Adsorption heat pumps
Adsorption heat pumps and chillers can be used for the supply of heat or cold where heat is available to drive a thermal compression process. This can be different kind of heat sources (e.g. solar thermal, heat from combustion processes (gas boiler, CHP) or waste heat from other sources). The temperature level that is necessary to drive the process (high temperature level) differs for different refrigerants and sorption materials used. Typical materials are silica gel, zeolite or active carbon that work with the refrigerants water, methanol or ammonia and allow a driving temperature of below 100 °C.
For the operation in heat pump mode, the useful energy is released at a medium temperature level whereas it has to be dumped via a re-cooler unit for an adsorption chiller. At a third – the low temperature level – either heat has to be supplied (e.g. from ambient air, brine or solar thermal) for the heat pump mode or is the useful energy for the chiller.
An animated operation principle of the process can be found here (only in German).