IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ
This research aims to improve the performance of solar distillation systems by incorporating a rotating cotton cloth into the distillation chamber. This contributes to enhancing the thermal efficiency of the system by improving heat distribution and accelerating the evaporation process. Experimental...
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Репозитарії
Vidnovluvana energetika| _version_ | 1871104102745767936 |
|---|---|
| author | Sahip , Z. Akbara Naseer , T. Alwan Barhm , Mohamad Mohammed , Abuidam |
| author_facet | Sahip , Z. Akbara Naseer , T. Alwan Barhm , Mohamad Mohammed , Abuidam |
| author_institution_txt_mv | [
{
"author": "Z. Akbara Sahip ",
"institution": "Technical Engineering College, Renewable Energy Research Center – Northern Technical University, Kirkuk, Iraq"
},
{
"author": "T. Alwan Naseer ",
"institution": "Department of Oil & Gas Techniques Engineering – Northern Technical University, Kirkuk, Iraq"
},
{
"author": "Mohamad Barhm ",
"institution": "Department of Petroleum Technology, Koya Technical Institute, Erbil Polytechnic University, Erbil, Iraq"
},
{
"author": "Abuidam Mohammed ",
"institution": "Diwaniyah Municipality Directorate, Al- Qadisiyyah, Iraq"
}
] |
| author_sort | Sahip , Z. Akbara |
| baseUrl_str | https://ve.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-18T06:32:24Z |
| description | This research aims to improve the performance of solar distillation systems by incorporating a rotating cotton cloth into the distillation chamber. This contributes to enhancing the thermal efficiency of the system by improving heat distribution and accelerating the evaporation process. Experimental results showed that the highest water production was achieved at a rotation speed of 0.2 rpm, reaching 1840 ml/day, followed by a rotation speed of 0.5 rpm (1755 ml/day), and a rotation speed of 1 rpm (1670 ml/day). The study also demonstrated that environmental factors such as solar radiation intensity, temperature, humidity, and wind speed significantly affect system efficiency. The research concludes that the rotating cloth technology represents a promising solution for improving the efficiency of solar desalination systems, especially in areas with high solar radiation such as Kirkuk city, Iraq. |
| doi_str_mv | 10.36296/1819-8058.2026.1(84).201-211 |
| first_indexed | 2026-03-31T01:00:08Z |
| format | Article |
| fulltext |
201
Відновлювана енергетика. № 1/2026 | Сонячна енергетика
6.24: 004.942 https://doi.org/10.36296/1819-8058.2026.1(84).201-211
IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC:
A CASE STUDY IN KIRKUK CITY, IRAQ
Received Jan. 08, 2026; accepted Mar. 23, 2026
Available online Mar. 31, 2026
Sahip Z. Akbara1, Naseer T. Alwan2,
Barhm Mohamad3, Mohammed Abuidam5
Author for correspondence: Barhm Mohamad
e-mail: barhm.mohamad@epu.edu.iq
Abstract. This research aims to improve the performance of
solar distillation systems by incorporating a rotating cotton
cloth into the distillation chamber. This contributes to en-
hancing the thermal efficiency of the system by improving
heat distribution and accelerating the evaporation process.
Experimental results showed that the highest water produc-
tion was achieved at a rotation speed of 0.2 rpm, reaching
1840 ml/day, followed by a rotation speed of 0.5 rpm (1755
ml/day), and a rotation speed of 1 rpm (1670 ml/day). The
study also demonstrated that environmental factors such as
solar radiation intensity, temperature, humidity, and wind
speed significantly affect system efficiency. The research con-
cludes that the rotating cloth technology represents a prom-
ising solution for improving the efficiency of solar desalination systems, especially in areas with high solar radia-
tion such as Kirkuk city, Iraq.
Key words: conventional solar still, thermodynamic analysis, solar radiation intensity, Energy economic analy-
sis, optimization techniques.
ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ СОНЯЧНОГО ДИСТИЛЯТОРА ЗА ДОПОМОГОЮ ОБЕРТОВОЇ
БАВОВНЯНОЇ СІТЧАСТОЇ ТКАНИНИ: ПРИКЛАД МІСТА КІРКУК, ІРАК
Отримано 08 січ. 2026 р.; рекомендовано до публікації 23 бер. 2026 р.
Доступно онлайн 31 бер. 2026 р.
