基于Galerkin法的地下粮仓围护结构传热特性数值模拟

摘要

The element-free Galerkin method is a new numerical simulation method that has many advantages such as no mesh or elements, convenient node insertion or elimination, high computational accuracy, and rapid convergence, etc. In this paper, the element-free Galerkin method (EFGM) is extended to solve the heat transfer problem of building envelopes of underground warehouses. Based on a real underground warehouse, the EFGM program for the ground-coupled heat transfer problems of underground warehouse is developed in MATLAB software. Heat transfer laws of building envelopes of underground warehouses is studied by using the EFGM numerical simulation method. The prediction precision of the element-free Galerkin method was validated by comparison between the predicted and measured temperatures of building envelopes of underground warehouses. In the steady-state analysis of heat transfer of underground warehouses, the sensitivity analysis of soil thermal conductivity, outdoor surface wind speed, and distance of the roof from the ground surface were carried out. Furthermore, the relationship between heat transfer of underground structures and insulation thickness, length and layout of the location were investigated in detail. Results of numerical simulation show the maximal error between predicted and measured temperatures of building envelopes of underground warehouses is-0.17℃in the summer. In addition, the maximal error between predicted and measured temperatures of building envelopes of underground warehouse is 0.24℃in winter. It implies the element-free Galerkin method proposed in this paper has a higher forecasting precision. In the unsteady analysis of heat transfer of underground warehouses, parameter sensitivity investigations show that heat transfer of building envelopes of underground warehouses is very sensitive to the soil thermal conductivity. Therefore, the soil thermal conductivity should be determined cautiously. The temperature gradient is larger in the region above the roof of underground warehouses. The absolute value of the amplitude and mean of the roof heat flux significantly decrease due to insulation, and it is well advised to install the insulation in the roofs of underground warehouses. When the insulation is installed in the roof of underground warehouses, internal thermal insulation is better than external thermal insulation. Results of numerical simulation of heat transfer of underground warehouse in this paper can provide the reference and basis for the engineering design of underground warehouses.%无网格伽辽金法是一种新兴的数值计算方法，具有无需单元或网格、节点任意增减、计算精度高、收敛快等优点。该文提出利用无网格伽辽金法研究地下粮仓围护结构的传热问题。以实际地下粮仓为实例，利用MATLAB软件开发了无网格伽辽金法程序，采用无网格伽辽金法实现了地下粮仓围护结构传热规律的数值模拟。将 MATLAB 数值模拟结果与实际地下粮仓的实测数据进行对比分析，验证了无网格伽辽金法的预测精度。分析了土壤导热系数、地表风速及顶板距地表面距离对地下粮仓围护结构传热的敏感性，探讨了保温层厚度及布置方式对围护结构传热的影响。数值模拟研究结果显示夏季地下粮仓围护结构温度实测值与预测值之间的最大偏差为-0.17℃，冬季地下粮仓围护结构温度实测值与预测值之间的最大偏差为0.24℃，说明无网格伽辽金法具有较高的预测精度。地下粮仓围护结构传热对土壤导热系数的变化非常灵敏，因此需要谨慎确定土壤导热系数。地下粮仓顶板上部区域的温度梯度较大，顶板安装保温隔热层可显著减小地下粮仓顶板的热流密度，采用内保温比外保温有更好的保温隔热效果，因此地下粮仓顶板应采用内保温的保温隔热方式。地下粮仓围护结构传热的数值模拟结果可为地下粮仓的工程设计提供参考和依据。