Innovative configurations for spherical solar distillation: Ball rotation and preheating for improved productivity

Solar stills are acknowledged as an environmentally friendly desalination method that addresses water scarcity issues in remote areas; however, they contend with a productivity challenge. This work presents a combination of novel arrangements for the spherical solar distiller (RBSD) to augment its productivity. Rotational sphere was anticipated. The influence of speed for RBSD (0, 0.5, 1, 1.5, and 2 rpm) with and without wick was tested. Also, the effect of utilizing a preheater to supply the RBSD with hot feed water under various preheating temperatures, specifically 45, 50, 55, 60, 65, and 70 °C with and without condenser was investigated. Results revealed that the optimized speed is 0.5 rpm and 1 rpm for the RBSD with and without wick, respectively, where the productivity rise reached 62 % and 45 %, respectively. Also, the best preheating temperature that provided the highest performance for RBSD was 65 °C, where the CSD produced 3250 mL/m².day, while, at 0.5 rpm and 65 °C, the RBSD with a preheater produced 6200 mL/m².day with an increase in productivity by 91 %. When integrating the external condenser to RBSD with wick and preheater, the productivity of RBSD (6800 mL/m².day) was augmented by 116 % over that of the CSD (3150 mL/m².day). Also, the thermal efficiency of CSD and RBSD with wick, preheater and condenser was 32 % and 62 %, respectively. Finally, the cost of distilled water for CSD, RBSD with wick, RBSD with wick and preheater, and RBSD with wick, preheater, and condenser was found to be 0.220$/L, 0.075$/L, 0.055$/L, and 0.030$/L, respectively.