Сахіп З. Акбара¹, Насір Т. Алван³,
Бархм Мохамад⁴, Мохаммед Абуїдам⁵
Автор для кореспонденції: Бархм Мохамад
e-mail: barhm.mohamad@epu.edu.iq
Анотація. Метою цього дослідження є підвищення
ефективності систем сонячної дистиляції шляхом ви-
користання обертової бавовняної тканини в камері
дистиляції. Це сприяє підвищенню теплової ефектив-
ності системи завдяки кращому розподілу тепла та
прискоренню процесу випаровування. Виходячи з ре-
зультатів проведених експериментальних дослі-
джень, найбільший обсяг виробництва води досяга-
ється при швидкості обертання 0,2 об/хв, що
становить 1840 мл/добу. При швидкості 0,5 об/хв
продуктивність становить 1755 мл/добу, тоді як при
швидкості 1 об/хв — 1670 мл/добу. В ході дослідження
також продемонстровано, що такі фактори навко-
лишнього середовища, як інтенсивність сонячного випромінювання, температура, вологість та
1 Research Scholar
https://orcid.org/0009-0007-2961-3395
2 Lecturer
https://orcid.org/0000-0003-3955-6420
3 Lecturer
https://orcid.org/0000-0001-8107-6127
4 Research scholar
https://orcid.org/0009-0000-4312-8459
1 Technical Engineering College, Renewable
Energy Research Center – Northern Technical
University, Kirkuk, Iraq
2 Department of Oil & Gas Techniques
Engineering – Northern Technical University,
Kirkuk, Iraq
3 Department of Petroleum Technology, Koya
Technical Institute, Erbil Polytechnic University,
Erbil, Iraq
4 Diwaniyah Municipality Directorate, Al-
Qadisiyyah, Iraq
1 науковий співробітник
https://orcid.org/0009-0007-2961-3395
2 викладач
https://orcid.org/0000-0003-3955-6420
3 Lecturer
https://orcid.org/0000-0001-8107-6127
4 науковий співробітник
https://orcid.org/0009-0000-4312-8459
1 Технічний інженерний коледж, Центр дослі-
джень відновлюваної енергетики при Північ-
ному технічному університеті, м. Кіркук, Ірак
2 Кафедра нафтогазових технологій, Північний
технічний університет, м. Кіркук, Ірак
3 Кафедра нафтових технологій, Технічний ін-
ститут Коя, Ербільський політехнічний універ-
ситет, м. Ербіль, Ірак
4 Управління муніципалітету Діванія, провінція
Аль-Кадісія, Ірак
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Відновлювана енергетика. № 1/2026 | Сонячна енергетика
швидкість вітру, суттєво впливають на ефективність системи. Отримані результати свідчать про
те, що технологія застосування обертової тканини є перспективним рішенням, що дозволяє підви-
щити ефективність роботи системи сонячного опріснення води, особливо в регіонах з високою інтен-
сивністю сонячного випромінювання, таких як місто Кіркук (Ірак).
Ключові слова: традиційний сонячний дистилятор; термодинамічний аналіз; інтенсивність сонячного
випромінювання; енергетично-економічний аналіз; методи оптимізації.
Abbreviation Items Unit
CSS Conventional solar still -
SSSMC Suggested solar still mesh cotton -
S Standard deviation -
mew The yearly yield from the solar still system kg/m2.year
P Solar still system's annual production L/m2. year
I(t) Solar radiation intensity W /m2
CRF Factor for the sinking fund -
SFF The factor for the sinking fund -
FAC The first annual (yearly) cost $
CS The manufacturing and installation capital cost $
ASV The value of annual salvation $
AC Annual (yearly) cost $
AMC The cost of annual maintenance $
YCPL The yearly cost per liter $
η Thermal efficiency -
hfg The average latent heat J/kg
INTRODUCTION
The availability of high-quality drinking water is a crucial
factor in promoting the social and economic development
of any country. Saltwater constitutes approximately 97% of
the total water available on the Earth's surface [1]. Saltwa-
ter cannot be used for industrial, agricultural, or drinking
purposes. Hence, the urgent need to convert saltwater into
pure, usable water. To achieve this, desalination is the ideal
option, as it involves heating, evaporation, and condensa-
tion processes. Solar stills are among the most prominent
devices available for achieving effective and efficient desal-
ination [2]. Having clean drinking water is essential for hu-
man health. Solar distillation is an economical and effective
solution for desalination using solar energy. It harnesses
the sun's radiation to heat and evaporate salt water, then
condenses the steam to produce fresh water. This technol-
ogy represents a sustainable way to produce clean drinking
water in areas suffering from water scarcity [3]. Solar distil-
lation is a vital application in freshwater production, partic-
ularly in rural and remote areas. This system relies on sim-
ple technologies to convert salty or polluted water into
fresh water, without the need for fuel or non-renewable
energy sources [4]. Solar distillation relies on a principle
similar to that of natural rainfall. Solar radiation heats the
