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International Journal of Applied Research & Studies ISSN 2278 – 9480

iJARS/ Vol. II/ Issue I/Jan, 2013/302 1

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Review Paper

Review on Performance and Development of Experimental Setup

of Solar Water Distillation

Authors

1 Kanu Gohel*, 2 Avdhoot N. Jejurkar, 3 Chetan Jaiswal

Address for Correspondence:

1 Mechanical Engineering Department, Gujarat Technological University, Gujarat, India

2, 3 Assistant Professor, Mechanical Engineering Department, Parul Institute of Engineering &

Technology, Gujarat Technological University, Gujarat, India

Abstract:

In most of the developing countries an acute

shortage of good and clean drinking water is a

major problem. The water in case of streams, wells

and rivers are often found polluted and unsafe for

direct use as drinking water. In addition, there are

many coastal locations where sea water is in

abundance but not potable. Solar distillation is one such method which utilizes solar energy to make

potable water for small communities where natural

supply of fresh water is inadequate and of poor

quality.

I. INTRODUCTION

Solar distillation is a tried and true technology. The

first known use of stills dates back to 1551 when it

was used by Arab alchemists. Other scientists and

naturalists used stills over the coming centuries

including Della Porta (1589), Lavoisier (1862), and

Mauchot (1869).The first "conventional" solar still

plant was built in 1872 by the Swedish engineer

Charles Wilson in the mining community of Las

Salinas in what is now northern Chile (Region II).

This still was a large basin-type still used for supplying fresh water using brackish feed water to

a nitrate mining community. The plant used

wooden bays which had blackened bottoms using

logwood dye and alum. The total area of the

distillation plant was 4,700 square meters. On a

typical summer day this plant produced 4.9 kg of

distilled water per square meter of still surface, or

more than 23,000 liters per day. This first stills

plant was in operation for 40years! Over the past

century, literally hundreds of solar still plants and

thousands of individual stills have been built around the world. The basic principles of solar

water distillation are simple yet effective, as

distillation replicates the way nature makes rain.

The sun's energy heats water to the point of

evaporation. As the water evaporates, water vapor

rises, condensing on the glass surface for

collection. This process removes impurities such as

salts and heavy metals as well as eliminates

microbiological organisms. The end result is water

cleaner than the purest rainwater.

II. METHODS FOR SOLAR WATER

PURIFICATION [1]

Solar Water Disinfection (SODIS)

Solar water disinfection is a low technology, simple

process of purifying water using solar energy and

solar radiation. SODIS as a technology. The process involves contaminated water being filled in

transparent PET or glass bottles which are then

exposed to the sun for approximately 6 hours. The

UV rays of sun eliminate the diarrhea-causing

pathogens, thereby making the water fit for

consumption.

Solar Water Distillation

Solar water distillation uses a solar still to

condense pure water vapor and settle out harmful

substances to make clean, pure drinking water. This

process is used when the water is brackish

containing harmful bacteria, or for settling out

heavy metals and also for desalination of sea water.

Solar Water Pasteurization

Solar water pasteurization involves the use of

moderate heat or radiation to kill disease - causing

microbes. This heat is provided from cookers that



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trap solar energy. This method has proven to kill

bacteria, viruses, worms and protozoa.

Solar Water Purification

This method integrates electricity generated from

solar energy for water purification. Solar panels

generate power for a battery which is used for

filtration and purification systems. These structures

are generally mobile and are immensely helpful for

disaster - relief efforts. They also come in various

sizes meant for small scale use to commercial/community supply.

III. TYPES OF SOLAR WATER

DISTILLATION ACCORDING TO DESIGNS

Al-Hayek. Imad et al.[2]The first design is an asymmetrical still with mirrors on the walls. The

second design is a symmetrical still . The water

output of the asymmetrical still was measured to be

30% higher than the symmetrical version. The

asymmetrical design operated at a higher

temperature. This is mostly due to the mirrors on

the side and back walls. The mirrors reduced heat

energy loss and reflected all incoming solar

radiation towards the basin. Since the asymmetrical

design has three insulated walls where the mirrors

reside, there is less area for heat energy to escape.

FIG. 1: ASYMMETRICAL SOLAR STILL DESIGN

[2].

FIG. 2: SYMMETRICAL SOLAR STILL DESIGN

[2].

