Compressor cooling

Air or gas compression causes temperature increase which become high enough to cause trouble with the lubrication of the cylinder piston and packings.

Cooling  of the air and of the compressor cylinder reduce this problem and also the required work of compressions,approaching  the minimum of an isothermal process.

WHAT IS ISOTHERMAL PROCESS

an isothermal process is, thermodynamic process in which the temperature of a system remains constant. The transfer of heat into or out of the system happens so slowly that thermal equilibrium is maintained. At a particular constant temperature, the change of a substance, object or system is known as Isothermal Process. 

In general, during an isothermal process there is a change in internal energy, heat energy, and work, even though the temperature remains the same. Something in the system works to maintain that equal temperature.

This may be done by circulating atmospheric air or water over the cylinders.

another method is to compress the air only part way to its final pressure, extract some of the heat and then compress it to the final pressure. this is accomplished by passing the air through an intercooler, using air or water as a cooling medium.

(Intercooler is a mechanical device used to cool a gas after compression. Compressing a gas increases its internal energy which in turn raises its temperature and reduces its density. An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor.)

air cooled intercooler may consist of a small number of finned  tubes through which air under pressure passes. it may be of radiator type with many tubes.

A water-cooled intercooler consists of a nest of tubes through which air or water passes. the nest is enclosed in a shell or housing. 

The compressed air in some intercoolers passes over the outside of the tubes through a series of baffles to assure   maximum contact with cooling surfaces of the tubes.in other words the air passes inside the tubes and the coolant is outside.

WHAT IS THE DIFFERENCE BETWEEN AFTERCOOLER AND INTERCOOLER

While an aftercooler is a heat exchanger that operates by cooling the air emerging from a compression unit, an intercooler is a device attached to an air compressor that cools the air before engine intake.

An intercooler is usually used in turbocharged engines to provide cooling to compressed air before it enters the engine circulation. By functioning as an intake air cooling unit, an intercooler permits the supply of more air to the engine by increasing the air’s density which in turn boosts its overall efficiency and power output.

An aftercooler is a mechanical cooling unit that operates on the principles of heat exchange between two mediums usually water and air. Aftercooler units can be used to attain temperatures between 5-20°F immediately after compressed air is released from the compression unit.

An aftercooler is a heat exchanger used in turbocharged engines (after the compressor) to cool the compressed air off back to near ambient temperature as soon as it is discharged from the compressor. It uses ambient air to condense out moisture in the compressed air. This condensation process also helps to cool the air. An intercooler is a mechanical device used commonly on turbocharged and supercharged engines for intake air cooling. It cools air that has been compressed by either a turbocharger or a supercharger. It increases air density, which increases both the maximum power output and efficiency of the engine.