Thermal performance of thermoplastic natural rubber solar collector

The paper presents the thermal performance of a solar collector with TPNR (thermoplastic natural rubber) tubing as the absorber plate. A commercial blend of TPNR (dynamically vulcanised natural rubber—DVNR 9011) was used as the absorber plate which was of the parallel type and satisfies the test conditions indicated by the standard GB 4271-84. The values of the thermal performance parameters FR(τα) and FRUL were 0.72 and 9.67, respectively. A domestic hot water thermosyphon solar collector system with a vertical tank was used for performance monitoring. The thermosyphon hot water system is capable of producing temperature output up to 65 °C for a typical day of 550 W/m2. For monitoring purposes, two methods were used. In the first method, the storage tank was filled up with water the night before the test and the temperature readings were recorded for the next day’s test. The end-of-the-day temperature rise in the storage tank and the accumulated total solar radiation values were also noted over the same period. The test were repeated under varied environmental conditions that covers low and high radiation intensities. A temperature rise of 15 °C in the storage tank was obtained for this system at an accumulated solar radiation of 4.5 kW h/m2. In the second method, the temperature readings without draw-off or draining of the hot water from the storage tank were recorded for 6 days and a temperature of more than 60 °C can be achieved by the storage tank. Hence, this system has the potential to be used as domestic thermosyphon hot water system.