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 | |
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 | |
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 | |
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) |