided in two. The left part relates to Process data, the right part to Properties. You can set either one to Ignore, so that only the other is imported.

The PSF file itself is largely in basic SI units, and when imported to the input file the data can be viewed in whatever units have been set for process and property data.

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Normally, when you import Process and/or Properties data for a stream, any data you have already entered for that stream is overwritten. You can however, cause the Properties data to be added to any data currently present, provided that it relates to a different pressure. Use the Merge with Existing Data checkbox.

Click on OK to transfer the Process/Properties data selected from the PSF file to the input file. Select Process or Properties (old style) under the Input menu to see what has been imported.

5.7 Importing from HYSYSIf you can run the HYSYS Process simulator on your computer, you can select an exchanger in a HYSYS case, and import the data directly into your HTFS program. The exchanger can also be a HYSYS LNG block, when appropriate.

Select Import from HYSYS under either the Input or File menu and you will be presented with a view to select an existing HYSYS case.

HYSYS will then be started, load the chosen case and the import interface will generate a list of all heat exchangers within that case. You can select an exchanger, and for each stream in that exchanger, the temperatures and pressures will be shown.

Though this facility is available within most HTFS programs, it is clearly only directly useful when the HTFS program is for equipment corresponding to a HYSYS exchanger.

PSF file layout and contents are defined in the Help Text.

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You can revise the temperatures and pressures. If you then select OK, HYSYS will perform the flashes needed to generate the data for a PSF file. You can then review and select from the data as for a normal PSF import.

Figure 5.9

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5.8 Importing from a Properties Package

There is an option for importing properties and process data by accessing your company’s own physical properties software while you are running an HTFS program. If this facility has been made available, the Import from Other Package command under the File menu will be active.

When you select this option, you are asked to provide input on stream inlet/outlet conditions, stream compositions and components, and possibly also on the methods to be used, and the temperature/pressure range of data to be set up. When you have supplied the necessary information, a PSF file will be generated, and you will be taken to the PSF import facility, where you can opt to import the data you have created into the input file of your HTFS program.

To set up a facility to import data from your company’s own physical properties software you must write an interface to this property package and register it so that your HTFS program will recognise it. You

must create an executable with project name Properties Package and a class name PSFFileGen.

The Help Text provides detailed information on the structure of the interface, and on the contents of the PSF file it must generate.

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5.9 Properties OutputThe Physical Properties Package can be used to generate two types of output. The first is in file format, the second in Windows format. All the output relates to tables of property values which are set up at the beginning of the program, and subsequently interpolated during heat transfer and pressure drop calculations.

The first type of output can be either held in a separate file, or directed to the main Lineprinter file. The separate file is the default. If you want it in the main Lineprinter output, or turned off, select this on the Output Options view, using the Options command under the Input menu.

Putting the Physical Properties output in the Lineprinter file means that you will be able to see it in the Full Results output, in programs with this facility.

The contents of the file format Physical Properties output can be set via the Properties Output Options view, accessible from the main Physical Properties (old style) input view. The output is in four parts:

• Input data for each stream/pressure level.• Table of properties for each stream/pressure level.• Stream/phase compositions for each stream/pressure level.• Table of properties for each component.

The third and fourth items are only relevant where mixture calculations have been performed. Only the second item is produced by default. See the Help Text for more information on the contents of the various parts of the output. A further option, accessible via Output, lets you output stream data to a stream properties databank ().

The second type of Physical Properties Package output, in Windows format, is not yet available in all HTFS programs. When it is available, you will see Stream Properties and T-h-x as Output menu items.

Stream Properties gives the properties of each phase in both tabular and graphical forms. The graphical form has a range of options. The default is to plot all properties relative to their maximum value, so you can immediately see if any property does not have a smooth variation. This can be very useful for identifying typographical errors if you have input the properties data yourself.

For more information regarding properties databank, refer to Section 5.5 - Property Databanks.

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T-h-x gives tabular or graphical presentations of the temperature, specific enthalpy and quality (vapour mass fraction) for each stream. The graphical version also shows a set of interpolated points, so that you can see the way properties data (input or calculated) is interpreted when it is interpolated during heat transfer calculations.

5.10 Pressure DependenceThe effect of pressure on properties is most likely to be significant in the changes it produces in vapour density, and in dew and bubble points, which may be important when there is a close temperature approach between streams. Allowing for pressure dependence is optional in most HTFS programs (it is mandatory in PIPE).

