Comparative study on a solar-assisted ground source heat pump with CPC solar collector and phase change heat storage

To address the challenges of low solar energy utilization, soil temperature imbalance, and excessive energy consumption in traditional heating systems, a novel solar-assisted ground source heat pump (SAGSHP) with phase change heat storage is proposed. It integrates a compound parabolic concentrator (CPC) solar collector and a buried pipe heat exchanger for combined heating, using RT52, Na₂S₂O₃·5H₂O, and paraffin as phase change materials (PCM) to store excess heat. A TRNSYS model is developed to analyze its performance under different CPC concentration ratios and PCM configurations. Results show that the CPC collector can save approximately 33 % collection area compared to evacuated tube and flat plate collectors, with heat collection efficiencies of 75.5 % and 65.1 % at 2 times and 5 times of the concentration ratios, respectively. The SAGSHP reduces annual energy consumption by about 2000 kWh and improves the average soil temperature stability. The heating time corresponding to RT52, Na2S2O3·5H2O, and Paraffin is 123.75 h, 80.75 h and 75 h, respectively. The average coefficient of performance of SAGSHP with RT52 reaches 3.096, and the energy consumption is reduced by about 24.3 % after ten-year operation. Results confirms the SAGSHP's potential to enhance heating efficiency, optimize solar energy use, and save energy in long-term operation.