Low Solar Absorption Coating for Reducing Rail Temperature

Abstract

The feasibility of using low-solar-absorption coatings to reduce the temperature rise of rails in summer is investigated in this paper using numerical analysis. Finite element (FE) models were developed based on the theory of heat transfer for predicting temperature fields in the rail track structure. Field measurements of air temperature and rail temperature were used to verify the modeled temperatures. Analysis results show that the developed FE models provide reasonable predictions of rail temperature. The 3-D rail temperature field shows that rail temperature differs spatially in the natural environment, which indicates that the current average temperature models may not provide accurate prediction of peak rail temperature. The peak temperature was observed at the top of rail seated on the wood ties. The developed FE models were further used to analyze the influence of solar absorptivity and emissivity of coating materials on rail temperature. Decreasing the absorptivity and increasing the emissivity of rail surface may decrease the peak rail temperature at different levels. The effect of decreased absorptivity was found to be more significant. This indicates that when an engineered coating material is applied on rail side surfaces, the peak rail temperature can be decreased significantly, which provides an alternative solution to reduce rail buckling risk without decreasing train speed or increasing the laydown temperature of rail. The experimental investigation of the effect of low solar absorption coating on rail temperature is ongoing.