| Ground source heat pump(GSHP) have been recognized extensively as energy saving, high efficiency and environmental protection technology for air-conditioning systems in public and residential buildings. For the regions, where the buildings have different in cooling and heating load, so the heat getting through ground heat exchangers(GHE) of GSHP has great difference between the releasing into soil and extracting from the soil all the year round. Such as Chongqing in hot summer and cold winter areas, because the building cooling load in summer is more than the heating load in winter. It's easy to accumulate heat in the soil, so that the soil temperature around ground heat exchangers increase slowly rise with the running time and heat pump system is caused by a drop in performance. This paper is aimed to analyze and research underground temperature field change in the whole dynamic load function of GSHP systems in hot summer and cold winter areas, confirm the heat transfer model of vertical ground heat exchangers and calculation method of the design& simulation for GSHP systems and present system optimization design.In order to analysis and simulate, this paper has used Visual C# language to make visualization software of ground heat exchanger design and calculation, dynamic simulation of GSHP system, calculation of geo-thermal response test and zoning control simulation of GHE with the help of Visual Studio development platform.Firstly, heat transfer model of ground heat exchanger has been analyzed, and the design and calculation module of ground heat exchanger has been compiled to compare and analyze calculation methods of several typical the drilling thermal resistance using vertical double u-shaped GHE for analysis object ,combining with engineering design, and the best ground heat exchanger design model the was presented.Then, based on a line-source of finite length model outside the borehole and a quasi-three-dimensional model inside the borehole. The building dynamic load and dynamic performance of GHE have been set up coupling relationship, and dynamic simulation module of GSHP system has been compiled to compare the underground temperature field between traditional and composite GSHP system under the action of the dynamic load function in 1 year and 10 years, evaluate system's performance evaluation, give the analysis how imbalance of cold and heat of GSHP system influence the system life cycle. According to the heat source theory presented in《Specification of GSHP Engineering Technical》, calculation module of geo-thermal response test has been compiled based on the parameter estimation method. And combining with actual engineering, geo-thermal response test has been done to analyze variation law of the circulating water temperature in GHE with time. And then the thermal physical of soil has been analyzed and calculated, with variance of the fluid average temperature getting from the theoretical calculation and field measurement for objective function.Finally, three kinds of zoning control strategy of GHE have been presented: load control, time control and temperature control. The zoning control simulation module of GHE has been compiled, and then analysis of underground temperature changes and energy consumption situation under different operation modes has been given from dynamic simulation all year round, the best design scheme of zone control has been seek. |
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