Smart Grid and Renewable Energy, 2013, 4, 88-98
http://dx.doi.org/10.4236/sgre.2013.41012 Published Online February 2013 (http://www.scirp.org/journal/sgre)
Design and Performance Analysis of an Innovative Single
Basin Solar NanoStill
Moses Koilraj Gnanadason1, Palanisamy Senthil Kumar2, Vincent H. Wilson3, Gajendiran Hariharan4,
Navaneethakrishnan Shenbaga Vinayagamoorthi5
1Mechanical Engineering, PRIST University, Thanjavur, India; 2Mechanical Engineering Department, KSR College of Engineering,
Tiruchengode, India; 3Engineering & Technology, PRIST University, Thanjavur, India; 4Faculty of Mechanical Engineering, VOC
Anna University College of Engineering, Tuticorin, India; 5Department of Mechanical Engineering, Anna University of Technology,
Tirunelveli, India.
Received September 17th, 2011; revised August 6th, 2012; accepted August 13th, 2012
ABSTRACT
The provision of fresh water is becoming an increasingly important issue in many areas of the world. Clean water is a
basic human necessity, and without water life will be impossible. The rapid international developments, the industrial
growth, agriculture and population explosion all over the world have resulted in a large escalation of demand for fresh
water. The solar still is the most economical way to accomplish this objective. The sun’s energy heats water to the point
of evaporation. When water evaporates, water vapour rises leaving the impurities like salts, heavy metals and conden-
sate on the underside of the glass cover. Solar distillation has low yield, but safe and pure supplies of water in remote
areas. The attempts are made to increase the productivity of solar still by using nanofluids and also by black paint coat-
ing inside the still basin. Heat transfer enhancement in solar still is one of the key issues of energy saving and compact
designs. The essential initiative is to seek the solid particles having thermal conductivity of several hundred times
higher than those of conventional fluids. Recently, as an innovative material, nanosized particles have been used in sus-
pension in conventional solar still water. The fluids with nanosized solid particles suspended in them are called “nan-
ofluids”. The suspended metallic or nonmetallic nanoparticles change the transport properties, heat transfer characteris-
tics and evaporative properties of the base fluid, The aim of this paper is to analyze and compare the enhanced per-
formance of a single basin solar still using nanofluids with the conventional water. They greatly improve the rate of
evaporation and hence the increase in efficiency.
Keywords: Solar Still; Nanofluid; Nanoparticles; Productivity
1. Introduction
Water is a nature’s gift and it plays a key role in the de-
velopment of an economy and in turn for the welfare of a
nation. Non-availability of drinking water is one of the
major problem faced by both the under developed and
developing countries all over the world [1]. Around 97%
of the water in the world is in the ocean, approximately
2% of the water in the world is at present stored as ice in
polar region, and 1% is fresh water available for the need
of the plants, animals and human life [2]. Today, major-
ity of the health issues are owing to the non availability
of clean drinking water. In the recent decades, most parts
of the world receive insufficient rainfall resulting in in-
crease in the water salinity. The pollution of water re-
sources is increasing drastically due to a number of fac-
tors including growth in the population, industrialization,
urbanization, etc. These activities adversely affected the
water quality in rural areas and agriculture. In developing
countries, lack of safe and unreliable drinking water con-
stitutes a major problem. Worldwide drought and deser-
tification are expected to increase the drinking water
shortage to become one of the biggest problems facing
the world [3]. As population grows; there is less water
per capita. At the current trend of growth, it is predicted
that the global population will reach 8 billion by 2025
and the per captia water available will go down. Along
with depletion and pollution of existing water supplies,
the growing world population leads to the assumption
that two thirds of the population will lack sufficient fresh
water by the year 2025 [4]. Globally, 200 million hours
are spent each day, mostly by females, to collect water
from distant, often polluted sources. In the world, 3.575
million people die each year from water related diseases.
Majority of the rural people are still unaware of the con-
sequences of drinking untreated water [5].
Desalination is the oldest technology used by people

