The function of heat exchanger is to transfer heat efficiently and economically between two fluids. Heat is transferred from the fluid, which has higher temperature to the fluid, which has lower temperature. The modes of heat transfer are,
a. Conduction – Heat transfer in solids by momentum of molecules.
b. Convection – Heat transfer in liquids by movement of molecules.
c. Radiation – Heat transfer by energy waves.
There are three types of flow in heat exchangers
a. Parallel flow.
b. Counter flow.
c. Transverse flow.