Experimental and numerical evaluation on influential factors for thermal performance of coaxial-type ground heat exchanger

摘要：

　　Thermal behaviour of Ground Heat Exchanger(GHEX)is affected by environmental factors,operating conditions,and the configuration of heat exchange pipes.Moreover,heat transfer in GHEXs is governed by the convection phenomenon among the circulating fluid,the wall of heat exchange pipe,the borehole grout and the ground formation.The convection is variable with flow conditions within the heat exchange pipe(i.e.,laminar or turbulent flow),which is a significant variable in the thermal performance of GHEXs.Especially,in case of coaxial-type GHEXs,the occurrence of turbulent flow with sufficient heat exchange area is considerably critical due to the geometric characteristics of the concentric tube-in-tube configuration.In this paper,the coaxial-type GHEX was constructed in a test bed,and the in-situ thermal performance test(TPT)was carried out to estimate the thermal performance of the coaxial-type GHEX.In addition,a Computational Fluid Dynamic(CFD)model was developed by calibrating with the field test results.In order to simulate turbulent flow inside the pipe,the K-epsilon model was applied.Then,parametric studies were conducted with consideration of various configurations(i.e.,depth,inner and outer diameters,and flow rate)to figure out the optimal configuration for coaxial-type GHEXs.As the flow rate and depth increased,the heat exchange amount of coaxial-type GHEX increased.In particular,as the hydraulic diameter increased,the heat exchange amount increased,which means that a reduction in the fluid velocity through the annular space is more dominant in determining the heat exchange amount.

关键词： Turbulent flow Coaxial-type Ground Heat Exchanger In-situ thermal performance test (In-situ TPT) Computational Fluid Dynamic (CFD) model Parametric study

作者: Kwanggeun OH Seokjae LEE Minkyu KANG Sangwoo PARK Hangseok CHOI

作者单位: School of Civil,Environmental and Architectural Engineering,Korea University,Seoul 02841,Korea Department of Civil Engineering and Environmental Sciences,Korea Military Academy,Seoul 01805,Korea

会议类型: 国际会议

会议名称: The 17th International Conference on Sustainable Energy Technologies(SET2018)(第17届可持续能源技术国际会议暨2018世界著名科学家来鄂讲学武汉论坛)

会议地点: 武汉

会议语种:英文

页码: 426-435

在线出版日期: 2018-08-21（万方平台首次上网日期，不代表论文的发表时间）