Absorption Cooling
An absorption chiller is a refrigerator that uses a heat source (e.g. a CHP or a biomass boiler) to provide the energy needed to drive the cooling process instead of using electricity to run a compressor. When combined with CHP, this is referred to as Tri-generation.
An absorption chiller is in many ways similar to an ordinary compressor refrigerator where refrigeration takes place by evaporating a liquid with a very low (sub-zero) boiling point. In both cases, when a liquid evaporates or boils, it takes some heat away with it, resulting in cooling. This process continues either until the liquid is all boiled, or until everything has become so cold that the sub-zero boiling point has been reached. The difference lies in how the gas is changed back into a liquid so that it may be used again. An ordinary refrigerator uses a compressor to increase the pressure on the gas, forcing it to become a liquid again. An absorption chiller uses a method that requires no moving parts and is powered only by heat.
Compressor refrigerators typically use an HCFC, while absorption refrigerators typically use ammonia as a refrigerant.
Summary
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Heat-driven cooling process for space cooling applications
- Constraints: cannot do refrigeration cooling temperatures with ease, low coefficient of performance compared with other cooling technologies
- Advantages: can help create base heat demand for CHP technology in summer
- Typical Lifetime of 10-15 years
Examples
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Absorption cooling in Woking
- Tri-generation at Natural History Museum
Links
Technical summary and graph. Click here.