The normal way of ensuring pressure dependence is allowed for is to provide properties data at two pressure levels.

If you are using the program to calculate stream properties for a mixture of known composition, then it is very simple to define two pressure levels in the properties input. This normally happens by default when you are using COMThermo. If you are using Physical Properties (old style) input you will need to use the Add Pressure key. You must then specify the pressure for each level (if you only have one level, you can use a default pressure). You should select the pressures to span the range expected in the exchanger.

You can specify data at more than two pressure levels for a stream if you want. This is unlikely to be necessary if the stream pressure change is less than 30% of the (absolute) inlet pressure.

When data are available at only one pressure, the PPP can, if specified, estimate an allowance for pressure dependence, using the Clausius Clapeyron equation. This will be less accurate for wide boiling range mixtures. To allow for pressure dependence in such cases, use the checkbox on the main Physical Properties (old style) input view.

If you are supplying pre-calculated properties data at two pressures, you should use specific enthalpies, not heat loads, and ensure that the enthalpies have a consistent zero.

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If the properties data you have available are not isobaric data, but contain some inherent pressure dependence, for example from inlet to outlet, then in many cases you can use this data with relatively minor inaccuracies. You should not select Pressure Dependence in such cases. Data with an inherent pressure dependence are, however, not acceptable for two-phase streams that are pure substances, or azeotropes, or for which the change in saturation temperature due to pressure changes is comparable with, or larger than, the isobaric boiling range.

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6 Other Facilities

6-1

6.1 Overview...........................................................................................3

6.2 User Fin Databank ...........................................................................3

6.3 Project File Structure ......................................................................4


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6.1 OverviewThis chapter introduces you to some of the other facilities, which are available with MUSE.

6.2 User Fin DatabankYou can set up a databank containing fin geometry and performance information for any fins where you have this information, both distributor fins and main fins. Each fin is identified by a number in the range 100 to 9999. To identify that a particular fin is used in some part of an exchanger it is simply necessary to specify its number at the appropriate place in the input data, as an alternative to lower numbered fins (1 upwards) for which data must be provided in the main input.

The Fin Databank is a text file. Its layout is essentially the same as that of the fin data within the input data file. The Help Text gives more information. When you create a fin databank file, you should name it FINDAT, without any file extension, and place it in the program directory

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6.3 Project File StructureA MUSE project is initially set up as an input file. The various files are outlined in the following table.

When you run calculations from the User Interface, all these output files are set up by default. You can switch off most of the other files if required. Click on the Input menu, select Options, then the Output Options tabbed page, and you will see drop-down lists controlling these outputs.

You cannot switch off the .MUF file, which is needed for the main output views, or the Error/Warning Log.

The file extension .MUA is used for an edited copy of the input data. This is the version stored internally by the User Interface, which you can run without saving. If you save the file, the main input, name.MUI is updated. The .MUA file is not preserved when MUSE is shut down.

File Name Description

name.MUI MUSE input file, where name is the name of the project. After you have run the project, some or all of the following files will also have been set up.

name.MUF The so-called INTOUT file, containing all the main input and results. The format of this file is described in a document on the Program CD. All the MUSE result Windows, which you can view under Output, take data from this file. You can use this file as a source of information for in-house software.

name.MUL The Lineprinter output file.

name.MUT The 80-column output file.

name.MUE The Error/Warning Messages file.

name.MUV The Brief Summary output file.

name.MUP The Physical Properties output file.

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7 Examples

w.cadfamily.com EMa document is for study

7.1 Overview...........................................................................................3

7.2 Case 1 Design ..................................................................................4

7.2.1 Start Up ....................................................................................57.2.2 Process Data............................................................................57.2.3 Stream Definition......................................................................67.2.4 Running the Design..................................................................87.2.5 Results from Design (PFIN) .....................................................9

7.3 Case 1 Simulation..........................................................................11

7.3.1 Creating a Simulation Case....................................................117.3.2 Input Geometry For Simulation ..............................................127.3.3 The Input Exchanger Diagram ...............................................137.3.4 Other Input For Simulation .....................................................137.3.5 Results from a MUSE Simulation ...........................................14

