There are three main types of gas air-conditioning cycles used today: compression, absorption, and dehumidification.
In both compression and absorption cycles, air temperature and humidity are tailored to meet variations in surrounding air conditions and changes in room occupancy. Both of these cycles evaporate and condense a refrigerant. They require energy for operation. Mechanical energy is used in the compression type. Heat energy is used in the absorption type. The dehumidification cycle is used primarily in industrial and commercial applications. Dehumidification reduces the moisture content of the air.