中深层套管换热器分段传热解析模型构建  

The Heat Transfer Model of Medium-depth Downhole Coaxial Heat Exchanger Based on the Piecewise Analytical Solution

作　　者：马凌 赵亚洲[2] 许文杰 尹洪梅 杨轩 赵军[1] MA Ling;ZHAO Yazhou;XU Wenjie;YIN Hongmei;YANG Xuan;ZHAO Jun(Key Laboratory of Efficient Utilization of Low and Medium Grade Energy(Tianjin University),Ministry of Education of China,Tianjin 300350,China;Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing100029,China)

机构地区：[1]中低温热能高效利用教育部重点实验室(天津大学),天津300350 [2]中国科学院地质与地球物理研究所页岩气与地质工程重点实验室,北京100029

出　　处：《工程热物理学报》2023年第1期217-225,共9页Journal of Engineering Thermophysics

基　　金：天津市重点研发计划项目(No.17YFZCGX00580)。

摘　　要：基于时间和空间尺度的分段计算方法,建立了中深层套管换热器传热理论解析模型,并结合文献工程案例进行了验证,对雷诺数、地温梯度和供水温度三个关键参数进行分析,提出了吸热效率η作为新的传热性能评价指标。结果表明,η随雷诺数从0.90×10^(4)增至8.10×10^(4)提升了36.26%,但随地温梯度和供水温度的变化很小;降低供水温度、增加地温梯度与雷诺数都可以提升每米孔深换热量ql,但雷诺数增加引起的ql提升幅度逐渐减小;不同工况下ql的变化范围为54.83~117.17 W·m^(-1)。To describe the heat transfer processes of medium-depth downhole coaxial heat exchangers (MDCHEs) effectively,an analytical solution that couples the transient heat conduction in surrounding soil (or rock) with the quasi-steady heat transfer process in borehole was developed in this study.The proposed model was validated with reported experiments,and the heat extraction efficiency was defined for comprehensive evaluation of heat transfer performance of MDCHEs.In addition,the impacts of Reynolds number,geothermal temperature gradient and inlet fluid temperature on the heat transfer performance of MDCHEs were analyzed.It is found that the heat extraction efficiency of MDCHEs increased by 36.26% with the Reynolds numbers increasing from 0.90×10^(4)to 8.10×10^(4),but varied slightly with the geothermal temperature gradient and the inlet fluid temperature.The decrease of the inlet fluid temperature and the increases of the geothermal temperature gradient and Reynolds number could increase the heat flux per unit length of MDCHE ql,while the increments caused by the Reynolds number declined gradually.Under different operation conditions,the heat flux per unit length of MDCHE qlranged from 54.83 W·m^(-1)to 117.17W·m^(-1).

关 键 词：地热能 中深层套管换热器 解析解 分段计算 吸热效率 

分 类 号：TK259[动力工程及工程热物理—动力机械及工程]