7.4 Case 1, Layer by Layer Calculations (MULE) ..............................17

7.4.1 Layer Patterns ........................................................................177.4.2 Running the Calculation Engines ...........................................197.4.3 Double Banking ......................................................................197.4.4 Results from MULE Layer by Layer Calculations ...................20

7.5 The Zig-zag.....................................................................................22

7.5.1 What is a Zig-zag? .................................................................227.5.2 Zig-zag Options ......................................................................237.5.3 Zig-zag Assessments .............................................................23

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il:[email protected],if tort to your rights,please inform us,we will delete

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7.1 OverviewThe following examples will guide you through the various ways in which MUSE can help you with assessing or designing plate fin heat exchangers. The examples concentrate on a relatively simple case for a notional cryogenic duty with three streams. Plate-fin exchangers, of course, very often have a much larger number of streams, but once you understand what is needed for each stream, it is no more difficult to supply it for many streams. You are shown first how to produce a ‘first shot’ design, then how to undertake a basic MUSE Simulation, and finally how to perform a more detailed layer by layer calculation.

The other simplification in the examples is that stream physical property data are obtained using the internal NEL40 databank. In reality it is often critically important to get accurate property information for cryogenic processes using plate-fin exchangers, so it is best to generate these properties outside of MUSE, and set up tables of property data in the input file, either directly, or by importing via a PSF File. Because of the large amounts of data involved, none of the examples use these methods. More information on importing data is given in the Help Text.

All the examples relate to brazed aluminium exchangers. MUSE can simulate plate-fin type exchangers made of stainless steel or other materials, but the design facility should not be used for such exchangers unless you are aware of the very different manufacturing constraints, which apply.

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7.2 Case 1 DesignThe first example is a simple gas-gas exchanger in which an air stream is cooled in succession by two cold nitrogen streams. It is required to design a plate fin exchanger for this duty. The stream conditions are as follows:

Start up MUSE (see introduction). Select the New button on the Welcome view, and the Start up view will appear.

Stream Air (1) Nitrogen (2) Nitrogen (3)

Total mass flow kg/h 15000 12000

Inlet temperature K 300 120 210

Outlet temperature K 125 200 290

Inlet pressure bar 10 3 2.5

Allowed pressure drop bar 0.5 0.3 0.3

Figure 7.1

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7.2.1 Start Up1. Set the Calculation Mode to Design-PFIN, and set the Number of

Streams to 3. Leave the fins set to 0, since you do not need to specify any input about fins in simple design cases.

2. Click on the Basic Mode checkbox, since this is a simple example, with no need for any less common inputs.

3. Fill in a Job Title, such as Simple Example Number One, and an Equipment Item Number such as Ex1, then click on OK.

7.2.2 Process DataThe Process Data Input view will appear. The first thing to observe is the units, which are set to SI/deg C. The information supplied has temperatures in Kelvin, so the units must be changed.

1. Click on the Units field, and you will see a form where the units for all the various sections of input can be specified. (This view can also be access via Preferences under the File menu).

2. Change the Process & Properties data units to SI/deg. K. None of the other input sections are relevant to this example, so their units need not be changed.

When you change units, you are offered the option of converting the existing inputs. Since no data have yet been provided, answering either Yes or No is acceptable.

3. Clicking on OK on the units takes you back to the Process data view.

4. Enter the information for the streams 1 to 3, using the values in the table at the beginning of the example.

Since plate-fin exchangers normally handle clean fluids, fouling resistances are assumed to be zero.

5. Click on OK to save the Process data.

The flow of air has not been specified, but this is not a problem, since it will be evaluated via a heat balance when the program is run. Similarly, no heat loads need be input, since they will be evaluated from flowrates and input and outlet temperatures.

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7.2.3 Stream DefinitionHaving specified the process conditions, it is next necessary to define the streams. This can be done in various ways, using either the NEL40 or the COMThermo databanks. Using just NEL40 is simplest in this instance, so is recommended, but the more usual procedure using COMThermo is also described.

The method using NEL40 is as follows:

1. Click on Physical Properties (old style), under the Input menu. You will see tabbed pages for three streams. Go through these in turn, and set the Data Source to Single Component from NEL40, and from the Code drop-down list, select Air for stream 1, and Nitrogen for streams 2 and 3.

