The document describes the design and manufacturing process of a solar still. It discusses the operational principle of solar stills, which uses evaporation and condensation to desalinate water. It also analyzes the heat transfer within a solar still and discusses recommendations for its orientation and insulation to maximize efficiency. While not economically feasible at a large scale, solar stills can play an important role in providing clean water in remote areas lacking infrastructure by distilling brackish water.

1. Design and Manufacturing of
solar still
Topics Objective
Introduction
Operational principle
Heat transfer analysis
Orientation of solar still
Draw back of solar still
Conclusion and recommendation

2. Objective: To design the solid mechanics and manufacture a
solar still.
Introduction:
Distillation is one of the many processes for separating a portable
desaline water from brackish one with the help of an external source
of energy based on difference in boiling point.
Mode of heat transfer
• conduction
• convection
free convection
forced convection
• radiation

3. Operational principle
Operates on the basic principle of evaporation and
condensation.
Heat transfer analysis
Assumption: One dimensional heat transfer
Basin and cover area are equal
It is analyzed by taking energy balance at the cover
and basin water.

4. Fig. Basic thermal net work for a basin type still

5. Heat balance on cover:
It relates heat transfer from water to cover, the absorption of
radiation in cover and heat lost from cover to ambient.
Qga =αg I + Qwc
Qga=qra + q ca
hc = 0.884[(Tw-Tg)+Tw(Pw-Pg) / (2016-Pw)]1/3
hw=2.8 + 3 V

6. qe= 9.15*10-7hc ( Pw-Pg )
qr = fσ( Tw
4-Tg
4)
qc=hc (Tw-Tg )
qra=εcσ( Tg
4-Ts
4 )
qca = hw (Tg-Ta)
Heat balance on water basin:
It relates the heat absorbed by the black lined basin reservoir,
heat capacity of water and heat lost from water and reservoir.

7. Orientation of solar still
Glass cover: The two glass covers are arranged with an
inclination 140 from the horizontal for its maximum intensity
of solar radiation arrival and attached at the top with sheet steel
with sealant.
A standard 4mm window glass is better to withstand hailstorms.

8. Trough or gutter: For easily flow of the condensate into the out
late the trough should be slightly inclined.
Basin reservoir: In order to reduce the energy required to lift the
water vapor to the glass, the reservoir height should be as
minimum as possible.
Insulation: An expanded polystyrene foam (styro foam) which is
commonly used inside cardboard packaging to protect
electronic equipment is covered the entire wall and bottom of
the still to reduce the heat loss to the atmosphere.
Out side cover: Due to the light weight of the insulation there
should be an out side cover to protect the insulation from being
dispersed by wind.

9. Drawback of solar still
• Higher initial cost compared to productivity
• The condensate doesn’t contain minerals (i.e. iron) which
people are accustomed. It may taste initially a little strange)
Conclusion
Heat transfer of solar still is modeled by assuming one
dimensional heat transfer and energy and mass balance of
solar still at different parts.( i.e. glass and cover)
Though it’s not economically feasible to implement solar still
commercially with regard to portable water sold with cents, it
has a pivotal role in supplying portable desalinate water from
brackish one and to prevent water born diseases like cholera in
remote areas.

10. Recommendation
The solar still will be more economical if it is possible enough to
change the sheet still reservoir with plastic and use the flushed
water for a number of application. (i.e. for household purposes,
for crops)

11. We would love to praise those who were interested in
Sharing their ideas.
The End
Questions?