Comparative heating performance evaluation of hybrid ground-source heat pumps using serial and parallel configurations with the application of ground heat exchanger

Abstract

Hybrid ground-source heat pumps (HGSHPs) were introduced to prevent performance degradation under thermal imbalance between heating and cooling loads. However, the performance of an HGSHP with a parallel configuration has been rarely investigated in heating-dominated areas. In this study, the heating performances of HGSHPs with serial and parallel configurations are analyzed experimentally by varying the entering secondary fluid temperature (EFT) and flow rate of the supplementary heat exchanger as well as the ground temperature. Compared with the serial configuration, the parallel configuration demonstrates a 16.3% greater heating capacity and 12.6% higher coefficient of performance at an optimal flow rate of 10 LPM with an EFT and ground temperature of 19 degrees C and 14 degrees C, respectively. Moreover, for EFTs less than 22 degrees C, the parallel configuration demonstrates a reduced heat extraction rate from the ground as well as a higher exergy efficiency. Overall, the parallel configuration exhibits superior heating performance, even under severe ground thermal conditions.