This document presents an experimental study on a stepped basin solar still. The study aims to improve the productivity of a single slope solar still by constructing multiple steps in the basin. An experimental setup was fabricated with a stepped basin and observations were taken in Allahabad, India. Results show that productivity can reach over 6 liters per day per square meter when multi-wicks are added to the basin. Overall productivity is increased by 20.5% compared to a setup without wicks. Temperature, solar intensity, and productivity measurements are presented and discussed. The study concludes that a stepped basin design with wicks added can enhance the performance of solar stills.

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International Journal of Advanced Research in Engineering and Technology
(IJARET)
Volume 6, Issue 7, Jul 2015, pp. 24-29, Article ID: IJARET_06_07_004
Available online at
http://www.iaeme.com/IJARET/issues.asp?JTypeIJARET&VType=6&IType=7
ISSN Print: 0976-6480 and ISSN Online: 0976-6499
© IAEME Publication
_____________________________________________________________________
EXPERIMENTAL STUDY ON A STEPPED
BASIN SOLAR STILL
Neha Khare, Ajeet Kumar Rai and Vivek Sachan
Department of Mechanical Engineering, SSET, SHIATS – Allahabad,
U. P. India
ABSTRACT
In the present work an attempt has been made to improve the productivity
of a single slope solar still by constructing many steps to the basin of the solar
still. Experimental setup was fabricated and observations were taken in the
premises of SHIATS Allahabad, U.P., INDIA. It is observed that productivity
can be reached up to more than 6 liters per day for 1 metre square area of the
basin when multi-wicks are added to the system. Overall increase in the
production of stepped basin solar still using wick type arrangement in the
basin is 20.5 % more than without using wick arrangement
Key words: Stepped basin solar still, Solar distillation and Solar intensity.
Cite this Article: Khare, N. Rai, A. K. and Sachan, V. Experimental Study on
A Stepped Basin Solar Still. International Journal of Advanced Research in
Engineering and Technology, 6(7), 2015, pp. 24-29.
http://www.iaeme.com/currentissue.asp?JType=IJARET&VType=6&IType=7
_____________________________________________________________________
1. INTRODUCTION
Solar distillation is the process of producing potable water from the brackish water,
Since it requires simple technology, it is of low maintenance and can be used
anywhere without environmental pollution. Main problem with this type of system is
the low productivity per unit installation area compared to fuel base desalination
method. Increasing the productivity of the solar still has therefore been the focus of
many researchers. Number of attempts have been made by many researchers to
improve the absorptivity of the basin liner by using different heat absorbers such as
gravel [1], sponge cubes [2], rubber [3], charcoal [4, 5], dyes and ink [6, 7]. Many
researchers experimented with solar still that are coupled to reflectors [8, 9], flat plate
collectors. Velmurugan et al. experimented on fin-type passive solar still and found
that the yield was increased by 52%. Productivity of the solar still increases with
increase in absorber area [10]. Kalidasa Murugvel [11] have used wick materials to
spread the water throughout the basin of a passive double slope solar still to enhance
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2. Experimental Study on A Stepped Basin Solar Still
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the productivity the still. Rai et al [14, 15] have used latent heat storage materials in
the basin liner to enhance nocturnal output.
In the present work an attempt has been made to improve the productivity of the
solar still by making stepped basin. Performance is further increased by adding wick
to the basin.
2. EXPERIMENTAL SETUP
The experimental setup consists of a passive solar distillation unit with a glazing glass
cover inclined at 26°. Since the geographical location Allahabad lays 26° in northern
hemisphere thus it is justified to take inclination for glass cover to receive maximum
insolation. This tilted glass cover of 3 mm thickness, served as solar energy
transmitter as well as a condensing surface for the vapour generated in the basin.
Basin having area 1.00 m × 1.00 m is made up of Galvanized Iron has an effective
area of 1.00 m2
. This solar still consist of stepped base construction having 8 trays of
100 × 12 × 2 cm3
each, placed in the basin of solar still. Trays are blackened, for
having maximum possible absorption of solar energy. The basin of the distiller was
blackened to increase the solar energy absorption. For the better performance of
stepped-type solar still wick material is added on side absorber of the basin. A
distillate channel was provided at end of the basin. For the collection of distillate
output, a hole was drilled in the channel and plastic pipe was fixed through it with an
adhesive (Araldite). An inlet pipe and outlet pipe were provided at the top of the side
wall of the still and at the bottom of the basin tray for feeding saline water into the
basin and draining water from still for cleaning purpose, respectively. Rubber gasket
was fixed all along the edges of the still. All these arrangements are made to make the
still air tight. Water gets evaporated and condensed on the inner surface of glass
cover. It runs down the lower edge of the glass cover. The distillate was collected in a
bottle and then measured by a graduated cylinder.
Thermocouples were located in different places of the still. They record different
temperature, such as glass cover and water temperature in the basin and ambient
temperature. In order to study the effect of salinity of the water lacally available salts
were used at various salinities. All experimental data are used to obtained the internal
heat mass transfer coefficient for single slope still.
Figure 1 Photographic view of stepped basin solar still

