Research On Operating Performance Of Ground Source Heat Pump Systems With Multiple Ground Heat Exchangers

This paper based on the research and analysis of the existing underground heatexchanger models, according to the theoretical model of inner heat source of undergroundheat exchanger and combined with a hotel building of the ground source heat pumpsystem in Wuhan, set up the multiple ground heat exchangers of the simulation model.Next using the TRNSYS (Transient System Simulation Program) to simulate and analyzethe building of the annual energy consumption, so as to get the building of the whole yearhourly dynamic load, In the dynamic load, the paper uses fluent software for the tool tosimulate and analyze the soil temperature field around the multiple ground heatexchangers, which run in continuous operation and intermittent operation two operationmodes in winter heating period.Then, simulating and analyzing the soil temperature fieldof the GSHP system under different ratios of operation/shutdown and different intermittentcycle operating conditions, in order to get optimization operation mode and realizelong-term,stable and high efficient operation of the GSHP system.Analysis results indicate: Intermittent operation condition relative to continuousoperation condition, in winter heating period the soil temperature field distribution is moreuniformly around the multiple ground heat exchangers soil, temperature decline is slowerand temperature variation affected area is bigger, Heat transfer ability is stronger, andrunning time of the system is longer. For this reason, it is more conducive to heat to spreadand heat transfer between the soil and the ground heat exchanger, also it is moreconducive to make full use of geothermal energy. When the system operates underdifferent ratios of operation/shutdown, the smaller the ratio of operation/shutdown, thesmaller the decline range soil temperature, and soil temperature distribution more even;When the system operates in different intermittent cycle operation modes, the smaller theintermittent cycle, the slower the soil temperature declines, the greater the single wellinfluence radius, also it has stronger ability of heat transfer. Therefore, small ratio ofoperation/shutdown and small intermittent cycle operation mode is more advantageous tothe long-term stability of the heat pump system operation and making use of thegeothermal energy fully. But this will lead to frequent switching and more complex control of the multiple ground heat exchangers. So we must control intermittent operationperiod of the ground source heat pump system effectively combined with practicalproblems, in order to realize the optimum operation.