water inside the distillation tanks, causing it to evaporate
and separate impurities, salts, and other substances. When
the temperature of the water vapor drops, it returns to its
liquid state and is collected as pure water[5]. There are
many factors that influence the production of freshwater
using solar stills, including operating and design conditions,
as well as the surrounding environment. Among these fac-
tors, some environmental conditions, such as humidity, so-
lar radiation intensity, and ambient air temperature, are
difficult to control and directly impact the efficiency of
these devices [6][7]. Several researchers have studied the
impact of environmental conditions on the efficiency and
performance of solar stills. A recent study demonstrated
that environmental factors, such as solar radiation intensity
and ambient air temperature, play a pivotal role in improv-
ing or reducing freshwater production, underscoring the
importance of these variables in improving system effi-
ciency [8],[9]. Another study found that the distillation rate
increases with increasing solar radiation intensity and am-
bient temperature. However, the study indicated that in-
creasing wind speed leads to a decrease in the efficiency of
the condensation and evaporation processes, negatively
impacting the performance of the solar still [8]. In this con-
text, researchers have found that adding certain materials,
such as black cloth, to a distillation system can enhance its
efficiency. Studies by Gad et al. [10] have shown that using
black cloth as a heat-absorbing material enhances evapora-
tion efficiency and increases freshwater production, mak-
ing this technology a promising solution for improving the
performance of solar stills. Essa et al. [11] study showed
that the use of black cloth increases heat absorption in
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Відновлювана енергетика. № 1/2026 | Сонячна енергетика
solar stills, enhances evaporation efficiency, and increases
freshwater production. Mohamed et al. [12] found that
black fabric contributes to accelerating the evaporation
process and increasing productivity due to its solar radia-
tion absorption property. After studying the effect of black
cloth on still performance, additional experiments were
conducted to improve productivity and increase system ef-
ficiency. Among these experiments was the use of rotating
cloth. The researchers Abdullah et al. [13] conducted a
study on adding a rotating black cloth belt to a solar still,
which increased water productivity by up to 300% com-
pared to conventional stills. Also, Haddad et al. [14] study
demonstrated that using a vertical rotating cloth in a solar
still improved productivity by 51.1% in winter and 14.72%
in summer. In addition, Essa et al. [15] investigated the ef-
fect of adding rotating fabric systems inside solar stills, and
the results showed that this modification significantly in-
creased water productivity by up to 315% compared to con-
ventional stills. These studies have demonstrated the im-
portance of using rotating fabric as an effective tool for
improving the performance and efficiency of solar desalina-
tion systems. Although the rotating cloth is effective in im-
proving the productivity of solar stills, studies have not ad-
dressed the effect of rotating mesh cotton inside the solar
still. This study, being conducted in the city of Kirkuk, Iraq,
aims to fill this gap by examining the effect of rotating mesh
cotton through a full cycle of two minutes on the perfor-
mance of the solar still.
Explaining the concept of improvement
In this research, a solar distillation system was improved by
incorporating a moving black fabric within the distillation
chamber. The fabric rotates one full cycle every two
minutes, contributing to the improved thermal efficiency of
the system. This moving fabric increases the system's heat
absorption, enhancing evaporation, as proposed by Qader
et al. [16][17]. These modifications are expected to lead to
a significant increase in water production, especially in ar-
eas with high solar radiation, such as Kirkuk city in Iraq.
Experimental setup
Fig. 1 illustrates the design of the solar still used in this
study, which includes two monoclinic solar stills in Kirkuk,
Iraq (latitude: 35.4686, longitude: 44.38933). To optimize
solar radiation absorption, the solar panels were oriented
southward, with an area of 1 m2 per panel. Considering Kir-
kuk's geographical location, the glass covers of the stills
were tilted at a 35˚, in line with the local latitude. 1 cm thick
Russian plywood was used to construct the main structure
of the still.