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill 89
for water purification in the world. Solar energy is avail-
able in abundant in most of the rural areas and hence so-
lar distillation is the best solution for rural areas and has
many advantages of using freely available solar energy
[6]. A solar still operates similar to the natural hy-
drologic cycle of evaporation and condensation. It is a
simple technology and more economical than the other
available methods [7].
The use of solar energy is more economical than the
use of fossil fuel in remote areas having low population
densities, low rain fall and abundant available solar en-
ergy. The attempts are also made to increase the produc-
tivity of water by painting black coating inside the basin
and by providing insulation to the still basin. But the
novel approach is to introduce the nanofluids in solar still
with conventional water. The poor heat transfer proper-
ties of these conventional fluids compared to most solids
are the primary obstacle to the high compactness and ef-
fectiveness of the system. The essential initiative is to
seek the solid particles having thermal conductivity of
several hundred times higher than those of conventional
fluids [8]. The use of additives is a technique applied to
enhance the heat transfer performance of water in the still
basin. An innovative idea is to suspend ultrafine solid
particles in the fluid for improving the thermal conduc-
tivity of the fluid. The fluids with solid-sized nanoparti-
cles suspended in them are called nanofluids [9]. The
suspended metallic or nonmetallic nanoparticles change
the transport properties, heat transfer characteristics and
evaporative rate of the base fluid. The carbon nanotube
(CNT)-based nanofluids are expected to exhibit superior
heat transfer properties compared with conventional wa-
ter in the solar still and other type of nanofluids and
hence the increase in the productivity and efficiency of
the solar still.
2. Conventional Solar Still
As the available fresh water is fixed on earth and its de-
mand is increasing day by day due to increasing popula-
tion and the rapid increase of industry, hence there is an
essential and earnest need to get fresh water from the
saline/brackish water present on or inside the earth. This
process of getting fresh water from saline/brackish water
can be done easily and economically by desalination. The
changing climate is one of the major challenges the entire
world is facing today. Gradual rise in global average
temperatures, increase in sea level and melting of gla-
ciers and ice sheets have underlined the immediate need
to address the issue. All these problems could be solved
only through efficient and effective utilization of renew-
able energy resources such as solar, wind, biomass, tidal,
and geothermal energy, etc. Owing to the diffuse nature
of solar energy, the main problems with the use of solar
thermal energy in large-scale desalination plants are the
relatively low productivity rate, the low thermal effi-
ciency and the considerable land area required. Apart
from the cost implication, there are environmental con-
cerns with regard to the burning of fossil fuels [10]. Solar
energy can directly or indirectly be harnessed for desali-
nation. The solar stills are simple and have no moving
parts.
Working of solar still is based on the simple scientific
principle of Evaporation and condensation. There are
several types of solar stills the simplest of which is the
single basin still. But the yield of this is low and falls in
the range of 3 - 4 litres per day per square metre [11].
Different still designs have been used in different regions
globally, where high quality drinking water supplies are
scarce and the solar option is viable. The operation of
Solar still is very simple and no special skill is required
for its operation and maintenance. Solar stills use natural
evaporation and condensation, which is the rainwater
process. A solar still is a low-tech way of distilling water,
powered by the heat from the sun. In the conventional
solar still, saline water is stored in the basin of still,
where it is evaporated by means of the sunlight through
clear glass. The pure water vapour condenses inside the
glass surface and the pure water is collected in the beaker
as shown in Figure 1. The various factors affecting the
productivity of solar still are solar intensity, wind veloc-
ity, ambient temperature, water glass temperature differ-
ence, and free surface area of water, absorber plate area,
temperature of inlet water, glass angle and depth of water.
The solar intensity, wind velocity, ambient temperature
cannot be controlled as they are metrological parameters
whereas the remaining parameters, free surface area of
water, absorber plate area, temperature of inlet water,
glass angle and depth of water can be varied to enhance
the productivity of the solar stills. By considering the va-
rious factors affecting the productivity of the solar still,
various modifications are being made to enhance the pro-
ductivity of the solar still [12].
3. Experimental Setup
3.1. Solar Still Made up of Aluminium Sheet
A Single basin solar still made up of Aluminium Sheet is
Figure 1. Solar still.

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill
90
fabricated. It consists of a basin made up of Aluminum of
1 × 1 meter with maximum height of 50 mm and thick-
ness 2 mm thick as shown in Figure 2. Aluminum has
higher thermal conductivity compared to Galvanized Iron
so that the rate of heat transfer to water in the still is more.
The colour of aluminum sheet is silvery here it is painted
with black colour so it will be better to absorb the maxi-
mum amount of solar radiation falling on them and con-
vert it in to heat. The black colour paint needed for
painting the basin is about 100 ml. The aluminum also
has a smooth surface to make it easier to paint the black
paint.
When the aluminum sheet is used without black colour
painting, it absorbs less solar radiation. The basin is made
water proof using, M-seal. The top of the basin is covered
with transparent 5 mm window glass inclined by nearly
10˚ angles with the horizontal. There are certain specifi-
cations needed for the used glass cover in the still. They
are (a) Minimum amount of reflection for solar radiation
energy (b) High thermal resistance for heat loss from the
basin to the ambient. The spacing between the glass
cover and the basin water surface is 120 mm to 200 mm.
The slope of the glass cover does not affect the rate at
which the distillate runs down its inner surface to the
collection trough. The glass cover that is no more than
from the water surface will allow the still to operate effi-
Figure 2. Schematic diagram of our solar still.
ciently. Consequently, a glass-to-water distance increases,
heat loss due to convection become greater, causing the
still efficiency to drop.
3.2. Experimental Setup
Figure 3 shows a single basin solar still is fabricated.
This solar still consists of a basin made up of Aluminum
of 1 × 1 meter with maximum height of 50 mm and
thickness 2 mm thick. The cover is sealed tightly using
silicon sealant to reduce the vapor leakage. Two pipes of
10 mm diameter are fitted to the basin; one for filling the
brackish water in to the basin and other for flushing the
brackish water out from the basin of the solar still. A
condensate channel runs along the lower edges of the
glass cover which collects the distillate and carries it out-
side the still. The entire assembly is placed on a stand
structure made up of M.S. angles. The outlet is connected
to a storage container through a pipe. Provision is made
to change water in the still.
The still is filled with the brackish water in a thin layer
as shown in Figure 4. The experiment is carried out
keeping water depth of 1cm. During the experiment every
day the solar radiation, atmosphere temperature and day
time wind speed were also measured. The feed water is
changed and the distilled water collected is measured at
7:00 a.m. every morning. The hourly productivity of
fresh water is collected through a graduated flask. Day by
day the salts deposited are removed manually. Each and
every hour the potable water output is measured corre-
spondingly the prevailing conditions are noted down.
When the water is maintained at 1 cm level the output
gain is more if it is more than 2 cm. A cross section pipe
of diameter 6 cm of length 1 meter is used to carry down
the pure condenses water from the solar stills to the col-
lector which is provided outside the solar still. Eventually
the output of the solar still is increased by hour by hour in
the mid period of 11:00 a.m. to 3:00 p.m.
3.3. Terminology
Length of the base = 1 m
Figure 3. Still basin painted with blac k c olour.

