耦合强制对流井式土壤源热泵系统模拟研究

The numerical simulation of the coupling force convection wells with underground heat exchangers system

以耦合强制对流井式土壤源热泵系统为研究对象,以等效内热源理论为基础,建立了2U型埋管换热器及含水层热-质运移耦合模型。采用FEFLOW6.1计算软件,针对两类运行模式中粗粉砂含水层温度场分布规律及强制渗流过程对地埋管换热能力的影响开展了模拟研究;引入埋管换热器能效系数E,对地埋管能效特性进行量化分析。研究结果表明,含水层中的强制渗流过程可有效地缓解埋管井群区域土壤热失衡1现象,增加埋管进出口温差,提高单位管井换热能力。与单独使用埋管换热器工况相比,耦合强制对流井模式在第5年的排热、取热阶段,能效系数E分别提高了7.6%和4.8%。

A mathematical and physical model coupling of heat transferring of 2U-type ground heat exchangers and groundwater seepage and thermal transferring movement in shallow aquifers was established based upon the theoretical model of equivalent inner heat source, which the coupling forced convection wells and multi-borehole heat exchangers system is taken as the research object.The calibrated numerical model is used to probe into the variation regularity of the geo-temperature field in the coarse silt aquifer and the effect of groundwater seepage condition on heat transfer performance of 2U-type ground heat exchangers in two operation modes adoption of software FEFLOW6.1. The energy efficiency coefficient E is introduced to quantify the energy efficiency performance of the 2U-tube heat exchanger. The results show that temperature difference between the inlet and outlet and the heat transfer capacity of the 2U-tube heat exchanger are increased while the groundwater seepage process improve, which the underground thermal imbalance can be avoided effectively around the boreholes region. The simulated calculation indicates that the energy efficiency coefficient E is increased 7.6%, 4.8% during the extracted heat and the emitted heat in the 5thperiod separately, comparing to no seepage condition.