Study On Intermittent Operation Of Hybrid Ground-source Heat Pump System

Ground Source Heat Pump uses renewable geothermal energy for cooling andheating, this new technology is characterized by energy-saving and environmentalprotection. In areas like Wuhan, the issue of soil heat accumulation is serious，after thesystem run several years, which will increase the soil temperature and decrease theefficiency of the heat pump. How to solve this problem can effectively improve theefficiency of heat pump system.In this study, a new solution to the heat accumulation was proposed. Intermittentoperation between ground heat exchanger (GHE) and cooling tower can solve thisproblem. The effect of intermittent operation on office building was evaluated.Intermittent operation of hybrid ground source heat pump (HGSHP) is conducive to therecovery of the soil temperature, what’s more, which can also increase the heat transfer ofsoil and raise efficiency of heat pump. In order to study the effect of intermittent operation,a HGSHP system was designed for an office building. In addition to the HGSHP system,an extra cooling tower was chosen, whose capacity was equal to the GHE, so that thesystem can run regularly when the GHE didn’t work. On this basis two intermittentoperating conditions were designed and a HGSHP model was established by Fluent, thenthe continuous operation strategy and two intermittent operation strategies were simulatedfor three years.Simulation results showed that, under the condition of two intermittent operations,the exiting fluid temperatures were lower and the efficiency of heat pump was higher.Intermittent operation of HGSHP can solve the issue of heat accumulation and saveoperating costs, which is conducive to long-term stable operation of the system. Theresults from this study have some reference value in practical engineering.