Thickness of heat insulation layer of electric heating snow and ice melting pavements

In order to study the influence of thermal insulation layer thickness and carbon fiber heating wire temperature on the snow and ice melting of the pavement under pavement daily cycle thermal boundary conditions, the heat conduction equation of the conventional asphalt pavement structure is built when the heating wire is laid horizontally, and the numerical solution of the temperature field is obtained by solving the partial differential equation using MATLAB PDE toolbox. The example chooses the freezing meteorological conditions on a certain winter day in Hunan Province, the temperature of the constrained pavement is above 4.8 ℃, and the temperature of the heating wire is 30-50 ℃. The temperature rise rates of the pavement are calculated when the thickness range of the thermal insulation layer is 5-40 mm. Results showed that in the hot summer and cold winter areas represented by Hunan Province, the average temperature rise rate of road surface with a thermal insulation layer thickness of 5mm is about 3.5-9 times higher than that without thermal insulation layer; while that with a thermal insulation layer thickness of 10 mm is increased by 3.55-9.5 times. After the thickness of the thermal insulation layer exceeds 10 mm, the increase trend of the average temperature rise rate of road surface is not obvious. At the same time, the temperature rise rate of the road surface is not only nonlinear with the thickness of the thermal insulation layer but also nonlinear with the temperature of the heating wire. Therefore, it is not that the thicker the thermal insulation layer, the better the temperature rise and defrosting effect of the road surface. In addition, the additional heat insulation layer prevents most of the heat generated by the heating wire from flowing underground, so that the temperature distribution of the road surface is more uniform. The pavement temperatures with insulation are also higher than those without insulation. The simulation results for the cold and harsh places reveal that the heating wire temperature should be increased to 50-70 ℃ when the limited road temperature is likewise over 4.8 ℃, and the effect of insulation layer thickness is still consistent with the example. Theoretically, considering the road surface heating performance and the engineering costs, it is considered that the hot wire temperature of 30-70 ℃ and the thermal insulation layer of 5-10 mm are more suitable. The conclusions are also applicable to cold and severe regions and can provide a reference for choosing the optimum economical thickness of the insulation layer when the heating wire assists the deicing or snow-melting on the road surface with the periodic thermal boundary condition.