TYPES OF HEAT EXCHANGERS ACCORDING

TO TRANSFER PROCESS

Classification of heat exchangers according to transfer process

• A heat exchanger is a device built to either eat or cool off elements by transferring heat from one medium to another, ideally liquid or gas.

• Heat exchangers are classified into direct contact type heat exchangers and indirect contact type heat exchangers in terms of their transfer process.

Direct Contact Type Heat Exchangers

• In these exchangers, two fluids come in a direct contact to exchange heat and then separate away.

• They are cost-effective, facilitate high heat transfer and easy installation.

• These devices have no separating wall, and avoid any foul behaviour.

• They are benign when the hot and cold fluids of the same fluid medium are at varying temperatures.

• Direct contact type heat exchangers are further classified into:

1. Immiscible fluid exchangers: The energy is transferred through straight contact of two immiscible fluids i.e. two non-mixing liquids together.

2. Gas - Liquid exchangers: These machines have one fluid media that is a gas while the other fluid being liquid, usually water.

3. Liquid Vapour exchangers: Heat transfer in them takes place by condensing a steam, entirely or partly by using water or by heating water through steam; both are carried out by direct contact.

Indirect Contact Type Heat Exchangers

• These heat exchangers are also known as surface heat exchangers.

• Two fluids, hot and cold, are kept physically separated from each other, with a metal wall, to avoid contamination of both.

• The heat, however, is transferred in an ephemeral way.

• They are divided into the following types:

1. Direct transfer type heat exchanger: Unceasing warmth is transported from hot to the cold fluid through a partition, with the two fluids flowing through separate channels.

2. Storage type heat exchanger: Two fluids flow alternatively in the same passage due to which the heat transfer is irregular.

3. Fluidized bed heat exchanger: They are two-fluid exchangers with a side immersed in a bed of finely distributed solid material.

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