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Table 2 Design parameters of a passive solar still

From: A review of optimum parameter values of a passive solar still and a design for southern Bangladesh

Parameters Significance in output/yield Optimum value Ref.
No. of slopes Single slope has a higher yield than double slope Single slope Garg and Mann (1976)
No. of Basins Double basin gives higher yield than single basin stills Single basin in the context of easy making of the still Mahdi (1992)
Inclination of glass cover Angle of inclination has to be equal to the latitude to get maximum normal solar radiation 23.5\(^\circ\) for Dhaka Singh and Tiwari (2004)
Glass cover thickness Lowering glass cover thickness increases the temperature difference between water and inner glass cover 3- to 4-mm glass cover thickness Ghoneyem and Ileri (1997)
Gap distance between water and glass cover Decreasing the gap distance between the glass cover and water surface can improve yield up to 11% 8-cm gap distance can be used Ghoneyem and Ileri (1997)
Stepped solar still To lower gap distance between glass cover and water surface stepped solar still can be used Water depth of 4–5 mm and 100–120 mm tray width is used Velmurugan et al. (2008)
Energy absorption and storing materials Charcoal or fins of aluminum covered with cotton cloth. Small (20–30mm) black stones or gravels can be used as energy storage medium Charcoal and small black stones can be used Abdallah et al. (2009), Cooper (1972)
Insulation thickness Insulation thickness has to be maximum so that no heat loss can occur but we have to consider the cost as well 0.9- to 0.13-m insulation thickness Garg and Mann (1976), Al-Karaghouli and Alnaser (2004), Al-Hinai et al. (2002)
External and internal reflector External and internal reflectors both increase distillate productivity Internal reflectors can be added with side walls and external reflectors at the back side of the still Tanaka and Nakatake (2006), Tanaka (2009, 2011)
Sun tracking system Sun tracking can improve the efficiency of the still but because of movable parts and other electrical circuitry requirement it is not that much cost-effective Sun tracking can be avoided to maintain the cost-effectiveness Kalogirou (1996), Abdallah and Badran (2008)
Wick material Black cotton cloth or charcoal particle is the best wick for passive solar still Light black cotton cloth can be used Minasian and Al-Karaghouli (1995), Murugavel and Srithar (2011)
Condenser Condenser always increases the yield in solar still A passive condenser should be added Fath and Elsherbiny (1993)