3. Neha khare, Ajeet Kumar Rai and Vivek Sachan
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2.1. Productivity and efficiency of the still
The hourly productivity Ph is calculated using the following equation [12]
= ℎ − × 3600⁄ (1)
The daily productivity Pd as well as the daily efficiency without and with wick are
calculated using the following formulas
= ,
∑ ∆
× 100"%$ (2)
= ,
∑ ∆
× 100"%$ (3)
Where is the daily average of the latent heat of vaporisation of water and ∆% is the
time interval during which the solar radiation is measured.
Exergy efficiency of the system can be calculated by using the following
expressions [13]
& =
'& ( ) +, -, +. /+01( / 200
'& ( ) 23-, + /+01( / 200
(4)
45+, -, = 45 61- =
7
89:: /. <=
× ">1 −
?1@AB8
? @AB8
C (5)
Where is hourly yield of solar still (kg/h), L is the latent heat of vaporization (j/kg),
Ta is the ambient temperature (°C) and Tw is the water temperature (°C).
45+, -, = 45 61- =
7
89:: /. <=
× ">1 −
?1@AB8
? @AB8
C (6)
Where Exsun (solar still) is the exergy input to the solar still through radiation and can
be obtained from the following equation
45/,3"DEFGH D%IFF$ = J/ × K"%/$ × L1 −
M
8
× >
?1@AB8
?/@AB8
C +
=
8
× >
? @AB8
?O
C
M
P (7)
Where As is the area of basin in solar still (m2
). I (ts) is the solar radiation on the
inclined glass surface of solar still (W/m2
) and Ts is the sun temperature, 6000 K.
3. RESULTS AND DISCUSSIONS
Figure 2 shows variation in solar intensity with respect to time of the day experiments
were carried out of several days in the month of may and june with and without wick
in the stepped basin. Variation of solar intensity in Figure 2 with the time of the day in
the month of may with and without wick. The value of maximum intensity reaches
1200 W/m2
at around 12 o’clock for the day when wicks are used in the stepped
basin. Whereas maximum intensity of 1000 W/m2
reaches around 1 o’clock on the
day when stepped basin was used without multi-wick.
Figure 3 shows variation of wind velocity with respect to time of the day with and
without multi-wick arrangement.

4. Experimental Study
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Figure 2 Variation of the Solar Intensity with time of the Day
Figure 3 Variation of Wind Velocity with t
Figure 4 Variation of Temperature with Time of the Day
Experimental Study on A Stepped Basin Solar Still
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Variation of the Solar Intensity with time of the Day
Variation of Wind Velocity with time of the Day
Variation of Temperature with Time of the Day
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Variation of the Solar Intensity with time of the Day

5. Neha kha
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Figure 4 shows variation of temperature of different component of solar still with
respect to the time of the day. Water temperature without wick is more than the water
temperature with wick in
when wicks were attached to the basin. This due to the fact that due to addition of
wicks to the basin, rate of evaporation increases, which causes the temperature of the
water to decrease. Glass temperature with wick is more due to high solar intensity on
the day.
Figure 5 Variation of the Productivity with Time of the Day
Figure 5 shows the variation of productivity with respect to time of the day. For
two different cases (1) basin with wick (2) basin without wick. It is observed that
productivity with multi-wick arrangement is higher than without wick arrangement.
Use of wick to the basin increases day time productivity by 14 %. Night time
productivity of distil water u
using wick. It is due to thermal inertial effect of the wick material. Overall increase in
the production of stepped basin solar still using wick type arrangement 20.5 % than
without using wick arrang
4. CONCLUSION
A single-slope solar still is
measured in the Allahabad climatic conditions of U.P India. Energy efficiency 60% is
obtained for stepped basin solar still, which is further increase
wicks are added to the basin. Exergy efficiency of the system is calculated as 10.7 %
for without wick and 10.2 % for multi
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Neha khare, Ajeet Kumar Rai and Vivek Sachan
http://www.iaeme.com/IJARET/index.asp 28 editor@iaeme.com
4 shows variation of temperature of different component of solar still with
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Variation of the Productivity with Time of the Day
5 shows the variation of productivity with respect to time of the day. For
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wick arrangement is higher than without wick arrangement.
Use of wick to the basin increases day time productivity by 14 %. Night time
productivity of distil water using wick to the basin increases by 50.5 % than without
using wick. It is due to thermal inertial effect of the wick material. Overall increase in
the production of stepped basin solar still using wick type arrangement 20.5 % than
without using wick arrangement.
slope solar still is fabricated with stepped basin and its performance is
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4 shows variation of temperature of different component of solar still with
respect to the time of the day. Water temperature without wick is more than the water
spite of the fact that the solar intensity is more on the day
when wicks were attached to the basin. This due to the fact that due to addition of
wicks to the basin, rate of evaporation increases, which causes the temperature of the
ease. Glass temperature with wick is more due to high solar intensity on
Variation of the Productivity with Time of the Day
5 shows the variation of productivity with respect to time of the day. For
(1) basin with wick (2) basin without wick. It is observed that
wick arrangement is higher than without wick arrangement.
Use of wick to the basin increases day time productivity by 14 %. Night time
sing wick to the basin increases by 50.5 % than without
using wick. It is due to thermal inertial effect of the wick material. Overall increase in
the production of stepped basin solar still using wick type arrangement 20.5 % than
with stepped basin and its performance is
measured in the Allahabad climatic conditions of U.P India. Energy efficiency 60% is
s 64.7 % when multi
wicks are added to the basin. Exergy efficiency of the system is calculated as 10.7 %
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6. Experimental Study on A Stepped Basin Solar Still
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