Performance Analysis of Flow Control in a Ground Source Heat Pump Using a Heat Pump Simulator

This study investigates the performance of a ground source heat pump (GSHP) system using variable-flow control based on the temperature difference between the source-side inlet and outlet (ΔT), which is affected by the entering water temperature (EWT) and flow rate. A laboratory-scale test facility equipped with a thermostatic bath was utilized to analyze the coefficient of performance (COP) during both cooling and heating operations. A regression-based model for predicting COP was developed from the experimental data. The findings revealed that, under the same EWT conditions, increasing the flow rate gradually improved the COP, particularly in high-efficiency operating regions. Using the developed model, a 10-year long-term simulation was conducted to assess system-level performance. The optimal ΔT values for minimizing total energy consumption were found to be ΔT = 5℃ in cooling mode and ΔT = 4℃ in heating mode. Notably, increasing ΔT during cooling significantly reduced circulation pump power consumption, leading to enhanced overall system efficiency.