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill 91
Figure 4. Skeleton of Solar Still.
Breadth of the base = 1 m
Thickness of the base = 1 mm
Volume = LBH = 1 × 1 × 0.001 = 0.001 m3
Density of salt water = 1078 kg/m3
Density of aluminum = 7833 kg/m3
Mass of aluminum = Density*volume = 7833 × 0.001
= 7.833 kg/m3
Surface area of the base = 1 m*1 m = 1 m2
Volume of salt water = l*b*h= 1*1*0.005 = 0.005 m3
Mass of salt water = Density*volume = 1078 × 0.005 =
5.39 Kg
In solar still the basin is painted with black colour
gives a daily production of 2220 ml of water/day. The
average solar radiation is 906 W/m2. The yield of dis-
tilled water is depending on the several factor wind ve-
locity, solar radiation, and ambient temperature.
The measuring devices used in the system are as fol-
lows:
1) Solar meter (Sun meter) is used to measure the solar
radiation. This device measures the instantaneous inten-
sity of radiation in (W/m2), Range 0 - 1999 Watt/m2.
2) A hygrometer is an instrument used for measuring
the moisture content in the environmental instrument.
3) A digital anemometer is used to measure wind
speed.
4) Five thermocouples (type-k) coupled to digital Ther-
mometer with a range from 0˚C to 99.9˚C with ±1˚C ac-
curacy are used to measure the temperatures of the vari-
ous components of the still system.
3.4. Measurements
The solar still made up of aluminum, inside bottom black
paint coated is operated at ambient conditions from 6:00
a.m. to 7:00 p.m. during the months of April and May
2012. The measurements of the temperatures, solar ra-
diation intensity, and the production of distilled water are
taken hourly to study the effect of each parameter on the
still productivity. In this study various operating condi-
tions have been examined such as; different water depth,
insulation thickness, ambient temperature and salt con-
centration without using nanofluids inside the till. The
variables such as ing T, out, a, w, p and pro-
ductivity are measured hourly. The total productivity and
solar Intensity for each day are also measured. Also, dif-
ferent experimental tests are carried out at different am-
bient conditions. From about 2:00 p.m., water tempera-
ture decreases due to the losses from the solar still which
becomes larger than the absorbed solar radiation. It can
be noted that the basin temperature gets closer to the wa-
ter temperature because of the continuous contact be-
tween them which leads to heat equilibrium.
g
TT T T
As the glass temperature is much lower than the va-
pour temperature, it causes condensation of vapour on the
glass. In the early hours of the morning 8:00 - 9:00 a.m.,
the glass temperature is higher than the water and vapour
temperatures causing small productivity due to the small
energy absorbed by the water at these times. Increase in
the solar intensity in the early morning until it reaches the
maximum at around 12:00 to 2:00 p.m., and then de-
creases in the late afternoon. The solar intensity has an
important effect on the solar still productivity. As the solar
intensity increases, the productivity increases due to the
increase in heat gain for water vaporization inside the still.
The productivity rate varies as time passes from the
early morning until late afternoon. In the morning, the
temperature of water is low; therefore it needs high en-
ergy to change its phase from saturated liquid to satu-
rated vapour phase. The results show that temperature
and required heat are inversely proportional. In the early
afternoon the temperature of water reaches the maximum
so it needs less heat to vaporize, and vice versa in the late
afternoon.
Experimental Readings
After the fabrication of the solar still successfully com-
pleted the experimental readings of the solar still is taken
place. The various factors are considered along with the
output. The water level in the solar basin is maintained to
a level of 1 cm. The hour by hour reading is tabulated in
the below tabular column. In Table 1 the various pa-
rameter are predicted such as wind velocity, wet bulb
temperature, dry bulb temperature, anemometer, and py-
rometer. From the above tabular column we can able to
understand that the output of the solar still is increased
when there is a sufficient sequence parameter prevails.
The experiment is carried out to determine the output of
the solar still when its basin is painted with black colour.

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill
92
Table 1. Time vs solar radiation.
Time duration DBT WBT Wind
velocity Solar radiation Water collection
Hour ˚C ˚C m/s W/m2 ml/m2
06 a.m. - 07 a.m. 27 24 0.5 1250 20
07 a.m. - 08 a.m. 28 25 0.9 1250 50
08 a.m. - 09 a.m. 30 26 1 1250 80
09 a.m. - 10 a.m. 32 27 1 1250 100
10 a.m. - 11 a.m. 34 27 0.7 1275 280
11 a.m. - 12 a.m. 35 28 4.5 340 350
12 p.m - 13 p.m 36 27 0.5 1143 360
13 p.m. - 14 p.m. 37 27 2.1 1060 280
14 p.m. - 15 p.m. 36.5 28 1.8 338 360
15 p.m. - 16 p.m. 36 27 2.5 750 300
16 p.m. - 17 p.m. 33 25 2.3 1100 220
17 p.m. - 18 p.m. 31 24 2.5 904 120
18 p.m. - 19 p.m. 28 23 2.0 700 30
4. Modified Solar Still
4.1. Nanofluids
Suspended CuO and Al2O3 (18.6 and 23.6 nm,) with two
different base fluids: water and ethylene glycol (EG) and
gives four combinations of nanofluids: CuO in water, CuO
in EG, Al2O3 in water and Al2O3 in EG. Their experi-
mental results showed that nanofluids have substantially
higher thermal conductivities than the same liquids
without nanoparticles. The CuO/EG mixture showed en-
hancement of more than 20% at 4 volume% of nanopar-
ticles. In the low volume fraction range (<0.05 in test), the
thermal conductivity ratios increase almost linearly with
volume fraction. Although the size of Al2O3 particle is
smaller than that of CuO, CuO-nanofluids exhibited better
thermal conductivity values than Al2O3 nanofluids [13].
The thermal conductivity of four kinds of nanofluids such
as MWCNTs in water, CuO in water, SiO2 in water, and
CuO in ethylene glycol are compared and found that the
thermal conductivity of MWCNT nanofluid is increased
up to 11.3% at 1 volume%, which s relatively higher than
that of the other groups of nanofluids [14].
Using the MWCNT (dia 20 - 60 nm) with water as base
fluid with temperature of 30˚C shows that the thermal
conductivity varies linearly below 30˚C but above 30˚C it
is independent [15]. When 0.1% of MWNT is used it is
found that thermal conductivity increased for 0.6% of
volume fraction but both CMWNT and CDWNT gives
34% increased in thermal conductivity for 0.6% volume
fraction [16].
Using the same nano particle with same base fluid but
the size is reduced to 28.6 nm and 36 nm shows that the
thermal conductivity depends on volume fraction, di-
ameter, and bulb temperature. It is concluded that when
the size of the nano particle decreases the thermal con-
ductivity get increased based on the temperature range
[17].
Multiwalled carbon nanotubes (MWCNTs) have been
a topic of tremendous scientific interest in recent years
due to their excellent thermal and electrical properties.
They consist of several annular layers of rolled up gra-
pheme sheets held together by interlayer van der Waal’s
forces. The typical diameter of the outermost layer


