Heating performance enhancement for a road unit by using sectorial-finned pipe

Abstract

This study proposes a sectorial-finned pipe in the hydronic road heating system with a three-dimensional road model to enhance the road heating performance. Three primary fin parameters, including sectorial fin angle, height, and spacing, were analyzed. The range analysis and ANOVA (analysis of variance) of the final average road surface temperature (Tasf), the maximum temperature difference of road surface (Tds), and the overall utility (Ut) were conducted through the orthogonal test method. The results showed that compared with the bare pipe, Tasf and Tds of the finned pipe increased by 0.63–1.37 K and 0.27–0.66 K, respectively, and ts0 of the finned pipe decreased by 0.22–0.44 h when the fin parameters were changed in specific ranges at the average air temperature of 258.15 K. The fin angle of 210° had the most suitable performances for road heating in terms of the thermal and economic targets. The range analysis revealed that the ranks of influence degree for Tasf, Tds, and Ut were height > spacing > angle, height > spacing > angle, and angle > spacing > height, respectively. ANOVA indicated that the parameters of height, spacing, and angle contributed Tasf in proportions of 80.56%, 10.25%, and 9.19%, those contributed Tds in proportions of 98.58%, 1.29%, and 0.13%, and those contributed Ut in proportions of 60.06%, 36.20%, and 3.74%, respectively. The optimum parameter combination for Ut was 210°, 20 mm, and 45 mm for the fin angle, height, and spacing, respectively. The results can provide a good guide for the design of sectorial-finned pipes in the hydronic road heating system.