A numerical and experimental study of a pavement solar collector for the northern hemisphere

Abstract

Solar energy is a renewable energy source that is globally available. To utilise this type of energy, novel technologies are developed across the globe. Among these, the pavement solar collector (PSC) technology has a considerable potential. A PSC consist of pipes, that are embedded into the upper pavement layers through which fluid is circulated. Solar radiation heats the pavement surface, and the absorbed heat is transferred to the circulating fluid. One applications is to use the heat for recharging shallow geothermal boreholes with solar energy during summer, thereby reducing the electricity consumption of ground source heat pumps during winter. In Scandinavia, however, the knowledge on the PSC application is limited. The Swedish transport administration has therefore established a field station to gain more insight on the PSC in Scandinavia. This paper reports the findings of the investigation from the summer of 2018 and how the efficiency of the PSC is affected by altering the albedo, fluid flow rate, and pipe spacing. The measured harvested energy is 245 kWh/m2 with a solar efficiency of 42%. It is found that by altering the albedo and flow rate, the efficiency could be enhanced by up to 49%. This high efficiency achieved in this study is dependent on the short pipe spacing of 5 cm and results in surface condensation on several occasions. Condensation on PSC has not been reported previously but should not pose a risk to road traffic because surface temperatures are above freezing.