Heat Pumps – Gas – Absorption
Gas-fired absorption heat pumps are a relatively new technology that employs the same absorption cycle as the more established gas absorption chillers. What makes the gas heat pump a commercially viable option is the development, by Robur, of a valve that reverses flow to six circuits, adding the heating component to a previously cooling only technology. In addition to residential homes, the gas-fired absorption heat pump can be used in light commercial and industrial applications, or up to five units can be piped into modular configurations to satisfy greater heating and cooling requirements.
How It Works
Like absorption cooling equipment (see Absorption Chillers for a description of the absorption cycle), gas absorption heat pumps employ the principles of boiling a solution, condensation, evaporation and absorption to produce chilled water down to 37.4°F, which is circulated through cooling coils indoors. The solution used in the system can consist of water or ammonia as the refrigerant and lithium bromide or ammonia as the absorbent—all environmentally safe elements. In heating mode, the single effect GAX cycle (generator absorber heat exchanger) is reversed with the aid of the valve to supply 140°F to 149°F hot water for heating.
Thermodynamic cycle in heating mode of the GAHP-AR reversible heat pumps – Robur
Robur, manufacturer of the gas absorption heat pump, offers two models: the GAHP Line AR Series is an air-source heat pump and the GAHP Line W Series can extract heat from either the ground or water. Unlike vapor compression systems using a motor-driven compressor, the gas heat pump uses heat exchangers and only a few moving parts, decreasing the risk of failure and increasing equipment life and reliability.
The gas heat pump boasts heating efficiencies up to 150% and as high as 100% when the ambient temperature falls to minus 4°F. Only minimal electricity is required—about 20% that of an equivalent size electric compressor driven unit.