Experimental investigation of a solar absorber and nocturnal radiator hybrid system for simultaneous water heating and cooling

An experimental study of a Solar Absorber and Nocturnal Radiator (SAANR) hybrid system used for simultaneous water heating and cooling in Gaborone, Botswana is presented. A SAANR hybrid system was designed and fabricated and the system consists of major components that include a 1.4 m(2) SAANR hybrid panel, 100 L hot and cool water storage tanks, chlorinated polyvinyl chloride (CPVC) plumbing and a 0.2778 kg/s circulation pump, all mounted on a steel frame that is inclined at 30 °C to maximize solar absorption and self-cleaning of the panel. Experiments carried out in December 2020 in Gaborone with water at an initial temperature of 26 °C produced 100 L of hot water at 60 °C and similarly 100 L of cool water at 23 °C, during the day and at night respectively. These results provide proof that the SAANR hybrid system could be used simultaneously for applications of domestic water heating and building envelope cooling in Botswana and similar climates. This technology can therefore be used instead of electric water heaters and air-conditioners and thus save energy.