Performance Analysis of Solar Water Heater at Possible Flow Rates with and Without Phase Change Material

Abstract

To store excess solar energy from the sun, in this project we pro-vide phase change materials (PCM) at the bottom of the absorber plate.Experiments were conducted in the cascaded solar water heater withand without phase change materials at different flow rates. During thesun-shine hours, the phase change material (PCM) absorbs latent heatof solar energy and stores the same energy up to its melting point. Simi-larly during off-sunshine hours, the phase change material releases theenergy, which is used to heat the water. The set up can result a higherefficiency of the solar collector system. In this work, the paraffin waxhas been selected as a phase change material due to its low cost, easilyavailability and considerable thermo-physical properties. The PCM unitstores the heat during the sun-shine hours and supplies hot water dur -ing the night and overcast periods. An attempt was made to producehot water even after sun-shine hours every day. The performance of thisPCM based thermal energy storage system is compared with conven -tional latent heat storage system and the conclusions drawn from themare presented. The conventional solar water heater gives better efficiencyduring day time because of the energy absorbed by phase change mate-rial. Thus a solar water heater integrated with phase change materialunit gives little better efficiency during off sun-shine hours due to thepresence of thermal energy storage system.