The absorption cycle relies on transferring thermal energy from the heat source to the heat sink via an absorbent and refrigerant fluid. Currently, there are six manufacturers of absorption chillers in the United States. Natural gas chillers are available in sizes from 3.5 and 1,660 refrigerant tons. This low temperature is transmitted to the chilled water that returns to the building. As the concentrated solution of lithium-bromide absorbs more refrigerant vapor, it dilutes and loses its affinity for the refrigerant vapor.
Natural gas is relatively inexpensive in most parts of the country.
Since peak demands for natural gas occur in cold winter months, there is an ample capacity of natural gas that is not being utilized in the summer. Although natural gas absorption cooling technologies have progressed in recent years, they still have a few critical downfalls that often make electric cooling more attractive. Electric centrifugal units can obtain COPs of up to 6.0. Gas absorption chillers generally cost 1.5 to 2.5 times that of electric chillers and often require larger cooling towers and pump modifications. With high initial cost and comparably low system efficiency, natural gas absorption chillers are only economically feasible in areas with high electrical demand rates, low natural gas summer rates and rebate and incentive plans offered by local gas utility companies.