Effect of surface cooling and tube thickness on the performance of a high temperature standalone tubular solar still

The present study describes the effect of the surface cooling and thickness on the performance of the hi; temperature standalone tubular solar still (HTS-TSS). TSS is integrated with a parabolic concentrator sol tracking system (PCST). The test was performed under the climatic conditions of Hail city (27.64 N, 41.75T) Saudi Arabia. Results showed that reducing TSS tube thickness 40% enhances water productivity and efficien by 21% and 13.35% respectively and lowers the cost of water production by 37.5%. Unlike conventional bas solar stills, results showed a negative impact on the IITS-TSS performance under tube surface cooling. Ts different techniques of cooling were used. First technique is to spray cooling water over the whole tube surface a rate of 10 ml every 30 min which reduces TSS productivity and efficiency by 10% and 7.79% respectively. the second technique, cooling water flows in the gap between two concentric tubes with a rate of 40 ml/m which also reduces the productivity and the efficiency by 43.8% and 42.63% respectively. Cooling tube surfa is not recommended for standalone TSS systems. Tube dimensions and properties are key design elements of T which needs more intensive investigations.