Desalination of water using solar energy #VNR VJIET

PERFORMANCE ANALYSIS OF STEPPED SOLAR
STILL AUGMENTED WITH CHARCOAL AND MAGNETS
A Major-Project report
submitted in partial fulfilment for the award of the degree of
BACHELOR OF TECHNOLOGY
IN
MECHANICAL ENGINEERING
Submitted by
AKHIL RAJEEV 17075A0301
D. NIKHIL KUMAR 17075A0305
SHIVA KUMAR 17075A0306
M. SURESH 17075A0310
K. DURGESH 17075A0311
Under the guidance of
Dr. K. Ajay Kumar, Associate Professor

DEPARTMENT OF MECHANICAL ENGINEERING
CERTIFICATE
This is to certify that the Project report entitled “Performance
analysis of stepped solar still augmented with charcoal and magnets”
has been carried out at VNR VJIET, Hyderabad and submitted by
AKHIL RAJEEV 17075A0301
D.NIKHIL KUMAR 17075A0305
SHIVA KUMAR 17075A0306
M.SURESH 17075A0310
K.DURGESH 17075A0311
In partial fulfilment of the requirement for the award of degree of
Bachelor of Technology in Mechanical Engineering to Jawaharlal Nehru
Technological University Hyderabad at VNR Vignana Jyothi Institute of
Engineering and Technology during the period of 2017-2020 is a record
of bonafide work carried out by them under my guidance and supervision.
The results embodied in this project have not been submitted to any other
University or Institute for the award of any degree.
Dr. K. Ajay Kumar Dr.G. Srinivasa Gupta
Project Guide Head of Department
Associate Professor Mechanical Engineering
Mechanical Engineering VNR VJIET
City Office: Vignana Jyothi, H.NO. 7-1-4, Adjacent to Colorama Printers, Begumpet, Hyderabad-500 016
Phone: 040-2374 0538, 2374 0558 Fax:040-2373 1555, Email: vignanajyothi@hotmail.com

iii
APPROVAL CERTIFICATE
Viva- Voice examination conducted for the dissertation work entitled
“Performance analysis of stepped solar still augmented with charcoal
and magnets” is conducted on , and the work is approved
for the award of Degree of Bachelor of Technology in Mechanical
Engineering.
INTERNAL EXAMINER EXTERNAL EXAMINER

`
DECLARATION
We, the undersigned declare that the project report entitled
“Performance analysis of stepped solar still augmented with charcoal
and magnets” has been carried out and submitted in partial fulfilment of
the requirements for the Award of the Bachelor of Technology in
Mechanical Engineering at VNR Vignana Jyothi Institute of Engineering
and /Technology, affiliated to Jawaharlal Nehru Technological
University, Hyderabad is an authentic work and has not been submitted to
any other university.
Place: AKHIL RAJEEV
Date: D. NIHIL KUMAR
SHIVA KUMAR
M. SURESH
K. DURGESH

v
ACKNOWLEDGEMENTS
We wish to express our deep sense of gratitude to our principal Dr.
C.D.Naidu, & Dr. G. Srinivasa Guptha Head of the Department of
Mechanical Engineering, VNRVJIET for their encouragement, which
went a long way in the successful completion of this project.
We express our gratitude to our guide Dr. K. Ajay Kumar,
Associate Professor for his valuable suggestions, constant encouragement
and support of our Endeavour.
Our cordial regards to our Major project coordinator Mr.Tiwari,
Assistant professor for his encouragement and moral support.
Finally, we thank our parents and friends who directly or indirectly
influenced us to propel the project to its completion.

vi
ABSTRACT
Water plays a significant role in all our everyday lives and its
intake is rising with each day owing to the enhanced quality of living of
humanity. Several people around the world are extremely concerned over
water shortages and pollution. The humanity's desire for fresh water can
only be fulfilled by desalination turning usable salt water into drinking
water. The desalination business will be made competitive in the event
that it is transformed as a renewable energy supply.
Solar based desalination is the most appealing and straightforward
procedure for desalination process yet endures low thermal effectiveness.
The objective of this project is to enhance the productivity of water for
the clean water production. A stepped type aluminium basin is provided
to increase the evaporation rate. Each step has a base area of 0.05m2
and a
total of 0.25m2
with a depth of 5cm each acts as a wall between two
steps. These walls acts as fins and increases the evaporation rate. It has
been observed that the distilled water production has increased by 275ml
for the 1cm depth, 350ml for 2cm and 125ml for 3cm depth.
Experiments were conducted by integrating this design with charcoal
powder (75µm) as charcoal acts as a good heat absorber and observed a
further increase of 75ml, 75ml, and 50ml respectively. Efforts were made
to increase further by introducing static magnetic field in the water along
with the charcoal powder and observed a significant rise in the heat
transfer coefficient. These tests were carried out for three different depths
of water i.e. for 1cm depth efficiency of 45.63%, for 2cm (55.75%) and
for 3cm depth (41.43%) and it can be observed that the 2cm depth is
more efficient.
Exergy analysis were conducted for the solar stills components that
is basin liner, water and glass cover and found out that the exergy
destroyed is maximum in the basin liner.
KEYWORDS: Solar still, stepped basin, static magnetic field, charcoal,
desalination, renewable energy, exergy.

