Thermal performance comparison and new layout scheme study of high geothermal tunnel insulation layer

Abstract

In order to solve the problem of designing the thermal insulation layer for high geothermal tunnels, this paper studies the nature of thermal insulation materials and the structure of the thermal insulation layer. Based on the mechanisms of heat transfer from the cylinder wall and the flat plate, combined with the physical and thermophysical properties of the materials tested, the selection of thermal insulating materials for high geothermal tunnels as well as the layout were analyzed. The results of the study showed that polyurethane materials proved to be a better overall insulation material, with better water resistance and lower thermal conductivity, as well as better compressive strength. The flat plate heat transfer model can be used to predict the temperature distribution of the lining structure, which simplifies heat transfer calculations and analysis. This paper proposed a new insulation design solution using polyurethane-corrugated steel insulation lining with a double layer deployment. Numerical simulation results show that the thermal insulation design scheme can effectively reduce the temperature of the lining structure, which is beneficial to improve the thermal performance of the lining structure. The results of the study may provide new ideas for the design of heat-insulating structures for high geothermal tunnels.