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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.