Performance analysis of a heat pump with desuperheater for residential buildings using different control and implementation strategies

In this study, an extensive analysis of a desuperheater (DES) applied in a combined solar and air-source heat pump (ASHP) system for a residential low heating energy building (45 kW h/(m2 a)) is carried out using the climatic conditions of Graz. The heat pump system uses R410A as refrigerant and has a heating capacity of 4.9 kW (@ A-12W35). The main focus of the investigation lies on the analysis of five different control strategies and types of integration of the DES into the system. For the investigations a validated TRNSYS heat pump model is implemented into a system simulation model, which comprises a buffer storage, a thermal solar collector and the heat distribution and heat dissipation system.

The results show energy saving potentials by applying a DES compared to the reference system without DES. This is mainly due to the lower amount of heat provided for “direct” domestic hot water (DHW) preparation by the heat pump. The results for the investigated control strategies show a maximum increase of the seasonal performance factor (SPF) and electrical energy savings of 5.3% and 5.0%, respectively, for an extra hydraulic loop of the DES with its own circulation pump. The other four strategies show annual electrical energy savings of about 4% compared to the reference system without DES.