vii
TABLE OF CONTENTS
APPROVAL CERTIFICATE................................................................... iii
DECLARATION.......................................................................................iv
ACKNOWLEDGEMENTS........................................................................v
ABSTRACT ..............................................................................................vi
TABLE OF CONTENTS .........................................................................vii
LIST OF FIGURES...................................................................................ix
LIST OF TABELS.....................................................................................xi
NOMENCLATURE .................................................................................xii
CHAPTER 1 ...............................................................................................1
INTRODUCTION...................................................................................1
1.1 Introduction: ...................................................................................1
1.2 Working of Solar Still: ...................................................................1
1.3 Classification of solar stills:...........................................................2
1.4 Objectives:......................................................................................3
CHAPTER 2 ...............................................................................................4
LITERATURE SURVEY .......................................................................4
CHAPTER 3 ...............................................................................................6
THEORETICAL ANALYSIS.................................................................6
3.1 Introduction ....................................................................................6
3.2 Internal Heat transfer:.....................................................................7
3.3 Second law analysis of the still:.....................................................9
3.4 Exergy destruction of solar still components.................................9
CHAPTER 4 .............................................................................................12
Designing of solar still...........................................................................12
4.1 Design objectives: ........................................................................12
4.2 Design parameters:.......................................................................12
4.3 Design:..........................................................................................13
CHAPTER 5 .............................................................................................18
Experimental setup................................................................................18
CHAPTER 6 .............................................................................................22

viii
RESULTS AND DISCUSSIONS .........................................................22
CHAPTER 7 .............................................................................................42
CONCLUSION .....................................................................................42
CHAPTER 8 .............................................................................................44
REFERENCE ...........................................................................................44

ix
LIST OF FIGURES
Figure 3. 1 Working principle.......................................................................................6
Figure 3. 2 Schematic Representation...........................................................................7
Figure 4. 1 Dimensions of the rectangular basin.........................................................13
Figure 4. 2 SOLIDWORKSS model for rectangular basin..............................................14
Figure 4. 3 Dimensions of stepped still........................................................................14
Figure 4. 4 SOLIDWORKS Model for stepped basin .....................................................15
Figure 4. 5 Dimensions of the wooden insulation box, with glass..............................15
Figure 4. 6 SOLIDWORKS Model for the rectangular still ............................................16
Figure 4. 7 SOLIDWORKSS model for the stepped still.................................................16
Figure 4. 8 Cross section of the stepped still...............................................................17
Figure 4. 9 SOLIDWORKSS model of stepped still with Magnets ................................17
Figure 5. 1 SOLIDWORKS model of the stepped still with magnets........................18
Figure 5. 2 Pictograph of the still................................................................................19
Figure 5. 3 View of rectangular still representing thermocouple location
..............................................................................................................................20
Figure 5. 4 View of stepped still representing thermocouple location .......................20
Figure 5. 5 Pictograph of experimental setup .............................................................21
Figure 6. 1 Fluctuation of Solar Intensity and wind speed w.r.t time.........................22
Figure 6. 2 Fluctuation of basin temperature for the magnet with charcoal still
w.r.t time...............................................................................................................24
Figure 6. 3 Fluctuation of coefficient of total internal heat transfer with
respect to time.......................................................................................................25
Figure 6. 4 Fluctuation of Water, Glass and ambient temperature
w.r.t time...............................................................................................................26
Figure 6. 5 Fluctuation of distillate yield for three stills w.r.t time ............................27
Figure 6. 6 Fluctuation of evaporative heat transfer coefficient from
water to glass w.r.t time........................................................................................28
Figure 6. 7 Fluctuation of convective heat transfer coefficient from
water to inner glass w.r.t time...............................................................................29
Figure 6. 8 Fluctuation of radiative heat transfer coefficient from
Figure 6. 9 Fluctuation of coefficient of total internal heat transfer from
Figure 6. 10 Fluctuation of productivity of distillate w.r.t time..................................31
Figure 6. 11 Fluctuation of instantaneous efficiency w.r.t time .................................31
Figure 6. 12 Fluctuation of exergy efficiency.............................................................32
Figure 6. 13 Comparison of exergy of sun and total exergy destruction
w.r.t time...............................................................................................................33

x
Figure 6. 14 Fluctuation of exergy destruction of basin, water and glass
surface w.r.t time ..................................................................................................33
Figure 6. 15 Distribution of average exergy of the sun in a day.................................34
Figure 6. 16 Fluctuation of exergy destruction w.r.t depth of water...........................35
Figure 6. 17 Fluctuation of water temperature w.r.t time for 1cm depth....................36
Figure 6. 18 Fluctuation of total heat transfer coefficient with respect
to time for 1cm depth............................................................................................36
Figure 6. 19 Fluctuation of cumulative distillate yield w.r.t time for
1cm depth .............................................................................................................37
Figure 6. 22 Fluctuation of cumulative distillate yield with respect
to time for 3 cm depth...........................................................................................40
to time for 3 cm depth...........................................................................................41

xi
LIST OF TABELS
Tabel 4. 1 Specification of still.................................................................12
Tabel 4. 2 Thermo physical properties.....................................................13
Tabel 5. 1 Instruments used with its Range and Accuracy ......................20

