Max 97

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September 9, 1999 1

his version for Excel 97 only! Other

Tversions are available for Excel

5.0~ 7.0

This manual covers version 1.11 of

MAX©, a software package th at calculates

performance and design of MaximICE™liquid ice thermal energy storage systems.

If you know the cooling loads, MAX will

help you choose the right size MaximICE

ice generator, condensing unit and storage tank. It calculates system performance over a design

day (or design week) and displays the results in both graphical and tabular format.

MaximICE is a trademark of the Paul Mueller Company for its liquid ice system. All rights

reserved worldwide.

This software package and manual were prepared by Y.T. Li Engineering, Inc. for the Paul

Mueller Company. The software and manual are both copyright 1995-1999. All rights

reserved worldwide.

Neither the Paul Mueller Company nor Y.T. Li Engineering, Inc. assume any liability for the

use or misuse of the software. The software is made available as an analysis aid only. Any

equipment selected should be confirmed by appropriate Paul Mueller Company

representatives.

Y.T. Li Engineering, Inc. makes no express or implied warranties with regard to performance

or accuracy of the software and specifically disclaims any implied warranties of fitness for any

particular purpose. Y.T. Li Engineering, Inc. shall not be held liable for any consequentialdamages that may possibly occur through the use of the software.

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I n s ta l l a t i on Requirements: Microsoft Excel 97 or later. It needs about 1000K memory on a hard drive. The

spreadsheet will print in color or gray-scale if your printer supports that capability.

N ote: There is another version of the MAX software available for Excel 5.0 through 7.0!

Microsoft Excel 97 for Windows has minimum system requirements of a 386 or better

computer, Windows 95 or later (or Windows NT 3.51 or later). MAX recalculates fairly

quickly with any Pentium class CPU.

IBM PC

1. Create a directory named MAXIMICE & copy both template MAX.XLT and add-in

MAX.XLA into it

2. Launch Excel and open template MAX.XLT. If the feed flow label (cell B10) in the Daily

worksheet contains engineering units, then installation is complete!

If several worksheet cells contain #N AME? then continue with steps 3 through 9

3. Excel can’t find the functions in the add-in, so you need to register the add-in with the

template. Open the Tools...Add-Ins menu. Make sure that MAX is listed and that its

box is checked. If it does not appear, click the Browse... button and locate add-in

MAX.XLA in th e C:\ MAXIMICE directory. Click OK to register the add-in.

5. Change to Daily sheet in workbook. C lick on any cell in Input section. Next, click

anywhere in the formula bar. Then hit Enter.

6. The spreadsheet should now recalculate and any cells that had contained #NAME? will

change to numbers.

7. Select the File...Save As menu. Change the Save file as Type to Template. Change thefilename to MAX.XLT then hit enter.

8. Close template MAX.XLT

9. Open template MAX.XLT (these last two steps allow support of Notes and F8 & F9

buttons)

Installation is now complete!

W h y a Sp r e a d s h e e t ?Calculations are contained in an Excel 97 spreadsheet to

! shorten the learning curve by taking advantage of user familiarity with spreadsheets

! let the user reformat results to suit presentation requirements! run software in foreign countries, and even present results in local language

! simplify program maintenance

! be compatible with software industry trends such as Visual Basic

! permit integration into studies or proposals through OLE 2.0

! model scenarios never contemplated by program author

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nputs are displayed in blue and areIcontained within blocks surrounded by a

double line border. Results and labels are

in black. Warnings are in red.

StandardICE

Optimize

Engineering calculations are performed by a set of functions and subroutines to maintain

calculation integrity. The user can change the inputs or presentation of results, but cannot

change the details of the calculations.

O v e r v i e wAll of the engineering calculations are performed by Visual Basic subroutines & functions

contained in the MAX.XLA file. The main function PERF returns all the values contained in

the Results section of the spreadsheet. It in turn calls supporting functions for refrigerant

physical properties, compressor performance, condenser performance, MaximICE performance,

etc. These functions all appear in the User Defined category in the Insert Function menu.

When you first open the spreadsheet

template, the input section is filled with

default data and the results section contains

numbers without any supporting formulas.

In this condition, you can quickly replace

the default input data with more appropriate

values for the problem at hand (i.e. without

waiting several seconds after each entry for the spreadsheet to recalculate). Various formulas

link the input data, input labels and results labels. As you make entries in certain cells, cells

further down in the spreadsheet will change in response. For example, when you change the

condenser type from “air-cooled” to “water cooled”, the daily high & low ambient

temperatures change from dry bulb to wet bulb. For this reason, it is important to do your

initial data entry starting at the top and working down.

The green StandardICE but ton tries to optimize the entire system(MaximICE, tank and start ing inventory) using standard size

components. To use it, enter your data, push the button and wait a

couple of minutes for the calculations. The status bar at the bottom of the window displays

messages on calculation progress periodically. When StandardICE is finished, the window

changes to a graphical display of the results.

The three optimize buttons try to find (respectively) the minimum size

MaximICE unit, minimum size ice storage tank, and maximum size starting ice

inventory. Each button is located near the thing it is trying to optimize. To

use them, enter your data, push the button and wait 5 to 60 seconds for the

calculations. The status bar at the bottom of the window displays messages on calculationprogress. When the optimize button is done, the window & results are updated. Normally,

you would optimize the MaximICE unit first, then choose a standard size MaximICE &

condensing unit. Next, you would optimize the tank size, then choose a standard model.

Finally, you would optimize the ice starting inventory, then print out the results.

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s a general rule, use F9 to trigger

A recalculations. Doing so avoids the

annoying wait for the spreadsheet to

recalculate after changing each datum.

t’s important to enter data from the top to

Ithe bottom of the spreadsheet. Default

data is updated automatically, but user

overrides are not. A similar situation arises

with the Input Units. By entering data from

top to bottom, you avoid the problem of

changing the meaning of previously entered

data.

You may also trigger spreadsheet calculation with the F9 key. This key calls the PERF

function using the input data and thereby updates the results section. F9 calculations are

useful if you are trying to fine-tune your MaximICE performance model.

F9 r ecalculations replace each cell in the

results section with the numeric valuecalculated by PERF. There are no

supporting formulas, so the spreadsheet

won’t update after you change input data.

This “feature” can be a time-saver if you

plan to change more than one or two data

entries. The status bar at the bottom of the screen displays a reminder of the need to F9 again

after you finish changing your data.

