Thermodynamic analysis of a novel solar water heating system during low sun radiation in Iran

This paper reports a plenary thermodynamic model of a novel solar system for water heating in buildings. Energy and exergy analyses are used to characterize the exergy destruction rate in any component and calculate system overall efficiency. The system consists of a solar evaporator, a heat exchanger to produce hot water, and an auxiliary pump. A computer simulation program using EES software is developed to model the solar water heating system. The system provides hot water during the hours of low sun radiation. Thermodynamic analysis involves the designation of effects of heat exchanger pinch point and ambient temperatures on the energetic and exergetic performance of the solar water heating system. The performance parameters computed are exergy destruction, and energetic and exergetic efficiencies. The result showed that the main source of exergy destruction is the solar evaporator. In the solar evaporator, 92.85% of the input exergy was destroyed. The other main source of exergy destruction is the heat exchanger, at 4.15%. The overall energetic and exergetic efficiencies of the solar water heating system were approximately 60.17% and 3.002% respectively.