Introduction of Air Conditioning

The term air conditioning most commonly refers to the cooling and dehumidification of indoor air for thermal comfort. In a broader sense, the term can refer to any form of heating, ventilation, coolin disinfection that modifies the condition of air. An air conditoner is an appliance, mechanism or system designed to extract heat from an area, typically using a refrigeration cycle but sometimes using evaporation, most commonly for comfort cooling in buildings and transportation vehicles.

The concept of air conditioning is known to have been applied in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th Century, and the first large-scale electrical air conditioning was invented and used in 1902 by W.H Carrier.

Introduction Refrigeration

Refrigeration is the process of removing heat from an enclosed space, or from a substance, and rejecting it elsewhere for the primary purpose of lowering the temperature of the enclosed space or substance and then maintaining that lower temperature. The term cooling refers generally to any natural or artificial process by which heat is dissipated. The process of artificially producing extreme cold temperatures is referred to as cryogenics.

Cold is the absence of heat, hence in order to reduce a temperature, one does not "add cold", rather one "removes heat." In order to satisfy the Second Law of Thermodynamics, some form of work must be performed to accomplish this. This work is traditionally done by mechanical work but can also be done by magnetism, laser or other means. However, all refrigeration uses the three basic methods of heat transfer : radiation, convection, or conduction.