intercooling

Intercooling is the process of cooling the working fluid between successive compression stages in a multi-stage compressor or turbine. By reducing the temperature rise caused by compression, intercooling increases the gas density at the next stage, allows more mass to be compressed with less work, and lowers thermal stress on equipment. It is commonly implemented in both industrial compression systems and piston-engine supercharging or turbocharging setups. An intercooler is the heat exchanger used to achieve this cooling and can be air-to-air or liquid-to-air (water or glycol).

In internal combustion engines, intercooling (often called charge air cooling) places a heat exchanger between the compressor and the intake manifold. The cooler, denser air improves engine efficiency and power, and it reduces the tendency for knock in spark-ignition engines at higher boost. In diesel engines, intercooling helps maintain air density and can improve response and efficiency as well. Intercooling is also used in some gas turbine and compressor designs, though it is less common in modern simple-cycle turbines due to added complexity.

In refrigeration and heat pump cycles, intercooling refers to cooling the refrigerant between compression stages. This reduces the work required for subsequent stages and lowers discharge temperatures, contributing to higher overall cycle efficiency and component protection. Intercoolers are typically selected for their heat-exchange capability, pressure drop, and compatibility with the cooling medium.

Limitations of intercooling include added cost, weight, potential pressure losses, and space requirements. The performance gain depends on the operating conditions, such as compression ratio, ambient temperature, and available cooling power. Intercooling is most beneficial in high-boost or high-temperature applications where efficient air compression is critical.