Improvement in the performance and cost of passive solar stills using a finned-wall/built-in condenser: An experimental study

In the current study, a passive single-slope solar distillation unit has been proposed. An incorporated condenser has been integrated into the system to promote the condensation rate and hence improve the unit productivity. External fins have been used as a means to enhance the condenser performance further. The system performance has been examined experimentally for seven consecutive summer days in Mashhad city located at 36° 18′56.12″ N latitude and 59° 34′4.66″ E longitude. The unit yield and efficiency have been compared to the corresponding data for a conventional solar still tested in Tehran city. The results reveal that using fins increases the distillate in the condenser by 35%. But, there is only a 5% increase in the total unit productivity due to a reduction in distillate on the glass cover by 8%. Compared to the typical solar still tested in Tehran, up to 92.3 and 86% increase in daily productivity can be achieved using the current still with and without fins, respectively. The thermal efficiency of the currently proposed structure is about double than is it for the traditional solar still. The economic feasibility of the current solar still has been compared to some passive and active designs found in the literature, where it has been found not only efficient but less costly as well. The system without fins is the least expensive with CPL=0.007$/l/m2, while the one with fins is slightly more expensive with CPL=0.0117$/l/m2 but still economically outstanding.