Water is one of the most basic resources on Earth. Solar desalination is one of the most optimal methods for solving the freshwater problem. The vertical solar still is a type of solar desalination system that occupies minimal space due to its geometric design. However, its efficiency is generally lower compared to other types of solar stills, and researchers are continually seeking methods to maximize its performance with minimal cost. In this study, a sectional evaporative cooling system, designed to match the still’s geometry, was implemented to improve the performance of the vertical solar still. A cotton wick was applied to the absorber surface, and the system was evaluated under the climatic conditions of Semnan, Iran. Key parameters measured included freshwater production, energy efficiency, exergy efficiency, recovery ratio, economic analysis, environmental analysis, radiative heat transfer coefficient, and convective heat transfer coefficient. The maximum freshwater production was achieved at flow rates of 100, 150, and 200 (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">${{\text{cm}}^{3}}\,{\text{min}}^{-1})$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mrow> <mtext>cm</mtext> </mrow> <mn>3</mn> </msup> <mspace width="0.166667em" /> <msup> <mrow> <mtext>min</mtext> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, 2771, 2532, and 2316 (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">${\text{mL}}{{\text{m}}^{2}\text{day}^{-1}}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>mL</mtext> <mrow> <msup> <mrow> <mtext>m</mtext> </mrow> <mn>2</mn> </msup> <msup> <mtext>day</mtext> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </mrow> </mrow> </math></EquationSource> </InlineEquation>), respectively. With the implementation of the cooling system, these values increased to 3469, 3168, and 2873 (<InlineEquation ID="IEq3"> <EquationSource Format="TEX">${\text{mL}}{{\text{m}}^{2}\text{day}^{-1}}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>mL</mtext> <mrow> <msup> <mrow> <mtext>m</mtext> </mrow> <mn>2</mn> </msup> <msup> <mtext>day</mtext> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </mrow> </mrow> </math></EquationSource> </InlineEquation>), respectively. The highest energy and exergy efficiencies were obtained at a flow rate of 100 <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$({{\text{cm}}^{3}}\,{\text{min}}^{-1})$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <msup> <mrow> <mtext>cm</mtext> </mrow> <mn>3</mn> </msup> <mspace width="0.166667em" /> <msup> <mrow> <mtext>min</mtext> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> with cooling, achieving 35.56% and 1.2%, respectively. The highest recovery ratio, 10.8%, was also recorded at 100 cm3 min−1 under cooling conditions. The most cost-effective production cost per liter of water was 0.058 <InlineEquation ID="IEq5"> <EquationSource Format="TEX">$\left({{\$}{\text{ m}}^{2}}{\text{L}}^{-1}\right)$</EquationSource> <EquationSource Format="MATHML"><math> <mfenced close=")" open="("> <mrow> <mi mathvariant="normal">$</mi> <msup> <mrow> <mspace width="0.333333em" /> <mtext>m</mtext> </mrow> <mn>2</mn> </msup> </mrow> <msup> <mrow> <mtext>L</mtext> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </mfenced> </math></EquationSource> </InlineEquation> in cooling mode.

Potentials of a sectional evaporative cooling unit for performance improvement of a vertical solar desalination system designed for hot and dry climate: experimental study and 4E analysis

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发表日期：

2026年4月28日

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Kamin Family,
Amir Mohammad Jadidi,
Saman Rashidi

摘要

Water is one of the most basic resources on Earth. Solar desalination is one of the most optimal methods for solving the freshwater problem. The vertical solar still is a type of solar desalination system that occupies minimal space due to its geometric design. However, its efficiency is generally lower compared to other types of solar stills, and researchers are continually seeking methods to maximize its performance with minimal cost. In this study, a sectional evaporative cooling system, designed to match the still’s geometry, was implemented to improve the performance of the vertical solar still. A cotton wick was applied to the absorber surface, and the system was evaluated under the climatic conditions of Semnan, Iran. Key parameters measured included freshwater production, energy efficiency, exergy efficiency, recovery ratio, economic analysis, environmental analysis, radiative heat transfer coefficient, and convective heat transfer coefficient. The maximum freshwater production was achieved at flow rates of 100, 150, and 200 ( ${{\text{cm}}^{3}}\,{\text{min}}^{-1})$ ${cm}^{3} {min}^{- 1})$ , 2771, 2532, and 2316 ( ${\text{mL}}{{\text{m}}^{2}\text{day}^{-1}}$ $mL m^{2} {day}^{- 1}$ ), respectively. With the implementation of the cooling system, these values increased to 3469, 3168, and 2873 ( ${\text{mL}}{{\text{m}}^{2}\text{day}^{-1}}$ $mL m^{2} {day}^{- 1}$ ), respectively. The highest energy and exergy efficiencies were obtained at a flow rate of 100 $({{\text{cm}}^{3}}\,{\text{min}}^{-1})$ $({cm}^{3} {min}^{- 1})$ with cooling, achieving 35.56% and 1.2%, respectively. The highest recovery ratio, 10.8%, was also recorded at 100 cm³ min⁻¹ under cooling conditions. The most cost-effective production cost per liter of water was 0.058 $\left({{\$}{\text{ m}}^{2}}{\text{L}}^{-1}\right)$ $($ m^{2}, L^{- 1})$ in cooling mode.