围岩热物性对隧道衬砌热交换器换热的影响研究

摘要

Based on the heat transfer characteristics of tunnel lining exchanger,this paper estabilished three-di-mensional heat transfer numerical model which fully considers convective heat transfer between air and lining, heat transfer between heat carrier liquid and surrounding rock and the heat conduction in surrounding rock.The accuracy of numerical results was verified with the field test monitoring data.The influence of surrounding rock thermal physical parameters(such as thermal conductivity,specific heat capacity)on the heat exchange rate of surrounding rock was studied to provide guidance for the design of the tunnel lining GHEs.The geothermal energy output of tunnel lining GHEs presents a linear variation with the thermal conductivity increase,and the growth rate does not change with the running time.The heat exchange pipe should be laid in the surrounding rock with good thermal conductivity.The geothermal energy output of tunnel lining GHEs decreases exponentially with the increase of flow rate.The effect of specific heat capacity increase on geothermal energy output gradually weaken with the increase of running time,it is better that the ground source heat pump system adopts the intermittent op-eration mode.%基于隧道衬砌热交换器的传热特点，建立隧道衬砌热交换器的三维传热数值计算模型，并与现场试验数据进行对比验证。隧道衬砌热交换器的热交换管路埋设于不同级别围岩中，而不同级别围岩的热物性存在显著差异。依据不同级别围岩裂隙参数的取值范围，计算围岩导热系数和比热容的取值区间，数值计算分析导热系数和比热容对衬砌热交换器换热的影响。研究结果表明：衬砌热交换器的换热量随围岩导热系数呈线性增加趋势，且增长速率不随运行时间而改变，宜选择在导热性好的围岩中铺设热交换管；围岩比热容对衬砌热交换器换热量的影响具有时效性，在系统运行初期，热交换量随围岩比热容的增大而增加，但随着运行时间的增加，比热容对围岩换热量的影响逐渐减弱，建议地源热泵系统采取间歇运行的模式。