Numerical Investigation of Harvesting Solar Energy and Anti-Icing Road Surfaces Using a Hydronic Heating Pavement and Borehole Thermal Energy Storage

Abstract

Hydronic Heating Pavement (HHP) is an environmentally friendly method for anti-icing the roads. The HHP system harvests solar energy during summer, stores it in a Seasonal Thermal Energy Storage (STES) and releases the stored energy for anti-icing the road surface during winter. The aims of this study are to investigate: (i) the feasibility of HHP system with low fluid temperature for harvesting solar energy and anti-icing the road surface; and (ii) the long-term operation of the STES. In this study, a Borehole Thermal Energy Storage (BTES) is considered to be the STES. The HHP system and the BTES are decoupled from each other and their performances are investigated separately. A hybrid 3D numerical simulation model is developed to analyze the operation of the HHP system. Moreover, a 3D numerical simulation model is made to calculate the temperature evolution at the borehole walls of the BTES. The climate data are obtained from Östersund, a city in the middle of Sweden with long and cold winter periods. Considering the HHP system with the inlet fluid temperature of 4 °C, the road area of 50 m × 3.5 m as well as the BTES with 20 boreholes and 200 m depth, the result showed that the harvested solar energy during summer is 352.1 kWh/(m2∙year), the required energy for anti-icing the road surface is 81.2 kWh/(m2∙year) and the average temperature variation at the borehole walls after 50 years is +0.5 °C. Installing the HHP system in the road leads to a 1725 h shorter remaining number of hours of slippery condition on the road surface during winter and a 5.1 °C lower temperature on the road surface during summer, compared to a road without the HHP system.