Air Conditioner

Air conditioners often use a fan to distribute the conditioned air to an enclosed space such as a building or a car to improve thermal comfort and indoor air quality. Electric refrigerant-based AC units range from small units that can cool a small bedroom, which can be carried by a single adult, to massive units installed on the roof of office towers that can cool an entire building. The cooling is typically achieved through a refrigeration cycle, but sometimes a passive cooling system such as evaporation or free cooling is used. Air conditioning systems can also be made based on desiccants (chemicals that remove moisture from the air). Some AC systems reject or store heat in subterranean pipes.