Study On Methods For Estimating Parameters Of Ground Heat Exchanger Based On Thermal Response Test

The effective thermal conductivity，volume specific heat and borehole thermal resistanceare fundamental parameters for designing vertical U-tube ground source heat pump system.These parameters are usually obtained by thermal response test. In principle, parameters areestimated based on tested water temperatures and flow rates.In this thesis, based on linear heat source analytical model, a linear-slope method and athree-parameter estimation method were studied; an empirical correlation is built betweenvolume specific heat and thermal conductivity and a two-parameter estimation method hasbeen given. As to two-parameter estimation method, comparisons were conducted betweenresults obtained by the line heat source analytical model, cylindrical heat source analyticalmodel and a1-d numerical model.The linear-slope method can estimate effective thermal conductivity，volume specificheat and borehole thermal resistance. However, appropriate formula for borehole thermalresistance shall be used.The three-parameter estimation method can estimate effective thermal conductivity，volume specific heat and borehole thermal resistance. The value of thermal conductivity andborehole resistance obtained by the three-parameter estimation method are close to that by thelinear-slope method. However, volume specific obtained by the former significantly differsfrom that by the latter.The two-parameter estimation method is fast and can guarantee reasonable results.Comparisons show that the1-d numerical model can be used estimate the effective thermalconductivity，volume specific heat and borehole thermal resistance.