NATIONAL INSTITUTE OF TECHNOLOGY CALICUT
DEPARTMENT OF MECHANICAL ENGINEERING
IMPROVING SOLAR STILL PERFORMANCE WITH:
HEAT PIPE, PULSATING HEAT PIPE & PCM
ALBINJEEV S S
M230612ME
THERMAL SCIENCES
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DESALINATION
 More than 70% of earth is covered with water.
 Conversion of SALINE WATER TO PURE WATER.
 Several methods can be used for Desalination:
 REVERSE OSMOSIS
 WATER TREATMENT PLANTS
 HUMID AIR CONDENSATION
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SOLAR STILLS
 Solar desalination methods include:
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Multiple-effect humidification (MEH)
Multi-stage flash distillation (MSF)
Multiple-effect distillation (MED)
Multiple-effect boiling (MEB)
Humidification–dehumidification (HDH)
SOLAR STILLS
 Advantages of Solar Stills :
 Low cost design
 Environmental friendliness
 Disadvantages of Solar Stills :
 Low water production rate
 Depends on Solar energy
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HEAT PIPE
IMPROVEMENT
IN PERFORMANCE
USING
PULSATING HEAT
PIPE
PHASE CHANGE
MATERIALS
HEAT PIPE
 A heat pipe is a heat-transfer device that employs phase transition to
transfer heat between two interfaces.
 Volatile liquid in contact with a thermally conductive solid surface turns
into a vapor by absorbing heat. The vapor then travels along the heat pipe
to the cold interface and condenses back into a liquid, releasing the latent
heat. The liquid then returns to the hot interface through capillary action,
centrifugal force, or gravity and the cycle repeats.
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PULSATING HEAT PIPE
 A closed-loop pulsating heat pipe (PHP), usually consists of a sealed,
meandering channel connected end-to-end, first evacuated; and then
partially filled with a working fluid.
 Has a sequence of internal vapor bubbles and liquid slugs. The liquid slugs
occur when the diameter of the channel is small enough to be capillary.
 The vapor plugs act mechanically as a pump piston. Since the PHP is
closed and connected end-to-end, an expansion of vapor in one point is
transmitted through the whole system.
 This can result in an Oscillation Or Pulsation of the fluid.
 PHP does not have a wick structure.
 The device is also able to work without gravity.
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PULSATING HEAT PIPE
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PHASE CHANGE
MATERIALS

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Substances which absorb
or release large amounts
of ‘LATENT HEAT’ when
they go through a change
in their physical state.
During the latent heat
absorption or latent heat
release, the temperature
of the PCM remains
constant.
The latent heat absorbed
by the PCM can be stored
therein, hence PCMs are
highly efficient thermal
storage means.
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COMPARISON
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EXPERIMENTAL SET-UP

