Simulation Study of Single-Adsorber Heat Pump Cycle with Heat Recovery Through Stratified Storage in Both Adsorber and Evaporator/Condenser Loops

A modified single-adsorber cycle for a gas-fired adsorption heat pump (GAHP) is described and analyzed through dynamic simulation with Modelica. The adsorption modules are based on the SAPO-34 / water working pair with parameters taken from a recent R&D project. A stratified storage integrated into the primary heat pump loop is employed for heat recovery of the adsorber as well as the EC heat exchanger (functioning both as an evaporator and condenser). A heating system of a stock multifamily residential building in Germany is assumed as the load to be covered by the heat pump. Representative load points according to VDI 4650-2 and DIN EN 12309-6 rules are considered. The hydraulic system design and implications of the storage integration on degrees of freedom during operation are discussed. The results show that, for a well-stratified storage, similar COP values to a dual-adsorber heat pump cycle based on the same adsorption module type are achievable. Possible additional benefits of the storage are discussed.