Optimization design of the road unit in a hydronic snow melting system with porous snow
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Optimization design of the road unit in a hydronic snow melting system with porous snow Wenke Zhao1 · Wentao Su2 · Lei Li1 · Yaning Zhang1 · Bingxi Li1 Received: 24 February 2020 / Accepted: 9 April 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
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. Keywords Hydronic snow melting system · Porous snow · Embedded pipe depth · Embedded pipe spacing · Supplied fluid temperature List of symbols Cp Specific heat at constant pressure [kJ (kg−1 K−1)] Cpa Specific heat at constant pressure of the air [kJ (kg−1 K−1)] Cpi Specific heat at constant pressure of the ice [kJ (kg−1 K−1)] Cps Specific heat at constant pressure of the snow [kJ (kg−1 K−1)] Cpw Specific heat at constant pressure of the water [kJ (kg−1 K−1)]
Wenke Zhao and Wentao Su have contributed equally to this work. * Yaning Zhang [email protected] 1
School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
College of Petroleum Engineering, Liaoning Shihua University, Fushun 113001, China
2
h Height of the wind velocity close to road surface (m) hc Convective heat transfer coefficient (W m−2 K−1) H Total enthalpy (kJ kg−1) L Latent heat of fusion [W (m−2 kg−1)] Mf Ratio of snow melting for the total snow layer Mi Mass of the ice (kg) Ms Mass of the snow (kg) Mw Mass of the water (kg) ΔMm Mass of melted snow per time step (kg) q Heat flux by conduction (W m−2) qc Convective heat flux abo
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