Combined effect of utilizing a PHP
with PCM on solar still performance
has not been previously investigated.
In this study, SEVEN solar still
configurations were subjected to
experimentation.
 THREE SINGLE-SLOPE SOLAR STILLS :
 CONVENTIONAL SOLAR STILL
 THERMOSYPHON HEAT PIPE SOLAR
STILL
 PULSATING HEAT PIPE SOLAR STILL
 With the same absorber area were
compared.
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EXPERIMENTAL SET-UP
 The solar stills were constructed from galvanized plate with a thickness of 0.005m.
 The absorber surface with an area of 0.5 m × 0.5 m was coated with black dye.
 Solar radiation enters the absorber area through a glass with a thickness of 0.004
m and a slope of 30 degrees.
 The solar still’s exterior is insulated with 0.05 m thick polyurethane foam.
 Four evacuated tubes made up of thermosyphon heat pipes (THP) and pulsating
heat pipes (PHP) were utilized.
 PHP were filled with distilled water (as a working fluid) with a filling ratio of 30 %
and pressure of 175.
 The paraffin wax was employed as a phase change material (PCM).
 The PCM was heated to liquefy before being put into the evacuated tube.
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CONFIGURATIONS
Conventional solar still
(CSS)
Solar still with
thermosyphon heat
pipe(HP) evacuated
tube solar collector
(SSTHP)
Solar still with
thermosyphon HP
containing 0.9 m PCM
(SSTHP-PCM-1)
Solar still with
thermosyphon HP
containing 1.8 m PCM
(SSTHP-PCM-2)
Solar still with pulsating
heat pipe( PHP ) solar
collector (SSPHP)
Solar still with PHP
containing 0.9 m PCM
(SSPHP-PCM-1)
Solar still with PHP
containing 1.8 m PCM
(SSPHP-PCM-2)
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THEORETICAL BACKGROUND
 Energy input: Radiant energy absorbed from the sun by the basin and the
evacuated tubes solar collector.
 Energy output: Sum of the heat lost from the system and the latent heat of
evaporation.Heat loss occurs through convective and radiative heat transfer from
the evacuated tubes solar collector, glass and walls of the system to the
surrounding environment.
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THEORETICAL BACKGROUND
 Minimizing heat loss in a solar desalination system directly correlates to
the increased energy recovery or water production. Therefore, the
thermal efficiency of a solar desalination system is defined as the RATIO
OF THE RECOVERED ENERGY TO THE TOTAL ENERGY INPUT TO THE
SYSTEM
 Daily and Instantaneous energy efficiencies of a solar desalination system
are:
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THEORETICAL BACKGROUND
Exergy analysis is used in performance evaluation of a solar desalination
system. The exergy efficiency is the ratio of the system’s produced exergy to
the total inlet exergy.
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COST ANALYSIS
 Cost Per Liter(CPL) of generated fresh water:
 M is the system’s average annual water production. The system’s annual cost
(UAC) is the sum of the first annual cost (FAC) and the annual maintenance cost
(AMC), minus the system’s annual salvage value (ASV):
 UAC = FAC + AMC − ASV
 FAC = P × CRF
 P is the capital cost of the system and CRF is the capital recovery factor:
 In this study, the interest rate and system life span have been supposed at 20 %
and 20 years, respectively. Annual maintenance cost is considered as 10 % of the
first annual cost of the system.
 AMC = 0.1 × FAC
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COST ANALYSIS
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UNCERTAINITY ANALYSIS
 Klein proposed an equation to obtain the uncertainty of a measurement:

u and a are the standard uncertainty and accuracy of devices.
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RESULTS
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CONCLUSION
 The SSPHP-PCM-2 system produced 40 % more water than a conventional
solar still.
 The system employing pulsating heat pipe generated 3.4 % more
freshwater than solar still using heat pipe.
 Furthermore, the freshwater produced by the pulsating heat pipe/filled
PCM evacuated tube system was 10.8 % higher than the freshwater
produced by the pulsing heat pipe without PCM.
 The ability of heat pipe-PCM combinations to store thermal energy and
release it slowly over time can significantly improve the efficiency of solar
stills, particularly during periods of low solar radiation.
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CONCLUSION
 The use of PCM increases the water temperature of the system after
decreasing the solar radiation due to remove the thermal energy from it.
 The influence of pulsating heat pipe on productivity of solar still is higher than
the thermosyphon heat pipe.
 Using of PCM in combination of pulsating heat pipe in evacuated tube
improved the thermal efficiency by 42.9 % compared to conventional still.
 The exergy efficiency of the system utilizing the pulsing heat pipe/ filled PCM
evacuated tube was 23.04 % greater than the system using the heat pipe/filled
PCM evacuated tube .
 The CO2 reduction of the conventional system, heat pipe system, and
pulsating heat pipe system was approximately 14.56 tons, 17.93 tons, and
18.45 tons, respectively, while the CO2 emission was approximately 0.017
tons, 0.0178 tons, and 0.0189 tons.
 The NO reduction and emission of the PHP system were 425.5 tons and 0.427
tons, respectively
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REFERENCE
I.
Improving solar still performance with heat pipe/pulsating heat pipe evacuated
tube solar collectors and PCM: An experimental and environmental analysis Amir
Hemmatian a , Hadi Kargarsharifabad b,c,* , Ahad Abedini Esfahlani c , Nader
Rahbar c , Shahin Shoeibi c
II.
H. Hassan, M.S. Yousef, M. Fathy, M.S. Ahmed, Assessment of parabolic trough
solar collector assisted solar still at various saline water mediums via energy,
exergy, exergoeconomic, and enviroeconomic approaches, Renew. Energy 155
(2020) 604–616
III. ChatGPT
IV. https://worldscientific.com
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THANK YOU
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