Numerical simulation of heat transfer characteristics of building envelopes of underground warehouse based on element-free Galerkin method

Abstract: 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.