Comparative study of intermittent operating conditions for hybrid ground-source heat pump

Given the low thermal diffusivity and heat transfer rate of soil, the continuous operation of ground-source heat pump may result in heat accumulation in the soil. Intermittent operation could help heat recovery of the soil and increase the efficiency of the system. This paper used an office building in Wuhan as the research object to modify the conventional hybrid ground-source heat pump (HGSHP) system by creatively designing an intermittent operating condition for this system. The HGSHP system model was built up on Fluent, and one continuous and two intermittent operation conditions were simulated for three years. To get an intermittent control strategy that not only saves energy but also restores soil temperature, energy consumption between continuous and intermittent operating conditions were compared. The simulation results show that the soil heat accumulation problem can be solved under a reasonably designed intermittent operating method, and for buildings located in Wuhan, intermittent operating condition 2 is better than intermittent operating condition 1, and the payback period of the additional initial cost is six years under intermittent operating condition 2.