Nano-coated condensation surfaces ٍenhanced the productivity of the single-slope solar still by changing the condensation mechanism

Abstract Solar stills are considered an environmentally friendly technique to produce fresh water. The condensation surface plays an essential role in controlling the efficiency of the solar still. This main parameter is critically affected by the wettability of the condensation surface that affects the condensation mechanism, namely drop-wise or film-wise condensation. This study aims to enhance the efficiency of solar stills by altering the surface wettability hence changing the condensation mechanism using nanomaterials. In this experimental work, different condensation surfaces were coated by silicone nanoparticles to change the condensation mechanism from film to dropwise. Scanning electron microscopy and Atomic force microscopy analyses were utilized to assess the status of the nanoparticles deposited on the transparent condensation surfaces. To check the results, similar designs of solar stills were used to compare their productivity during dropwise and film condensation modes while operated under the same condition of solar radiation. Results showed that dropwise condensation improved the productivity of solar still considerably. For instance, the productivity of solar still during film condensation was 4828 ml/m2, while it reached to 5807 ml/m2 during dropwise condensation for a glass cover at a condensing surface tilt angle of 45°.