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How does Absorption Chillers work?
One of the oldest methods to mechanically cool a space is with absorption technology. It seems unreasonable to burn a flame to produce cooling, but that is what happens inside an absorption chiller.
Absorption cooling uses a thermo chemical "compressor" and makes use of the property of certain materials to be chemically drawn to dissolve in one another. Two fluids are used: a refrigerant and an absorbent. The refrigerant changes phase and circulates through the entire system. Two common refrigerant/absorbent combinations are water and lithium bromide solution because its extremely hygroscopic
A regular refrigerator uses a compressor to increase the pressure on the gas, forcing it to become a liquid again. An absorption refrigerator uses a different method that requires no moving parts and is powered only by heat, a thermal compressor that consists of an absorber, a generator, a pump, and a throttling device, and replaces the mechanical vapor compressor.
The refrigerant used is actually water, as that is the working medium that experiences a phase change that causes the cooling affect.
The second fluid that drives the process is a salt, generally lithium bromide. Heat is used to separate the two fluids; when they are brought back together in a near vacuum environment, the water experiences a phase change to remix with the salt at a very low temperature (at normal atmosphere pressure, water vaporizes at 212F; in an absorber, water vaporizes cold enough to produce 46F chilled water.)
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| Chemical compressor |
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| Applications |
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Large Tonnage Space Cooling
Industrial Process Cooling
Cogeneration and Trigeneration.
Waste Heat utilization
Waste-to-Energy utilization |
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