Fig. 1. Schematic diagram of the suggested solar still mesh cotton (SSSMC) and conventional solar still (CSS). 1) Transpar-
ent Plexiglas cover; 2) MDF; 3) Cotton cloth; 4) Water basin; 5) Metal legs; 6) The water basin; 7) The basin water; 8) Mo-
tor 12 volt; 9) Graduated cylinder; 10) Control unit; 11) Solar panel; 12) Feed water tank
To ensure system efficiency and reduce energy waste, a sil-
icone rubber strip was installed around the edges of the
clamps to prevent vapor leakage. Furthermore, the
wooden structure was painted matte black, including the
interior surfaces of the basins, to further enhance heat ab-
sorption. A black mesh fabric (1 × 0.5 m) was installed
within the system to enhance solar radiation absorption
and accelerate the evaporation process. A 12 V motor was
also installed to enable the black fabric to rotate one full
cycle in 2 min. This continuous movement of the fabric
helps distribute heat evenly across the system surface, pre-
venting heat buildup at specific points, accelerating evapo-
ration, and reducing heat loss. To reduce heat loss, glass
wool insulation was used around the edges of the system,
which contributed to reducing thermal leakage. A channel
was designed within the distiller to improve water flow,
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Відновлювана енергетика. № 1/2026 | Сонячна енергетика
while maintaining the water level in the basin at approxi-
mately 1 cm, ensuring optimal evaporation conditions. The
experimental trials were conducted from August 1 to 3,
2025, in the extremely hot environment of Kirkuk. Figs. 2
and 3 illustrate the complete experimental setup, including
the location of the solar panels, the position of the black
mesh fabric, and the insulation properties, providing a real-
istic visualization of the system used in this study.
Fig. 2. A photograph of the suggested solar distiller and the conventional solar distiller
Modified model
The proposed solar distillation system uses a cotton mesh
fabric that rotates one full rotation in two minutes. This ro-
tation occurs in three stages, with the fabric rotating at
speeds of 0.2, 0.5, and finally, 1 rpm. This rotation signifi-
cantly improves the thermal efficiency of the system. It
evenly distributes heat across the surface of the cotton fab-
ric, improving the absorption of solar radiation and its con-
version to heat, thereby raising the temperature of the
water inside the tank and increasing the evaporation rate.
Furthermore, the fabric rotation helps improve the interac-
tion between the fabric and water, thereby enhancing the
evaporation process. It also reduces the effect of unbal-
anced heat buildup within the system, improving heat re-
tention and reducing heat losses to the surrounding air
through conduction. Consequently, fabric rotation in-
creases the overall productivity of the system, improving
the overall efficiency of solar distillation.
Fig. 3. Cotton mesh connected to a 12V motor inside the improved solar still
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Відновлювана енергетика. № 1/2026 | Сонячна енергетика
Method of experimentation
The experimental setup of the solar stills for both systems
was designed to evaluate their efficiency. To optimize solar
light absorption, the stills were oriented southward, and sil-
icone rubber was used to seal the glass lids to ensure vapor
resistance. A constant water level was maintained in the
tanks, adjusted to approximately 1 cm using a regulated
piping system. During the experiment, measurements were
taken hourly from 8:00 to 18:00. A (K) type data logger was
used to measure temperatures at multiple locations, while
wind speed was measured hourly using an anemometer.
Ambient air temperature was also measured using a mer-
cury thermometer. Hourly solar radiation intensity was
measured using a TM heliometer, as shown in Fig. 4.
Fig. 4. A schematic diagram of the measuring devices
Uncertainty analysis
Uncertainty analysis is an essential step to ensure the relia-
bility of experimental results. It is necessary to verify the ac-
curacy of each measuring instrument used in the study be-
fore proceeding with the uncertainty analysis [18]. Table 1
shows the accuracy values and measurement ranges associ-
ated with each measuring instrument. The uncertainty anal-
ysis was then performed using the equations shown below.
Standarddeviation(S) = √
∑ (xi−x′)2n
i=1
n−1
(1)
Standarderror(S. E) =
S
√n
(2)
Error% =
S.E
X′
× 100 (3)
X′ =
∑ Xin
i=1
n
(4)
The measured value (Xi), the average of the measured val-
ues (X’), and the number of measurements (n) are the basic
inputs to the formula.
Table 1. Accuracy, measurement error and range for each device
Equipment Accuracy Measuring range Error range% Unit
Anemometer 85% 0-25 1.5 m /s
Data logger %98 −200-1370 1.9 0C
TM solar power meter 98% 0-2000 1.9 W /m2
Thermocouple %98 −100-200 1.9 0C
RESULTS AND DISCUSSIONS
Productivity rate at a speed of 1 rpm
At a fabric rotation speed of 1 rpm, the experiment demon-
strated a significant improvement in the efficiency of the
solar still compared to the CSS system. In this context, the
impact of several environmental factors on productivity
was analyzed, as shown in Fig. 5. The relationship between
solar radiation intensity and temperature during the exper-
iment period is shown. At 13:00, solar radiation peaked at
1010 W/m², while the temperature recorded 48.6°C. The
positive relationship between these two factors demon-
strates the effect of the heat generated by solar radiation
on the evaporation process inside the solar still, which con-
tributes to accelerating the process and increasing produc-
tivity.
