What Is Absorption Air Conditioning ?
The notable difference between an air conditioner and absorption chiller is that the former uses mechanical energy to function whereas absorption air conditioning is powered by heat energy. An a/c has a compressor to change the low temperature and low pressure vapor into high pressure and temperature. Absorption air conditioner uses chemical and generator to do so. Let’s see how?
When we talk of refrigerant, it is Freon that flashes before most of our mind. But absorption does not work with Freon. It uses a solution of water and ammonia or lithium bromide. A heat source is used to boil the solution. The heat sources that can be used are steam, geothermal heated, natural gas, kerosene, solar heated water, liquefied petroleum, water or resistance heating that utilizes electricity. Natural gas is commonly used. An advantage of using it is that it can be used in remote places where there is no electric power.
The Absorption System
An absorption system also has an evaporator and condenser coil just as a normal A/c does. The compressor is replaced by a generator, pump and an absorber. The heat source as already discussed above will boil this solution to increase its temperature and pressure. The boiling will separate the lithium bromide from water. The lithium bromide reaches the absorber. The water vapor goes to the condensing coil to get condensed at high temperature and pressure that will be released to outside surrounding. The liquid is forced to go through a valve where its pressure drops. With drop in pressure the temperature also drops. It then reaches the evaporator. Here it absorbs the heat from the room air that is passed over the coils. Absorption of heat causes the liquid to boil. The boiling liquid again goes to the absorber where it becomes liquid lithium bromide solution by mixing with lithium bromide. This cycle continues to provide cooling.
Advantages
• It has low operational cost
• It does not us CFC that harms the atmosphere(ozone layer); it is eco-friendly
• The process works well with solar energy and natural gas; it does not need electricity in that case.
However you have to get the unit serviced. The chemical ammonia is toxic and flammable when it gets diffused into the air. The unit should be checked for leakages from time to time. Ammonia and lithium bromide are also highly corrosive and reacts with some metals. The units should have pipes and fittings made of steel or aluminium to prevent this.