In p u t D a t aWhen first opened, MAX displays the C ustomer worksheet, which contains names, phone

numbers and addresses relevant to the project. Client name & company and Project name &

owner are automat ically passed to cells on the Daily & Weekly worksheets. The other

information requested is merely for your inquiry records.

Each worksheet (Daily & Weekly) contains its own (independent) Input Data. You may copy

the input data from one worksheet to the other, however. You may also copy input data from

a previous run (assuming you saved the data file).

Some cells affect others appearing lower in

the spreadsheet. For example, Condenser

coolant type determines whether theambient conditions should be wet bulb or

dry bulb. Although the labels change

automatically when you select a different

Condenser coolant, user specified ambient

conditions are not updated and you must

remember to change them manually.

General inputs are organized into sections

(Customer, Units, MaximICE & High Side, Ice Slurry Tank, Ambient & Load Conditions),

all of which appear on page 1 of the worksheet. In addition, cooling load and yes/ no data

specifying whether the MaximICE is OK to run must be input for each hourly period duringthe period being modeled. These hourly inputs appear next to the results section which follows

the graphical results presentation.

Most input data cells contain formulas or function calls to set default values. For example, the

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o restore the formulas, type “Ctrl r”T (using the Control key). This will be

useful when you are changing an old (and

fully optimized) data sheet for new

conditions. Formulas affected include those

for Solution volume, Tank volume, Starting

inventory, Condensing unit capacity and

Tank Height.

Condensing unit capacity, MaximICE feed

flow and Solution volume all depend on

MaximICE capacity. You may override

these formulas by entering fixed values or

even enter your own formulas. These

changes may be saved with the workbook.Because MAX.XLT is a template, however,

default values and formulas are restored on

the next new job.

Customer

Project name is the building or project name; it is used to label the performance graph. Its

source is the Name field in the Project section of the Customer worksheet.

Owner is name of the owner or end-user of the project. It is printed for reference only. Its

source is the Owner field in the Project section of the Customer worksheet.

Client is the name of the contact person at the company requesting MaximICE information. It

is printed for reference only. Its source is the Name field in the Client section of the

Customer worksheet.

Company is the name of the engineer or contractor requesting MaximICE information. Its

source is the Company field in the Client section of the Customer worksheet.

Input & Output Un its

Entries here affect the engineering units associated with labels as well as interpretation of

numeric input and results data. Labels and default values will change immediately. Input

numbers entered instead of default values do not change—you must make any modifications

necessary manually. For this reason, it is always best to enter data from top to bottom. TheResults section (both tabular data and graph) will change after you recalculate the spreadsheet

(such as with a button or F9).

Input distance affects the units for feed flow, solution volume, tank size, tank height & length

(or diameter). Choices are “feet” or “meters”. The program examines only the first

letter, and accepts either upper case or lower case. For feed flow, the units will either be

GPM or m / hr, depending on the Input Distance code entered.3

Input temperature affects the units for ) P allowance to compressor suction & condenser (both

of which are pressure drops stated as losses in saturation temperature). It also affects

the condenser subcooling, suction superheat, daily high & low, and chilled water

supply to the building. Choices are “F” or “C”. The program examines only the firstletter, and accepts either upper case or lower case.

Input energy affects the un its for Insulation R-factor, total load & baseload chiller capacity.

Choices are “tons” or “ton-hrs”, “BTU” or “MBTU”, “Mjoules”, “kW”, and “Mkgcal” or

“Mcal”. The program examines only the first two letters, and accepts either upper case

or lower case. Insulation R-factor units will either be hr-ft -EF/ BTU or m -EC/ watt,2 2

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depending on whether an English or metric Input Energy code was entered.

Output distance affects nothing in the current version of MAX.

Output temperature affects the units for feed solution temperature. Choices are “F” or “C”. The

program examines only the first letter, and accepts either upper case or lower case.

Output Energy affects MaximICE Capacity and ice slurry tank Inventory. Choices are “tons” or

“ton-hrs”, “BTU” or “MBTU”, “Mjoules”, “kW”, and “Mkgcal” or “Mcal”. The programexamines only the first two letters, and accepts either upper case or lower case.

MaximICE & H igh Side

MaximICE capacity refers to its nameplate or nominal ice-making capacity, measured in

refrigeration ton s (short tons of ice/ day). Stan dard MaximICE units are 25, 50 or 100

ton capacity. Combinations of these modules may used to satisfy customer

requirements. In actual fact, this input sets the amount of heat transfer area in the

evaporator. System capacity is then determined by the intersection between the

evaporator curve (Q= UA ) T) and compressor curve (defined by condensing unit

capacity).

Condensing unit capacity refers to the nominal ice-making capacity. It is initialized equal to

MaximICE capacity, but may be larger or smaller to suit customer requirements.

Capacity is always measured in refrigeration tons (short ton s of ice/ day). When

modelling real compressors, the condensing unit capacity is defined as 104.167% of the

actual compressor capacity at 20°F saturated suction, 100°F saturated discharge, 0°F

suction superheat and 0°F subcooling. MAX will calculate compressor performance at

other operating conditions. Appendix A tabulates the condensing unit capacity for

various brands and models of compressors.

Condenser coolant refers to the type of condensing unit being used. Choices include “air

cooled”, “water cooled” or “evap cooled”. The program examines only the first letter,

and accepts either upper case or lower case. Water cooled and evap cooled condensersare presumed to have a 18°F approach to wet bulb temperature (at standard

conditions); air cooled condensers are presumed to have 24°F approach to dry bulb

temperature.

Feed flow refers to the flow rate of solution into the MaximICE. It is initialized at 2.6

GPM/ ton of MaximICE capacity, but may be overridden.

Refrigerant refers to the name of the refrigeration fluid. At present, only R-22, R-134a and R-

717 (ammonia) are implemented in the program. The prefix “R-” is optional.

Suction line saturation temp loss refers to the refrigerant’s saturation temperature loss between

the MaximICE and compressor suction. The default value varies with condenser type.

Actual pressure drop is site specific, varying according to the length of tubing, tube

size, orientation and number of fittings. Override the default as necessary. Discharge line saturation temp loss refers to the refrigerant’s saturation temperature loss between

compressor discharge and middle of the condenser. The default value varies with

condenser type. Actual pressure drop is site specific—varying according to condensing

unit internal pressure drop plus orientation, length of tubing, tube size and number of

fittings in the interconnecting piping. Override the default as necessary.

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his restriction to full hour operationTmeans the ice inventory may

occasionally slightly exceed the “full tank”

inventory. For this same reason, it willprobably be impossible to find an optimized

design which drives the ice inventory to

exactly zero at some point in the cycle.

