Solar Still with Integrated Solar Heater and Nanoparticle-Enhanced Energy Storage Material

A design of a solar distillation unit with nanoparticle-enhanced heat storage material and an integrated solar thermal water heater is presented. Solar stills are robust devices that utilize solar energy to desalinize water and produce potable water. However, they suffer from low productivity due to inefficient energy utilization and low evaporation rates. In the present design, a paraffin wax phase change material (PCM) layer is added beneath the basin of the still to absorb the sun’s energy during the daytime and so extend its operational hours. However, the thermal conductivity of paraffin wax is very low (0.29 W/mK). To overcome this, the energy-storing PCM is enhanced by dispersing iron oxide nanoparticles to improve the heat transfer rates. After nanoparticle addition in PCM, its heat storage rate and retrieval rates were found to be increased by 15.82% and 56.36%, respectively. Moreover, the operation time of the solar still was further increased in the evening hours. Additionally, the solar still was integrated with a copper pipe solar thermal absorber to increase the inlet water temperature, which led to an increased evaporation rate, increasing the efficiency of the still by 25.11%.