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Відновлювана енергетика. № 1/2026 | Сонячна енергетика
Fig. 5. Relationship Between Solar Radiation Intensity and
Temperature at 1 rpm
Fig. 6 shows an analysis of the relationship between rela-
tive humidity and wind speed. The data indicates that hu-
midity was high in the morning hours and then gradually
decreased throughout the day, which contributed to im-
proving the evaporation process. Wind speed was low most
of the time, which reduced surface cooling and thus sup-
ported the evaporation process. These environmental fac-
tors significantly contributed to enhancing the efficiency of
the improved system.
Fig. 6. Relationship Between Relative Humidity and Wind
Speed at 1 rpm
Fig. 7 shows the relationship between the productivity of
the improved still and that of the conventional still. It
clearly indicates that the improved design achieved signifi-
cantly higher output, reaching 1670 ml/day compared to
1000 ml/day for the conventional system. This enhance-
ment in productivity can be attributed to improved heat
distribution within the still, facilitated by the movement of
the fabric. The fabric motion reduced heat loss and pro-
moted faster evaporation, thereby increasing overall distil-
late production.
Fig. 7. Productivity comparison of an improved solar still
versus a conventional model at a rotation speed of 1 rpm
It can be concluded that the combined effect of intense so-
lar radiation and high temperatures, along with low humid-
ity and limited wind speed, significantly improved the still's
throughput at 1 rpm, making the improved still more effi-
cient at water production compared to the conventional
system.
Productivity rate at a speed of 0.5 rpm
At a cloth rotation speed of 0.5 rpm, the experiment
demonstrated improved still productivity compared to the
CSS system. The effect of several environmental factors on
performance was analyzed. Fig. 8 shows the relationship
between solar radiation intensity and temperature. The so-
lar radiation intensity was 1002 W/m² at 13:00, a level suf-
ficient to enhance evaporation. At the same time, the tem-
perature reached 49°C, which helped accelerate the
evaporation process and improve productivity. The rela-
tionship between these factors indicates that the heat gen-
erated by solar radiation played a significant role in increas-
ing the evaporation rate inside the still.
Fig. 8. Relationship between solar radiation intensity and
temperature at 0.5 rpm
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Fig. 9 shows the relationship between relative humidity and
wind speed. In this case, the relative humidity was lower than
at other speeds, which helped effectively improve evapora-
tion. Furthermore, the wind speed was low most of the time,
reducing the cooling effect on the surface and thus helping
raise the temperature inside the still and increase evaporation.
Fig. 9. Relationship between relative humidity and wind
speed at (0.5 rpm)
Fig. 10 shows the relationship between productivity in the
improved still and productivity in the conventional still. The
data show that the productivity of the improved still was
1755 ml/day, a significant improvement over the 955
ml/day in the conventional system. This productivity in-
crease is due to improved fabric movement, which contrib-
utes to more even heat distribution within the system.
Fig. 10. Productivity of improved solar still vs. conventional
solar still at 0.5 rpm
Productivity rate at a speed of 0.2 rpm
At a cloth rotation speed of 0.2 rpm, the experiment showed
higher productivity compared to other speeds (0.5-1 rpm),
with a total production of 1840 ml/day, outperforming both
the 0.5 rpm speed, which produced 1755 ml/day, and the 1
rpm speed, which produced 1670 ml/day. The effect of sev-
eral environmental factors on the distiller's performance was
analyzed. The relationship between solar radiation intensity
and temperature is shown in Fig. 11. The solar radiation in-
tensity reached 1065 W/m² at 13:00, which helps accelerate
evaporation and increase productivity. The relationship be-
tween these factors indicates that solar radiation had a sig-
nificant effect on raising the water temperature and increas-
ing the evaporation rate inside the distiller.
Fig. 11. Relationship between solar radiation intensity and
temperature at 0.2 rpm
Fig. 12 shows the relationship between relative humidity
and wind speed. In this case, the relative humidity was low,
which helped improve evaporation effectively, while the
wind speed was at low levels most of the time, which
helped reduce surface cooling and increase evaporation.
These environmental factors played a significant role in in-
creasing the thermal efficiency of the solar still.
Fig. 12. Relationship between relative humidity and wind
speed at 0.2 rpm
Fig. 13 shows the relationship between the productivity of the
improved still and the productivity of the conventional still. At
0.2 rpm, productivity was the highest among the three speeds,
reaching 1840 ml/day, higher than the productivity achieved
at 0.5 rpm (1755 ml/day) and 1 rpm (1670 ml/day). This signif-
icant improvement in productivity is due to the effect of slow
fabric movement, which increased heat absorption and re-
duced heat loss in the system, resulting in continuous evapo-
ration throughout the day.