o
d
CNT
varies between a few nanometers (nm) and hundreds of
nanometers, while the length can be as high as
100 μm. Due to the high thermal conductivity ( =
3000 W/mK [18] and aspect ratio

CNT
L

k


CNT o
A
RLd of
MWCNTs, adding them to a liquid improves the effec-
tive thermal conductivity of the suspension medium
(nanofluid) significantly, compared to that of the original
liquid. Depending on the properties of the base liquid,
CNT geometry, and volume fraction, a wide range of en-
hancement has been reported in the literature. With as
small as 1% volumetric fraction of MWCNT loading,
the thermal conductivity of water is enhanced by ∼40%
[19].
4.2. Preparation of Carbon Nanotubes
The multiwalled carbon nanotubes are prepared by using
the chemical vapor deposition methods using methane as
an energy source and iron particles are used as a sub-
strate. The as-produced CNT soot contains a lot of impu-
rities. The main impurities in the soot are graphite
(wrapped up) sheets, amorphous carbon, metal catalyst,
and the smaller fullerenes. These impurities will interfere
with most of the desired properties of the CNTs. The
most common method used to purify the CNT is acid
treatment [20]. First of all, the surface of the metal must
be exposed to sonication. The CNTs remain in suspended
form. When using a treatment in nitric acid (HNO3), the
acid only has an effect on the metal catalyst. It has no
effect on the CNTs and other carbon particles if a treat-
ment in hydrochloric acid (HCl) is used; the acid has also
a little effect on the CNTs and other carbon particles. The
diameter and the length are measured by transmission
electron microscopy (TEM) and the structures of the
CNTs are analyzed using scanning electron microscopy
(SEM).
Mass production of carbon nanotubes (CNTs) by a cost
effective process is still a challenge for further re- search
and application of CNTs. Our group has focussed on the
deposition of CNTs on a continuously-fed carbon sub-
strate via arc discharge at atmospheric pressure. This
process produces MWNTs using carbon from the sub-

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill 93
strate. The method differs in other respects from the con-
ventional batch arc discharge method by using lower cur-
rents (<20 A) and larger inter-electrode gaps. To help
define the local conditions of nanotube growth, the sub-
strate surface temperature (Ts) was measured by optical
pyrometry. Here, we report the influence of inter-elec-
trode gap, substrate velocity and arc current on this tem-
perature. It is found that carbon nanotube growth is fa-
vourable over a certain temperature range and retention
time in the arc.
4.3. Preparation of Nanofluid
Figure 5 clearly shows that the multiwalled carbon na-
notubes are entangled and not ready to be dispersed into
fluids. Generally, carbon nanotubes are in hydrophobic
nature, prone to agglomerate together, and settled quickly.
To maintain stable and even suspension, two different
methods are adopted for producing stable CNT nanoflu-
ids [20]. One is to use a surfactant, and sodium dodecyl
sulfate (SDS) and is adopted as a surfactant in this study.
At first, SDS is dissolved in DW at the rate of 1.0 wt%
and then the mixture of CNTs and SDS solution is soni-
cated to make well-dispersed and homogenous suspend-
sions.
The other method is to attach hydrophilic functional
group on to the surfaces of CNTs. Nitric/sulfuric acid
mixture was used to modify the surfaces of CNTs. In a
typical treatment of the present work, SDS surfactant is
used to prepare the stable nanofluids. 2.0 wt% of SDS
give homogeneous dispersion of carbon nanotubes in the
nanofluids [21]. UV-vis spectrophotometric measure-
ments are used to quantitatively characterize colloidal
stability of the dispersions. Few existing nanofluid ther-
mal properties studies have used this type of particle.
Heat transfer behavior also depends on other properties
(specific heat, density, viscosity). Macroscopic theory
based on Maxwell’s predictions for dielectric behavior of
composites, Predicts increase in conductivity in nanoflu-
ids is approximately independent of particle size and par-
ticle conductivity liquids and materials that can be va-
Figure 5. Thermal conductivity measure ment.
porized at low to moderate Temperature. Small particle
size, but little control over size.
4.4. Stability Evaluation
Usually, the stability of the oxide particles in suspension
is determined by measuring the sediment volume versus
the sediment time. However, this method is not suitable
for the CNT dispersion. So the quality of the stability is
characterized by using UV-vis spectrophotometer. It
works on the principle of Beer-Lamberts law (i.e.) ab-
sorption of the solution is directly proportional to the
solution concentration). In aqueous solution, the absorp-
tion of CNTs appeared at 283 nm. With increasing sedi-
ment time, the absorbance of CNTs in the supernatant
aqueous solution is diminished.
4.5. Measuring the Thermal Conductivity of the
Nanofluids
The thermal conductivity of the base fluid and nanofluid
is measured by using transient hot-wire method. In this
study, the transient hot-wire method for measuring elec-
trically conducting fluid has been applied because the
particles used in this experiment are electrically conduc-
tive. It is a well-known method and generally used to
measure the thermal conductivity of nanofluids. Teflon-
coated platinum wire, which diameter is 76 nm and the
thickness of Teflon insulation layer is 17 nm, is used for
a hot wire in the measurement system. Initially, the pla-
tinum wire immersed in media is kept at equilibrium with
surroundings. When a uniform voltage is supplied to the
circuit, the electric resistance of the platinum wire rises
with the temperature of the wire and the voltage output is
measured by an A/D-converting system at a sampling
rate of ten times per second. The relation between the
electric resistance and the temperature of platinum wire is
well known. The measured data of temperature rise are
linear against logarithmic time interval. The thermal con-
ductivity is calculated from the slope of the rise in the
wire’s temperature against logarithmic time interval.
4.6. Nanostill
Researches in heat transfer have been carried out over the
previous several decades, leading to the development of
the currently used heat transfer enhancement techniques.
The use of additives is a technique applied to enhance the
heat transfer performance of water in the still basin. Re-
cently, as an innovative material, nanosized particles
have been used in suspension in conventional solar still.
The fluids with nanosized solid particles suspended in
them are called “nanofluids”. The suspended metallic or
nonmetallic nanoparticles change the transport properties
and heat transfer characteristics of the water in the still.
Thus the water temperature in the basin increases. The

