How Air Conditioners Work

Ahmed M. Rahman

An Air conditioner is a common electronic device. It used offices and home in everywhere, especially in the tropical region. An air conditioner (often referred to as AC) is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle. In construction, a complete system of heating, ventilation and air conditioning is referred to as “HVAC”.In 1758, Benjamin Franklin and John Hadley, professor of chemistry at Cambridge University, conducted an experiment to explore the principle of evaporation as a means to rapidly cool an object. Franklin and Hadley confirmed that evaporation of highly volatile liquids such as alcohol and ether could be used to drive down the temperature of an object past the freezing point of water. They conducted their experiment with the bulb of a mercury thermometer as their object and with a bellows used to “quicken” the evaporation; they lowered the temperature of the thermometer bulb to -14 °C (7 °F) while the ambient temperature was 18 °C (64 °F). In 1820, British scientist and inventor Michael Faraday discovered that compressing and liquefying ammonia could chill air when the liquefied ammonia was allowed to evaporate.
Air conditioners employ the same operating principles and basic components as your home refrigerator. Refrigerators use energy (usually electricity) to transfer heat from the cool interior of the refrigerator to the relatively warm surroundings of your home; likewise, an air conditioner uses energy to transfer heat from the interior of your home to the relatively warm outside environment.
An air conditioner cools your home with a cold indoor coil called the evaporator. The condenser, a hot outdoor coil, releases the collected heat outside. The evaporator and condenser coils are serpentine tubing surrounded by aluminum fins. This tubing is usually made of copper.
A pump, called the compressor, moves a heat transfer fluid (or refrigerant) between the evaporator and the condenser. The pump forces the refrigerant through the circuit of tubing and fins in the coils.
The liquid refrigerant evaporates in the indoor evaporator coil, pulling heat out of indoor air and thereby cooling your home. The hot refrigerant gas is pumped outdoors into the condenser where it reverts back to a liquid, giving up its heat to the outside air flowing over the condenser’s metal tubing and fins.
Throughout the second half of the 20th century, nearly all air conditioners used chlorofluorocarbons (CFCs) as their refrigerant, but because these chemicals are damaging to Earth’s ozone layer, CFC production stopped in the United States in 1995. Nearly all air conditioning systems now employ halogenated chlorofluorocarbons (HCFCs) as a refrigerant, but these are also being gradually phased out, with most production and importing stopped by 2020 and all production and importing stopped by 2030.
Production and importing of today’s main refrigerant for home air conditioners, HCFC-22 (also called R-22), has begin to be phased out in 2010 and will stop entirely by 2020. However, HCFC-22 is expected to be available for many years as it is recovered from old systems that are taken out of service.