Research On Thermal Anti-ice And Ice-melting Technology Of Highway Bridge

This paper was based on the background of anti-ice and ice-melting of Xiarong expressway Chishi Bridge in winter,starting from the meteorological parameters of the area to study the relevant problems of thermal anti-ice and ice-melting technology.The heat load of anti-ice and melting ice of Chishi Bridge was calculated,the ice-proof technology of heating cable and thermal pipe was simulated,and the ice-melting process of thermal pipe was simulated and experimentally studied.The work and research results of this article were as follows:Through the establishment of the calculation model of anti-ice and melting ice load,the design heat load of anti-ice melting of Chishi Bridge was obtained,and the relationship between the heat load of anti-ice and ice-melting with meteorological parameters and the influence of meteorological parameters on anti-ice heat load was analyzed.The results show that the anti-ice heat load of Cheshi Bridge was 336.5W/m~2,and the ice melting heat load was443.1W/m~2.The anti icing heat load was positively correlated with the outdoor wind speed,but negatively with the sky radiation temperature,moisture content,outdoor temperature and relative humidity.The influence degree of meteorological parameters on the anti-icing heat load was:moisture content>outdoor temperature>outdoor wind speed>sky radiation temperature>relative humidity.According to the actual body structure of Chishi bridge,the calculation model of three dimensional thermal anti-ice system was constructed.The relationship between the laying distance of the heating cable and the power of the cable,the distance between the thermal pipe and working temperature of outer surface and the ice-proof of the bridge was analyzed.The relationship between the power of the heating cable and the working temperature of the outer surface of the thermal pipe was related to the changes of outdoor ambient temperature and outdoor ambient wind speed.Under the same working condition,the smaller the laying distance was,the higher the average temperature of the bridge deck was,and the more uniform the temperature of the bridge deck was.When the anti-icing effect was met,the smaller the laying distance was,the lower the heating cable power and the outer surface temperature of the thermal pipe were,and the more uniform the bridge surface temperature was,for each drop of 1?.in ambient temperature,the cable power should be increased by3.83 W/m,and the working temperature on the outer surface of the thermal pipe should be increased by 2.78?.For every 1 m/s increased of wind speed,the cable power should be increased by 2.30 W/m,and the working temperature of the outer surface of the thermal pipe should be increased by 1.78?.The calculation model of melting ice with thermal pipe was established,the time limitation of thermal pipe melting process was explained,and the liquid phase rate of ice layer with the change of time,and the temperature in space with the change of time was calculated.The temperature variation of each structure layer with the change of time was analyzed.The results show that the ice melt starts from the middle and gradually extends to both sides.The melting speed of ice on the leeward side is faster than that on the windward side,and the melting speed of ice on the lower part is faster than that on the upper part.The temperature field is in the shape of a saddle and the closer it is to the thermal pipe,the greater the temperature gradient and the faster the temperature rise,the more uneven the temperature field distribution.The trend of the temperature of each structure with time is basica lly same,and verifies the reliability of numerical simulation.It provides the basis for the feasibility of the anti-ice and ice-melting technology of thermal pipe in practical engineering.