Performance monitoring of a thermosyphon solar hot water heater with a parallel thermoplastic natural rubber tube absorber

Performance monitoring of a domestic hot water thermosyphon solar collector with TPNR (thermosplatic natural rubber) tubing as the absorber plate was conducted. A commercial blend of TPNR (DVNR 9011) was used as the absorber plate. The domestic hot water thermosyphon solar collector system used was the parallel-type absorber plate. An output temperature output of 65°C was obtained from the collector for a typical day of 550 W m−2 and ambient temperature of 26°C. For the performance monitoring, two methods were used. In the first method, the storage tank was filled up with water the night before the test and temperature readings were recorded form sunrise to sunset. The tank was then drained during the night-time, refilled and made ready 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 tests were repeated under varied environmental conditions that covered low and high radiation intensities. A temperature rise of 30°C in the storage tank was obtained for this system at an average yearly value of accumulated solar radiation of 4.5 kWh m−2. In the second method, the temperature readings without draw-off or draining of the hot water from the storage tank were recorded for six days and a temperature range of 60–70°C was obtained in the storage tank. Hence, this system has the potential to be used as a domestic thermosyphon solar hot water heating system.