2. You can, if required, change the stream names from Stream 1, Stream 2 and Stream 3 to something more descriptive.

You will see that there is a Phase drop-down list, which is by default set to Two-phase. You could set this to Single Phase Vapour, but it is not necessary, as the program knows that the streams concerned are vapours over the temperature range of interest.

3. Click on OK to save the Properties data

The other method of setting properties uses the COMhermo databank.

1. Under the Input menu, click on Physical Properties.

2. For stream 1 click on Air<NEL40> as the Stream Data Source.

3. Click on the tab for stream 2. Set the stream name to N2/stream 2, and the Stream Type to Air/Other Gas.

4. Click on Add to set a new data source and you will be taken to the Data Source view.

5. You will see a list of components. Begin typing Nitrogen in the Match field and you will see the list of components reduce. When Nitrogen is visible, click on it then click Add, to move the list of components on the right side of the view.

If the air was condensing, it would be unwise to select it as a NEL40 component, since it is treated as an equivalent pure substance, with no boiling range.

With item 2 - air and water are treated as special substances, requiring only this simple setting.

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6. You should see the status bar at the lower right of the view turn green and display Ready. If you click on the Property Package tab, you will see that a default has been set appropriate to the stream type you entered. Close the Data Source view.

7. On the main Properties view, click on the data source Gas 1 that you have just set. You will see that a composition of 1.0 is set automatically, as this is a single component view.

8. Click on Get Properties. Pressure Level and Temperature Range information is required before properties can be calculated. These should have been set by default. You could set/revise them if required. They should cover the range relevant to the stream, but need not match inlet or outlet conditions exactly. You should see the Properties Table filled with data for stream 2. You should see that two pressure levels have been set up by default. Clicking on either one shows the data at that level.

9. Click on the table for stream 3. Select the same data source as for stream 2 (both streams are nitrogen). Check the pressure levels and temperature range (click on Options) are correct for stream 3. Revise them if necessary. Click on Get Properties to generate tables of property data as before.

10. Close the Physical Properties view, retaining the property data you have generated.

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7.2.4 Running the DesignSufficient information has now been provided for a design to be done.

1. Click on the Run icon, or under the Run menu, click on either Calculate All or Run PFIN.

You will be asked to save the changes to the input file, and will need to give a filename, for example EXCH1. The file extension .MUI will be added automatically to show that it is a MUSE input file.

As the program runs, you will see a Status view, which initially says Preparing Input File, and then records the various stages of the calculation. When the calculation is complete, the Results view appears. If any problems or unusual features had been encountered, a messages file would be displayed as well.

Figure 7.2

Run icon

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7.2.5 Results from Design (PFIN)The Results view gives overall information about the exchanger that has been designed. You should also see the Number of Errors and Number of Warnings both set to zero, indicating that there were no problems with the input provided. The Design OK message indicates that all the design constraints were met.

For a slightly more detailed record of the exchanger that has been designed, select Brief Output under the Output menu. This summarises the process conditions (including a value for the air stream flowrate that has now been evaluated) and also gives details of the internal structure of the exchanger for example:

• The number of layers for each stream.• The fins used.• The type and size of inlet and outlet distributors.

There is also a record of how much of the available pressure drop has been used for each stream, and how much margin there is on the design. A target overall design margin of 1.1 (that is ten percent oversurface) is used by default.

To see what the exchanger looks like, click on Output menu and select Exchanger Diagram. Alternatively, you can click on the View Geometry icon.

View Geometry icon

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You will see that in this simple example, stream 1 is cooled by stream 2 in the top part of the exchanger, and by stream 3 in the bottom part. In the middle of the exchanger is a distributor region, where stream 3 exits, and stream 2 enters.

When you view the diagram, an additional menu, Diagram, becomes available. Under this, you can click on Stream 1 Distributor, etc, to see the internal structure of the distributors. Although the exchanger design has been done in considerable detail, you should remember that it is only a ‘First Shot’ design, and has used typical fins and fin performance data, and simplified assumptions about mechanical design constraints. A plate-fin exchanger manufacturer would be able to use proprietary fins and fin performance data, and could well propose a slightly different design. For more complex designs, with large numbers of streams, the differences could well be more significant.