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill
94
carbon nanotube (CNT)-based nanofluids are expected to
exhibit superior heat transfer properties compared with
conventional water and other type of nanofluids [22].
4.7. Measurements
The solar still made up of Aluminum, inside bottom
black paint coated and addition of nanofluids is operated
at ambient conditions from 6:00 a.m. to 6:00 p.m. during
the months of April and May 2012. Addition of nanoflu-
ids with water in the basin increases the water tempera-
ture and thereby increasing the evaporation rate of the
modified solar still. The same measurement process is
repeated for various parameters to find out the enhanced
performance of the solar still using nanofluids and com-
pare the performance of them. Readings are taken for
various parameters to find out the enhanced performance
of the still with nanofluids and compare performance of
them. In this study various operating conditions have
been examined such as; different water depth, insulation
thickness, ambient temperature and salt concentration
with nanofluids inside the till. The mixing of nanofluids
with water inside still basin helps to increase heat trans-
fer. The suspended metallic or nonmetallic nanoparticles
change the transport properties and heat transfer charac-
teristics of the base fluid. Addition of nanofluids in-
creases the water temperature and thereby increasing the
evaporation rate. This improves the evaporation rate and
in turn improves the efficiency of the still to certain ex-
tent.
5. Discussion of Results
The single basin solar still made up of Aluminium sheet
is operated from 6.00 a.m. to 7.00 p.m. The measure-
ments of the temperatures, solar radiation intensity and
the production of distilled water are taken hourly to study
the effect of each parameter on the single basin still pro-
ductivity without using nanofluids. In this study, various
operating conditions have been examined such as differ-
ent water depths; insulation thickness, salt concentration,
ambient temperature and productivity are measured
hourly. The total productivity and solar Intensity are also
measured daily. The output of the solar still varies di-
rectly with the ambient temperature. The productivity
rate varies as time passes from the early morning until
late afternoon. In the morning, the temperature of water is
low; therefore it needs high energy to change its phase
from saturated liquid to saturated vapor phase. The re-
sults show that temperature and required heat are in-
versely proportional. In the early afternoon the tempera-
ture of water reaches the maximum so it needs less heat
to vaporize, and vice versa in the late afternoon.
The hourly output is maximum in afternoon hours
when the ambient temperature is at its daily peak. The
wind speed is found to be around 2 - 4 m/s. The water
temperature has a direct effect on the productivity
whereas the depth of water increases from 1 to 3 cm, the
daily still output decreases i.e. inversely proportional.
The solar radiation is absorbed by black painting inside
the bottom of the basin and thus increases the tempera-
ture of the water. The black paint absorbs all the incident
radiation falling on it. Due to this the amount of distillate
collected in this still made up of aluminium sheet is
higher and hence the increase in efficiency by 20%.
Aluminium has higher thermal conductivity which in-
creases the heat transfer rate. Due to this distillate col-
lected is higher for the still made up of aluminium sheet
and hence the increase in efficiency by 20% when com-
pared with the still made up of Galvanized Iron sheet for
the same basin area.
The efficiency increases when the insulation thickness
increases. This is due to the decrease in the heat loss from
the still to the surroundings. The insulation material
should be dimensionally and chemically stable at high
temperatures, and resistant to weathering and dampness
from condensation. Usually, glass-wool insulation 10 cm
thick is recommended. It would be between if the insula-
tion also could contribute to the structural rigidity of the
collector, but more rigid insulating materials are often
less stable than glass-wool. Temperatures in flat-plate so-
lar collectors can be high enough to melt some foam in-
sulations, such as Styrofoam. And some foam give off
corrosive frames at high temperatures, which could da-
mage the absorber plate. The efficiency increases by 20%
by providing insulation for a thickness of 10 cm. The
theoretical value of absorbtivity multiplied with trans-
missivity is a function of the solar intensity and the am-
bient condition.
Figure 6 shows that the productivity increases with
time until reaching the maximum value in the afternoon.
At the maximum, the incident solar radiation is larger
than heat losses early in the afternoon. When the radia-
tion from the sun increases the heat gained by the solar
stills also get increased thereby the heat stored in the so-
lar stills also raised inspite of that the water gets heated
quickly and starts to vaporize finally the vapour are con-
densed and potable water are collected.
Figure 6 shows that the output water level is very low
at period of 9:00 a.m. to 10:00 a.m. the water collected at
that time is 80 ml but the yield is increased at the peak
time of the day between 14:00 p.m. to 15:00 p.m. to the
water level of about 360 ml/hr which shows that at a cer-
tain period of time the output gain is more than the initial
State. Figure 6 also shows that the output water level is
low at 13:00 p.m. due to clouds formation and they cover
the sun and there is reduction in output.
Figure 7 shows the temperature variation along with
the time. The wet bulb temperature indicates the amount

