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This experimental study investigated the combined impact of integrating novel fin geometries on the absorber plate with appropriate paint coatings to enhance the absorber plate temperature. Three geometries of fins, namely hemispherical, trapezoidal, and trapezoidal fins with fillet projections, were designed and machined on aluminum absorber plates measuring 10 cm × 10 cm using a Vertical Machining Center (VMC) machine for research work in the climate conditions of Rajkot, Gujarat, India. Four commonly available black coatings, including spray paint, oil paint, blackboard paint, and nail polish, were tested on the absorber plate in this study. An experimental setup under a closed glass cover system was employed to evaluate the thermal performance without water in the basin, isolating the effect of various fin geometries and surface coatings. The results indicated that the absorber plate coated with oil paint delivered the highest temperature (65.07 °C) attained in the closed system, owing to its superior heat retention properties. Among the fin geometries, hemispherical fins showed the best performance, achieving the highest average plate temperature (68.10 °C) and best shape factor (0.9), indicating superior thermal retention with reduced radiative losses. The results suggest that using oil paint and a novel hemispherical fin geometry is a cost-effective and efficient solution for enhancing the thermal performance of solar stills, particularly in low-cost rural applications.Keywords: Solar distillation; solar still; fins; coating
Mehta et al. (Tue,) studied this question.