1
CHAPTER 1
INTRODUCTION
1.1 Introduction:
Water occupies 70% of our world, so it is hard to believe that it is
still abounding, yet consuming fresh water, washing, irrigating and
farming is extremely rare, fresh water is just 3% of the world's surface,
although two-thirds of it is frozen or otherwise inaccessible
icefield (WorldWildLife). The rapid expansion of population,
urbanization and industrial revolution and the rather limited natural
resources of potable water are generally responsible for a growing scarcer
of freshwater in arid and remote regions, Groundwater contains high
salinity and over-contamination of arsenic in coastal areas (Saha, Dey
NC, Rahman M, Bhattacharya P, & d Rabbani GH, 2019).
1.2 Working of Solar Still:
“Solar Still is an instrument that enables the evaporation
condensation technique to harness solar energy to generate fresh drinking
water from saline water”(Asiful, Ashif, & Kironmoy, 2019).”Solar stills
can provide a response for those territories where there is plenty of solar
energy available but quality of water is not appropriate. This unit is
suitable for drinking water production. Solar stills are inexpensive and
have small maintenance costs but the solar issue remains poor
performance” [3].
“Solar Desalination is considered one of the safest and most widely
agreed methods for the conversion of seawater into clean water”. It is a
dependable strategy which produces “99.9% genuine purging of most
sorts of polluted water in developing countries”, sun based refining is
utilized to deliver drinking water, “solar distillation is used to produce
drinking water or to produce pure water for laboratories, batteries,

2
hospitals and commercial products” (S. C. Bhatia & R. K. Gupta, 2019).
Conventional distillation devours enormous energy per unit of water and
the expensive filtration and deionization methodologies are even higher
and will not clean up the water by removing all contaminants, but solar
stills wholly reliant on sun and just use the free photon energy from the
sun. This process is entirely eco-friendly.
Desalination technology is split into two groups by a concept of the
distinction of salt and fresh water solutions. The separation of fresh water
through the stages adjusts through increasing the heat to the solution of
salt water is accomplished in advances of evaporative or thermal
desalination.1.3 Classification of solar stills:

3
1.4 Objectives:
This project deals with the passive type solar stills which are
ancient technology and throughout the years it is being modernized in
every way possible to achieve highest efficiency while the yield is small,
our still continues to produces fresh water even when the sun goes down.
We are seeking to increase the solar performance in various ways:
 By breaking the hydrogen bond, resulting in lower surface trndion
and rise in the water evaporation by the use of strong magnetic
field.
 By using the stepped type basin to increase the exposure area and
also it brings the water surface closer to the inner glass cover there
by providing less thermal resistance.
 By mixing saline water with the charcoal powder, more heat is tend
to get absorbed by the water and the evaporation rate is increased.
 By varying depth of water
 Developing exergic analysis and find out the performance of the
still

4
CHAPTER 2
LITERATURE SURVEY
(Apurba, 2018) [4] “carried out a solar-type basin test still using various
heat absorbing materials such as black ink, black dye solution on brackish
water and black tonner on brackish water surface, and it is observed that
14.7%, 20.4% and 27 % increase in the cumulative distillate yield by
using black ink, black dye and black tonner respectively”.
(Shukla, hailendra and Sorayan, & V.P.S, 2005) [18] had developed a
new technique for enhancement in the distillate output of passive solar
still by use of Jute cloth. They found that, jute cloth possesses a property
to increase evaporation due to reduction of saline water inside the basin.
They also compared and found good consensus between theoretical and
experimental results.
(Pankaj, Yash, Aman, & Dr.Dhananjay , 2019) [11] Two similar modern
solar stills with ferrous magnets in the one still to magnetize water were
tested experimentally and numerically. This magnetization contributed to
a 49.22 per cent higher distillate along with the higher internal coefficient
of heat transfer.
(Aliakbar, Reza, & Abazar, 2017) [3] The magnetic field effect on an rise
in water evaporation is recognized in these work experiments. Tangent
magnet field on the water-air interface shows no sensitive effect but the
magnetic field perpendicular to the air=water shows a rate up to 18.3
percent increase when magnetic field is less than 100 Mt. This effect is
described on the basis of the kinetic energy movement of water molecules
at the interface and power of Lorentz force splitting hydrogen bonds.

5
(Sanjay Kumar & G. N. TIWARI, 1996)[14] “The heat transfer values of
C for the convective mass transmission of different grasshofs are
suggested as C=0.0322, n>0.4114 when grasshofs number is in this
range (1.794x106 < Gr<5.724x106) for the passive solar still and
C=0.0538, n=0.384 when grassofs number is in this range (5.498 x 106<
Gr < 9.128 x 106) for the active solar still. A thermal transfer for various
sites has been developed”.
(Abdenacer, Kaabir, & Nafia, Smakadji, 2007) [2]had conducted several
experiments on passive solar still by varying the water and glass
temperature on the efficiency and yield. They found that the temperature
of the glass cover is critical, which increases efficiency and return when
higher.
(Lucyna, Aleksandra, & Emil, 2007) [7] Over the process of a 5 minute
span they subjected water and electrolytic solutions to a low static
magnetic field and observed the magnetic field affects conductivity and
evaporation of liquids.
(Raj S.N & Tiwari G.N, 1983)[14] “They have investigated the
performance of a single solar basin with a flat plate collector. The daily
average distilled water production for this type is still found”.

