Theoretical modeling of a glass-cooled solar still incorporating PCM and coupled to flat plate solar collector

The performance of a modified solar still was investigated considering the following cases: solar still with glass cooling (SC), SC connected to an external collector (SCC), and SCC with phase change material (SCCP). Three different PCMs were used; sodium acetate trihydrate, sodium thiosulfate pentahydrate, and paraffin wax. The effect of various parameters; controllable (hot water circulation rate, PCM mass, and cooling water flowrate) and uncontrollable parameters (solar irradiation, ambient temperature, and wind speed) were investigated. Increasing the solar irradiation from 200 to 700 W/m² increased the productivity from 0.9 to 3.4, 2.35 to 10, and 3 to 11.9 ml/min for the SC, SCC, and SCCP (with SAT as PCM) systems, respectively. The addition of external collector and PCM increased the productivity 2.4 times. Increasing the coolant mass flow rate from 0 to 10 kg/s, increased the productivity from 1 to 2.14, 1 to 6.65, and 1 to 7.5 ml/min for the SC, SCC, and SCCP systems, respectively. Additionally, increasing the hot water circulation rate of external collector from 0 to 0.1 kg/s increased the productivity from 2.4 to 6 and from 4 to 7.4 ml/min for SCC and SCCP system, respectively. The optimum mass ratio of basin water: PCM was found to be 2:1, while the best PCM type was found to be the one with the highest melting point and latent heat of fusion. The 24-h operation for a typical May month weather data in Jordan, revealed that the productivity improved 1.8 times for SCC and 2.3 times for SCCP-SAT compared with SC system.