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill 95
60
80
100
120
140
160
180
200
220
240
260
280
300
320
340
360
380
9 10111213141516171819
WATER COLLECTIO N (ml)
TIME IN HOURS
WATER
COLLECTION
(ml)
Figure 6. Time vs water collections.
30
31
32
33
34
35
36
37
38
9 10111213141516171819
TEMPERATURE (OC)
TIME IN HOURS
TEMPERATU
RE
Figure 7. Time vs temperature.
of moisture content in the atmospheric air. Wind is
caused by the uneven heating of the earth surface.
Depends upon the time period of flow of wind the
output varies as shown in Figure 8. It can be concluded
that as the solar intensity increases, the heat loss de-
creases and the water and ambient temperature difference
increases considerably due to the increase of the water
temperature through conduction process between the
black base and the water. As the ambient temperature in-
creases, the efficiency increases.
The same measurement process is repeated for various
parameters to find out the enhanced performance of the
solar still by mixing nanofluids with water inside still
basin which helps to increase heat transfer. Addition of
nanofluids increases the water temperature and thereby
increasing the evaporation rate and in turn increases the
efficiency of the still 60%.
The average daily output is found to be 6 litres/day for
the basin area of 1 m2. The optimized glass cover angle is
10˚. The efficiency is calculated as 100% higher when
compared with stills being used worldwide. In this paper
the solar still made up of aluminium is fabricated and
tested for both the conditions i.e. with and without use of
nanofluids. The measurements are taken separately and
the experimental data are compared here as shown in
Table 2. The distillate collected is higher for the still
using nanofluids when compared with the conventional
fluid. The yield during the period between 6:00 a.m. to
7:00 p.m. is also high in the solar still made up of alu-
minium sheet.
0
1
2
3
4
5
9 10111213141516171819
WIND VELOCITY m/s
TIME IN HOURS
WIND VELOCITY m/s
Figure 8. Time vs wind velocity.
Table 2. Time vs water collection comparision.
Water collection Water collection
Time duration Ordinary still Still with nanofluids
Hour ml/m2 ml/m2
06 a.m. - 07 a.m.20 100
07 a.m. - 08 a.m.50 250
08 a.m. - 09 a.m.80 300
09 a.m. - 10 a.m.100 400
10 a.m. - 11 a.m.280 500
11 a.m. - 12 a.m.350 500
12 p.m. - 13 p.m.360 550
13 p.m. - 14 p.m.280 600
14 p.m. - 15 p.m.360 650
15 p.m. - 16 p.m.300 550
16 p.m. - 17 p.m.220 450
17 p.m. - 18 p.m.120 350
18 p.m. - 19 p.m.30 200
The readings are plotted on a graph in Figure 9 and the
readings are compared. When comparing both the solar
stills, the solar still using nanofluid inside the basin yields
higher output for the same solar radiation. The average
daily output of 6 liters/day is achieved when compared to
that of 3 litres/day in an ordinary solar still painted with
black paint. The solar radiation from the sun is higher at
the mid noon period depend upon the time period and
also the radiation the yield of pure water is depended on
these factor.
For a solar still made up of aluminum sheet using na-
nofluids, graphs are drawn for productivity and time for
various salt concentrations of 0%, 10% and 20% and for
the depth of water level 1cm. It reveals the lower the salt
concentrations the higher will be the productivity as
shown in Figure 10.
For a solar still made up of Aluminum sheet without
using nanofluids, graphs are drawn for productivity and
time for different depths of water level 1 cm, 3 cm and 5
cm for salt concentrations of 10%. It reveals an increase
in the productivity for minimum depths of water level. It
also shows that the lower the salt concentrations the
higher the productivity as shown in Figure 11.

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill
96
Figure 9. Comparision of yield output.
Figure 10. Productivity Vs Time for various concentrations.
Figure 11. Productivity vs time for various water level.
The mixing of nanofluids with water inside still basin
helps to increase heat transfer. The suspended metallic or
nonmetallic nanoparticles change the transport properties
and heat transfer characteristics of the base fluid. Addi-
tion of nanofluids increases the heat transfer rate and
thereby increasing the water temperature. This increases
the evaporation rate and in turn improves the efficiency
of the still to certain extent. Thus the productivity is
higher for the solar still using nanofluids in compared
with the still using conventional fluids like water.
5.1. Thermal Analysis
The energy received by the saline water in the still (from
the sun and base) is equal to the summation of energy lost
by convective heat transfer between water and glass, ra-
diative heat transfer between water and glass, evapora-
tive heat transfer between water and glass, and energy
gained by the saline water:

loss
d
d
b
bbb pbcbw
T
I
tA mCQ Q
t

 


 (1)

cb wcb wbbw
QhATT





(2)

loss bb a
QUATT (3)
Substitute Equations (2) and (3) in Equation (1) to
solve the thermal equation.
The energy received by the saline water in the still


It solar radiation and cbw convective heat transfer
between basin and water are equal to the summation of
energy lost by
Q
cw g
Q

convective heat transfer between
water and glass, rw Qg

radiative heat transfer between
water and glass, ew g
Q

evaporative heat transfer be-
tween water and glass and energy gained by the saline
water:


d
d
ww cbw
w
cw grw gew gwpw
ItAQ
T
QQQmCt





 


(4)
w

Substitute to solve the thermal equation.
absorptivity of the water

cw gcw gwwg
QhATT



 (5)
The convective heat transfer coefficient between water
and glass was given by,


