Experimental Study of a Combined Solar Heating and Radiative Cooling Device with an Adaptive Cover
Abstract
Nowadays, climate change impact is becoming more important in our daylife and the use of renewable energy sources to cover the space conditioning and Domestic Hot Water (DHW) demands is growing every year. In this study, a new device that works with renewable energies and combines two different concepts, radiative cooling and thermal solar collection, is presented. The device is called Radiative Collector and Emitter (RCE) and it consists of a modified solar collector based on an adaptive cover. The absorber is covered by a polyethylene film and the glass of the solar collector is removed during the night to allow the radiative cooling effect. Due to this adaptive cover, during daytime the greenhouse effect is allowed because of the glass cover, favoring the solar collection; and during nighttime, radiative cooling is allowed through the polyethylene film in the same device. The adaptive cover allows the different properties of the materials to be used according to its mode of operation. This equipment has been experimentally tested during summertime 2019, in the University of Lleida, where the climate corresponds to a Semi-Arid Climate (BSk according to Köppen and Geiger climate classification). Results show that the RCE performs similarly to a solar collector during the day, with average heating values of 573.69 W/m2, and is able to provide extra cooling at night, at an average cooling rate of 15.57 W/m2.