Figure 7.3

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7.3 Case 1 Simulation

7.3.1 Creating a Simulation CaseHaving performed a design for example 1, it is of interest to see what performance is predicted when the performance of the exchanger is simulated. Simplifying assumptions are made during the design process, and it is of interest to check these out with a somewhat more rigorous simulation calculations. Differences would not be expected to be large, but for plate-fin exchangers small differences in performance can be crucial, so checking out a design via Simulation is always advisable.

After a design has been performed, it is straightforward to generate a Simulation case.

1. Select Create Simulation Case under the File menu.

You will first be required to provide a filename for the Simulation case, and by default will be offered your current filename (or a contraction of it) with an S on the end.

2. Click on Save, and you will be shown the table of Alternative Designs to select from. In this case, and very often, there is only one design shown, so click on OK, and your current case will be closed, and the Simulation Case opened.

3. Go to the Start up view, under the Input menu, and you will see that the Calculation Type is set to Simulation-MUSE. Check also that the Basic Mode checkbox is not checked, unset it if it is. This will ensure that you can see all the possible input items.

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7.3.2 Input Geometry For SimulationExamine the Geometry Input views for the simulation case. You will see that values have been filled in from the results of the design calculation. If you wanted to simulate an existing exchanger, these are the values you would need to supply.

Look particularly at the Stream Geometry and Distributors and Nozzles views. On Stream Geometry you will see that the Number of Layers, Main Fin Number, Length of Main Fin and Distance to Main Fin are set for each stream. These are fundamental items, which must always be set. Check also that it is specified that Stream 3 is in the Same Layers as Stream 2.

Under Distributors and Nozzles you will see that dimensions, distributor types and fins used are specified for the inlet and outlet distributor for each stream. If you are unsure what any of the input items mean, position your cursor on that item and press F1. This will take you to the Help Text for that item, from which you can where necessary find a diagram, for example for Distributor Type.

If you are supplying input for an existing exchanger, information on distributors and nozzles is optional. MUSE will simulate the thermal performance of an exchanger, without simulating the distributors. You should, however, remember that the reported pressure drop will not

Figure 7.4

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include the distributor and nozzle losses if the relevant input information is not provided.

7.3.3 The Input Exchanger DiagramWhen you open a Simulation Case, you will usually see an Exchanger Geometry Preview (Input) Diagram, and will observe that this is based on the data you have provided. MUSE has two diagrams, one derived from the Input data, and one derived from the calculated results. When looking at a Simulation case derived from a previous Design calculation, the Input diagram should be essentially the same as the Results diagram from the previous design. When you are supplying geometric data from an existing exchanger, the Input diagram is a very valuable check that the information you have specified is correct, particularly with relation to the location of streams along the exchanger length, and the layout of headers around the exchanger.

7.3.4 Other Input For SimulationYou will observe that even when input has been supplied from the results of a previous design calculation, many input items are blank because they relate to optional information. The Layer Pattern input, for example, is optional in MUSE simulation, and is not predicted by the Design. The Layer Pattern, or Stacking Pattern, defines the sequence in which the layers of the various types are arranged. The Layer Definitions input defines each Layer Type in terms of the sequence of streams it contains.

The assumption is made in both the Design, and in this form of Simulation, that there is a ‘good’ layer pattern, with a high degree of intermingling of hot and cold layers.

Finally, look at the Fins data under the Input menu. You will see data for just two fins are required for this simple example, a serrated fin for the heat transfer region and a low frequency perforated fin for the distributor region. If you are simulating an existing exchanger, Fin Geometry information must be supplied. Fin Performance information is optional, since the MUSE calculation engines contain correlations, which are used by default.

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7.3.5 Results from a MUSE SimulationIt is always good practice to look through the completed input data. You can then click on the Run icon to run the MUSE Simulation. You will see the status view appear, to be replaced by the Results Summary view and/or Messages Viewer once the calculation is complete. The main results for a Simulation are the calculated heat loads, outlet temperatures and pressure changes, but the results view also records other key process data supplied, such as flowrates, inlet temperatures, qualities and fouling resistances, to give an overall picture of exchanger performance.

Figure 7.5

Run icon

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If you select Brief Output, under the Output menu, you will find similar information, but accompanied by a record, in parentheses (…), of any initial estimates you provided for outlet conditions, heat loads or pressure changes. From this, you can rapidly compare whether key aspects of the exchanger performance are as required.