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Відновлювана енергетика. № 1/2026 | Сонячна енергетика
Fig. 13. Productivity of the improved solar still versus
a conventional solar still at 0.2 rpm
The effect of moving cloth rotation speed on heat distri-
bution and evaporation efficiency in solar still systems
Analyzing the temperatures of the moving fabric at differ-
ent rotation speeds as shown in Fig. 14 for the following
rpms: (0.2, 0.5, and 1), a clear effect on heat distribution is
evident. At 0.2 rpm, the temperature starts at 45.7°C and
reaches 84.1°C halfway through the cycle, then gradually
decreases to 54.9°C, reflecting the increased thermal en-
ergy and accelerated evaporation due to slower move-
ment. At 0.5 rpm, the temperature starts at 41.4°C and
reaches 77.7°C halfway through the cycle, then decreases
to 50.1°C, indicating accelerated evaporation but with
faster heat loss at the end. At 1 rpm, the temperature starts
at 41.4°C and reaches 70.3°C halfway through the cycle,
then decreases to 53.2°C. The rapid temperature decrease
reduces evaporation efficiency compared to slower speeds.
Fig. 14. Temperature distribution at different fabric rota-
tion speeds (0.2, 0.5, 1 rpm)
The productivity of SSSMC at speeds of 0.2, 0.5, and 1 rpm
Comparing the output of distillers at different fabric rota-
tion speeds (0.2, 0.5, and 1 rpm), significant results are ev-
ident in the effect of fabric movement on productivity, as
shown in Fig. 15. At 0.2 rpm, the highest output of 1840
ml/day was recorded. This is due to the even heat distribu-
tion that improves evaporation and increases solar energy
absorption, boosting productivity. At 0.5 rpm, the output
was 1755 ml/day, showing an improvement over the con-
ventional system. However, the heat is distributed une-
venly, resulting in a slight decrease in productivity com-
pared to the 0.2 rpm system. At 1 rpm, the output was the
lowest of the three speeds, at 1670 ml/day. Although the
fabric absorbs more solar energy, the rapid movement re-
sults in heat being lost before it can be utilized for evapo-
ration, reducing the system's efficiency.
Fig. 15. Productivity of cotton mesh fabric at different ro-
tation speeds (0.2, 0.5, 1 rpm)
The performance analysis of active and passive solar distil-
lation systems is primarily based on evaluating their ther-
mal efficiency. According to the referenced study, a distinc-
tive assessment method is employed to determine the
thermal efficiency of passive solar distillers [19].
ηss−th =
mew∗hfg
i(t)s×As
(5)
hfgis the average latent heat in (J/kg).
hfg = 103[2501.9 − 2.40706 × Tw + 1.192217 × 10−3 × Tbw
2 − 1.5863 × 10−5 × Tw
3 ] (6)
209
Відновлювана енергетика. № 1/2026 | Сонячна енергетика
mew =
hev(Tw−Tg)As
hfg
(7)
Fig. 16. Hourly efficiency of the improved still at speeds of
1, 0.5, and 0.2 rpm
Analysis of production cost
Besides the primary goal of increasing daily desalinated wa-
ter production using solar energy, it is also important to
consider production costs. In this context, Fatah et al. [20]
conducted an economic analysis to identify the main
factors affecting the annual cost of producing one liter of
desalinated water. These factors included: capital cost (CS),
depreciation fund factor (SFF), first annual cost (FAC), an-
nual scrap value (ASV), annual cost (AC), annual mainte-
nance cost (AMC), and the annual cost per liter of produc-
tion (YCPL). These factors were calculated according to
established economic methods. The details are in Ta-
bles 2–5, respectively.
CRF =
i(1+i)n
[i(1+i)n−1]
(8)
SFF =
i
[i(1+i)n−1]
(9)
FAC = SC × CRF (10)
According to Shehata et al. [21], the salvage value of desal-
ination using solar energy is equal to 0.2 of the capital cost
of manufacturing and installation. Based on this, ASV is cal-
culated as follows:
ASV = S × SFF (11)
The AMC constitutes fifteen percent of the initial annual
cost. According to the study by Kapil et al. [22], the annual
cost was determined according to the following equation:
AC = FAC + AMC − ASV (12)
Finally, YCPL is as follows:
YCPL =
AC
P
(13)
In this case, P represents the solar still system's annual
production.
