The effect of vapour space temperature on the productivity of a passive solar still integrated with multi-functional floating absorber

Solar still based on floating absorber, capable of heat localization, has gained popularity in the recent years for water distillation owing to its superior design, functionality and energy utilization. However, as the design is relatively new, there are various aspects of such a design, especially the vapour space, that must be examined in detail to improve the still productivity under actual working conditions. The present study investigates the influence of the various parameters in the vapour space, like the internal relative humidity, vapour space temperature, and glass cover temperature, on the performance of a three-layer multi-purpose floating absorber (TSS304CC) based solar still. The diurnal performance of the multilayer absorber in a passive still is compared with an Aluminium floating absorber based solar still. It was found that the relative humidity and vapour space temperature adversely affected the solar still productivity of the modified still in the afternoon hours. The vapour space temperature of T-SS304CC still increased by nearly 133%. Similarly, the internal relative humidity of the modified still was 38% lower than the Aluminium based still on the same day, due to the increase in vapour space temperature. Based on cost analysis, it was estimated that the cost per litre of freshwater would decrease by nearly 36%, as compared to the reference still, in the absence of the adverse effect of the vapour space.