For a more comprehensive overview of the specified input data and calculated results, click on Full Results.

Figure 7.6

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When you run a Simulation case generated after a Design calculation, you would expect the calculated results to be in good agreement with the estimated values. In practice, there will normally be small discrepancies because:

• The Design calculation uses a design margin (defaulted to 1.1), while the simulation calculation ignores this, so calculated heat loads will in general be slightly bigger than estimates based on design requirements.

• In a multi-stream exchanger, even if the total overall hot-to-cold stream heat load were correct, individual streams may be responsible for slightly more or slightly less of this heat load than expected.

• In a Design calculation, not all of the available pressure drop for a stream may be used. This applies particularly for streams present in only a small number of layers.

• Pressure changes in Simulation include gravitational effects, while for design purposes only frictional changes are normally considered.


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7.4 Case 1, Layer by Layer Calculations (MULE)

7.4.1 Layer PatternsThe basic Simulation-MUSE option assumes that there is a good layer pattern, so that all the layers of any stream behave in the same way. In other words the simulation is done on a stream-by-stream basis. However, it is sometimes important to check how good this assumption is. To do this the layer pattern must be input, and the Layer by Layer calculation engine, MULE, must be run.

Deciding on a layer pattern is normally the province of the exchanger manufacturer, and selecting the best layout from a very wide range of possible options is not easy, particularly for complex exchangers with large numbers of streams.

The guiding principle for determining layer patterns is that the various types of hot and cold layer should be distributed as evenly as possible throughout the pattern, so that there is no local excess of either hot duty or cold duty in any part of the pattern. One way of doing this is to gather sets of layers together into groups, each of which either have a balanced set of hot and cold layers, or are close to balance. These groups can then be uniformly distributed across the exchanger. Having symmetry about the centre of the pattern is also desirable, since this will minimise any thermal stresses across the exchanger.

In this example, there are 18 hot layers, containing stream 1 and 31 cold layers, containing stream 2 at one end, and stream 3 at the other. There are thus two types of layer, which can be desingated A (hot) and B (cold). Layer Type A will be identified as containing stream 1 and Layer Type B as containing streams 2 and 3.

Since there are significantly more cold layers than hot, it is clear that there must be some pairs of adjacent cold layers in the layer pattern. Looking at the numbers of layers, it can be seen that they could be divided into six groups, each with three hot layers and five cold layers.

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7-18 Case 1, Layer by Layer Calculations

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This would leave one cold layer over, which could go in the middle of the pattern. The groups of three plus five could be BABBABBA.

When specifying the Layer Pattern input, there is a simplified way of defining repeated groups, by putting the group in parentheses, and including an oblique followed by a number indicating how many times the pattern occurs. The layer pattern could then be specified as

(BABABBA/3) B M.

where the M indicted there is mirror symmetry in the pattern, about a single central layer 1.

It would also have been possible to designate the pattern as

BABBABBA BABBABBA BABBABBA B M

or

BABBABBA BABBABBA BABBABBA B ABBABBAB ABBABBAB ABBABBAB.

Specifying the full pattern, rather than identifying the symmetry will approximately double the number of calculations performed by MULE, but should not affect the results. Spaces may be left at any point. They are ignored by the program input, but can be useful in checking that your input is correct.

The Layer Pattern and Layer Types are the only additional inputs required by MULE. For MUSE they are optional. In either case, if you supply both the number of layers per stream, and the layer pattern, a check for consistency will be performed when the program is run, and a warning message produced if necessary.

1. Enter the Layer Pattern in either of the first two forms.

2. Go to Layer Types and set Type A with stream 1 and Type B with streams 2 and 3.

3. Go to the Start up view under the Input menu, and change the Calculation type to Layer-by-layer - MULE.

4. Click on the Run icon.

Run icon

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7.4.2 Running the Calculation EnginesYou may observe that changing the Calculation Type changes (slightly) the data items which you see. Any data items entered with a previous setting remain present. It also changes the default calculation engine, which is initiated by the Run icon. If you go to the Run menu, you will see that in addition to Calculate All (default calculation item), you have the ability to Run any of the Calculation Engines (MUSE, MULE, PFIN etc) at any time. If it is not the default engine, you will be asked to confirm your choice. Of course, a Run will only be successful if you have provided appropriate input data.