The symmetrical design has more area where heat

loss occurs. In conclusion, the asymmetrical solar

still with mirrors is a superior design with greater

efficiency and higher overall water output. In

conclusion, the basic asymmetrical still design is

more efficient and less expensive.

IV. ABOUT THE SOLAR WATER

DISTILLATION

Existing desalination plants used fossils fuels as a

source of energy. The conventional distillation

process namely reverse osmosis, electro dialysis,

multi-effect evaporation etc are not only energy

intensive but also uneconomical when the demand

for the fresh water is small [3]. Solar distillation is

the only attractive process for saline/brackish water

by using solar energy. The basin type solar stills are

simple in design, manufacturing, operation and

economical .But the productivity of fresh water is

low on an average of 2.5 l/m2 day. Enhancing the

still’s yield has been studied by several investigators, suggesting various approaches. M.S.

Sodha et al [4] analysized solar still with double roof

.R.A Collins et al [5] made tests on a simple solar

still coupled with an external condenser. M .Boukar

et al [6] made comparative study on simple basin

solar still. A solar powered distillation device will

contain three basic components: a basin in which

the contaminated water is contained, a surface

above said feed water for the water vapor to

condense onto (i.e. a glass pane), and a catch basin

for the distilled water to drain into [7].

FIG. 3: BASIC SOLAR POWERED WATER DISTILLER [7]

.

During operation of the distiller, solar energy is

collected by the feed water. When enough energy is

absorbed by the water, the water undergoes a phase

change. The water vapours then rises and comes

into contact with the cooler transparent, inclined

surface. Here the vapour once again goes through a

phase change from vapour back to liquid. The

water then condenses and runs off the transparent inclined surface into a collection bin. The

distillation process rids the contaminated water of

any impurities and most commonly found chemical

contaminants within the environment. These

contaminants are left behind in the basin [7].

V. DESIGN PARAMETER

There are a number of parameters which affect the

performance of a solar still. These are broadly classified as [8]

[1] Climatic Parameters

Solar Radiation

Ambient Temperature

Wind Speed



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Outside Humidity

Sky Conditions

[2] Design Parameters

Single slope or double slope

Glazing material

Water depth in Basin

Bottom insulation

Orientation of still

Inclination of glazing

Spacing between water and glazing

Type of solar still

[3] Operational Parameters

Water Depth

Preheating of Water

Coloring of Water

Salinity of Water.

VI. EXPERIMENTAL APPROACH

R Prasad. NL Singh. Et al.[9] have been made to

enhance the performance of a single slope solar water distiller by the application of various

techniques separately as well as combining all the

techniques together, like change in water depth,

performance with reflector or without reflector, or

use of various material.

FIG. 4: TIME VS. TEMPERATURE AND DIFFERENT

WATER DEPTH [9]

.

FIG. 5: TIME VS PRODUCTIVITY OF DISTILLED WATER

WITH AND WITHOUT REFLECTOR [9]

.

FIG. 6: EFFECT OF SODIUM LAURYL SULPHATE ON

PRODUCTIVITY OF DISTILLED WATER [9]

.

FIG. 7: EFFECT OF KMNO4 WATER SOLUTION ON

PRODUCTIVITY OF DISTILLED WATER [9]

.

Rajesh.Bharath. et al.[10] have been made to

enhance the performance of a active distillation

system with flate plate collector or without flate

plate collector.

FIG. 8: EXPERIMENTAL SET UP WITH COLLECTOR

[10].

FIG. 9: EXPERIMENTAL SET UP WITHOUT COLLECTOR [10]

.

FIG. 10: VARIATION OF HOURLY TEMPERATURE FOR

RIVER WATER COUPLED WITH FPC [10]

.



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FIG. 11: THE VARIATION OF HOURLY TEMPERATURE

FOR RIVER WATER WITH SOLAR STILL ALONE [10]

.

MD Irfan Ali et al.[11]have presented performance

on the experimental set up of double slope solar

still. It consists of condensing cover having angle

of 15 degree. They had used to grandunar activated

carbon for increasing efficiency of still.

FIG. 12: SKETCH OF A SOLAR STILL

[11].

The experiment was performed at SRM University

Chennai, on two different dates july 15th and 17th,

for two different water heights in the still mixing

the water with granular activated carbon.