Condenser subcooling refers to the reduction of refrigerant temperature below the saturation

temperature at condenser outlet. Subcooling increases refrigeration capacity by reducing

the amount of flash gas generated after the expansion valve. For program purposes,

subcooling may occur either in the condenser, an economizer or a waste heat recovery

exchanger. Do not enter subcooling which results from a suction line heat

exchanger—see below. Condenser subcooling is initialized at zero to be conservative.Suction superheat refers to the increase in refrigerant temperature above the saturation

temperature measured at the compressor suction. Since MaximICE doesn’t produce any

superheat, the program assumes that superheat results from a suction line heat

exchanger. This would increase subcooling at the expansion valve, thereby increasing

refrigeration capacity. Suction superheat is initialized at zero to be conservative.

Ice Slurry T ank

The spreadsheet distinguishes between the solution volume and the size of the ice slurry tank.

The solution volume is the more important process parameter because it affects the freezing

temperature and maximum ice inventory. From the program’s viewpoint, tank size and shape

are important only in determining the heat gain from the environment.

The tank size must be chosen large enough to contain the solution volume, plus allowances for

volume expansion during freezing, spray headers above the ice pack, and liquid below the (full

tank) ice level switch. The spreadsheet displays a warning if the tank won’t hold at least 130%

of the solution volume.

The ice slurry tank is considered full if the

solution volume has over 50% ice. At this

ice fraction, about 20 gallons of solution are

necessary to store 1 ton-hour. If the tan k isfull at the beginning of an hourly period and

load is less than MaximICE capacity, the

MaximICE system will not run. O nce

started, however, the spreadsheet assumes

the MaximICE runs all hour.

Tank volume refers to the storage capacity of an empty tank. Solution volume (above the ice

level switch) is then determined by dividing by 1.4. Tank volume is initialized to 480

gallon/ ton of MaximICE capacity for the Daily worksheet, and 1250 gal/ ton for

Weekly. Bigger values may be needed to minimize MaximICE capacity.

Starting ice inventory refers to the amount of energy stored in the tank at the beginning of spreadsheet calculations. If final inventory equals starting inventory, the spreadsheet

has modeled a steady state problem (the daily or weekly cycle will repeat ad infinitum).

Normally, the user should let the Optimize buttons choose an appropriate value for

starting ice inventory.

Shape refers to the ice slurry tank shape and orientation. Choices are “cylindrical” and

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“rectangular”. The program examines only the first letter, and accepts either upper case

or lower case. Cylindrical tanks are always vertical. Rectangular tanks always have a

square footprint. Depending on the shape chosen, a subsequent cell will ask for either

the length of a rectangular tank or the diameter of a cylindrical one.

Height refers to the nominal height of the ice slurry tank. It is used to check tank size against

solution volume and determine tank surface area for heat gain from the environment. Length refers to the nominal length & width of the ice slurry tank footprint. It is used to

check tank size against solution volume and determine tank surface area for heat gain

from the environment. It is initialized to make the tank size 140% of solution volume.

Diameter refers to the nominal diameter of the ice slurry tank. It is used to check tank size

against solution volume and determine tank surface area for heat gain from the

environment. It is initialized to make the tank size 140% of solution volume.

Solution volume is normally calculated from tank volume by dividing by 1.4. This calculation

can be overridden if desired, with the new value affecting MAX output.

Insulation R-factor refers to the insulation applied to the ice slurry tank sides and top. It is used

to calculate heat gain from the environment.

Parasitic & accessory losses are added to the calculated heat gain from the environment. This

entry accounts for heat gain from circulating pumps, solar gain & air exchange.

Freezing point depressant refers to the additive used to promote the slush formation. It acts

through freezing point depression. Choices are salt water, propylene glycol and ethylene

glycol. The program examines only the first letter, and accepts either upper or lower

case.

Concentration (wt%) refers to the additive used to promote the formation of slush. It is

initialized at 7%, which is high enough to avoid problems with freeze-up.

Ambien t & Load Conditions

Ambient temperatures refer either to dry bulb, wet bulb or cooling water return temperaturesdepending on the condenser coolant specified earlier in the input. The labels and default values

change automatically when a different condenser coolant is specified.

Ambient temperatures are assumed to follow a roughly sinusoidal variation between a high

and low temperature. Hourly data from Atlanta, GA between July 19 and August 4, 1995

(collected in preparation for the ’96 Olympics) have been used to model this variation.

Daily high refers to the high temperature for the day.

Daily low refers to the low temperature for the day.

Tank ambient temp refers to the average temperature surrounding the ice storage tank.

Return temp T ES side of PHE refers to the temperature of solution leaving the TES side of theplate heat exchanger at full load. This input has no significance when the MaximICE is

fed directly from the tank. When the MaximICE is fed with a blend of cold solution

from the tank and warm return solution from the plate heat exchanger, this input is an

upper limit on the feed temperature (when system capacity exceeds the load).

M aximICE feed source code refers to the source of feed solution to the MaximICE. A code of 1

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refers to a blend of return solution from the cooling load together with solution from

the tank. A code of 2 refers to feed taken directly from the tank.

Page 2 inpu ts

Cooling loads and allowable hours of operation are input in columns on left side of the Results

section.

OK to run MaximICE? refers to whether the energy management strategy allows MaximICE

operation during this hour. Choices are “yes” or “no”. The program examines only the

first letter, and accepts either upper case or lower case. To reduce the amount of data

entry on the Weekly worksheet, Tuesday through Friday are set equal to the previous

day’s data. All hours on Saturday & Sunday are assumed to be OK to run. These

defaults are easily overridden.

Total Load refers to the total cooling load (i.e. both to baseload chiller and TES system) for

the building or process. To reduce the amount of data entry on the Weekly worksheet,

Tuesday through Friday are repeats of the previous day’s data. Saturday & Sunday

loads are initially set to zero. These defaults are easily overridden.

Baseload Chiller refers to that portion of the total cooling load for the building or process

which is handled by a baseload chiller.

R esu l t sThe Results section tabulates MaximICE performance hour by hour over a daily or weekly

cycle, depending on the worksheet. All values are determined from the input data by compiled

functions.

hr ending refers to the hourly period ending at the specified time.

TES Load refers to that portion of the total cooling load for the building or process which ishandled by the TES system. The TES Load equals the total load minus that portion

handled by the baseload chiller.

