Dynamic simulation during summer of a reversible multi-function heat pump with condensation-heat recovery

A numerical code for the hourly simulation of reversible electric air-to-water heat pumps has been implemented. It applies to reversible multi-function heat pumps, which, during summer, are used for both space cooling and domestic hot water (DHW) production, with recovery of the condensation heat to produce DHW while cooling. The method can be used both for on-off heat pumps and for inverter-driven ones, coupled with storage tanks for air-conditioning and for DHW production, and integrated by a gas boiler for DHW. The numerical code has been used to evaluate the summer performance of the multi-function inverter-driven heat pump employed in the retrofit of a residential building in Bologna (North-Center Italy). The results show a 30% seasonal saving in non-renewable primary energy with respect to a traditional solution, where the heat pump provides only air-cooling and the gas boiler provides DHW. A validation of the code by comparison with TRNSYS, in the case of cooling-only operation, is provided.