Optimization design of the road unit in a hydronic snow melting system with porous snow

Abstract

Hydronic snow melting systems are renewable and reliable to eliminate the slippery conditions on the road. In this study, a hydronic snow melting system was implemented in Harbin, China. The characteristics of porous snow were applied to develop a transient two-dimensional model, according to the experimental results. It is the first time that the snow microstructure was considered in the model for the hydronic snow melting system. Three parameters (embedded pipe depth, embedded pipe spacing, and supplied fluid temperature) were compared and analyzed to optimize the design of the hydronic snow melting system in the cold regions. The results indicated that the snow can be cleared in 4.5 h regardless of the fluctuation of parameters. The rank of influence degree was embedded pipe depth > supplied fluid temperature > embedded pipe spacing when the target was the maximum melting rate. However, the rank of influence degree changed as supplied fluid temperature > embedded pipe depth > embedded pipe spacing when the target was the average road surface temperature at the heating time of 6 h. The embedded pipe design should be the embedded pipe depth of 80 mm and embedded pipe spacing of 140 mm at the effects of thermal stress and pipe cost. The control strategy was that the supplied fluid temperature should be 298.15 K in the heating period of 0–1 h, then gradually increased to 308.15 K in the heating period of 1–4 h, and eventually decreased to 298.15 K in the heating period of 4–6 h to save energy. This work can offer a good reference for the optimization and design of hydronic snow melting systems in cold regions.