13
3
273
0.884 268.9 10
wgw
cw wwg
w
PPT
hTT P













(6)
Here ,
w
P
g
P - Partial pressure of glass and water.

rw grw gwwg
QhATT





(7)
The radiative heat transfer coefficient between water
and glass was given by,



2
2
273
273 546
rw geffw
gwg
hT
TTT





 


(8)
g
T, —Temperature of Glass and Water (˚C)
w
T

-Stefan–Boltzmann constant (W/m2·K4)

ew gew gwwg
QhATT



 (9)
The evaporative heat transfer coefficient between wa-
ter and glass was given by,

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill 97

3
16.273 10wg
ew gcw gwg
PP
hh
TT


 

 





(10)
Energy gained by the glass cover (from sun and con-
vective, radiative and evaporative heat transfer from wa-
ter to glass) is equal to the summation of rw g Q

energy
lost by radiative and cgsky convective heat transfer
between glass and sky and energy gained by glass:
Q

d
d
g
gcwgrwgew
g
rg skycg skygpg
ItAQQ Q
T
QQmC
t







g

(11)
1
11
1
eff
wg







(12)
w

,
g

—Emissivity of water and glass Substitute
Equations (5), (7), (9) and (13) in Equation (11) to solve
the thermal equation.


rg skyrg skyggsky
QhATT

 (13)
The radiative heat transfer coefficient between glass
and sky is given by,
 
44
273 273
gsky
rg skygsky
TT
hTT 











(14)
The effective sky temperature,
6
sky a
TT (15)
The changes in basin temperature


db T, increase in
saline water temperature 

dw T and glass temperature


d
g
T are used in the above Equations.
The daily efficiency 
d

is obtained by summing up
the hourly condensate production


w
m

, multiplied by
the latent heat of vaporization

L
, and divided by the
daily average solar radiation over the still area

It


A
.
The overall Thermal Efficiency of still


is given
wfg
s
mh
A
I





 (16)
where, w = mass of the distilled water collected as
output in kg/s.
m
A
= Area of the basin in m2

It = Solar radiation with respect to time W/m2 and
L
= Latent heat of vaporization (hfg) in KJ/s:






64
93
2.49351019.4779 101.3132 10
4.797410Lower than 70 C
LT
T



 


 



64
3.1615 1017.6160 10
Higher than 70 C
LT







(18)
The still efficiency is defined as the ratio of heat en-
ergy used for vaporizing the water in the basin to the total
solar Intensity of radiation absorbed by the still.
5.2. Cost Estimation
The overall cost of the aluminium solar still experimen-
tal setup is given in Table 3.
5.3. Economic Analysis
The payback period of the solar still setup depends on
overall cost of fabrication, maintenance cost, operating
cost and cost of feed water.
The overall fabrication cost is Rs. 13,000 ($260).
The maintenance cost, operating cost and cost of feed
water are negligible.
The overall cost of the project = Rs.: 13,000 ($260).
Cost of water produced per day = Daily yield × Cost of
water per litre = 7.5 × Rs. 15 = Rs. 120 ($2).
The payback period is less than 1 year.
6. Conclusion
A single basin solar still made up of aluminium sheet is
fabricated and tested for both the conditions with and
without nanofluids. The distilled water production rate of
a single basin solar still can vary with the design of the
solar still, absorbing materials, depth of water and salt
concentrations inside the still. The aluminium has higher
thermal conductivity which increases the heat transfer so
that the solar still made up of aluminium sheet yields
more output of 6 litres/day. The efficiency of the solar
still is increased by 55%. The efficiency of the solar still
is increased further 20% by providing insulation to the
still which reduces heat loss.
The efficiency of the solar still is 15% increased fur-
ther by painting black colour in inside bottom of the still
Table 3. Cost estimation.
72
T

(17)
Sl. No. Description Amount in Rs.
1 Aluminum sheet 1600
2 Plywood 1600
3 Glass 550
4 Supply tank with accessories 400
5 Collecting tank 600
6 Thermo cool 150
8 Nanofluids 7600
9 Overhead charges 500
Total Rs. 13,000

