基于桩土相互作用的嵌岩能源桩传热计算

Heat Transfer of End-bearing Energy Pile by Considering Pile-soil Interaction

针对螺旋地埋管嵌岩能源桩传热,提出一种新的计算模型,可考虑基岩温度、大气地面对流换热、桩顶处绝热处理、流体速度和流体热量损耗对其传热影响。首先求解土体温度自由场;接着考虑桩体运行时系统传热相互作用的影响,得到桩体温度场;然后将土体温度场问题转化为一系列未知系数求解;最后通过边界条件得到土体附加温度场。分析表明:在桩顶和桩底两倍桩径范围内,土的附加温度变化幅度最大;桩土传热系数对能源桩传热性能影响最大,减小桩土传热系数可显著提高能源桩传热性能;流体导热系数及流速对桩的传热效果影响不可忽略;土的导热系数及大气地面对流传热系数对其传热性能影响很小。

By considering the effects of bedrock temperature,the convective heat transfer between air and ground,thermal insulation treatment on top of the pile,the flow velocity,heat loss of the fluid,a new heat transfer model is proposed.The free thermal field of the soil was obtained firstly.Then,considering the soil-pile interaction during the operating of the energy pile,temperature field of the pile was calculated.The boundary value problem of the soil temperature field was transformed into the determination of a series of unknown coefficients.Finally,the additional temperature field of the soil was obtained in the light of the boundary conditions.Parametric study showed that within the range of double diameter of the pile top and bottom,the additional temperature changing of soil varies greatly.With the decreasing of the heat transfer coefficient between the soil and pile,the heat transfer performance improves greatly.The convective heat transfer between the pile and ground has the greatest influent on the heat transfer performance of energy pile.The influence of fluid thermal conductivity and velocity on the heat transfer effect of energy pile can not be neglected.The convective heat transfer between pile and ground has little effect on the heat transfer performance of the energy pile.