MaximICE mode refers to the mode of operation during the specified period. It may be either

“Ice-making”, “Chilling”, “Off” or “Tank full”. Ice-making occurs when the feed

temperature and cooling load are low enough that the MaximICE is making ice.

Chilling occurs when the MaximICE runs as a chiller because feed temperature and

cooling load are too high to permit ice formation. Off occurs when the energy

management strategy does not permit operation (OK to Run MaximICE?= “no”). Tank

full occurs when the system doesn’t run because the tank is full of ice.

Feed solution temp refers to the feed entering the MaximICE evaporator.

MaximICE capacity refers to the actual refrigeration duty of the MaximICE evaporator,whether it be chilling or ice-making.

High Side Power refers to the power consumption of the compressor and fan motors. It does

not include power consumption of either the circulating pumps or the orbital drive on

the MaximICE.

Inventory refers to the amount of latent heat energy storage in the tank. This value may

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se the StandardICE button for “plainU vanilla” applications under 1000 tons

capacity. First, enter your data, then hit

the StandardICE button. The spreadsheetthen solves your problem automatically,

choosing appropriate size MaximICE &

condensing units, then selecting a suitable

tank.

slightly exceed the “maximum” inventory if the tank wasn’t quite full at the beginning

of a period and the MaximICE ran all hour. Negative values have no physical

significance and represent an error condition which must be corrected. For this reason,

all negative inventories are displayed in red. To get rid of a negative inventory, you

might increase starting ice inventory, solution volume or MaximICE capacity.

Totals refer to the TES Load, Baseload Chiller, Total Load, MaximICE capacity and HighSide Power for the entire worksheet.

S t a n d a r d I C EThe green StandardICE but ton at the top of each worksheet tries to simplify user interaction

with the program by selecting standard size components which satisfy the given conditions.

Pressing the StandardICE button is

equivalent to the following steps:

Optimize MaximICE capacity, then

select the closest standard

MaximICE & condensing

units

Optimize Tank Size, then select the

closest standard size tank

Optimize Starting Ice Inventory

Display the results in a graphical

presentation

Because these steps involve many iterative calculations, the complete process for a weekly cycle

takes two minutes on a 486-66. The status bar at the bottom of the window will show

progress.

If the optimum component size is larger than the standard sizes built into the program, a

warning message displays alerting the user to that fact. If that occurs, you must consult Paul

Mueller representatives for advice on component sizing. Once you have their input, you can

use that value to complete the optimization manually.

O p t im iz in gThere are three Optimize buttons on each worksheet. Each one is located adjacent to the

particular input being optimized: MaximICE capacity, Tank Size or Starting Ice Inventory.

After an Optimize button is clicked, a Visual Basic subroutine goes through iterative

calculations to determine th e optimum steady state value of that parameter. Steady state here

means a solution that can repeat indefinitely if the input conditions should continueoccurring. After completing the optimization, the subroutine updates the results section. For

this reason, you must manually trigger recalculation (using another button or F9) if you

change the input data after an optimization.

Optim ize MaximICE capacity finds the smallest MaximICE system that gives a steady state

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ptimizing in sequence is a goodO strategy for designing a

MaximICE system. The overall goal

is to select the smallest MaximICE

and ice slurry tank. Because tanks

and MaximICE units only come in

certain sizes, the resulting system will

always have reserve capacity. It’s

these last results (showing the reserve

capacity) that the customer wants.

or a quick peek at theFgraphical results, double click

any cell which doesn’t contain

notes.

solution using the given solution volume (and other input data). To reach steady state, the

starting ice inventory is adjusted to equal the final ice inventory. The optimum MaximICE

capacity occurs when the minimum ice inventory is close to zero. The bisection algorithm is

used with ten iterations for good accuracy (0.1%). In the bisection algorithm, there is both a

MaximICE capacity too small to reach steady state, as well as one larger than necessary to

reach steady state. The average of the high and low values is tested, and then becomes thenew value for either the high or low limit. The status bar (at the bottom of the window)

describes progress of optimization.

Optimize T ank Size finds the smallest tank (and hence solution volume) that gives a steady

state solution using the given MaximICE system (and other input data). To reach steady state,

the starting ice inventory is adjusted to equal the final ice inventory. The bisection algorithm

is used, with ten iterations.

Optimize Starting Ice Inventory finds the solution with the largest reserve capacity. Reserve

capacity is the minimum ice inventory at any point during the period being studied. This

situation (which happens to be steady state) occurs when the starting inventory is adjusted to

equal the final ice inventory. The bisection algorithm is used, with ten iterations.

Sequential optimization

1. Input customer conditions. Try to guess a

reasonable size MaximICE capacity.

2. Optimize MaximICE capacity

3. Select a standard increment of MaximICE and

condensing unit capacity that is equal or

larger than the minimum capacity identified

in the preceding step4. Optimize Tank Size

5. Select a standard increment of ice slurry tank

6. Optimize Starting Ice Inventory

7. Print the results

After running an Optimize button, the spreadsheet

is left in manual recalculation mode. After each subsequent change in input data, you need to

F9 to recalculate the solution. The status bar at the bottom of the window contains a

reminder notice about the current recalculation mode.

G r a p h i c a l r e s u l t sFor a quick peek at graphical results, double-click on

any cell which does not contain a small red triangle in

its upper right corner. The chart will then display for

15 seconds before returning to the spreadsheet.

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on’t override the default unless youDknow how to calculate compressor

performance at standard conditions!

Vendor catalogs usually tabulate

performance with superheat & subcooling

to make capacity seem larger and efficiencybetter.

it F9 to recalculate the results inH the Performance Map. This

avoids the aggravation of waiting for

the spreadsheet to recalculate each

time you change an input.

Pe rf o r m a n c e M a p W o r k s h ee tThis worksheet calculates the performance of a MaximICE system at solution inlet

temperatures from 24~ 50°F (or equivalent °C range). This range covers common chilling and

ice-making regimes possible for a standard system.

Inputs are basically the same as for the Daily & Weekly worksheets, except for the condensingunit, whose performance model can be fine-tuned. See the section on Stand ard sizes of

MaximICE, condensing un its and tanks for further details (including formula for

calculating compressor performance).

Standard capacity refers to the refrigeration

duty of the condensing unit at

standard conditions (20°F saturated

compressor suction, 100°F saturated

compressor discharge, no superheat

and no subcooling). Default data is

taken from the StandardICE

worksheet, but may be overridden to

model a specific condensing unit.

Standard approach refers to the difference between saturated compressor discharge temperature

and ambient (or cooling water return) temperature, measured at standard conditions.

