The document discusses a study on improving the productivity of basin solar stills by incorporating fins into the design. The results indicate that increasing the number of fins enhances heat transfer, leading to a productivity increase of up to 24.21% compared to conventional designs. Experimental findings suggest that finned solar stills have improved daily efficiency and productivity, demonstrating their potential for better performance in solar water desalination.

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International Journal of Mechanical Engineering and Technology (IJMET)
Volume 7, Issue 3, May–June 2016, pp.119–124, Article ID: IJMET_07_03_011
Available online at
http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=7&IType=3
Journal Impact Factor (2016): 9.2286 (Calculated by GISI) www.jifactor.com
ISSN Print: 0976-6340 and ISSN Online: 0976-6359
© IAEME Publication
STUDIES ON FINNED BASIN SOLAR STILL
Vivek Sachan and Ajeet Kumar Rai
Department of Mechanical Engineering, SSET,
SHIATS-Allahabad, U. P., India
ABSTRACT
In the present work an attempt has been made to improve the heat transfer
rate from basin liner to the water. Fins are used in the basin of the still to
increase the heat transfer rate. Performance of a finned basin still is
compared with that of a conventional still. It is observed that the productivity
of the still increases with increasing the numbers of fins. When number of fins
increase thrice, productivity increases by 25% as compared with the
conventional still. Daily productivity increases with increasing number of fins
in the basin.
Key words: Basin Solar Still, Fins and Evaporative Heat Transfer Coefficient
Cite this Article Vivek Sachan and Ajeet Kumar Rai, Studies on Finned
Basin Solar Still. International Journal of Mechanical Engineering and
Technology, 7(3), 2016, pp. 119–124.
http://www.iaeme.com/currentissue.asp?JType=IJMET&VType=7&IType=3
1. INTRODUCTION
Access to safe, fresh and clean drinking water is one of the major problems in many
regions of the world [El Kharraz et al. (2012) Droogers et al. (2012)]. In
underdeveloped and developing countries, more than 768 million people drink water
from unreliable sources. Solar still can solve part of the problem in those area where
sun’s energy available in plenty. Solar still are simple in design, have zero operating
and low maintenance cost. Detailed reviews of different designs were reported by
Kumar et al. (2015). Many attempts were made by Velmurugana et al (2011), Muftah
et al (2015) to improve the productivity of the still. Velmuruga et. al (2009), El-Sebaii
et al (2014), Ali et.al (2014), El-Sebaii et. Al (2015) and Sadhana et al (2015) have
used extended surfaces in the basin of the still to enhance the heat transfer rate and so
the productivity of the still. In present work attempts have been made to incorporate
fins in the basin of the still, effect of number of fins on the productivity of still is also
obtained.

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2. EXPERIMENTAL SETUP
Two similar double slope solar still are used in the present study .modification were
made in one of stills and performance were measured for both still. For purpose of
comparative study both stills were kept on same platform. A modification made in
the still adding number of fins of specified size provision was made to change the
number of fins in the basin of the still to be modified. The height of the fins is 1 cm,
and the pitch between two successive fins is taken 0.09m and kept constant. Fins are
made of galvanized iron sheet for its good thermal conductivity and cheaper cost. The
basin is covered with 0.05 m thick glass sheet inclined at nearly 260
from horizontal
which is the latitude of Allahabad city of Uttar Pradesh in India to maximize the
amount of incident solar radiation the tilted glass cover (0.05 m thick) served as solar
energy transmitter as well as a condensing surface for the vapour generated in the
basin. The stills are made of galvanized iron sheets, with basin area of 0.72 m2. The
whole basin surface is coated with black paint from inside to increase the absorptivity.
Also the still is insulated from bottom to side walls with Styrofoam insulation sheet to
reduce the heat loss from the still to ambient. The insulation is paste by the Fevicol-
909 adhesive. A distillate channel was provided at each end of the basin.
Experimental setup photographic view
3. EXPERIMENTAL PROCEDURE
Experiments were conducted at SHIATS Allahabad in month of May from sunrise to
sunset. Experimental setup is kept in the North South direction to receive maximum
solar radiation throughout the year. The solar radiation, atmospheric temperature,
basin temperature, saline water temperature, glass temperature and distilled water
productivity were measured. However, the accumulated productivity during the 24 h
had also been measured in each test. A constant water level of saline water was
maintained by adding makeup water.

