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Classification of heat exchangers Page 1

Assignment # 1

Classification of Heat Exchangers

Table of Contents

Heat exchangers can be classified on the basis of: .........................................................................................2

Nature of Heat Exchange Process ................................................................................................................. 2

Flow arrangements .......................................................................................................................................3

According to Construction .............................................................................................................................3

Plate heat exchangers ...................................................................................................................................3

Gasket Plate Heat Exchanger .........................................................................................................................4

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Classification of heat exchangers Page 2

A heat exchanger is a device that is used to transfer thermal energy between two or more fluids at different

temperatures, separated by a boundary or they may be in direct contact.

Heat exchangers are the backbone of industry. Almost every industry needs the heat exchanger. So, it is

necessary to understand the classification of heat exchanger. So, we can classify heat exchangers as follows

Heat exchangers are classifiesd on the basis of:

Nature of Heat Exchange Process (direct contact or indirect contact)

Surface Compactness (compact or non-compact)

Process Function (cooler, heater, evaporator or condensers)

Heat Transfer mechanism , (single phase, multi-phase )

Relative direction of motion of fluids (parallel, counter and cross flows)

Mechanical design of heat exchange surface (tubular, plates and extended surfaces)

Number of Fluids

Physical state of heat exchanging fluids (condensation or evaporation)

How Energy Supplied

Nature of Heat Exchange Process

Indirect Contact Type

Recuperators Regenerative Heat Exchangers

Recuperators

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Classification of heat exchangers Page 3

In an indirect contact heat exchanger, the heat energy is exchanged between hot and cold fluids through a

heat transfer surface, i.e. a wall separating the fluids. The fluids flow simultaneously on either side of a

separating wall, the heat transfer, without mixing or physical contact with each other.

Heat is transfer by convection and conduction.

Examples: Concentric tubes heat exchangers, Extended surfaces heat exchangers, Shell and tube heat

exchangers etc.

Regenerative Heat Exchanger

The hot and cold fluids pass through the same channels in the packing, alternately, both fluids washing the

same surface area. Hence a fluid incoming to a process is heated using the energy contained in the fluid

exiting this process.

Direct Contact Type

Evaporative heat exchangersIn open heat exchanger, the heat transfer between the hot and cold fluids is brought about by their complete

physical mixing, there simultaneous transfer of heat and mass.

For example water cooling tower, jet condensers in steam power plants.

Classification on the basis of Flow arrangements

Single pass Heat Exchangers

A fluid is considered to have made one pass if it flows through a section of the heat exchanger through its full length

and leave through other end. These heat exchanger can be of

Co Current Flow Counter current Flow Cross flow

Classification on the basis of Construction

Concentric tube heat exchangers Extended surface heat exchangers Tubular heat exchangers

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Classification of heat exchangers Page 4

Compact heat exchangersPlate heat exchangers

Has a differences in

1. Types of plates used, and

2. In configurations of plates

3. Gasket Plate Heat Exchanger

Extended Surfaces

When additional metal pieces are attached to the ordinary heat transfer surfaces such as fins or appendages ,

they extend the surface area available for heat transfer

Gasket Plate Heat Exchanger

The plate-and-frame or gasketed plate heat exchanger consists of a number of thin rectangular metal plates

sealed around the edges by gaskets and held together in a frame.