Simulation Study on the System Performance of Solar-Ground Source Heat Pump Using Return Water of the District Heating Network as Supplementary Heating

Abstract

To alleviate the pressure on the district heating network and address the soil thermal imbalance issue of the ground source heat pump, a solar-ground source heat pump system using return water of the district heating network as supplementary heating(SGSHPS-DHNSH)has been proposed. This system compared with parallel and series connections of solar energy and geothermal heat pump systems for simulation and analysis. The results show that can increase the evaporator temperature while storing heat in the buried pipe. The soil temperature of SGSHPS-DHNSH only decreased by 0.16 °C, which is 8% and 9.8% lower than that of the series and parallel system, respectively. The evaporator inlet temperature remains above 14.77°C, which is 6.7°C and 5.3°C higher than the series and parallel systems, respectively. The system COP is improved by 20% and 13.7% compared to the series and parallel systems, respectively. The total energy consumption of the system during the heating season is 63 MW.h, which is reduced by 24% and 19% compared to the series and parallel systems, respectively. SGSHPS-DHNSH has a significant effect on improving system performance and eliminating the soil thermal imbalance caused by the operation of solar-assisted ground source heat pumps.

Keywords: Waste heat recovery, Heat storage, Multi-source heat pumps, Renewable energy utilization