套管式地埋管换热器传热模型研究

Study on heat transfer model of coaxial borehole ground heat exchangers

传热模型是套管式地埋管换热器设计和模拟的重要依据,现有套管式地埋管换热器传热模型存在精度低或计算时间较长的问题。提出了一种新的套管式地埋管换热器传热模型:采用热阻热容模型分析钻孔内的二维(径向和轴向)传热,采用无限柱热源模型分析钻孔外的一维(径向)传热。将该模型应用于一个分布式热响应测试,并将模拟结果与实验数据及其他模型结果进行了对比。结果显示,该模型的计算结果与实验结果吻合较好,所计算的短时间内的流体温度分布及进出口流体温度具有较高的精度。

Heat transfer model is an important basis for the design and simulation of coaxial borehole heat exchangers,however,the existing heat transfer models of coaxial borehole heat exchangers have some disadvantages,such as low precision or too much computation time.A new heat transfer model of coaxial borehole heat exchangers is proposed,in which two-dimensional(radial and axial)heat transfer in the borehole is analysed by the thermal resistance and capacity model,and one-dimensional(radial)heat transfer outside the borehole is analysed by the infinite cylindrical-source model.The model is applied to a distributed thermal response test,and the simulation results are compared with the experimental data and the results of another model.The results show that the calculation results of the model match better with the experimental data,and that the short-time fluid temperature distribution and inlet and outlet fluid temperatures calculated by the model have high precision.