6
CHAPTER 3
THEORETICAL ANALYSIS
3.1 Introduction
Solar stills is an old technique where solar power is used to
generate fresh water through condensation. Water is ample yet very salty
in nature, very few are drinkable, solar stills also transforms salt water
into bottled water. In ancient days, the pit is sunk along the shores and the
transparent cover is put over the top of the pit, the water from the earth is
evaporated and collected on the inside of the transparent cover and flows
down as seen in Figure 3.1, the collection container is positioned inside
the pit to capture the purified water and then, at the end of the day, the
transparent cover is withdrawn and the water is stored. (Wikipedia,
2020).
Figure 3. 1 Working principle

7
Figure 3. 2 Schematic Representation
The solar still is one of the methods which can use unpalatable
water for fresh water production. The basic working principles of solar
still distillation are evaporation, condensation and difference in basin
material temperature. Figure 3.2 shows the working principles of solar
still. The unpalatable water which is in the basin gets heated by the
absorption of solar thermal radiation. Due to this, convection current of
air is formed by the temperature effect and difference in the salt content
in the water. The rise in the temperature increases the evaporation rate
and the air current along with the moisture enhances condensation on the
transparent roof surface (Omid, MA, R, & Saad, 2015). The beads
condensate runs off through the straight forward slanted surface into an
assortment channel, which is associated in a container.
3.2 Internal Heat transfer:
The convective intensity of heat transfer between water and glass can
be described as:

8
The relationship between the values of Nusselts, Grasshofs and Prandle
numbers are as follows (P.K. Nag, 2011)
The value of the ℎ , is (Raj S.N & Tiwari G.N, 1983):
The values of the partial vapour pressure is found by using the following
formula:
The coefficient of heat transfer due to the radiation from saline water to
the interior of the glass sheet is given as:
ℎ , = 𝜀 × 𝜎 × ((𝑇 + 273.15) + 𝑇 + 273.15 × (𝑇 + 𝑇 + 546.2)
The overall heat transfer rate from water to inner glass surface can be
evaluated as (Pankaj, Yash, Aman, & Dr.Dhananjay , 2019):
𝑞 = 𝑞 + 𝑞 + 𝑞 = ℎ × (𝑇 − 𝑇 )

9
3.3 Second law analysis of the still:
Value of the exergy efficiency is calculated by:
𝜂 =
𝐸𝑥𝑒𝑟𝑔𝑦 𝑜𝑢𝑡𝑝𝑢𝑡
𝐸𝑥𝑒𝑟𝑔𝑦 𝑖𝑛𝑝𝑢𝑡
=
𝐸
𝐸
The value of 𝐸 is (Petela, 2003):
𝐸 = 𝐼 1 +
1
3
𝑇
𝑇
−
4
3
𝑇
𝑇
Ts stand for Sun’s Temperature i.e. (5,777K) (Sivakumar & Ganapathy,
2014).
𝐸 = ℎ , (𝑇 − 𝑇 ) 1 −
𝑇
𝑇
3.4 Exergy destruction of solar still constituents
The combo of energy conservation law and non-exergy
conservation is used to find exergy equilibrium for any system or its
components
3.4.1 Basin liner
Exergy destroyed in the basin is give as:
τg, τw ,and αb are mentioned in nomenclature

10
The gross coefficient of heat transfer between the atmosphere and the
aluminium basin is given by ℎ (W/m2
K) (Sivakumar & Ganapathy,
2014)
3.4.2 Saline water:
Exergy destroyed in the saline water is given as:

11
3.4.3 Glass cover:
V stands for the wind speed in (m/s).
𝑇 Stands for sky temperature (K)

12
CHAPTER 4
Designing of solar still
4.1 Design objectives:
For higher evaporation:
 The basin is made into steps and separating walls acts as fins
This increases surface area.
 Coating the surface area to carbon black.
 Shallow water depth
For large temperature difference:
 Making the joints leak proof
 Using insulation like wood and thermocol to prevent heat
loss
 Using high thermal conductive material as the basin material
for better heat transfer
 Using less clear glass
 Reducing the distance from the glass to the inner glass
cover.
4.2 Design parameters:
Tabel 4. 1 Specification of still

13
Tabel 4. 2 properties of materials
4.3 Design:
The models were designed and developed in SOLIDWORKSS
Figure 4. 1 Dimensions of the rectangular basin

14
Figure 4. 2 SOLIDWORKSS model for rectangular basin
Figure 4. 3 Dimensions of stepped still

15
Figure 4. 4 SOLIDWORKS 3D Model of stepped type basin
Figure 4. 5 Dimensions of the wooden insulation box, with glass

16
Figure 4. 6 SOLIDWORKS Model for the rectangular still
Figure 4. 7 SOLIDWORKSS model for the stepped still

17
Figure 4. 8 Cross-sectional view of stepped still
Figure 4. 9 SOLIDWORKSS model of stepped still with Magnets

18
CHAPTER 5
Experimental setup
During the experiments one still is equiped with rectangular basin and the
other 2 stills are equiped with the stepped type, one of the stepped type
still contains plain water and the other is tested either with charcoal or
(charcoal + magnet).
The magnets here used are permanent type 60 mm OD and 25 mm
ID ferrite ring magnets of 10 mm thickness. The magnets were mounted
in the stepped chamber such that the magnetic energy of the field is
uniformly spread.
Figure 5. 1 SOLIDWORKS model of the stepped still with magnets
1) Glass Cover, 2) Collection tube, 3)Plastic cover, 4) Measuring jar, 5)Wooden
Insulation, 6) Ferrite Ring Magnets, 7)Aluminium Still(Coated Black) 8)Slot with
rubber Gasket
The magnets used here are ideal for both heat absorption and water
magnetisation.
1
2
3
4
5
6
7
8

