Study on Operating and Control Strategies for Hybrid Ground Source Heat Pump System

Abstract

The application of hybrid ground source heat pump (HGSHP) system with cooling tower as supplemental heat rejecter is popular in the cooling-dominated area, which can mitigate the heat accumulation effect in the soil and improve the system performance. In this paper, three common operating and control strategies of the HGSHP system were analysed for optimizing selection. Simulation models of the compound ground source heat pump system were established in order to quantify the effects of different control strategies on the system performance. A comparative study was presented to investigate the advantages and drawbacks of various operating strategies in a HGSHP system using cooling tower as supplemental heat rejection based on this simulation model. An actual small office building in Shanghai was employed as the research object. The conclusion is drawn that taking the fluid temperature in the inlet of the ground-loop heat exchanger as the main control parameter while the difference between the outlet fluid temperature of heat pump and the local wet-bulb temperature as the subordinate control parameter is the best way to optimize the performance of HGSHP system.