Thermal modelling of solar still can be done manually using a model or can be don on comparative basis using different software and compilers like ANSYS, C, MATLAB and different desalination

1. Thermal Modelling Of Solar Still
And Different Desalination
Techniques
S H A N TA M WA R K A D
2 0 2 11 8 2 1 0
M . Te c h . ( R E )
Guided by:
Dr. Gaurav Dwivedi
Assistant Professor
MANIT, Bhopal.
Dr. Jay Mant Jha
Assistant Professor
MANIT, Bhopal.

2.  Introduction
 Application
 Major review
 Objective
 References
Contents

3. Introduction
 Water Distribution On Earth
• Seawater - 96.54%
• Freshwater - 2.53 %. Of freshwater, 69% resides in glaciers, 30%
underground, and less than 1% is located in lakes, rivers, and swamps.
 Classification Of Desalination Processes
• Desalination can be classified as : membrane based and thermal based.
• Membrane based processes : Reverse Osmosis (RO), Electrodialysis (ED),
Electrodialysis-reversal (EDR).
• Thermal based processes : multi-effect distillation (MED), multistage flash
distillation (MSF), vapor compression (VC) distillation (Mechanical and
thermal).

4.  Solar still
 The solar still is the device that uses the
energy of the sun to serve the required
purpose of desalinating the water.
 A solar still basically is a container with
clear plastic or glass cover on the top for
sunlight entry with proper insulation at
every wall/sides of the container, usually
made of concrete, galvanized iron sheet, or
fiber-reinforced plastic
 It also consists of an aluminum plate that
is painted black in color for better
absorption of solar radiation.
 The glass top is a sloping surface
supported by the frame for the proper
passage for the dripping water, this covers
the pan and is kept airtight sealed to stop
vapor leakage.
Source : https://doi.org/10.1002/ep.13227

5. Solar
distillation
Passive
distillation
Wicked and
stepped type
solar still
Stepped
type
Wick
type
Single
wick
solar still
Multi-
wicked
type still
Concave
wicked
type
solar still
Conventiona
l solar still Fins
Solar stills
with
reflectors
Heat
storage
Sensible
heat
storage
Latent
heat
storage
Unconventional
shapes
Triangular
still
Hemispherical
still
Tubular still
Multiple
slopes
Verticle
stills
Active
distillation
High
temperature
distillation
Using flat
plate
collector
Using
parabolic
concentrator
Using
evacuated
tube
collector
Using heat
pipe
Using a
solar pond
Using a
hybrid
system
Nocturnal
distillation
Pre heated
water
distillation
Classification of solar distillation

6. Application
• Desalination technology may be one way to generate cost-effective,
climate-independent water supplies of regulated quality.
• Many desalination processes like RO, MSF, ED are most widely used
techniques in the world. Especially in middle-eastern regions where
seawater is only source of water.
• Devices like solar still are constantly being studied due to the fast pace
of research in desalination, brought about by global demand for cost-
effective clean water production.
• More than 16,000 desalination plants have been established globally,
while more than 50% are RO-based plants. Middle Eastern region has
about 53% of the global market share; this is due to the lack of
availability of fresh water for domestic and industrial purposes. They are
mostly dependent on the desalination of seawater from the coastal
region for freshwater availability.

7. Major Review
This review presents various desalination technologies and their economic
analysis based on the studies of various authors. Water desalination
technologies and processes include membrane and thermal technologies are
presented. Desalination techniques are very much important in the regions
where water scarcity. The demand for clean water has increased due to various
factors like population rise, climate change impacts on agriculture overuse of
fresh water for industrial purposes. Hence technologies for cleaner water are
required which is cost-effective and technologically stable for use.
Topic : Different Desalination Techniques and its Economic
Analysis a Short Review
References : 140+
Current status : Under Review

8. Following conclusions can be drawn from the review paper.
• Reverse osmosis (RO) is a process that is very efficient and is used globally
with about 65-70%, followed by MSF with about 18% of global
desalination market share.
• MED, MSF, MVC are more renewable compatible technology that can be
used with most renewable energy sources.
• Out of the other desalination techniques, RO stands on the top, followed by
MED and ED for the studies in the respective topics for further research and
development to boost the desalination in the required area.
• Solar still integrated with heat input devices yields higher productivity than
various conventional still designs.
• In an economic analysis of solar still of moderate capacity having the capital
cost of about ₹15500 per unit, working for 250 days, having 5 L/m2 as
daily productivity will yield the cost of water as ₹4.85/L.

9. 67.47
49.98
163.71
88.38
64.47
100.75 102.29
118.08
92.72
98.52
64.57
105.04
80.41
74.61
0
20
40
60
80
100
120
140
160
180
Unit cost of water (₹/m3)

10. • Solar desalination studies show the rising curve over the years. This is due
to the higher cost-effectiveness and easy operation of solar-based
desalination techniques.
0
1000
2000
3000
4000
5000
6000
7000
1995-2000 2001-2005 2006-2010 2011-2015 2016-present
359
571
943
2080
6586
Year range
Solar desalination studies
number of articles published under the the subject area of "Solar Desalination"

11. Objective
• To estimate and study variation in the internal heat transfer coefficients
(convective, evaporative and radiative) for various times of day for different
thermal models.
• Also to study the performance of still with variation in temperature, flow,
water depth, wind speed, and application of different external auxiliaries
such as mirrors/reflectors.

12. Start
Input 1 : Assuming initial values for temperature of glass cover, humidity, brackish water
temperature, water depth, wind speed.
Input 2 : operating, design, and climatic data.
Calculate:
• Convective heat transfer coefficients
• Evaporative heat transfer coefficients
• Radiative heat transfer coefficients
• Overall heat transfer coefficient
• Rayleith number, Nusselt number
From saline water to humid air.
From humid air to glass cover
Findings :
Updated temperatures based on modelling software.
End
The algorithm of solution by the approach of thermal
modeling

13. 1. G. Xiao et al., “A review on solar stills for brine desalination,” Appl. Energy,
vol. 103, pp. 642–652, 2013, doi: 10.1016/j.apenergy.2012.10.029.
2. M. Hedayatizadeh et al., “A detailed thermal modeling of a passive single-slope
solar still with improved accuracy”, Groundwater for Sustainable Development,
Vol. 11, 2020, https://doi.org/10.1016/j.gsd.2020.100384.
3. L. Zhang et al., “Modeling and performance analysis of high-efficiency
thermally-localized multistage solar stills”, Applied Energy, Vol. 266, 2020,
https://doi.org/10.1016/j.apenergy.2020.114864.
4. G. N. Tiwari, H. N. Singh, and R. Tripathi, “Present status of solar distillation,”
Sol. Energy, vol. 75, no. 5, pp. 367–373, 2003, doi:
10.1016/j.solener.2003.07.005.
References

14. THANK YOU