Effects of condensing cover inclination and water depth on the convective heat transfer coefficient and yield have been studied for a passive solar still. Three solar stills with an effective basin area of $1m2$ each have been studied for three inclinations of condensing cover, namely, $15deg$, $30deg$, and $45deg$. An identical solar still, but with a fixed cover inclination of $30deg$, has also been tested to evaluate the effects of varying water depth. Outdoor experiments have been conducted for New Delhi climatic conditions $(28°37′N∕77°13′E)$. Hourly variations of temperatures (water, vapor, and cover) and of distillate yield have been recorded and analyzed to determine convective heat and mass transfer coefficients. The resulting calculative extrapolation of experimental data from clear-day operation shows that the combination of minimum water depth and $15deg$ inclination of the condensing cover leads to maximum annual distillate yield for the climatic conditions of New Delhi. However, a cover inclination of $45deg$ is almost equally effective on an annual basis, but with better winter performance.

1.
Hay
,
H. R.
, 1965, “
New Concepts in Solar Still Design
,”
Proceedings of the First International Symposium on Water Desalination
,
Washington, DC
, Vol.
1
, pp.
511
527
.
2.
Hay
,
H. R.
, 1973, “
Plastic Solar Stills: Past, Present, and Future
,”
Sol. Energy
0038-092X,
14
(
4
), pp.
393
404
.
3.
Dunkle
,
R. V.
, 1961, “
Solar Water Distillation: The Roof Type Still and a Multiple Effect Diffusion Still
,”
Proceedings of the International Development in Heat Transfer
,
, Pt. V, p.
895
.
4.
Malik
,
M. A. S.
,
Tiwari
,
G. N.
,
Kumar
,
A.
, and
Sodha
,
M. S.
, 1982,
Solar Distillation
,
Pergamon
,
London
.
5.
Tiwari
,
G. N.
, and
Lawrence
,
S. A.
, 1999, “
New Heat and Mass Transfer Relations for a Still
,”
Energy Convers. Manage.
0196-8904,
31
, pp.
201
203
.
6.
Kumar
,
S.
, and
Tiwari
,
G. N.
, 1996, “
Estimation of Convective Mass Transfer in Solar Distillation System
,”
Sol. Energy
0038-092X,
57
, pp.
459
464
.
7.
Tripathi
,
R.
, and
Tiwari
,
G. N.
, 2005, “
Effect of Water Depth on Internal Heat and Mass Transfer for Active Solar Distillation
,”
Desalination
0011-9164,
173
, pp.
73
88
.
8.
Delyannis
,
E.
, 2003, “
Historic Background of Desalination and Renewable Energies
,”
Sol. Energy
0038-092X,
75
(
5
), pp.
357
366
.
9.
Tiwari
,
A. Kr.
, and
Tiwari
,
G. N.
, 2006, “
Effect of Water Depth on Heat and Mass Transfer in a Passive Solar Still: In Summer
,”
Desalination
0011-9164,
195
, pp.
78
94
.
10.
Tiwari
,
G. N.
, 2002,
Solar Energy
,
1st ed.
,
Narosa
,
New Delhi
/
CRC
,
New York
, p.
506
.