中深层套管式地埋管换热器取热性能研究及经济性分析

Research on heat extraction performance of deep coaxial borehole heat exchanger and its economic analysis

使用FLUENT软件建立了中深层套管式地埋管换热器三维数值传热模型,基于正交试验极差法,分析了入口温度、埋深、内管径、岩土热导率、地温梯度对中深层套管式地埋管换热器换热性能的影响.结果表明:这五项因素对中深层套管式地埋管换热器换热性能的影响显著性依次为:埋深、地温梯度、入口温度、岩土热导率、内管径;其次基于平均能源成本法建立中深层套管式地埋管换热器经济性评价方法.研究结果表明:中深层套管式地埋管换热器的平均能源成本随埋深增加呈先下降后上升趋势,在选定参数条件下,2 500 m埋深的中深层套管式地埋管换热器平均能源成本最低、经济性最优,所使用方法及所得结论可为中深层套管式地埋管优化研究与工程应用提供参考.

The paper, FLUENT software is used to establish a three-dimensional numerical heat transfer model of deep coaxial borehole heat exchanger, and based on the orthogonal test range method, the effects of inlet temperature, buried depth, inner diameter, geotechnical thermal conductivity and geothermal gradient on the heat transfer performance of deep borehole heat exchanger are analyzed. The results show that the significant effects of these five factors on the heat transfer performance of deep coaxial borehole heat exchanger are as follows: buried depth, geothermal gradient, inlet temperature, geotechnical thermal conductivity and inner diameter. Then, based on the average energy cost method, the economic evaluation method for deep coaxial borehole heat exchanger is established. It is found that the average energy cost decreases first and then increases with the increment of buried depth. With the given parameters in this paper, the deep coaxial borehole heat exchanger with 2 500 m buried depth has the lowest average energy cost and the best economy. The methods and conclusions can provide reference for the optimization research and engineering application of the deep coaxial borehole heat exchanger.