Default data is taken from the StandardICE worksheet, but may be overridden.

Standard compressor power refers to the electric power (kW) consumed by the compressor at

standard conditions

Standard fan power refers to the electric power (kW) consumed by the fans on the condensing

unit at standard conditions.

Function PerfMap calculates the Performance Map

(results) section when you hit F9. You can change

more than one input before recalculating.

Sol’n In refers to the solution temperature

entering the MaximICE

Sol’n Out refers to the solution temperature

leaving the MaximICE. Th is temperature

won’t be any lower than freezing temperature.

Freezing Temp refers to the freezing temperature of the ice slurry. In chilling regimes, it is

calculated using the input concentration of freeze point depressant. In ice-makingregimes, it is the taken as the solution inlet temperature.

Capacity refers to the refrigeration duty of the condensing unit

Power refers to the kW energy consumption of the condensing unit (compressor & fan). It does

not include energy consumption of the MaximICE orbital drive, feed pump & ice

slurry pump

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escriptions of each input & output

Dappear when you double-click any

cell containing a Note marker (small red

triangle).

Efficiency refers to the energy efficiency, COP or EER of the condensing unit using the above

Power & Capacity

THR refers to the total heat of rejection to the condenser, including both compressor power

and refrigeration duty

Evap refers to the saturated refrigerant temperature leaving the MaximICE. It does not include

the suction line temperature loss (from the input data).Cond refers to the saturated refrigerant temperature leaving the compressor discharge. It does

not include the discharge line saturation temperature loss (from the input data).

Although the user has no control over which data is calculated in the Performance Map, you

can control the appearance of the printed output. For example, suppose you don’t want to

publish the freezing temperature. Merely select that column and hide it using the

Format...Column...Hide menu.

H e lpDetailed descriptions of each input and output

are provided by Comments which display

automatically whenever the cursor moves over

a cell. Cells containing notes have a small red

triangle in their upper right corner. If this

proves disconcerting, turn the feature off using

the Tools…Options…View…Comments menu. To view a Comment, double-click on the cell.

It will display for 15 seconds, then return to the spreadsheet.

You can change the Comments display duration by going to Visual Basic Module1. In sub

MaximICEinfo (the second one in Module1) the variable DisplaySeconds controls duration of

Comments display.

For technical support, contact Brad Yundt of Paul Mueller Company at (417) 831-3000 X336.

His FAX number is (417) 831-4175.

H o w t o M o d i f y Yo u r T em p la t eYou may wish to modify your spreadsheet template to change the appearance of your output.

For example, you may wish to standardize on different input and output units than chosen for

the spreadsheet defaults. Feel free to do so, because the integrity of the results is protected by

the program. However, you must not change the column order in the Results section (their

order is hard coded in the Visual Basic functions)! Once the changes are complete, you should

save the workbook as a template in its standard starting condition.

Saving revised workbook as template:

1. Launch Excel & open template MAX.XLT

2. Make the desired changes to template (such as formatting or default data)

3. Select the Weekly worksheet and F9 (this will speed up template loading). Move the cursor

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to a standard location (such as cell A7—MaximICE capacity)

4. Select the Daily worksheet and F9. Move th e cursor to the standard location.

5. Select the Splash worksheet

6. Select the File...Save As menu. Change the Save file as Type to Template. Change the

filename to MAX.XLT then hit enter.

7. Close the workbook

P ro g r a m Co m p i la t i o n ( b y P au l M u e lle r p e r s o n n e l o n l y !)The spreadsheet and supporting functions & subroutines are all contained in workbook

MAX.XLW, which has six worksheets and seven Visual Basic modules. Four of the

worksheets (Splash, Customer, Daily, Weekly & Performance Map) and Module1 are th e basis

of the spreadsheet template MAX.XLT. The remaining worksheet (StandardICE) and other

six modules (Compressor, Tank, Bohn & ORE, Feed Code, Properties, Misc) are the basis of

the compiled add-in MAX.XLA. When making changes or updates to the program, the

changes should be made to workbook .XLW; the .XLT and .XLA files are then produced

from the revised workbook.

A dd-in preparation:

1. Launch Excel

2. Open MAX.XLW and make the desired changes

3. Make sure to save MAX.XLW workbook! Subsequent steps destroy the copy in memory.

4. Using the Tools...Add-Ins... menu, uncheck MAX

5.Select the Weekly worksheet (by clicking on that tab)

6. Using the Edit...Delete Sheet menu, delete the Weekly worksheet

7. Repeat the procedure to delete Daily, Performance Map, Compressor Map, Splash and

Customer worksheets

8. Switch to Visual Basic editing by hitting Alt F11.9. Using the Tools...References... menu, uncheck MAX

10. Using the project explorer window, look for Module1. If it does not appear, then double-

click Modules.

11. Using the File…Remove menu, delete Module1.

12. Switch back to the Excel worksheets by hitting Alt F11.

13. Using the File...Save As... menu, change the Save as type to Microsoft Excel Add-In

(*.XLA) and the File name to MAX.XLA. Then hit enter to save the remaining

modules and worksheet into the MaximICE directory.

14. Close workbook MAX.XLW. Ignore the prompt reminding you to save the changes! Ignore

prompts about cannot find MaximICE_FKey or macro ...

Template preparation:

1. Open workbook MAX.XLW

2. Select the Weekly worksheet and F9 (this will speed up template loading). Move the cursor

to a standard location (such as cell A7--MaximICE capacity)

3. Select the Daily worksheet and F9. Move th e cursor to the standard location.

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4. Select the Performance Map worksheet and F9. Move the cursor to th e standard location.

5. Select the Compressor Map worksheet and F9. Move the cursor to the standard location.

6. Using the Tools...Add-Ins... menu, check MAX. If it does not appear, click the Browse...

button an d locate add-in MAX.XLA in th e C:\ MAXIMICE directory. Click OK to

register the add-in.

7. Select the StandardICE worksheet (by clicking on that t ab)8. Using the Edit...Delete Sheet menu, delete the StandardICE worksheet

9. Switch to Visual Basic editing by hitting Alt F11

10. Right-click MAX.xla in the project explorer window

11. Change Project Name to MAX

12. Ch ange Project Description to “MaximICE sizing & performance calculations. For Excel 97

only!”

13. Click the Protection tab, lock the project for viewing and enter a password

14. Using the File save menu, save the changes to the MAX Add-In properties

15. On the Tools...References... menu, move cursor to MAX. Make sure box refers to

C:\ MAXIMICE\ MAX.XLA. If MAX not in list, click the Browse... button and

locate add-in MAX.XLA in the C:\ MAXIMICE directory. Click OK to register the

add-in.