TABLE 1: HOURLY AVERAGE VALUES CALCULATED

USING 8 HOURS EXPERIMENTAL DATA FOR 0.3M OF

WATER DEPTH ON 15TH JULY [11]

.

TABLE 2: HOURLY AVERAGE VALUES CALCULATED

USING 8 HOURS EXPERIMENTAL DATA FOR 0.1M OF

WATER DEPTH ON 17TH JULY [11]

.

FIG. 13: PERFORMANCE OF STILL WITH AND

WITHOUT GAC AT DIFFERENT HEIGHTS WITH

RESPECT TO AMBIENT TEMP [11]

.

Stephen Coffrin.et al.[7] have presented about

development and analysis of the thermal circuit for

a simple asymmetrical solar distiller. This thermal

circuit models the convection, conduction, and

radiation of energy throughout the device, as well

as the evaporation and condensation processes.

From this thermal circuit, an energy balance at three nodes and a spreadsheet program was

developed. The thermal circuit was validated by

building and testing two small-scale prototypes,

and recording nodal temperature values.

FIG. 14: SIMPLE THERMAL CIRCUIT

[7].

Assumptions:

Temperature difference between one side

of the glass to the other is negligible.

Temperature difference between Tw and the basin is negligible.

There is no heat loss through the side

walls

Tw is uniform.

No vapor leakage.

qevap= qcond.



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From these energy balances, a spreadsheet program

was developed that allows for an iterative process

to determine required area for a specified water

output. Variable inputs include area of still, area of

glass, outside temperature of test location,

insulation length and thermal conductivity, known

daily sum of solar radiation (based on location),

average wind velocity of location, number of

daylight hours, and desired water output, as well as correlations for natural and forced convection heat

transfer coefficients on involved surfaces.

The solar still was determined to be about 1 m2 to

output 2 gallons of clean drinking water. These

inputs also gave a glass temperature of 334 K and a

water temperature of 354 K. This temperature

difference indicates that water will condense onto

the glass.

FIG.15: 2ND PROTOTYPE TESTING THERMOCOUPLE

RESULTS [7]

.

K.N. Sheeba. S.Jaisankar et al.[12] have designed

and tested Inclined solar water distillation systems

(ISWDS), under actual environmental conditions

of Trichy, Tamilnadu, India, one with bare plate

and the other with black cloth wick.

The design considerations of the system for

fabrication are explained in the figure. Outercase:l=930mm,b=730mm,w=18m,Type:Plyw

ood.GlassCover:l=900mm,b=700mm,w=5.5mm,Ty

pe:Transparentglass.AbsorberPlate:l=900mm,b=70

0mm,w=0.2mm. Type: Aluminum sheet.

Distribution Plate: D=12.7*10-6mm,l=670mm,no

of holes=6,Type: Steel, Pitch = 92mm. Black cloth

wick: l=900mm,b=700mm w=240 GSM. Other

components: M-Seals, PVC pipes (2000m long,

15.875*10-6mm size), hoses (8000m, 19.05mm

size, two valve (12.7*10-6mm size), Four parallel

nipples (12.7*10-6mm size, 152.4* 10-6mm long GI Type).

FIG. 16: OVERVIEW OF ISWD SYSTEM [12]

Water is filled in the tank in the morning and the

valves are opened and fixed at a particular position

to maintain same inlet flow rates. Inclination angle

was taken in between 100

to 200

according to

environmental conditions of Trichy. Amount of water collected in ml were noted for every 60

minutes from 9am to 4pm of sunny days and were

tabulated.

The efficiencies of the two systems were calculated

at certain point of period of time. Plots are drawn

for different factors like intensity, flow rate of

distilled water, hot water temperature and distilled

water temperature and efficiency against time. The

following basic formula used for calculating the

solar still efficiency of the ISWD System.

η = (m*γ/I*A)*100

FIG. 17: VARIATION OF SOLAR INTENSITY WITH TIME

[12]



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FIG. 18: VARIATION OF SOLAR INTENSITY WITH

TIME [12]

The performance trend of solar still with black

cloth wick is same as that of bare plate but the

production of fresh water is increased and hot water

production decreased with higher temperatures than

bare plate. The feed water falls on to the absorber

plate (i.e bare plate); The water falls down on the

bare plate is not evenly distributed over the width of the plate. This is mainly due to buckling of plate

caused by increasing temperature and the feed

water has less residence time on the bare plate.

