Abstract: Due to the increasing population in world, the demand for energy is also increasing. There are lots of technologies to utilize the solar energy for the benefits of human society. Out of those techniques most popular technique is solar water heating. Mainly solar collectors used for heating a water are of flat type. It is used to increase the temperature of water up to 700C by direct solar radiation absorption. But the flat plate collector has low thermal efficiency due to less surface area. Other disadvantage of flat plate solar collector is improper thermal stratification. So to overcome these drawbacks, new solar geometry used with different tube arrangement. The main aim of this project is to fabricate a low cost solar water heater which gives hot warm water for bathing as well as washing purpose. In proposed system umbrella shape absorber geometry is used, which gives more effective area as compare to flat plate collector subjected to heat transfer. And spiral tube arrangement is being used which overcome the tracking requirement of system. And this system is quite simple in operation as well as in construction. The performance of this umbrella shape water heating system is carried out at Nagpur [21.060, 79.030] in the month of March with different combinations of selective coatings on the absorber surface, with different mass flow rate, with and without mirror conditions. After experimentation and analysis, it is found that umbrella shape solar water is more efficient as compare to flat plate solar collector. The maximum temperature achieved during the experimentation as 77.6 0C with corresponding instantaneous efficiency of 60.24% with mass flow rate of 0.192 kg/min.

Keywords: Absorber geometry, Spiral tube arrangement, Absorber coating, Cost, Thermosiphon circulation, Mirror.