16. Using the project explorer window, double-click the Compressor module

17. Using the File…Remove menu, delete the Compressor module. Do not export it!

18. Repeat the procedure to delete Tank, Bohn & ORE, Feed Code, Properties, Maps,

Optimization and Misc modules

19. Switch back to the worksheets by hitting Alt F11

20. Select the Splash worksheet (by clicking on that tab)

21. Select the File...Save As menu. Change the Save file as type to Template (*.XLT). Change

the File name to MAX.XLT. Then hit enter to save the remaining module and

worksheets into the MaximICE directory.22. C lose the workbook

A dd-in and template integration and testing:

1. Quit Excel

2. Launch Excel and open MAX.XLT

3. Make sure the add-in is registered with the template. Switch to the Module1 sheet in the

workbook. Open the Tools...Add-Ins menu. Make sure that MAX is listed and that its

box is checked. If it does not appear, click the Browse... button and locate add-in

MAX.XLA in th e C:\ MAXIMICE directory. Click OK to register the add-in.

4. Change to the Visual Basic editor by hitting Alt F11

5. Open the Tools...References menu. Make sure that MAX.XLA is listed and that its box ischecked. Uncheck any boxes like Missing...MAX.XLA.

6. Change back to the worksheets by hitting Alt F11

7. Change to Daily sheet in workbook. C lick on any cell in Input section. Next, click

anywhere in the formula bar. Then hit Enter.

8. The spreadsheet should now recalculate and any cells that had contained #NAME? will

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change to numbers.

9. Select the Splash worksheet (by clicking on its tab)

10. Select the File...Save As menu. Change the Save file as Type to Template. Change the

filename to MAX.XLT then hit enter.

11. Close template MAX.XLT

12. Open template MAX.XLT (the last two steps initialize Comments and F9 buttons)

H o w t o G e t O u t p u t i n L an g u a g e o t h e r t h a n En g l is hThe calculations are done in a spreadsheet, so the user has the opportunity to change labels

from English into any other language. The program maintains integrity of the answers though,

because the calculations are performed by compiled functions and are unaffected by these

changes. Once the desired changes have been made, the revised spreadsheet can be saved as a

template.

If you have a copy of Excel valid for a locale other than USA, then the spreadsheet

automatically uses the appropriate local format for dates, times and numbers (separators and

decimal points). Even if you have a copy of Excel valid for USA, you can reformat the output

to reflect local standards.

Units of measure are appended to the Input Data and Results section labels by compiled

functions. Although you can choose the desired un its (by specifying Input & Output units),

you will not be able to correct their spelling (unless you write your own functions).

Some input entries contain text information. The program examines only the first one or two

letters, and accepts either upper case or lower case. If the English word has the same initial

characters as the non-English equivalent, then no changes are necessary. Otherwise, you must

treat that input item as a code. The program will also accept numbers instead of letters if thatseems more appropriate.

Text input item required characters

Distance units f or 1, m or 2

Temperature units f or 1, c or 2

Energy units to or 1, mb or bt or 2, kW or 3, mj or 4, mk or mc or 5

Condenser coolant a or 1, w or 2, e or 3

Refrigerant initial R & - removed, only numerals important

Ice slurry tank shape c or 1, r or 2

Insulation R-factor initial R & - removed, only numerals important

Slush additive p or 1, e or 2OK to run MaximICE? y or 1, n or 2

Note that MaximICE mode is output as English text. You will not be able to convert it to

another language without changing the compiled functions.

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The names of the worksheet tabs (Daily and Weekly) are not used by the program, so you

may choose any other names desired. Although not apparent to the casual user, the

worksheets contain defined Names that refer to specific cell ranges. Do not change these

Names, because the compiled functions refer to them specifically.

Once you have completed all the changes to the spreadsheet, save it as a template by followingthe directions in H ow to Modify the T emplate.

A d v a n c e d M o d e l in g Is su e sAlthough the spreadsheet is intended to handle relatively simple problems, it can be fine-

tuned to deal with more complicated modelling issues such as demand limiting or existing

equipment. The subsequent discussion presumes you are proficient in both Excel spreadsheets

and the MAX.XLT template.

Demand limiting strategy

Calculate the results with MaximICE OK to run at all hours. Then insert a formula in the

MaximICE OK to run column that sets the value equal to “yes” if total demand is less than

the target or “no” if it exceeds the target. If total demand includes other equipment, then add

columns to reflect its demand and performance. Finally, repeat the performance calculations

and double-check to make sure that demand has been limited successfully. If desired, create a

graph showing other power, MaximICE power, and total power versus time.

Calculate utility bill

MAX can do calculations for average loads and ambients as well as design day (or week)

conditions. Use the design day results to determine demand charges. Use the average day

results to determine monthly energy consumption. Calculations may be repeated for each

month of the year (both design & average) if data is available. Peak kW and total kWh maythen be entered into a separate spreadsheet to determine the utility bill month by month over

the year.

Determine allowable time for maintenance without interrupting cooling

If you know the loads and long range weather forecast, you can model the performance of the

MaximICE system during a week with scheduled downtime for maintenance. Try to begin the

week with a full tank of ice. Because this is not a steady-state problem, you should ignore the

warning message that claims starting and final ice inventory don’t match. Be careful that the

program doesn’t calculate negative ice (shown in red), which would be evidence that the

cooling load won’t be satisfied.

M odel half-hour periods

Change the formula in the “hr ending” column to equal the value in the preceding cell +

1/ 48. Insert enough rows in the middle of the results section so the period modeled covers the

entire day or week. Divide the cooling load by 2 (because it covers a 30 minute period rather

than an hour). Multiply MaximICE capacity & performance by 2 to get the hourly

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equivalent. Total kWh and tons will still be correct, however.

Exceed high & low limits on heat flux

The program restricts MaximICE heat flux in ice-making mode (R-22 and R-134a systems) to

the range between 2500 and 7000 BTU/ hr-ft EF. R-717 systems have a lower limit (2500 to2

5300 BTU/ hr-ft EF). Outside that range, the program displays an error message and will not2

update the Results section. The upper limit avoids potential freeze-up conditions, which may

be a problem during shoulder season (low ambient temperature) when the ice inventory is low.

The lower limit avoids the erratic performance possible when the MaximICE is too large for

the condensing unit, which may be a problem during the design day (high ambient

temperature) at high ice inventory.

