循环单井井管-井孔-含水层传热模型

为了研究循环单井复杂的传热特性,依据能量守恒建立了循环单井井管-井孔-含水层耦合传热模型.并将井管壁和井孔壁的换热包含于控制方程中,便于含水层、井孔、井管温度场的整场求解;在含水层传热中,考虑了热弥散的影响.然后,对循环单井现场试验进行了数值模拟,模拟过程显示出模型的输出对含水层渗透系数和热弥散度最为敏感,尤其是热弥散度,有无热弥散效应对模型的输出影响重大,应在模型中考虑热弥散效应.模拟结果表明,抽水温度的模拟值与实测值吻合良好,误差在10%以内,也表明建立的循环单井井管-井孔-含水层传热模型是正确的,能够用于实际.

Heat transfer model for a standing column well geothermal system

A coupled heat transfer model for the standing column well (SCW) of a geothermal assisted heat pump system was established based on conversion of energy. This allows investigation of the complicated heat transfer characteristics of SCW. Heat exchange between the casing of the supply pipe and the borehole wall was included in the control equations to produce a whole-field solution to the temperatures of aquifer, borehole and supply pipe. Thermal dispersion was included in the heat transfer model of the aquifer. Numerical simulations of an in-situ test of SCW were created. The simulation showed that the output of the model was sensitive to the permeability coefficient and the thermal dispersion tensor of the aquifer, with the thermal dispersion tensor highly significant. Because of this, inclusion of thermal dispersion had a significant impact on results, suggesting thermal dispersion must be included when calculating heat transfer. The simulation results showed that there was a good agreement between the temperatures of pumped groundwater predicted by the model. In tests, the error was less than ten percent. This preliminary validation shows that the coupled heat transfer model for SCW systems is accurate enough to be useful for simulations.