基于不同G函数的U型中深层地埋管传热模型对比研究OA

The U-bend deep borehole heat exchanger(UDBHE)has a promising application po-tential.This paper is based on the G functions of infinite cylindrical source(ICS)and infinite line source(ILS)models,four heat transfer models of UDBHE are established,and they adopt the G function of ICS or ILS model,and consider or ignore the time-varying heat flow at the borehole wall,which are abbreviated as ICS-q,ILS-q,ICS-c and ILS-c models,respectively.The accuracy of the four models is studied by comparing with a more accurate two-dimensional numerical model and experimental data under two boundary conditions.The results show that the ILS-q model is the most accurate on the whole,and that the ICS-q model is the most accurate in analyzing the long-term performance of UDBHE.The four models have large errors in the early stage,but after enough long time,the errors of them are small except that the ILS-c and ICS-c models have large errors under the inlet temperature boundary condition.The errors mainly result from two aspects:the G functions of ICS and ILS models have some errors;ignoring the time-varying heat flow will cause some errors.The results can provide reference for the heat transfer model study of UDBHE.