Paul Mueller Company engineers may defeat this heat flux error checking by changing Visual

Basic code in either the .XLA add-in or the uncompiled workbook MAX.XLW. This code is

found in module Bohn & ORE near the end of function ORE. The heat flux limits are

specified in the Select Case block (i.e. Case Is < 2500 or Case Is > 7000). C hange either or

both limits, then rerun the data.

St a n d a r d s iz es o f M a x im ICE, c o n d e n s in g u n i t s & t a n k s Worksheet StandardICE contains tables defining MaximICE area, condensing unit

performance and tank dimensions for standard components. Th is worksheet is contained in

MAX.XLW, and so may be accessed only by Paul Mueller Company engineers. Condensing

unit & MaximICE data are used for all calculations; tank data is used only by the

StandardICE button.

You may add, delete or modify data contained in the tables using normal Excel spreadsheet

techniques. Enter data either as discrete numbers or as formulas. By convention, fullyaccepted data is entered in a roman (plain) font; other data is entered in an italic font .

The compiled functions refer to data by name, such as AirCndsrxl & AirCndsrDataxl, which

point to specific ranges of cells on the StandardICE worksheet. Each name starts with the

prefix StandardICE! so they don’t appear in the name menu for other worksheets. The range

definitions may be viewed (and changed) from the Insert...Name...Define menu. Each table

(surrounded by double-line border) contains two named ranges: one for the nominal size ( e.g.

MaximICExl) and the other for the supporting data (e.g. MaximICEDataxl).

StandardICE tables must always obey two rules:

1. Data must be arranged in descending order based on nominal size2. Make sure the range definitions of both names in each table are correct

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Q' Mass flow[ H v(20EF )% H

superheat & H

l(100EF )% H

subcool]


ondensing unit manufacturers neverC tabulate performance at the program’s

“standard” conditions of 20°F saturated

suction, 100°F saturated discharge, no

superheat and no subcooling. You’ll needto do some math to derate the published

capacity for the superheat and subcooling

that they invariably included.

After changing data in the StandardICE

tables, the program must be recompiled for

distribution. That way, casual users are

prevented from changing the database.

Condensing unitsCondensing unit tables (AirCndsr,

EvapCndsr & WaterCndsr) describe the

standard increments and performance of air

cooled, evap cooled and water cooled

condensing units. The nominal size of each

condensing unit should match the nominal size of the associated MaximICE modules. Actual

capacity, approach, compressor power and fan power are then entered for “standard” rating

conditions: 20EF saturated compressor suction temperature, 100EF saturated compressor

discharge temperature, no condenser subcooling & no suction superheat. If the compressor

manufacturer doesn’t tabulate data with zero subcooling & superheat, you can correct the

tabulated capacity by doing a heat & mass balance.

Using the manufacturers’ tabulated capacity, solve for the unknown mass flow. Increase the

mass flow by the ratio of absolute temperatures (SST+ superheat)/ SST. Then use the corrected

mass flow in the above equation without the superheat and subcooling terms to determine the

refrigeration capacity at “standard” rating conditions.

The approach temperature refers to the difference between compressor saturated discharge andcoolant inlet temperatures. Coolant inlet temperature means ambient dry bulb for an air

cooled condensing unit, wet bulb for evap cooled and cooling water return temperature for a

water cooled unit. If the condensing unit manufacturer doesn’t publish approach data, you

must either demand data from the manufacturer, measure the performance of an actual system

or back-calculate from published compressor & condensing unit data.

For open compressors, the required data must be slight ly adjusted. The approach and

compressor power are interpreted as though for a semi-hermetic or hermetic compressor.

Because the motor inefficiency in open compressors does not get rejected in the condenser, you

need to adjust the input data so MAX.XLT calculates the correct condensing temperature and

total energy consumption. The easiest way is to calculate the motor inefficiency and add it tothe actual fan power; approach and compressor power are then input as measured. For better

accuracy over a range of ambient conditions, enter the actual fan power, expected motor kW

for the compressor power, and a slightly reduced approach (by ratio of actual compressor kW

to expected motor kW).

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t’s OK to run a MaximICE module atImore than nominal capacity. A 100 ton

MaximICE mates nicely to a 130 ton

condensing unit.

MaximICE modules

MaximICE modules are presently available

in 3, 25, 50 and 100 ton nominal sizes.

They may be combined in any proportion to

get larger or in-between capacities. The most

economical system often has a larger orsmaller MaximICE nominal capacity than

condensing unit nominal capacity. For most economical system cost, avoid using 3 ton

modules if required capacity exceeds 10 tons. Also, never use more than one 25 or 50 ton

module in a system. The table incorporates these guidelines and lists standard combinations of

MaximICE modules under 1000 ton nominal size. The associated data field lists total surface

area (based on the average of tube ID and OD) for each combination.

Tanks

Data is presented for both cylindrical and rectangular tanks. Cylindrical tanks shown are

molded plastic and can be shipped completely assembled. Rectangular tanks will probably be

field-assembled. The program uses tank data only when the StandardICE button is clicked.

For cylindrical tanks, the required data includes the overall height , diameter and solution

volume. The program expects outside dimensions (to calculate heat gain). The nominal size is

the catalog value for tank volume.

For rectangular tanks, the required data includes the overall height, length, width and

solution volume. The program expects outside dimensions (to calculate heat gain). The current

version of the program assumes that length and width are the same, and so ignores the second

column. The nominal size is the catalog value for tank volume.

T r o u b l e s h o o t i n g Installation problems

#NAME? appears in Input Data cells

! MAX can’t find the MAX.XLA add-in. You need to register the add-in with the template.

Repeat instructions 3 th rough 9 in the Installation section.

! You tried to install the add-in without first quitting Excel. Because the add-in is loaded

every time you launch Excel, you cannot change it without first quitting Excel. Repeat

instructions 2 through 9 in the Installation section.

Printing problems

Pr int-out too slow! Color or gray-scale printing takes too long. Use a faster printer (such as laser or Hewlett-

Packard professional series ink-jet).

! Color or gray-scale printing takes too long and I’m not changing printers. If the appearance

is less important than speed, make a special copy of template MAX.XLT that

eliminates color. As a minimum, you must change the blue color used for input data,

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the special colors used in the schematic diagram (created using the Excel drawing

toolbar), and the line colors used in the graphical results presentation. You may also

wish to change the red color used to signal negative ice inventory in the Results and for

warning messages on page 1. The Excel User’s Guide gives detailed instructions.