19
“5 K type temperature sensors are used for basin measurement,
atmospheric, inner glass, outer glass, water temperature in” all the 3 stills.
Different temperatures were recorded using temperature indicator during
the experiment, to find the velocity of the wind anemometer is used for
every 1 hour peiod. A graduated beaker is used for measurement of
distille output.
Figure 5. 2 Pictograph of the still

20
Tabel 5. 1 Instruments used with its Range and Accuracy
Figure 5. 3 View of rectangular still representing thermocouple location
Figure 5. 4 View of stepped still representing thermocouple location

21
Figure 5. 5 Pictograph of experimental setup
The setup was arranged such that all the three stills were facing
geographically south direction, the experiments were conducted in
Bacupally, Hyderabad and tests were conducted for 9 days, before the
experiment day the setup were arranged at 6:00pm, so that at the start of
experiment the conditions inside the still becomes steady state,

22
CHAPTER 6
RESULTS AND DISCUSSIONS
The tests are conducted from 9:00 a.m. to 4:00 p.m. At the start of
the trial, the solar intensity was small. and the water inside the still less
than the ambient temperature and after few minutes water begin to
condensate on the inner part of glass and with the time the solar intensity
kept increasing till 12:00 h and it reduces It is observed that the basin
temperature varies according to the solar intensity peaking at 12:00 h and
distillate productivity also peaks around 12:00 and 13:00.
Figure 6. 1 Fluctuation of Solar radiation and wind speed w.r.t time
The experiments were carried out for 3 different depths that is 1cm,
2cm, 3cm and it is observed that the 2cm depth gives max distillate yield
but the 1cm evaporates quicker and after 13:00 h little to no water is left

23
in the basin because the area is only 0.25m2
and the total output of
distillate yield is less when compared to the 2cm depth
The combinations of experiments were as follows:
 Stepped type basin integrated with Charcoal and water
 Rectangular type of convectional basin with plain water
 Stepped type basin with plain water
To increase the productivity rate static magnetic field is introduced and
observed a significant increase in the heat transfer rate. So the following
combinations were used for 3 different depths
 Stepped basin with magnet and charcoal
 Rectangular basin with plain water
 Stepped basin with plain water
Three stills were run simultaneously from 9:00h to 16:00 h and
observed the following temperatures
 Basin temperature
 Water temperature
 Glass inside temperature
 Glass outside temperature
 Ambient temperature

24
Figure 6. 2 Fluctuation of basin temperature for the magnet with charcoal still w.r.t
time
The fluctuation of the temperature of basin for three different
depths were shown in the fig 6.2 it clearly indicates that the peak
temperature is high for 2cm depth around 13:00h, at the beginning of
experiment temperatures of 1cm is higher this is because of less water
volume which in turn requires less heat to raise its temperature, as it can
be seen that the 3cm depth values of temperature are lower, this is due to
the large amount of water needed to be heated to increase its temperature.

25
Figure 6. 3 Fluctuation of coefficient of total internal heat transfer w.r.t time
Fig 6.3 shows the fluctuation of coefficient of total internal heat
transfer w.r.t time, these fluctuations are for the magnet with charcoal
still, and it can be observed that it follows the same trend as the solar
intensity of radiation, with 2cm depth peaking at 13:00h and since heat
transfer coefficient depends on the temperatures, from 9:00h to 11:00h
the fluctuation for 1cm is greater than the rest and again from 15:00h 1cm
depth overtakes 2cm depth.

26
Figure 6. 4 Fluctuation of Glass , Water, and ambient temperature w.r.t time
From the fig. 6.4 it can be observed that the temperature for the
saline water is higher than the inner glass sheet this is because the water
evaporated gets condensate at the glass surface and keeps the inside
surface cooler compared to the water temp. At 9:00h the inner glass
temperature of (mag+char) still is 5.12% higher than the (Rec) still, while
the water temperature of (mag+char) still is 10% higher than (Rec) still.
The maximum temperature for the water and inner glass achieved at
13:00h, and then they continue to fall. At 13:00h the temperature of the
saline water of (mag+char) still is leading (Rec) still by 14.54%, whereas
the (charcoal) still is leading by 7.27% and the salt water temperature at
the end of the trial of (mag+char) still is 47°C which is 4.44% higher
than the (Rec) still.
0
10
20
30
40
50
60
70
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Temperature(oC)
Time (hr)
Tw(Rec)
Tci(Rec)
Tw(Charcoal)
Tci(Charcoal)
Tw(Mag+Char)
Tci(Mag+Char)
T amb

