A research article from Chang’an University in China on New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal, says that Its possible and effective to use an electric heat tracing system in the portal area. An electric heat tracing system in the portal area using wire as heating medium, transforms electric energy into thermal energy by electrifying the heating cable and then transfers the thermal energy to pavement, which is the radiant heating. With additional protection of the outer wall of heat insulation material, the significant effect of heat insulation and snow-melting can be received.
The researchers says with the advantages of high thermal efficiency, little impact on structure, excellent effect, excellent performance in energy conservation, simple design, convenient installation, zero pollution, long service life, and remote-automatic control, the electric heat tracing system has been successfully applied in various applications, and why not tunnels?
The electric heat tracing system, which is employed for snow-melting and deicing, is designed with the intermittent operation model. The heating cables generate thermal energy gradually, then the thermal energy is transferred to the snow cover through the asphalt concrete, and finally the snow will be melted after absorbing sufficient heat. In order to realize instant and automatic melting, it is required to preheat the pavement according to the actual weather conditions. It is recommended that an electric heat tracing system should be 50 m inside the tunnel and 50 m outside the tunnel, due to braking distance.
In order to effectively improve the heating efficiency, thermal insulation materials can be laid below the heating cables. Combined with thermal insulation materials, the electric heat tracing system with heating power of 200–400 W/m2 can sufficiently meet the requirements of pavement snow-melting when the air temperature is −20°C to 0°C.
Photo: Arild Petter Sovik
New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal
Jinxing Lai, Junling Qiu, Jianxun Chen, Haobo Fan and Ke Wang
Shaanxi Provincial Major Laboratory for Highway Bridge & Tunnel, Chang’an University, Xi’an 710064 and China School of Highway, Chang’an University, Xi’an 710064, China