Simulation of a Combined Heating, Cooling and Domestic Hot Water System Based on Ground Source Absorption Heat Pump

Ground source electrical heat pump (GSEHP) is extensively used as renewable energy technology over the world. However, in heating-dominated buildings, the ground thermal imbalance will lead to the decrease of soil temperature and deterioration of heating performance. The heating/cooling system based on ground source absorption heat pump (GSAHP) can reduce the ground thermal imbalance in cold regions. However, in some areas of cold region, the imbalance is still very obvious. A novel combined heating/cooling/domestic hot water (DHW) system is put forward to solve this problem. Performance of GSAHP using generator-absorber heat exchange (GAX) cycle is simulated under various working conditions. Combined systems based on GSAHP and GSEHP are comparatively simulated in TRNSYS. The thermal imbalance ratio, soil temperature variation, heat recovery and primary energy efficiency are analyzed. Results show that the thermal imbalance ratio of GSEHP is as negative as -77.0%, and can be reduced to -14.8% by GSAHP in Beijing. Besides, the annual variation of soil temperature is only 0.5°C for GSAHP, while it is 3.0°C for GSEHP. Moreover, the heat recovered by DHW in summer is in the range of 30.0~36.8kW and amounts to 71144kWh totally. COP of GSAHP is approximate 1.90 for heating, 1.28 for cooling, and 1.80~2.25 for DHW, while the primary energy efficiency can reach 151.3%. The combined heating/cooling/DHW system based on GSAHP is promising in reducing the thermal imbalance generally existing in GSHP systems.