Study on intermittent operation strategies of a hybrid ground-source heat pump system with double-cooling towers for hotel buildings

This study proposes intermittent operation strategies of a hybrid ground-source heat pump (HGSHP) system with double-cooling towers. The program aims at solving the problem of soil heat accumulation and optimizing the heat pump systems, that is, operating efficiently while reducing operating costs. The annual dynamic load of a hotel in Wuhan was calculated by Designer's Simulation Toolkit (DeST) software, and a GSHP system of the hotel was designed. The HGSHP model was constructed by TRNSYS. On the basis of hotel load patterns, four operating conditions were designed for this system including one continuous condition and three intermittent conditions conducted 20 years simulation. Several performance parameters of the HGSHP under four operating conditions were studied. These parameters included the following: average soil temperature, energy consumption, electricity fees reduction and investment payback period. Simulation results indicated that the proposed intermittent operation strategies evidently alleviated soil heat accumulation. The optimal intermittent operating condition that favors both energy consumption reduction and soil temperature recovery was found. For hotel buildings in cooling-dominated areas, the third intermittent operating condition was the optimal one among the three conditions, with an investment payback period of three years.