Can’t distin guish lin es on schematic or graph ical results! Output was optimized for color printing. Modify the template until you get satisfactory

results with your printer, then follow directions in the How to Modify Your Template

section. Black & white or gray-scale output must use line weights & patterns to

distinguish one line from anoth er. Both schematic & graphical results were created in

Excel, and may be modified as necessary for suitable contrast on black & white or

gray-scale printers.

Outpu t won’t fit on 2 pages (Daily) or 8 pages (Weekly)

! Output was formatted for an HP 855 printer using Arial font. Other printers & fonts may

print slightly larger, and therefore force one or more columns to appear on a separate

page. To make the Daily worksheet fit into 2 pages, select File...Page Setup...Page tab.

In the Scaling box, Adjust the output size to 90%. Use File...Print Preview to view the

results of the change. Continue fine-tuning th e output size percentage until the output

fits on 1 page wide by 2 pages long. Repeat the process on the Weekly worksheet (using

the Daily worksheet parameters as a starting point). N ote: don’t bother trying the

File...Page Setup...Fit to option, as you will lose the carefully chosen page breaks at the end

of the Input Data and each day’s tabular results.

Optimize convergence problems

MaximICE d id n ot converge (or con verged to larger size th an I expected)

!The tank is too small. If the formula relating tank size to MaximICE capacity wasoverwritten by previous optimizations, then the amount of ice needed to satisfy the

load during the hours MaximICE is not permitted to run may exceed the available

storage capacity. If so, no solution is possible. The tank size on the original template

was equal to 480 gallons/ ton of MaximICE capacity (Daily) or 1250 gallons/ ton

(Weekly). For the Daily tank size input cell, enter the following formula:

= A7*480/ VolumeUnits(D3)

MaximICE capacity should now optimize.

T ank size or starting ice inven tory did n ot converge

! MaximICE too small. Total MaximICE capacity must exceed the total cooling load plus

losses (as shown at the end of the results section). If not, a warning message appearsbelow the schematic diagram and it is impossible to optimize tank size or starting ice

inventory. Restore the tank size formula (see previous problem), increase MaximICE

(and condensing un it) capacity, then press the Optimize buttons again.

W arning messages

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N egative ice (displayed in red)

! Tank too small. In the graphical results, does the ice inventory reach and maintain a peak

value early in the off-peak hours? In the tabular results, MaximICE mode will

frequently be “Tank full”. If so, then the tank is too small to hold all the production

possible by the MaximICE system.

! MaximICE too small. Total MaximICE capacity must exceed the total cooling load pluslosses. Increase it and try again.

! Starting ice inventory too small. You probably also got a warning message about initial and

final ice inventories not agreeing. Optimize starting ice inventory.

In itial and fin al ice inventor ies don ’t match

! Starting inventory not optimized yet. Optimize it.

! MaximICE or tank too small. See preceding discussion for “Negative ice”.

Tank too large to standardize. Use your own judgement.

! The MAX.XLA add-in contains a table of standard size components. The largest cylindrical

tank in that list is 20,000 gallons. Larger tanks will be field-erected, so standardization

is less of an issue. Stay with the optimized size (shown in the Input Data) until

additional vendor data is available on possible tank sizes.

MaximICE or condensing unit too large to standardize. Use your own judgement.

! The MAX.XLA add-in contains a table of standard size components. If the required

MaximICE or condensing unit exceeds the biggest value in the table, consult Paul

Mueller representatives for more information on larger capacities. In the meantime, stay

with the optimized size (shown in the Input Data) until additional data is forthcoming.

T ank size doesn ’t match tank d imensions (too large or too small)

! The volume calculated from tank dimensions doesn’t match the specified tank size. This may

occur in rectangular tanks if the footprint is not square (as the spreadsheet assumes).

The spreadsheet calculates heat gain from the environment, and so needs to know the

exposed surface area. If you are satisfied that th is calculation is sufficiently conservative

(such as by adjusting the tank ambient temperature), then you can delete the warning

message.

H eat flux too large or too small

! MaximICE capacity must not be too much larger or smaller than condensing unit capacity

(typically 70% to 130%). The high flux limit protects against freeze-up conditions inshoulder season (low ambient) with low ice inventory. The low flux limit protects

against erratic performance on the design day (high ambient) with a full tank. Program

error checking may be defeated only by Paul Mueller Company engineers having access

to the Visual Basic source code. Details are provided in the section discussing advanced

modeling issues.

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Energy con sum ption seems too high

! Manufacturer’s data sheets are normally based on suction superheat and inlet subcooling,

both of which increase compressor capacity and decrease kW/ ton . Because MAX

defaults to zero superheat and zero subcooling, its projected energy consumption may

seem too high. Override the default input values for superheat and subcooling andMAX should come much closer.

! MAX includes fan power in its energy consumption, whereas compressor manufacturers do

not for their kW/ ton projections. MAX assumes that air-cooled condensers use 0.12

kW/ ton for the fans and that evap-cooled condensers use 0.06 kW/ ton. Water-cooled

condensers are not penalized by fan power.

! MAX bases its calculations on data from a 35 HP Copeland reciprocating compressor. Large

screw compressors may be more efficient. This problem can be corrected in the

Performance Map and C ompressor Map worksheets, but not in the Daily and Weekly.

! You are trying to model an energy-efficient condenser (with close approach). MAX assumes a

24°F approach for air-cooled condensers and 18°F for water-cooled and evap-cooled.

These assumptions can be overridden in the Performance Map and C ompressor Map

worksheets. They can be compensated for in the Daily and Weekly worksheets by

reducing the ambient temperature range to artificially lower values. Column K

(normally hidden) shows the condenser saturation temperature. Select columns H

through L, then use the Format…Column…Unhide menu to expose column K. Adjust

the ambient temperature range until the condenser temperature matches expectations.

Comp ressor capacity seems too high in chilling mode

! MAX cannot model economizers very well as system operation changes from ice-making to

chilling. If the subcooling is adjusted to the correct value, MAX will underpredict the

energy consumption. MAX will also fail to take into account the decrease in suctionflow which occurs in chilling mode due to increased mass flow through the economizer

port.

Error involving Match function

! The warning message may also reference functions Perf, ORE, Cope_Mass, Cope-watts,

Bohn_Temp or StandardICE. In all cases, the program has lost track of the data on the

StandardICE worksheet. The problem is usually resolved by closing the file and

reopening it. If that doesn’t work, try reinstalling the MAX.XLT master template.

OLE 440 Automation error

! This warning may be safely ignored. It results from a bug in Microsoft Excel.

Max 97

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