Mechanism And Principle Of Air Conditioning

Ever wondered how you get cool breeze from air conditioner. What is the mechanism actually involved in producing cold air in burning hot summers? Here is the simple diagrammatic explanation of working principle of an air conditioner. No matter what type of air conditioner you are using, windowed, split wall mounted (PTAC), cabinet floor standing or roof top type, basic principle is same for all of them. Even inverter air conditioner that has got modifications in primitive design still follows the same principle and laws of thermodynamics.

Basic Mechanism And Principle

Explanation:   Every air conditioner (also pronounced as AC, A/C or Air Cooler in certain regions of the world) has got a compressor inside it. It works to compress and pump the refrigerant gas. Compression of refrigerant produces heat. To dissipate this heat, compressed refrigerant is pumped to the condenser coils where a fan blows the heat out to outer atmosphere. During this process, refrigerant takes the liquid form. This liquid refrigerant is pumped towards expansion valve. Expansion valve has a temperature sensor connected to it which works in correlation with thermostat settings. Expansion valve releases the appropriate amount of refrigerant to evaporator (cooling coils) where liquefied refrigerant takes gaseous form. Conversion from liquid to gaseous state due to expansion causes cooling because energy is absorbed from the surrounding. Air when passes through fins (attached to coils) gets cooled and blown to the room. The gaseous refrigerant in cooling coils then enters the compressor and gets compressed once again. The cycle continues unless the compressor is shut down.

In a nutshell, air conditioner draws heat from the indoor and releases it to the outdoor. Indoor acts as a source and outdoor as a sink for heat.

In vehicle air conditioners, a Receiver-Drier is installed between condenser and expansion valve. It serves to collect excessive refrigerant when not required for cooling operation. It also has got a desiccant which absorbs any moisture present in the refrigerant.

Inverter air conditioners:   These air conditioners use an inverter to control the speed of compressor. Electricity is first rectified to DC (direct current) and then inverted back to required frequency AC (alternating current) using pulse width modulation. Thus compressor speed can increase and decrease according to the room temperature. Such air conditioners are extremely energy efficient and consume approximately 30-60 % less electricity than old fashioned air conditioners. Inverter air conditioners are expensive due to the additional machinery inside them but cost is slowly recovered in electricity bills. Their other advantages include quiet operation, faster cooling, no indoor temperature fluctuations and no voltage peaks caused by compressor.

Air conditioner as a heater:   When air conditioner is used as a heater, the process which is shown and explained above just simply gets reversed. As a result of reverse mechanism, hot air is propelled towards indoor and cool air towards outdoor.


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