27
Figure 6. 5 Fluctuation of distillate for three stills w.r.t time
The stepped basin with charcoal has distillate yield of 600ml at
16:00 h and this is due to charcoal being good absorber of heat and also
charcoal is good to absorb any odour in the water. It is observed at the
end of the experiment the total distillate amount in rectangular basin is
350ml, in the (magnet with charcoal) basin is 750ml This clearly shows
an increase in the efficiency.
It is detected that the output of (Magnet with charcoal) still is lower
or almost equal to the (rectangular) still at 9:00h, this is because of the
existence of magnets, which are also an energy consuming medium. The
productivity of this still overtakes at 11:00h. The accumulated distillation
production at the end of the experiment for the (magnet with charcoal)
still is 750ml which is 114.2% higher than the rectangular still, by using
the stepped basin without magnets the cumulative distillate output is
600ml which is 71.4% higher than the rectangular still, from above we
can conclude that the magnets have improved the cumulative distillate by
25% than compared to (charcoal) still.
0
100
200
300
400
500
600
700
800
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Cumullativedistillate(ml)
Time (hr)
RECTANGULAR
BASIN
CHARCOAL
MAGNET WITH
CHARCOAL

28
Figure 6. 6 Fluctuation of coefficient of evaporative heat transfer from water to glass
w.r.t time
It is witnessed from the fig 6.6, from 9:00h to 11:00h and at 16:00h
The measured values of hew are not really different between charcoal still
and the (magnet with charcoal) still, but after 11:00h the values of hew is
higher than the charcoal still. The maximum hew of (magnet with
charcoal) still is 20.58% higher than the charcoal still, this 20.58% shows
that the magnets increases the hew values.
0
5
10
15
20
25
30
35
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Evapoarativeheattransfercoefficient
(W/m2-K)
Time (hr)
RECTANGULAR BASIN
CHARCOAL
MAGNET WITH CHARCOAL

29
Figure 6. 7 Fluctuation of convective heat transfer coefficient from water to inner
glass w.r.t time
It is witnessed from the figure 6.7 that the maximum values of
coefficient of convective heat transfer for all the three stills are almost
equal and from 11:00h to14:00h the average coefficient of convective
heat transfer remains constant, 2.083 W/m2
-K.
Figure 6. 8 Fluctuation of coefficient of radiative heat transfer from water to inner
glass w.r.t time
0.0000
0.5000
1.0000
1.5000
2.0000
2.5000
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Convectiveheattransfercoefficient
(W/m2-K)
Time (hr)
RECTANGULAR BASIN
CHARCOAL
5.60
5.80
6.00
6.20
6.40
6.60
6.80
7.00
7.20
7.40
7.60
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Radiativeheattransfercoefficient
(W/m2-K)
Time (hr)
RECTANGULAR BASIN
CHARCOAL

30
The values of hrw as a function of time is shown in the fig 6.8. It
has been observed that the maximum value of hrw is 3.17% higher than
the rectangular still. This is due to the increased temperature in the
(magnet with charcoal) still.
Figure 6. 9 Fluctuation of coefficient of total internal heat transfer from water to inner
glass w.r.t time
It can be observed from the fig 6.9 that the lowest energy transfer
from water to glass is due to the hcw and the highest is due to hew, and the
influence of the hrw is in between those two. “On average the overall
internal heat transfer rate for” (magnet with charcoal) still leads
rectangular still by 18.59%. This fig has a similar pattern to solar
intensity because the heat transfer is a function of temperature and
fluctuation of temperature depends on intensity of solar radiation. “As
solar light decreases the temperature differential between the water and
the glass sheet raises, which raises the rate of evaporation”.
0
5
10
15
20
25
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Totalinternalheattransfer
coefficient(W/m2-K)
Time (hr)
RECTANGULAR BASIN
CHARCOAL

31
Figure 6. 10 Fluctuation of productivity of distillate w.r.t time
The fig 6.10 indicates the fluctuation of productivity for all the
three stills as a function of time. It is detected that the amount of distillate
output produced per hour is low at 10:00h this is because heat gets
observed by the ferrite magnets but after 11:00h the productivity
drastically increases and peaks at 13:00h and the productivity decrease
after 13:00h.
Figure 6. 11 Fluctuation of instantaneous efficiency w.r.t time
0
20
40
60
80
100
120
140
160
180
200
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Productivityofdistillatewater
(ml/hr)
Time (hr)
RECTANGULAR BASIN
CHARCOAL
0
10
20
30
40
50
60
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
InstantaneousEfiiciency(%)
Time (hr)
RECTANGULAR
BASIN
CHARCOAL
MAGNET WITH
CHARCOAL

32
The figure 6.11 indicates the fluctuation of instantaneous
efficiencies of all the three stills in variation of time. At 9:00h the
efficiency of (magnet with charcoal) still is “lesser by 40.34% when
compared with (charcoal) still at 11:00h the output is relatively less”, so
the instantaneous efficiency at 11:00 h is almost equal to the charcoal
still, after 11:00h it changes drastically and the efficiency peaks at
13:00h, the maximum instantaneous efficiency at 13:00h of the (magnet
with charcoal) still leads by 110.3% as compared to the conventional or
rectangular still with plain water. The use of magnets along with the
charcoal increases the efficiency by 37.8%.
Figure 6. 12 Fluctuation of exergic efficiency
The output of the energy is improved over time and peaks at about
13:00. having magnetic field along with the charcoal increases the
exergetic efficiency by 57.9% , the fluctuation of the exergetic
differences w.r.t time for the (magnetic with charcoal) still is plotted in
the fig 6.13

