Mohammad Ali Fazilati - PHD student, Mechanical department, Isfahan University of Technology
Ali Akbar Alemrajabi - Assistant professor, Mechanical department, Isfahan University of Technology

In this research, the effects of using Phase Change Materials (PCM) as storage medium on the performance of a solar water heater have been experimentally investigated. A type of paraffin with special thermodynamic properties is used as PCM in spherical capsules in conjunction with water as storage material in the tank of solar water heater. The solar radiation modeled as weak, mean and strong by circulating water with three temperature levels of 40, 60 and 80oC in jacket of tank. The energy and exergy efficiencies of solar water heater and the time the heater can supply hot water have been compared before and after use of PCM in tank. It is observed that using PCM in the tank the energy storage density is increased in the tank up to 39% and the exergy efficiency is enhanced up to 16%. Also, it is observed that solar water heater with PCM, can supply hot water with specified temperature at 25% larger time compared topure water tank. Improvement in thermal stratification has been observed by examining temperature histories of different water layers in the tank.

solar water heater, PCM, paraffin, encapsulation, Enhancement, energy and exergy efficiency