An 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 decreases its density. An intercooler typically takes the form of a heat exchanger that removes waste heat in a gas compressor. Intercoolers have a variety of applications, and can be found, for instance, in air compressors, air conditioners, refrigeration, gas turbines, and automotive engines. They are widely known as an air-to-air or air-to-liquid cooler for forced induction (turbocharged or supercharged) internal combustion engines, used to improve volumetric efficiency. This is accomplished by increasing intake air density through nearly constant pressure cooling.