Heat Exchanger

Sistem Permesinan

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References :• Introduction to Marine Engineering

• Marine Auxiliary Machinery• Maritime Engineering Reference

Handbook• Marine engineering

Dedi Budi Purwanto ST.,MT.

Introduction

At different temperature and thermal contact

Transfer thermal energy

Between two or more fluids

Between a solid

surface and a fluid

Between solid

particulates and a fluids

Heat exchanger

Components fluids stream

Single Multiple

Typical applications

Heating (Evaporation)

Cooling (Condensatio

n)

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Introduction Design consideration:

Corrosion

Fouling

Fluid temperature

Operating pressures

Pressure drop

Viscosity

flow rate

Material of Construction

Cooper

Best heat transfer performance of all metal

High thermal conductivity

Relatively poor corrosion resistance

Brass (an alloy cooper & zinc)

Is stronger than cooper while still retaining high thermal conductivity

Suffer from corrosion

Aluminum

Is a lightweight metal and has high heat transfer efficiency at a comparatively low cost

corrosion resistance

Stainless steel

Excellent corrosion resistance

Lower heat transfer efficiency

expensive

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Types of Heat Exchangers According to the heat transfer

process

In indirect contact heat transfer

In direct contact heat transfer

According to construction

the heat exchanger may incorporate shell & tube, plated, spiral, or air-cooled construction.

According to flow arrangements

the heat exchanger may be either single pass or multi-pass. It may incorporate cross-flow, counter-flow, or co-current flow

According to the number of fluids

the heat exchanger may incorporate two, three, or more than three heat transfer fluids in the system.

According to heat transfer mechanism

the heat exchanger uses single-phase convection, two-phase convection, and/or radioactive heat transfer on each side of the exchange

According to process function

Condenser, chiller, heater, coolers

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According to Transfer processes

Wet surface direct evaporative coolers typically use pump circulating water system to keep the media wet

In a typically indirect evaporation air cooler, the essential element is a heat exchanger in which dry air contact heat exchange surface whose other sides are cooled evaporative

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According to Construction

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Tubular heat exchanger The configuration give a large surface area in a small volume

Flexibility design : Easily by changing the tube diameter, length and arrangement

Design for high pressure

Easily cleaned

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Tube pattern

Recommended tube pitch (distance between tube centre) is 1.25 times the tube outside diameter

Tube arrangement

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Tube Design1. Finned tube2. Surface tube3. Straight tube4. U – tube

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Shell type (pass arrangement)

a. One pass shell (E shell)

b. Split flow (G shell)

c. Divided shell (J shell)

d. Two pass shell with longitudinal baffle (F shell)

e. Double split flow (H shell)

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Baffle

The choice baffle type, spacing, and cut is determinate largely by flow rate, desired heat transfer rate, allowable pressure drop, tube support

Flow induced vibration Spacing used ranged from 0.2 to 1.0 shell diameter

Optimum spacing will usually be between 0.3 to 0.5 time the shell diameter

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Plate heat exchanger Cannot accommodate very high pressure, temperature.

Lower fouling due to high turbulence in the exchanger

Higher heat transfer efficiency

Material selection is critical due to the thin wall thicknesses

They can easily be taken apart into their individual component for cleaning, inspection, and maintenance

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There are three main types of plated heat exchangers

plate and frame heat exchangers,

consist of a number of corrugated metal plates in mutual contact

spiral plate heat exchangers, and

are a type of welded plate heat exchanger with two parallel curved (spiral shaped) metal plates.

These plates create extremely high turbulent flow in a counter-current pattern. can be used with high-viscosity fluids.

plate coil heat exchangers.

hybrid of tube heat exchangers and plate heat exchangers.

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Extended surface heat exchanger Large heat transfer surface area

Type

Tube fin

Plate fin

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Regenerative Is a storage type heat exchanger

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According to Flow Arrangement Particular flow arrangement is dependent:

Required exchanger affectivities

Available pressure drop

Minimum & maximum velocity

Allowable thermal stresses,

Temperature levels

Piping considerations

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Single pass exchanger Counter flow

Parallel flow

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Single pass exchanger Cross flow

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Multi pass exchanger Multiphase cross flow

Multiphase shell & tubes

Multiphase plate

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According to Process Function

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Chiller Chilled water temperatures can

range from 35 to 45 degrees Fahrenheit (1.5 to 7 degrees Celsius)

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Typical water-cooled chiller system Indirect water-side economizer

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Condenser condensing the exhaust steam

from a steam and transferring the waste heat away from the power station.

The function of the condenser is to condense exhaust steam from the steam turbine by rejecting the heat of vaporization to the cooling water passing through the condenser

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Types of condensers

a) air-cooled

b) water-cooled

c) evaporative

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Air cooled heat exchangers may be either forced draft or induced draft.

Forced draft heat exchangers "force" or push air through the unit by installing fans at the inlet below the tube bundle

Induced draft heat exchangers pull air through the unit by installing fans at the outlet above the tube bundle

Coolers

Cathodic Protection Reducing the corrosion rate of a metal.

The principle is based on “Supplying electrons to the base material”

Material cathodic

Zinc

Aluminium

Magnesium

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Aplikasi di Kapal Lubricating Oil Cooler

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FO & LO heater

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Hot Water Heater

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