THERMAL PERFORMANCE TESTING OF LONG EVAPORATIVE SECTION THERMOSYPHONS USED IN SOLAR WATER HEATING SYSTEM

Abstract

In this study, the aim is to investigate the application of ethanol & acetone fluid thermosyphons as a heat transfer tool in a solar water heater (SWH). For this purpose, a long evaporative section thermosyphons (LEST) are designed, constructed  and  tested  at temperatures of 50˚C,60˚C&70˚C heat source(Hot Water). In this work the LEST are made of copper tube of 1000 mm length of internal diameter 24.4 mm and 1mm thickness. The working fluid employed  are ethanol & acetone with filling ratio (FR) 40%. The lengths of evaporator, adiabatic & condenser sections are 600mm, 200mm and 200 mm respectively.  Maximum heat transfer capacity of each LEST is 500W. The LEST placed centrally in 2 inch UPVC pipe. The 2 inch UPVC pipe water jackets are provided in both evaporative & condenser section of prescribed length for hot water circulation. Heat source at 50˚C,60˚C,70˚C&80˚C temperature of hot water taken during experimentation. Two Immersion water heaters of 3.5 KW were used for water heating process. The Inclination of the LEST varies between 0˚ to 90˚. Seven different tests were carried out in different orientation angle. The results show that efficiency of thermosyphons mode are in range of  50 %  to 71%.Experimentally found that the  vertical position is the best performance of thermosyphons for maximum mass flow rate of fluid. It was also found that there is no more differences in thermal performance of thermosyphons at an angle of 45˚, 60˚ & 90˚ as compare with vertical position (90˚). The overall thermal resistance also calculated in the range of 0.069˚C/W to 0.127 ˚C/W. Experimentally found that overall thermal resistance decrease from horizontal position to vertical position. Less overall thermal resistance causes better performance of thermosyphons. After comparison between two thermosyphon (acetone and ethanol fluid) performance it was found that long evaporative section acetone fluid thermosyphon can be used in solar water heating system, because it will gives better performance in  low temperature range .