Table 2. Manufacturing and installation capital cost of solar stills, $
Type of material Quality CSS ($) SSSBC ($)
Wooden board with a thickness of 1.8-cm 2 m2 30 30
Plexiglass cover with a thickness of 0.3-cm 1.2 m2 10 10
Silicone glue 2 pieces 3 3
Aluminum waterway 2 pieces 5 5
Aluminum basin 1 piece 15 15
Solar still base 1 piece 10 10
Thermal insulation glass wool 2 pieces 5 5
Heat-resistant black paint 2 pieces 4 4
Cotton cloth 1 m 5
Cotton fabric structure 20
Motor 12 volt 25
Mechanical water float 1 piece 1 1
The total cost 84 139
Table 3. Unit costs analysis for water produced, $
SSSMC CSS Standards
10 10 Solar still life expectancy, n
12 12 Interest rate per year, i
125 84 Capital cost (CS), $
0.177 0.1769 The factor for the recovery of capital (CRF)
0.057 0.0569 The factor for the sinking fund (SFF)
14.87 14.505 The first annual (yearly) cost (FAC), $
210
Відновлювана енергетика. № 1/2026 | Сонячна енергетика
16.8 16.4 The worth of salvage (S), $
3.36 0.933 The value of annual salvation (ASV), $
2.18 2.175 The cost of annual maintenance (AMC), $
13.68 15.748 Annual (yearly) cost (AC), $
670.6 474.5 Yearly yield from the solar still system
Table 4. Yearly cost per liter (YCPL), $
CSS SSSMC (1) SSSMC (0.5) SSSMC (0.2)
0.0349 0.778 0.739 0.705
Table 5: Experimental Setup Dimensions
Conclusions
This experimental study evaluated the thermal and eco-
nomic performance of a single-slope solar still integrated
with a rotating cotton mesh fabric under the climatic con-
ditions of Kirkuk (35.4686°N, 44.38933°E) during 1-3 August
2025. The SSSMC was compared with a CSS of identical ba-
sin area 1 m². The results demonstrated a substantial and
measurable improvement in freshwater productivity due to
the incorporation of the rotating fabric. The daily distillate
yield reached 1840 ml/day at 0.2 rpm, 1755 ml/day at 0.5
rpm, and 1670 ml/day at 1 rpm, compared with 955-1000
ml/day for the conventional still. At the optimum rotational
speed of 0.2 rpm, productivity increased by approximately
84–92% relative to the CSS, while even at 1 rpm the im-
provement remained within 67–75%. Thermal measure-
ments confirmed that lower rotational speed enhanced
heat retention and evaporation efficiency; the fabric tem-
perature peaked at 84.1°C at 0.2 rpm, compared with
77.7°C at 0.5 rpm and 70.3°C at 1 rpm, indicating that
slower movement allowed greater solar energy absorption
and reduced convective heat losses. Peak solar radiation
during testing ranged from 1002 to 1065 W/m², with ambi-
ent temperatures approaching 49°C, and low relative hu-
midity conditions further supported evaporation. Despite
identical environmental conditions, the rotating mesh con-
figuration consistently outperformed the conventional sys-
tem, confirming that the performance enhancement was
primarily attributable to design modification. Although the
capital cost increased from $84 for the CSS to $139 for the
modified system, the significant increase in annual water
yield reduced the effective cost per liter, with the lowest
yearly cost per liter corresponding to the 0.2 rpm configu-
ration. Finally, integrating a low-speed rotating cotton
mesh fabric markedly improves thermal efficiency, evapo-
ration stability, and freshwater productivity, making it a
technically simple and economically viable enhancement
for solar desalination systems operating in high solar radia-
tion regions.
Recommendations
Application in diverse environments: Conducting field stud-
ies in areas with different climates to evaluate the general-
izability of the system results.
Fabric rotation mechanism improvement: Studying im-
provements to fabric rotation speed to suit local conditions
to increase efficiency.
Improving thermal insulation: Working to improve the ther-
mal insulation properties of the system to reduce heat loss
and increase the efficiency of the distillation process.