When MULE runs, you will see the Status view followed by a Results view, in a very similar way to the MUSE Simulation, but you will notice two differences:

• The MULE run takes longer because it is doing more calculations.

• Two warning messages about double banking are produced.

7.4.3 Double BankingMULE (layer-by-layer) calculations do not need information on double banking fractions, since explicit calculations are performed for every layer. You are therefore reminded by a Warning message that any values you have input will be ignored.

Double Banking fraction is the fraction of stream 2 layer that occurs in double banked pairs. You will see in the example that there are 12 pairs (24 layers), five layers which have a 1 layer on either side, and 2 layers at the extremes of the pattern, which are counted as double banked since they are adjacent to only one hot stream. 26 of the 31 layers are thus effectively double banked.

The Double Banking fraction is important in defining the effective amount of heat transfer area for each stream. When you run a MUSE Simulation without a layer pattern supplied, it is important to know the double banking fraction, though in simple cases, it can be omitted from the input and MUSE will estimate it. You may have noticed that the MUSE input generated by Create Simulation Case, after you have done a design, contains double banking fractions, as used in the design. If you

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7-20 Case 1, Layer by Layer Calculations

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were to Run MUSE now you have supplied a layer pattern (try it later) you might find warnings after checks that your values corresponded to the true values from the pattern.

7.4.4 Results from MULE Layer by Layer Calculations

You will see that the form of results from the MULE Layer-by-Layer calculation is identical with those from MUSE, and that (in this case) the numerical values differ only very slightly, since you have input a good layer pattern. Many of the results from MULE are based on integrating values for all the layers in a stream, so that you have mixed mean values, which may be compared with the predictions of MUSE Simulations.

To see the differences between the outputs from MUSE Simulation and MULE Layer-by-Layer calculations, you will have to look in the detail, using Full Results, under the Output menu. There are sections in which the temperature variation along the exchanger, and the pressure change in every layer is identified. There is also a lineprinter graphic showing the variation of metal temperatures throughout the stacking pattern, at three points, end A, end B and the middle (M) of the exchanger. The more uniform these temperatures the better, because the smaller the temperature range at each point, the smaller the lateral thermal stresses.

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Figure 7.7

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7-22 The Zig-zag

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7.5 The Zig-zag

7.5.1 What is a Zig-zag?The Zig-zag, found under the Output menu, provides a graphical method of assessing how good a layer pattern is. It is produced after either a MUSE Simulation or MULE Layer-by-Layer run, when a layer pattern has been provided. This is a relatively advanced use of the program, and you may want to ignore this section on a first reading.

Technically the Zig-zag is a plot, at each parting sheet in the stacking pattern, of the cumulative heat load from the beginning of the pattern to that point. The graph goes up every time there is another cold layer (positive load) and down every time there is another hot layer. Hence, it zig-zags up and down.

The basic zig-zag is determined on the assumption that the total heat load for a stream is spread evenly among its layers. A good layer pattern will produce a zig-zag which oscillates uniformly about zero. A bad pattern will be significantly displaced from zero, because of local excesses of hot or cold load.

Figure 7.8

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7.5.2 Zig-zag OptionsLook at the Zig-Zag produced by the MULE run on Example 1. You will see that it is reasonably uniformly distributed about zero, because the layer pattern is good.

1. Click on Details, and you will be able to see a set of four zig-zags, evaluated for four separate regions along the exchanger length. In this simple example they are virtually identical, but in exchangers that are more complex, they may draw your attention to imbalances at certain points along the length.

2. Returning to the main Zig-Zag, (click on Whole Exchanger) you will see after a MULE run that you can click on the Actual Layer Based button.

This displays an alternative zig-zag based on the actual heat loads per layer, rather than the mean heat loads per layer. You will usually see that the zig-zag is slightly less pronounced, showing that the exchanger is compensating for imperfections in the layer pattern by conducting heat through the fins between non-adjacent layers.

7.5.3 Zig-zag AssessmentsTwo numerical measures are provided on the Zig-Zag of how good it is. The first is the Fraction of Zero Crossings, that is the fraction of the up and down lines forming the zig-zag which cross zero. This number should be equal to unity, or in very complex exchangers, as close as possible to unity.