33
Figure 6. 13 Comparison of exergy of sun and total exergy destruction w.r.t time
Figure 6. 14 Fluctuation of exergy destruction in the saline water, glass surface and
w.r.t time
The highest amount of exergy destruction stays in the rectangular
basin, water and glass 1257.33 W, 80.18 W, and 79.89 W, respectively
0
200
400
600
800
1000
1200
1400
1600
1800
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Exergy(w/m2)
Time(hr)
Toatal Exergy descruction Exergy of sun
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00
Exergy(W/m2)
Time (hr)
Basin (rec)
Water (rec)
Glass (rec)
Basin
(mag+char)
Water
(mag+char)
Glass
(mag+char)

34
and for the (magnet with charcoal) still the values are 843.07 w, 151.25
W, 87.39 W respectively.
Figure 6. 15 Distribution of average exergy of the sun in a day
The pie diagram represents the average exergy distribution of one
day (here it is from 9:00h to 16:00h) for the (magnet with charcoal) still
and it can be observed that on an average 65% of the exergy gets
destroyed where the exergy destruction by the basin constitutes 51%, the
saline water constitutes 9% and the glass constitutes 5%.
35%
51%
9%
5%
Exergy
of sun untilised
Exergy destruction
in Basin
Exergy destruction in
saline water
Exergy destruction
in glass

35
Figure 6. 16 Fluctuation of exergy destruction w.r.t water depth
Fig 6.16 indicates the fluctuation of average exergy destruction in a
day w.r.t the water depth, the exergy destruction for the glass cover are
47.6W/m2
, 52.6 W/m2
, and 28.8 W/m2
for 1cm, 2cm and 3cm
respectively and it can be observed that exergy destruction in water and
glass remains low compared to basin liner irrespective of the depth of
water and Glass and water exergy destruction increases with the lower
saltwater depth.
The following charts represent the fluctuation of temperatures,
coefficients of heat transfer and cumulative heat distillate for both
combinations for 1cm 2cm and 3cm, it follows the same trend as
explained above. But it is observed that the 3cm depth has the lowest
results because of its huge volume which requires more heat than
compared to its counterpart 1cm and 2cm depths
532.9
606.4
338.1
106.6 108.1
61.4
47.6 52.6
28.8
0
100
200
300
400
500
600
700
0 1cm 2cm 3cm
ExergyDestruction(W/m2)
Water Depth (cm)
Exergy destruction
in Basinliner
Exergy destruction
in water
Exergy destruction
in Glass

36
Figure 6. 17 Fluctuation of water temperature w.r.t time for 1cm depth
Figure 6. 18 Fluctuation of coefficient of total heat transfer w.r.t time for 1cm depth
0
10
20
30
40
50
60
70
Temperature(oC)
Time (hr)
RECTANGULAR BASIN
STEPPED BASIN
STEPPED BASIN WITH
CHARCOAL

37
Figure 6. 19 Fluctuation of cumulative distillate w.r.t time for 1cm depth
Figure 6. 21 Fluctuation of total heat transfer coefficient w.r.t time for 1cm depth
0
100
200
300
400
500
600
700
800
Cumulativedistillateyeild
(ml)
Time (hr)
RECTANGULAR
BASIN
STEPPED BASIN
STEPPED BASIN
WITH CHARCOAL
0
10
20
30
40
50
60
70
Temperature(oC)
Time (hr)
RECTANGULAR
BASIN
CHARCOAL
MAGNET WITH
CHARCOAL
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
9:00 10:0011:0012:0013:0014:0015:00 16:00
TotalheattransferCoefficient
W/m2K)
Time (hr)
RECTANGULAR
BASIN
CHARCOAL
MAGNET WITH
CHARCOAL

38
Figure 6. 22 Fluctuation of cumulative distillate yield w.r.t time for 1cm depth
0
100
200
300
400
500
600
700
800
Cumulativedistillateml
Time (hr)
RECTANGULAR
BASIN
CHARCOAL
MAGNET WITH
CHARCOAL
0
10
20
30
40
50
60
Temperature(oC)
Time (hr)
RECTANGULAR BASIN
STEPPED BASIN
STEPPED BASIN WITH
CHARCOAL
0
5
10
15
20
25
30
35
TotalHeatTransfer
Coefficient
Time (hr)
RECTANGULAR BASIN
STEPPED BASIN
STEPPED BASIN WITH
CHARCOAL

39
Figure 6. 27 Fluctuation of coefficient of total heat transfer w.r.t time for 3cm depth
0
100
200
300
400
500
600
700
800
900
Cumulativedistillateml
Time (hr)
RECTANGULAR
BASIN
STEPPED BASIN
STEPPED BASIN
WITH CHARCOAL
0
10
20
30
40
50
60
Temperature(oC)
Time (hr)
RECTANGULAR BASIN
STEPPED BASIN
CHARCOAL

40
Figure 6. 28 Fluctuation of cumulative distillate yield w.r.t time for 3 cm depth
Figure 6. 29 Fluctuation of temperatures of water w.r.t time for 3cm depth
Figure 6. 30 Fluctuation of total heat transfer coefficient w.r.t time for 3cm depth
0
100
200
300
400
500
CumulativeDistillate(ml)
Time (hr)
RECTANGULAR BASIN
STEPPED BASIN
CHARCOAL
0
10
20
30
40
50
Temperature(oC)
Time (hr)
RECTANGULAR BASIN
CHARCOAL
MAGNET WITH
CHARCOAL
0.00
5.00
10.00
15.00
20.00
25.00
Totalheattransfer
Coefficient(W/m2K)
Time (hr)
RECTANGULAR
BASIN
CHARCOAL
MAGNET WITH
CHARCOAL

