Effect of thermal conductivity of absorber plate on the performance of a solar water heater

The effect of thermal conductivity of the absorber plate of a solar collect or on the performance of a thermosyphon solar water heater is studied by th e use of the transient simulation system (TRNSYS) computer program. The sys tem is assumed to supply hot water at 55 degrees and 80 degrees C represent ing both domestic and industrial uses respectively. Hot water of volumes 50 , 125, and 250 l is consumed daily according to the Rand distribution profi le. The results have shows that the annual solar fraction of the system and the collector's characteristic factors (namely, fin efficiency factor, col lector efficiency factor, and heat removal factor) have a very strong depen dence on the thermal conductivity for its low values, and weak dependence i s observed beyond a thermal conductivity value of 50 W/m degrees C for the solar fraction and beyond a value of 100 W/m degrees C for the characterist ic factors. It is also observed that the annual solar fraction is improved by about 4%-7% and the characteristic factors are improved by about 12%-19% when a steel absorber plate is replaced by an aluminium one, whereas, the solar fraction and the characteristic factors are increased only about 1% a nd 3%, respectively, when a copper plate is used instead of an aluminium on e. (C) 1999 Elsevier Science Ltd. All rights reserved.