The second measure is termed the Deviation from Ideal, and is a measure of how close, on average, the centre of each up or down line in a layer is to zero. This number should be small. Numerical information on the Zig-Zag, and some additional measures of how good it is, are included in the MUSE and MULE Lineprinter outputs. It is difficult to give general guidelines on values to be expected, as such parameters have not previously been widely calculated. You may however be able to build up a body of experience as to enable you to judge new cases.

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You should in any case remember that the Zig-Zag is a simple facility developed before the capability of Layer by Layer calculations was widely available. The results of the Layer by Layer calculation should give a better basis for judging a layer pattern than a zig-zag.

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Index

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Numerics

80-column Output 4-6

A

Advanced Geometry 3-4Alternative Designs 4-3

B

Basic Input Mode 2-5Brief Output 4-6

C

Calculation EnginesMULE 1-4MUSC 1-4MUSE 1-4PFIN 1-4

Calculation ModesDesign 1-3Layer by Layer Simulation 1-3Simulation 1-3Thermosyphon 1-3

ComponentsCalculation of the Properties of a Mixture 5-13

D

Data Input 3-1, 3-8Databank 5-12Default Input Data File 3-13Design 1-3Design Calculations 1-6DIPPR 5-18Distributors 1-5Documentation 1-8

E

Equipment Item Number 2-6Error / Warning Message Log 4-8Errors and Warnings 3-14Examples 7-1Exchanger Diagram 1-3, 4-3Exchanger Geometries 1-5

Distributors 1-5Finning 1-5Overall Geometry 1-5

F

Fin Geometry 4-3

Fin Performance 4-3Find 1-8Finding Input Items 3-11Finning 1-5Fins 3-4Full Results 4-3

G

Geometry 3-4Geometry - Distributors 4-3Geometry - Overall 4-3Geometry - Streams 4-3Geometry Data Input 3-7

H

Heat Transfer and Pressure Drop 1-6Help Text 1-9, 3-10HYSYS 5-21

I

Importing from a Properties Package 5-23Importing from HYSYS 5-21Importing Properties and Process Data 5-19Importing PSF Files 5-19Input Directly 5-11Input Errors and Warnings 3-14Input File 3-12Input Items - Finding 3-11Input Units 3-8Input Views

Advanced Geometry 3-4Exchanger Geometry 3-4Fins 3-4Options 3-4Physical Properties Data 3-4Process 3-4

Introduction 1-1

J

Job Title 2-6

L

Layer by Layer Simulation 1-3Lineprinter Output 4-6

M

Mixture Calculations 5-14Mixture Calculations (Old Style) 5-14

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I-2 Index

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MUSE Icons 2-7

N

NEL40 5-13Number of Fins to be Directly Input 2-5

O

Options 3-4Other Facilities 6-1Output 4-1Output - Other 4-8Output Files

80-column Output 4-6Brief Output 4-6Lineprinter Output 4-6Physical Properties Output 4-6

Output Options 1-8Output Views 4-3Overall Geometry 1-5Overview 1-3

P

Physical Properties 3-4, 5-1, 5-4Physical Properties (Old Style) 5-4Physical Properties Output 4-6Preferences 3-9Pressure Dependence 5-25Process 3-4Process Data Input 3-6Profiles - Other 4-3Project File Structure 6-4Properties Data Input 5-4, 5-10Properties Data Input (Old Style) 5-10Properties Input 5-6Properties Output 5-24Properties Package - Importing 5-23Properties Used 5-5Property Data

Liquid 5-5T-h-x Data 5-5Vapour 5-5

Property Data Sources 1-7Property Databanks 5-17

DIPPR 5-18NEL40 5-18

PSF Files 5-19

R

Results Summary 4-3–4-4Run 2-6Running MUSE 2-6

S

Simulation 1-3Single Component Stream from NEL40 5-13Specified Duty 4-3Start up View 2-5Stream Compositions 4-4Stream Details 4-3Stream Properties 4-4

T

Temperature Profiles 4-3Thermosyphon 1-3Thermosyphon Details 4-3Thermosyphons 1-7T-h-x 4-4

U

User Databank 5-12User Fin Databank 6-3User Interface 1-3, 1-8Using MUSE 2-1

V

View Geometry Diagram 2-4

W

Warning Messages 3-14Welcome View 2-4

Z

Zig-zag Diagram 4-3

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