41
Figure 6. 31 Fluctuation of cumulative distillate yield w.r.t time for 3 cm depth
0
100
200
300
400
500
600
Cumulativedistillateyeild(ml)
Time (hr)
RECTANGULAR
BASIN
CHARCOAL
MAGNET WITH
CHARCOAL

42
CHAPTER 7
CONCLUSION
Three stills were experimentally investigated with one of them
having a rectangular basin and the other two with stepped basin, one of
the stepped basin is tested with plain water and the other with charcoal
mixed water of 2500 ppm and the same were experimented again but with
the 3rd
still being the combination of charcoal powder (75µm) and static
magnetic field, which is achieved by placing 10 ferrite ring magnets. This
setup was tested for 3 different depths of water that is 1cm, 2cm, 3cm.
“Significantly higher internal heat transfer and greater distillate
production were achieved with the use of charcoal”. The combination of
static magnetic field with the charcoal has increased as anticipated. On
the basis of experiment and theoretical study the following observations
were made::
 2cm depth of water gives the maximum distillate output
 The stepped basin has increased the distillation efficiency greatly
over the rectangular basin.
 For the stepped basin of (magnet with charcoal still) peak
productivity at 13:00 h is 150ml, 175ml 75ml for 1cm, 2cm and
3cm respectively and it can be observed that the 2cm still has
highest productivity
 The use of charcoal in the stepped basin observed a significant rise
in the coefficient of evaporative heat transfer.
 It was noticed that the measures improved the water production of
the purified water by 84.61 percent for 2 cm deep
 By integrating the charcoal powder with magnetic field has
increased the distilled output further by 23% than compared to the
rectangular basin for the 2cm depth.

43
 The efficiency boost attributed to the existence of a static magnet
field is attributed to the intermolecular forces' decrease i.e. for
water it is weakening of hydrogen bonds (Lucyna, Aleksandra, &
Emil, 2007).
 “The partial pressure difference between water and inner
condensation of the phases has been increased considerably by the
water magnetisation relative to the rectangular basin”
 The maximum efficiency has increased by 37.81% by using
charcoal and magnet in the stepped still for the 2cm depth.
 The study reveals that the lost main exergy is in the basin liner
accompanied by a saline water and glass.

44
CHAPTER 8
REFERENCE
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https://en.wikipedia.org/wiki/Solar_still
[2] Abdenacer, Kaabir, P., & Nafia, Smakadji. (2007). Impact of
temperature difference (water-solar collector) on solar-still global
efficiency. Desalination.
[3] Aliakbar, S., Reza, A., & Abazar, H. (2017). Increase in
water evaporation rate with increase in static magnetic ﬁeld
perpendicular to water-air interface. Chemical Engineering and
Processing.
[4] Apurba, L. (2018, february). Exergetic analysis of basin type
solar still. Engineering Science and Technology, an International
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[5] Asiful, H., Ashif, H. A., & Kironmoy, P. S. (2019). Solar
still for saline water desalination for low-income coastal areas.
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New Jersy: Hoboken- Wiley.
[7] Lucyna, H., Aleksandra, S., & Emil, c. (2007). Effects of a
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[10] P.K, N. (2011). Heat and Mass Transfer. Tata McGraw-Hill.

45
[11] Pankaj, D., Yash, K., Aman, S., & Dr.Dhananjay , R. M.
(2019). Comparative analysis and experimental evaluation of
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[12] Petela, R. (2003). Exergy of undiluted thermal radiation.
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[13] R, S. (2017). EXPERIMENTAL ANALYSIS OF DEW
DRAIN WATER. International Research Journal of Engineering
and Technology, 805-809.
[14] Raj S.N, & Tiwari G.N. (1983). Single basin solarstill
coupled with flat plate collector. Energy Conversion Management.
[15] S. C. Bhatia, & R. K. Gupta. (2019). Textbook of Renewable
Energy. Woodhead Publishing India PVT.
[16] Saha, R., Dey NC, Rahman M, Bhattacharya P, & d Rabbani
GH. (2019). Geogenic Arsenic and Microbial contamination in
Drinking Water sources: Exposure Tisks to the coastal Population
in Bangladesh. Frontiers in Environmental Science.
[17] Sanjay Kumar, & G. N. TIWARI. (1996). ESTIMATION
OF CONVECTIVE MASS TRANSFER IN SOLAR
DISTILLATION SYSTEMS. Elsevier Science limited, 459-464.
[18] Shukla, hailendra and Sorayan, & V.P.S. (2005). Thermal
modeling of solar stills: An experimental validation},. Renewable
Energy, 683–699.
[19] Sivakumar, V., & Ganapathy, S. E. (2014). Energy and
exergy analysis of single slope passive solar still: an experimental
investigation, Desalination and Water Treatment. Desalination and
Water Treatment, 1433-1444.
[20] Swinbank, W. (2012). Long- wave radiation from clear
skies. New York: Mc Graw Hill Publications.

46
[21] WorldWildLife. (n.d.). Retrieved may 22, 2020, from
www.worldwildlife.org:
https://www.worldwildlife.org/threats/water-scarcity

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