分层岩土中地埋管换热器传热解析模型与分析  

ANALYTICAL MODE AND ANALYSIS OF HEAT TRANSFER OF GROUND HEAT EXCHANGERS IN LAYERED STRATUM

作　　者：张琳邡 张东海 周扬[2,3] 高蓬辉 赵鹏[3] 李晓昭 Zhang Linfang;Zhang Donghai;Zhou Yang;Gao Penghui;Zhao Peng;Li Xiaozhao(Xuhai College,China University of Mining and Technology,Xuzhou 221008,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China;State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China)

机构地区：[1]中国矿业大学徐海学院,徐州221008 [2]中国矿业大学力学与土木工程学院,徐州221116 [3]中国矿业大学深部岩土力学与地下工程国家重点实验室,徐州221116

出　　处：《太阳能学报》2022年第10期378-385,共8页Acta Energiae Solaris Sinica

基　　金：江苏省高等学校自然科学研究面上项目(20KJD560008);国家自然科学基金项目(51876218);江苏省重点研发计划(BE2020038)。

摘　　要：为准确预测地埋管换热器在分层岩土中的传热特征,采用分离变量法和格林函数法,基于单个圆环热源基本传热单元问题的解答,建立考虑岩土结构分层和横观各项同性特征的地埋管传热解析模型。该模型适用于工程中常见的垂直钻孔和桩基埋管换热器分层传热问题,具有较好的普适性。以2层岩土为例,利用模型解答对分层岩土中地埋管的传热特征以及分层参数对其影响规律进行研究。结果表明:均匀介质假设计算误差随作用时间的增加而逐渐增大,在靠近热源处误差更加明显,预测地埋管长时间温度响应时,应采用分层传热模型;在临界区域范围内,可用均质假设模型预测地埋管的传热特性,均质等效热物性参数取为对应岩土分层的热物性参数值;分层岩土导热系数对地埋管传热性能影响较大,岩土平衡温度随分层导热系数比的增大而明显降低;地埋管长度和直径的比值对地埋管传热性能有所影响,岩土平衡温度随长径比的增大而升高,且其影响程度随分层导热系数比的减小而增强。In order to better describe the thermal behavior of ground heat exchangers(GHE)in a layer stratum,a general analytical model is developed and the corresponding analytical solution is obtained using Green’s function method;The Green’s function,which is the temperature response of single instantaneous ring source,is obtained using the separation of variables technique. The proposed model considers layer stratum and anisotropic properties,and it is applicable for both borehole heat exchanger and pile foundation heat exchanger which are two types of GHEs mostly used in engineering application. Computational examples of the model in a doublelayered stratum are presented. The results show that it is necessary to adopt the layered model when long-term temperature response of a GHE is considered,since the error of neglecting the inhomogeneous feature increases with increasing time. There is a critical zone,and the temperature response in this zone can be described by a homogenous model using thermal properties of the corresponding layer. The thermal conductivity of each layer has great effect on the temperature response of a GHE. The steady temperature of soil decreases markedly as the ratio of thermal conductivity between soil layers increases. The ratio of GHE length to diameter also affect the thermal behavior of a GHE,and the steady temperature increases with increasing ratio of GHE length to diameter. The effect of GHE length to diameter on the steady temperature is more pronounced when the thermal conductivity ratio is smaller.

关 键 词：地热能 地源热泵 岩土传热 地埋管换热器 岩土分层 解析模型 

分 类 号：TK521[动力工程及工程热物理—热能工程]