竖进平出型地埋管群换热器结构与控制优化

Structure and Control Optimization of the Buried Pipe Group Heat Exchanger With Vertical Inlet and Flat Outlet

【目的】为提高浅层地热能利用效率,亟须对影响地源热泵系统性能的地埋管换热器结构和控制开展优化设计。【方法】建立了一种竖进平出型地埋管群换热器模型,研究其换热系统性能,探究其最佳结构及运行方式。【结果】管群布置横纵比越低,单位面积换热量越大,横纵比超过0.15后对系统影响较小;换热器间距越小,土壤利用率越高,但热短路损失越大;双列双出型埋管每延米换热量相较于双列单出型结构提升7%以上;负荷较大工况下叉排布置结构的换热效果更好;整个夏季优化结构的平均出口温度下降2.28℃,换热器周围土壤温度下降1℃以上;实际运行过程中应优先考虑采用流速随负荷变化控制模式。【结论】研究结果可为地源热泵换热器的设计、制造提供理论依据。

[Objectives]In order to improve the utilization efficiency of shallow geothermal energy,it is urgent to optimize the structure and control of ground heat exchanger,which affects the performance of ground source heat pump system.[Methods]A model of the buried pipe group heat exchanger with vertical inlet and flat outlet was established.Based on heat exchange system performance,the optimal structure and operation control mode were explored.[Results]The heat transfer per unit area increases with the decreasing of transverse longitudinal ratio of the pipe group arrangement.The effect is small when the transverse longitudinal ratio exceeds 0.15.The smaller the heat exchanger spacing is,the higher the soil utilization rate is,but the greater the thermal short-circuit loss is.Compared with the double-row singleoutlet type,the heat exchange per linear meter of the doublerow double-outlet type buried pipe is increased by more than 7%.The fork arrangement is better when the load is larger.The average outlet temperature of optimization structure in the whole summer is decreased by 2.28℃,and the soil temperature around the heat exchanger is decreased by more than 1℃.In the actual operation process,the control mode of the flow rate changing with load should be given priority.[Conclusions]The research results can provide a theoretical basis for the design and manufacture of ground source heat pump heat exchanger.