Design and Performance Analysis of an Innovative Single Basin Solar NanoStill
98
to absorb more heat. The efficiency of solar still can be
increased further by mixing nanofluids with water inside
the still. Addition of nanofluids in the basin surface in-
creases the thermal conductivity by 40% which in turn
increases water temperature by increasing heat transfer
rate and thereby increasing the evaporation rate and in-
creases the efficiency by 60%.
The modified innovative nanostill has an enhanced
performance when compared with the still using conven-
tional fluids like water and more flexible with climatic
conditions. The system will serve a family of 4 members.
This gives the total water consumption to be around 7.5
litres/day/m2. This cost-effective design is expected to
provide the rural communities an efficient way to convert
the brackish water in to potable water.
REFERENCES
[1] V. Velmurugan and K. Srithar, “Performance Analysis of
Solar Stills on Various Factors Affecting the Producti-
vity,” Renewable Energy and Sustainable Energy, Vol. 15,
No. 2, 2011, pp. 1294-1304.
doi:10.1016/j.rser.2010.10.012
[2] G. N. Tiwari, H. N. Singh and R. Tripathy, “Present Sta-
tus of Solar Distillation,” Solar Energy, Vol. 75, No. 5,
2003, pp. 367-373. doi:10.1016/j.solener.2003.07.005
[3] O. O. Badran and M. M. Abu-Khader, “Evaluating Ther-
mal Performance of a Single Slope Solar Still,” Heat and
Mass Transfer, Vol. 43, No. 10, 2007, pp. 985-995.
doi:10.1007/s00231-006-0180-0
[4] S. Abdallah, O. Badran and M. M. Abu-Khader, “Perfor-
mance Evaluation of a Modified Design of a Single-Basin
Solar Still,” Desalination, Vol. 219, No. 219, 2008, pp.
222-230. doi:10.1016/j.desal.2007.05.015
[5] V. Velmurugan, K. K. J. Naveen, H. T. Noorul and K.
Srithar, “Performance Analysis in Stepped Solar Still for
Effluent Desalination,” Energy, Vol. 34, No. 9, 2011, pp.
1179-1186. doi:10.1016/j.energy.2009.04.029
[6] K. K. Murugavel, Kn. K. S. K. Chockalingam and K.
Srithar, “Progresses in Improving the Effectiveness of the
Single Basin Passive Solar Still,” Desalination, Vol. 220,
No. 1-3, 2008, pp. 677-686.
doi:10.1016/j.desal.2007.01.062
[7] M. K. Gnanadason, P. S. Kumar, G. Sivaraman and J. E.
S. Daniel, “Design and Performance Analysis of a Modi-
fied Vacuum Single Basin Solar Still,” Smart Grid and
Renewable Energy, Vol. 2, No. 4, 2011, pp. 388-395.
doi:10.4236/sgre.2011.24044
[8] Y. Hwang, J. K. Lee, C. H. Lee, Y. M. Jung, S. I. Cheong,
C. G. Lee, B. C. Ku and S. P. Jang, “Stability and Ther-
mal Conductivity Characteristics of Nanofluids,” Ther-
mochimica Acta, Vol. 455, No. 1-2, 2007, pp. 70-74.
doi:10.1016/j.tca.2006.11.036
[9] Y. Xuan and Q. Li, “Heat Transfer Enhancement of Na-
nofluids,” International Journal of Heat and Fluid Trans-
fer, Vol. 21, No. 1, 2000, pp. 58-64.
doi:10.1016/S0142-727X(99)00067-3
[10] G. M. Koilraj, P. Senthilkumar and G. Sivaraman, “De-
sign and Performance Analysis of a Vacuum Single Basin
Solar Still,” International Journal of Advanced Engineer-
ing Technology, Vol. 2, No. 4, 2011, pp. 174-181.
[11] M. K. Kalidasa, Kn. K. S. K. Chockelingam and K. Sri-
ther, “An Experimental Study on Single Basin Double
Slop Simulation Solar Still within Layer of Water in the
Basin,” Desalination, Vol. 220, No. 1-3, 2008, pp. 687-
693. doi:10.1016/j.desal.2007.01.063
[12] R. Tripathi and G. N. Tiwari, “Thermal Modeling of Pas-
sive and Active Solar Stills for Different Depths of Water
by Using Concept of Solar Fraction,” Solar Energy, Vol.
80, No. 8, 2006, pp. 956-967.
doi:10.1016/j.solener.2005.08.002
[13] S. Lee, S. U. S. Choi, S. Li and J. A. Eastman, “Measur-
ing Thermal Conductivity of Fluids Containing Oxide
Nanoparticles,” Journal of Heat Transfer, Vol. 121, No. 2,
1999, pp. 280-289. doi:10.1115/1.2825978
[14] Y. J. Hwang, Y. C. Ahn, H. S. Shin, C. G. Lee, G. T. Kim,
H. S. Park and J. K. Lee, “Investigation on Characteristics
of Thermal Conductivity Enhancement of Nanofluids,”
Current Applied Physics, Vol. 25, No. 4, 2005, pp. 609-
735. doi:10.1016/j.cap.2005.07.021
[15] M. J. Assael, C. F. Chen, N. Metaxa and W. A. Wakeham,
“Thermal Conductivity of Suspensions of Carbon Nano-
tubes in Water,” International Journal Thermophysics,
Vol. 2, No. 25, 2004, pp. 971-985.
doi:10.1023/B:IJOT.0000038494.22494.04
[16] H. Xie, J. Wang, T. Xi, Y. Liu, F. Ai and Q. Wu, “Ther-
mal Conductivity Enhancement of Suspensions Contain-
ing Nanosized Alumina Particles,” Journal of Applied
Physics, Vol. 4, No. 91, 2002, pp. 4568-4572.
doi:10.1063/1.1454184
[17] C. H. Li and G. P. Peterson, “Experimental Investigation
of Temperature and Volume Fraction Variations on the
Effective Thermal Conductivity of Nanoparticle Suspen-
sions (Nanofluids),” Journal of Applied Physics, Vol. 8,
No. 99, 2006, pp. 84-94.
[18] L. Jiang, L. Gao and J. Sun, “Production of Aqueous Col-
loidal Dispersion of Carbon Nanotubes,” Journal of Col-
loid Interface Science, Vol. 260, No. 1, 2003, pp. 89-94.
doi:10.1016/S0021-9797(02)00176-5
[19] T. K. Hong, H. S. Yang and C. J. Choi, “Study of the En-
hanced Thermal Conductivity of Fe Nanofluids,” Journal
of Applied Physics, Vol. 6, No. 97, 2005, pp. 1-4.
[20] S. A. Putnam, D. G. Cahill, P. V. Braun, Z. Ge and R. G.
Shimmin, “Thermal Conductivity of Nanoparticle Sus-
pensions,” Journal of Applied Physics, Vol. 8, No. 99,
2006, pp. 84-88.
[21] E. Natarajan and R. Sathish, “Role of Nanofluids in Solar
Water Heaters,” International Journal Advanced Manu-
facturing Technology, Vol. 8, No. 170, 2009, pp. 1876-
1882. doi:10.10007s00170-008-1876-8
[22] M. K. Gnanadason, P. S. Kumar, G. Jemilda and S. R.
Kumar, “Effect of Nanofluids in Vacuum Single Basin
Solar Still,” International Journal of Scientific and Engi-
neering Research, Vol. 3, No. 1, 2012, pp. 2229-5518.