Hence the production of fresh water is lesser than

black cloth wick type still where as hot water

production increased with smaller temperatures.

FIG. 19: VARIATION HOT WATER FLOW RATE WITH

TIME FOR BARE PLATE[12]

FIG. 20: VARIATION HOT WATER FLOW RATE WITH TIME FOR BLACK PLATE[12]

The system was tested with two variants: bare

plate, black-cloth wick. The effect of the wick on

the performance of the solar still was observed. The

fresh water generation rate increased when wick

was used instead of a bare plate. It was proved that

the longer the flowing water is held on the absorber plate, the greater the rate of evaporation, leading to

an increase in the amount of distilled water.

Therefore, it has been observed that the ISWD

System with wick has improved performance over

the bare type because of 1) Higher retaining

capacity of wick. 2) Higher retention time for

water. 3) Efficient utilization of absorbed

temperature.

NOMENCLATURE

Twater – Temperature of the water in the basin

Tglass – Temperature of the glass surface above the basin. As

seen in Figure 3, this is the surface that water will condense

onto.

Tair – Temperature of the air between the water and glass.

T∞ - Ambient temperature around the solar still

Qsolar –Solar energy entering the system

Qevap –Energy required to evaporate a given amount of water

qcond – Energy required to condense a given amount of water

A – Area of the basin

Ag – Area of the glass

kins – Thermal conductivity of insulation

lins – Length of insulation

h∞ - heat transfer coefficient for convection from Tg to T∞

hg – heat transfer coefficient for convection from Tair to Tg

hw – heat transfer coefficient for convection from Tw to Tair

σ – Stefan-Boltzmann Constant (5.670 x 10-8 W/m2 * K4)

ε – emissivity of glass

REFERENCES

1. Solar water treatment:

http//climatelab.org/solar_water_tretment

2. Al-Hayek, Imad. Badran.“The Effect Of Using

Different Designs Of Solar Stills On Water

Distillation”. Desalination, Volume 169. 2004. Pages

121-127., Omar O.

3. A.N Khalifa , “Evaluation and energy balance study

of solar still with an inernal condenser”, JSER 3(1)

1-11 (1985)

4. M.S Sodha, J.K Nayak,G.N Tiwari and A. Kumar ,

Energy conservation ,Mgmt 20,23(1980)

5. R.A Collins and T. Thomson , “Forced convection

multiple effect still for desalting and brackish water”

, proc,of the United Nations Conf. Rome 6 ,205-

217(1961)

6. Ahmad.S.Y, S.D Gomkale, R.L.Datta, and D.S.Datar

1968 slope and development of solar stills for water

desalination in India, desalination 5, 64-74

7. Stephen Coffrin, Eric Frasch,Mike Santorella, Mikio

Yanagisawa,“Solar Powered Water Distillation

Device” Department of Mechanical, Industrial and

Manufacturing Engineering College of Engineering,

Northeastern UniversityBoston, December 4, 2007.

8. Anirudh Biswas, Ruby, “Distillation of Water by

Solar Energy” VSRD international journal of mech.

Auto. & production engg. VSRD-MAP, Vol. 2 (5),

2012, 166-173

9. R Prasad, MK Kureel, NL Singh, “Experimental

Studies On Improvement Of The Performance Of A



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Solar Water Distiller Applying Various Techniques”

Inter J Curr Trends Sci Tech, 1(4): 194–206 (2010)

10. Rajesh .A.M , Bharath .K.N, Dept. of Mechanical

Engineering, S.J.M.I.T, Chitradurga, Karnataka, &

Dept. of Mechanical Engineering, Univ. B.D.T

College of Engineering, Davangere, Karnataka,

India.

11. MD Irfan Ali, R. Senthilkumar and R. Mahendren

“Modelling of Solar Still Using Granular Activated

Carbon in Matlab” Bonfring International Journal

of Power Systems and Integrated Circuits, Vol. 1,

Special Issue, December 2011

12. K.N. Sheeba, S.Jaisankar,

P. Prakash

“Performance

Study On An Inclined Solar Water Distillation

System” International Journal of Chemical and

Environmental Engineering, February 2012, Volume

3, No.1.

[email protected] * Corresponding Author Email-Id

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