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4. RESULTS AND DISCUSSIONS
4.1 Effect of Fins in Basin on productivity of solar still
Freshwater productivity of single basin solar stills is very low. To enhance the rate of
heat transfer from the basin liner to the basin water, fins were integrated at the basin
liner of the still. The effect of the number of fins on productivity and efficiency of the
finned basin solar still were also studied. Figure 4.1 shows the variation of solar
intensity with time of a day. Maximum average solar intensity is obtained at noon in
south facing glass cover.
Figure 4.1 Variation of solar intensity with time
Figure 4.2 and 4.3 shows the variation of temperature of different components of
the solar still. Figure 2 shows the variation of water temperature with time for the
finned and without finned basin solar still. Water temperature in the finned basin is
higher than water temperature in without finned basin double slope solar still. Glass
cover temperature in the finned basin is almost equal to the without finned basin
double slope solar still. Temperature of the south facing glass cover is higher than
north facing glass cover. It is almost unaffected by presence of fin in the basin.
Figure 4.2 Variation of water temperature with time
0
200
400
600
800
1000
1200
SolarIntensity(W/m2)
Time of a day (hr)
Solar Intensity(North)
Solar Intensity(South)
0
10
20
30
40
50
60
70
80
Temperature(0C)
Time of a day (hr)
TwN(with fin) TwS(with fin)
TwN(without fin) TwS(without fin)

4. Vivek Sachan and Ajeet Kumar Rai
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Figure 4.3 Variation of glass temperature with time
Figure 4.4 shows the variation of convective heat transfer coefficient for
conventional and modified basin solar still. Fins are used to enhance the heat transfer
coefficient; convective heat transfer coefficient is higher for finned basin solar still.
Average value of heat transfer coefficients for conventional solar still is 1.5119 W/m2
K where as this value increased by 10% up to 1.6649 w/m2
k .When a small
modification in the basin of still is made by attaching 30 numbers of fins.
Figure4.4 Variation of convective heat transfer coefficient with time
Figure 4.5 shows the variation of evaporative heat transfer coefficient with time of
a day. average value of evaporative heat transfer coefficients for conventional solar
still is 29.24 W/m2
K and of finned basin is 30.91W/m2
K .it is clear from here that
used of small and limited no of fins can increase the evaporation heat transfer
coefficient by 5.7 %.
Figure 4.5 Variation of evaporative heat transfer coefficient with time
0
20
40
60
80
Temperature(0C)
Time of a day (hr)
TgN(with fin) TgS(with fin)
TgN(without fin) TgS(without fin)
0
0.5
1
1.5
2
2.5
3
Convectiveheat
transfercoefficient
(hcw,W/m2K)
Time of a day(hr)
hcwN(with fin) hcwS(with fin)
hcwN(without fin) hcwS(without fin)
0
10
20
30
40
50
60
Evaporativeheat
transfercoefficient
(hew,W/m2K)
Time of a day(hr)
hewN(with fin) hewS(with fin)
hewN(without fin) hewS(without fin)

5. Studies on Finned Basin Solar Still
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Figure 4.6 shows the variation of distillate output from conventional and modified
basin double slope solar still .since total distillate collected from the still is the sum of
distillate collected from north side glass cover and south side cover .since productivity
is directly preop to the temperature difference between evaporative and condensing
cover surface. The finned basin solar still has improved both of the daily productivity
and daily efficiency by a relative percentage difference of approximately 28%
compared to the without finned solar still.
Figure 4.6 Variation of productivity with time
4.2. Effect of number of fins on productivity of solar still
Figure 4.7 show that as number of fins increase productivity increase. A comparison
is made between a conventional still with modified still varying number of fins as ten
and thirty. when ten number of fin were used 16.24% productivity increased and
when thirty number of fins used daily productivity increase by 24.1% .Water in
finned basin filled up to the top edge of the fins . Daily productivity increases with
increasing number of fins in the basin. A comparison is also made on the basis of the
efficiency of still .additions of the fins increases the daily efficiency. Daily efficiency
of the conventional still was found to be 39.38% where as 48.91% of finned basin
modified solar still. On a particular day, on the same plate form, when finned basin
with ten number of fins were compared daily efficiency of conventional still was
found to be 35.6% and 41.6 % of ten finned basin still. As number of fins increases,
the daily productivity also increases.
Figure 4.7 variation of daily productivity with number of fins
0
20
40
60
80
100
120
140
Productivity(ml)
Time of a day (hr)
PdN(with fin)
PdS(with fin)
PdN(without fin)
3540
3185
2850 2740
0
1000
2000
3000
4000
30 fins 10 fins
Productivity(ml)
Number of fins
with fin
without fin

6. Vivek Sachan and Ajeet Kumar Rai
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5. CONCLUSION
In the present work an attempt has been made to investigate the rate of heat transfer
from basin liner to the basin water as the rate of heat transfer is directly proportional
to the surface extended surfaces are used in the basin of the still to increase the heat
transfer rate . Effect of number of fins on the productivity of the still is also obtained.
It is observed that the productivity of the still increased by 16 % when 10 numbers of
fins were used. When number of fins increase up to 30, Productivity increased by
24.21% as compared with the conventional still. Daily productivity increases with
increasing number of fins in the basin.
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