Investigating the effect of pumice stones sensible heat storage on the performance of a solar still

In this communication, a single slope basin type solar still is investigated for the climatic conditions of Aligarh (27.89 degrees N, 78.08 degrees E), India. The solar still was tested for the change in the amount of energy storage material (pumice stones) for a constant amount of water (10 L) in the basin. An experiment was initially conducted without any energy storage material and was later compared with the experimental data of solar still with 5 kg and 10 kg pumice stones. Daytime yield for the solar still without energy storage material was found to be 1950 ml; and decreased for solar stills with 5 kg and 10 kg pumice stones as 1748 and 1618 ml of distillate, respectively. The productivity of the solar still during nighttime enhanced due to energy storing capacity of pumice stones but the overall production reduced by increasing the mass of pumice stones. Further, the three cases were also compared on the basis of heat transfer coefficients from water to glass, and glass to the ambient. The overall thermal efficiency of the solar still with no mass, 5 kg and 10 kg pumice stones was found to be 35.1%, 29.3% and 28.8% respectively.