Exergy analysis of a solar water heating system without a heat exchanger

This research target is to make an exergy analysis of a solar water heating system without a heat exchanger, (SWHS) coupled with a built-in solar water pump. The designed system consists of 1.58 m2 flat plate solar collectors, an overhead tank placed at the top level, the larger water storage tank without a heat exchanger at the lower level, and a one-way valve for water circulation control. The discharge heads of 1 and 2 m were tested. The pump could operate at the collector temperature of about 70?90?C and vapor gage pressure of 10?18 kPa. It was found that water circulation within the SWHS can change depending upon solar intensity and discharge head. The new SWHS with 1 m discharge head or lower is suitable for residential use. It adds less weight to a building roof and saves electrical energy for a circulation pump. It has lower cost compared to domestic SWHS. Solar irradiation and exergy values for z=1m height are higher than z=2m height both for solar irradiation and exergy values. The circulation of water gets easier and the system efficiency increases by decreasing overhead tank height. The potential energy of the overhead tank is the governing factor for determining exergy loss. Performing exergy loss calculations is a very useful method to determine the source of losses in a system.Key Words: Solar Energy, Exergy Analysis.