Night Radiative Cooling with Unglazed Pvt-Water Collectors: Experimental Results and Estimation of Cooling Potential
Abstract
A PVT-Water collector was built and tested 24 hours per day during a period of six months in Sydney, Australia. The results provided enough experimental data to accurately build and tune a PVT model of the system in TRNSYS. The experimental setup included a pyrgeometer used for the calculation of the radiation losses to the sky. This article presents the experimental results obtained during the night radiative cooling periods and results from simulations carried out with the tuned TRNSYS model for the estimation of the sky cooling potential for this application. The results show that the unglazed PVT water system can achieve good levels of night cooling (around 750 Wh/m2 of cooling per night during summer months) with radiation losses accounting for circa of 60% of the total cooling achieved and convection losses for 40%. Simulations show that similar night radiative cooling levels are obtained for other climates with minimum of 400 Wh/m2 per night in Singapore to around 900 Wh/m2 in Tucson, Arizona.
Keywords
Sky cooling, Night radiative cooling, Pvt-water