Analysis of a solar still with photovoltaic modules and electrical heater - Energy and exergy approach

The availability of drinkable water, along with food and air, is a fundamental human necessity. Because of the presence of higher amounts of salt and pollution, direct use of water from sources such as lakes, sea, rivers, and subsurface water reservoirs is not normally suggested. Solar is still a basic technology that can use solar energy to transform accessible waste or brackish water into drinkable water. Exergy analysis is a strong inferential technique for evaluating the performance of thermal systems. Exergy is becoming more popular as a predictive tool for analysis, and there is a rising interest in using it. In this paper, performance analysis on the aspect of energy and exergy from the proposed solar still (PSS) (conventional solar still with the photovoltaic modules-AC heater) was analyzed on three different water depths (Wd) conditions (1, 2, and 3 cm). Using a solar still with an electric heater, the daily potable water production was found as 8.54, 6.37, and 4.43 kg, for the variations in water depth (Wd) of 1, 2, and 3 cm respectively. The energy and exergy efficiency of the PSS at the Wd of 1, 2, and 3 cm were 75.67, 51.45, and 37.21% and 5.08, 2.29, and 1.03%, respectively. At 1 cm Wd, PSS produced the maximum freshwater yield as compared to the other two water depths. When the Wd is increased from 1 to 2 cm and from 1 to 3 cm, the yield is decreased up to 27.3 and 52.7%, respectively. Similarly, the energy and exergy efficiency is decreased up to 36.8 and 53.2% and 50.4 and 80.6%, respectively. The water cost of the modified solar still is calculated as 0.028 $/kg for the least water thickness.