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|
| id | veorgua-article-607 |
| institution | Vidnovluvana energetika |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-19T01:18:46Z |
| publishDate | 2026 |
| publisher | Institute of Renewable Energy National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | veorgua/72/70665033d44a2ee57e061da123bf8472.pdf |
| spelling | veorgua-article-6072026-07-18T06:32:24Z IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ СОНЯЧНОГО ДИСТИЛЯТОРА ЗА ДОПОМОГОЮ ОБЕРТОВОЇ БАВОВНЯНОЇ СІТЧАСТОЇ ТКАНИНИ: ПРИКЛАД МІСТА КІРКУК, ІРАК Sahip , Z. Akbara Naseer , T. Alwan Barhm , Mohamad Mohammed , Abuidam conventional solar still, thermodynamic analysis, solar radiation intensity, Energy economic analysis, optimization techniques. традиційний сонячний дистилятор; термодинамічний аналіз; інтенсивність сонячного випромінювання; енергетично-економічний аналіз; методи оптимізації. This research aims to improve the performance of solar distillation systems by incorporating a rotating cotton cloth into the distillation chamber. This contributes to enhancing the thermal efficiency of the system by improving heat distribution and accelerating the evaporation process. Experimental results showed that the highest water production was achieved at a rotation speed of 0.2 rpm, reaching 1840 ml/day, followed by a rotation speed of 0.5 rpm (1755 ml/day), and a rotation speed of 1 rpm (1670 ml/day). The study also demonstrated that environmental factors such as solar radiation intensity, temperature, humidity, and wind speed significantly affect system efficiency. The research concludes that the rotating cloth technology represents a promising solution for improving the efficiency of solar desalination systems, especially in areas with high solar radiation such as Kirkuk city, Iraq. Метою цього дослідження є підвищення ефективності систем сонячної дистиляції шляхом використання обертової бавовняної тканини в камері дистиляції. Це сприяє підвищенню теплової ефективності системи завдяки кращому розподілу тепла та прискоренню процесу випаровування. Виходячи з  результатів проведених експериментальних досліджень, найбільший обсяг виробництва води досягається при швидкості обертання 0,2 об/хв, що становить 1840 мл/добу. При швидкості 0,5 об/хв продуктивність становить 1755 мл/добу, тоді як при швидкості 1 об/хв — 1670 мл/добу. В ході дослідження також продемонстровано, що такі фактори навколишнього середовища, як інтенсивність сонячного випромінювання, температура, вологість та швидкість вітру, суттєво впливають на ефективність системи. Отримані результати свідчать про те, що технологія застосування обертової тканини є перспективним рішенням, що дозволяє підвищити ефективність роботи системи сонячного опріснення води, особливо в регіонах з високою інтенсивністю сонячного випромінювання, таких як місто Кіркук (Ірак). Institute of Renewable Energy National Academy of Sciences of Ukraine 2026-03-28 Article Article application/pdf https://ve.org.ua/index.php/journal/article/view/607 10.36296/1819-8058.2026.1(84).201-211 Vidnovluvana energetika ; No. 1(84) (2026): Scientific and applied Journal renewable energy ; 201-211 Возобновляемая энергетика; ##issue.no## 1(84) (2026): Scientific and applied Journal renewable energy ; 201-211 Відновлювана енергетика; № 1(84) (2026): Науково-прикладний журнал Відновлювана енергетика; 201-211 2664-8172 1819-8058 10.36296/1819-8058.2026.1(84) en https://ve.org.ua/index.php/journal/article/view/607/518 Copyright (c) 2026 Z. Akbara Sahip , T. Alwan Naseer , Mohamad Barhm , Abuidam Mohammed https://creativecommons.org/licenses/by-nc-nd/4.0 |
| spellingShingle | conventional solar still thermodynamic analysis solar radiation intensity Energy economic analysis optimization techniques. Sahip , Z. Akbara Naseer , T. Alwan Barhm , Mohamad Mohammed , Abuidam IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ |
| title | IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ |
| title_alt | ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ СОНЯЧНОГО ДИСТИЛЯТОРА ЗА ДОПОМОГОЮ ОБЕРТОВОЇ БАВОВНЯНОЇ СІТЧАСТОЇ ТКАНИНИ: ПРИКЛАД МІСТА КІРКУК, ІРАК |
| title_full | IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ |
| title_fullStr | IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ |
| title_full_unstemmed | IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ |
| title_short | IMPROVING SOLAR STILL EFFICIENCY USING A ROTATING COTTON MESH FABRIC: A CASE STUDY IN KIRKUK CITY, IRAQ |
| title_sort | improving solar still efficiency using a rotating cotton mesh fabric: a case study in kirkuk city, iraq |
| topic | conventional solar still thermodynamic analysis solar radiation intensity Energy economic analysis optimization techniques. |
| topic_facet | conventional solar still thermodynamic analysis solar radiation intensity Energy economic analysis optimization techniques. традиційний сонячний дистилятор термодинамічний аналіз інтенсивність сонячного випромінювання енергетично-економічний аналіз методи оптимізації. |
| url | https://ve.org.ua/index.php/journal/article/view/607 |
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