套管式地埋管换热器设计计算方法

 以线热源理论为基础建立套管式地埋管换热器换热的简化模型,给出基于热响应试验的套管式换热器设计计算方法。以湖南省韶山市一实际工程为实例对钻孔现场进行测试,采用该方法可计算出其综合导热系数和钻孔内总热阻。同时对该工程的另一钻孔进行双U测试及计算,以此作对比分析。考察两组测试在综合导热系数、钻孔内总热阻、换热温差和换热量上的内在联系。计算结果和测试结果表明,该计算方法在套管式换热器设计上具有适用性,避开了钻孔内层层热阻的复杂计算,简化了计算过程,可为实际工程提供计算参考。

Design Calculation Methods of Coaxial Pipe Type Ground Heat Exchanger

In this paper, a simplified model of the coaxial pipe type ground heat exchanger is built based on the theory of the line heat source and a design method of the coaxial pipe type heat exchanger based on the thermal response test is proposed. The method is used to obtain the complex thermal conductivity coefficient and the total thermal resistance of a borehole of a practical project in Shaoshan of Hunan Province, and the results are compared with test values. Meanwhile, the complex thermal conductivity coefficient and the total thermal resistance of another borehole of a double-U pipe in the same project is also tested and calculated for a comparison. The calculation method is proved to be applicable for the coaxial pipe type ground heat exchanger by analyzing the intrinsic relationship of the two tests with respect to the complex thermal conductivity coefficient, the total thermal resistance, the temperature difference of the heat transfer and the heat transfer rate. With this method, the complicated calculation of the thermal resistance of the inner layer of the borehole can be avoided and therefore, the calculating process is simplified. This method can be used for practical projects.