Thermal performances of the active and passive water heating systems based on annual operation

In this paper, the year round thermal performance evaluation of active and passive solar water heating systems for rural/urban area have been studied. Two types experiments are the normalized draw-off temperature profile and the normalized draw-off mixing profile conducted in the months of April 2003-March 2004. Effect of morning, mid-afternoon, evening draw-off and effect of water mixing in the morning and evening are also studied during the experiments. Thermal efficiency for the system and collection efficiency for the collectors were calculated during the experiments. The values of [F.sub.R] * ([tau][alpha]) of the collectors used in active and passive water heating systems were found 0.69 and 0.61 respectively. Ethylene glycol has a 50/50 glycol-to-water ratio used as a heat transfer fluid (HTF) in the systems due to the cold climate in South Korea. Keywords: Active; Passive; Solar water heating systems; Heat transfer fluid (HTF); Collector efficiency