Solar Distillation Research Articles

A numerical and experimental investigation of the impact of wire mesh on vertical solar still

One of the most pressing challenges facing human society is the lack of freshwater, Traditional desalination is energy-intensive, posing challenges in energy-scarce regions, especially in less developed nations. Solar stills are a promising alternative but face efficiency limits due to design constraints. Previous studies have employed techniques like integrating reflectors and combining them with other solar still to enhance the evaporation section, but these have resulted in bulky and space-consuming vertical solar still (VSS) designs. This research proposes and evaluates a new vertical solar still (VSS) design to boost freshwater production by increasing evaporation rates. The study uses numerical simulations with Fluent 18.2 and indoor experiments to evaluate the new VSS design. The proposed VSS design introduces a wire mesh plate as an expanded surface behind the wick, improving heat and mass transfer processes at three distinct radiation rates (in two designs: fully mesh plate and partially mesh plate). The study shows that the fully mesh VSS design can boost efficiency by 10.72%, producing 1384 of freshwater, while the partially mesh VSS design can increase efficiency by 6.2%, yielding 1328 . Wire mesh technology effectively enhances evaporation rates, addressing desalination energy challenges.

A new approach on the management of landfill leachate reverse osmosis concentrate: Solar distillation coupled with struvite recovery and biological treatment

The management of reverse osmosis (RO) concentrate remains a challenging task for operators of Landfill Leachates Treatment Plants. In this article we suggest an integrated treatment scheme for RO concentrate that combines solar distillation, struvite precipitation to reduce ammonia content of the distillate and biological treatment of the supernatant either with mixed cultures of bacteria or with microalgae. Experiments in a pilot-scale solar still, equipped with underfloor heating system, showed that the production rate of the distillate ranged up to 3.17 L/d m2. The distillate was characterized by elevated average concentrations of ammonium nitrogen; 2028 mg/L and 1358 mg/L in the two experiments conducted, respectively. A decreasing trend on concentrations of NH4+-N was noticed during these experiments, while the opposite was observed for COD. Struvite recovery experiments showed that the optimum Mg:NH4:PO3 ratio was that of 2:1:5.8. Under these conditions, the NH4+-N removal reached 88%. Further treatment of the process supernatant into a 4-L hybrid sequencing batch reactor with biocarriers and activated sludge achieved NH4+-N removal higher than 98% in Phases C and D, where 450 and 600 mL of supernatant were added, respectively. Similar removal was also observed in a 2-L bioreactor with microalgae Chlorella sorokiniana when 150 mL of struvite supernatant were added (Phase B) while further increase of the amount of added supernatant to 200 mL resulted to a sharp stop of NH4+-N consumption (Phase C). Calculations for a landfill serving 20,000 inhabitants and a daily RO concentrate production of 6 m3/d showed that the required area for the construction of the solar still was 1893 m2 and the volumes of the hybrid and the microalgae reactor were 54 m3 and 60 m3, respectively. The recovered solid material of struvite process, after characterization for heavy metals and organic micropollutants, could be reused to the fertilizers industry.

ZnO/nZVI nanoparticle-enhanced double-slope U-shaped solar distillation: A thermodynamic investigation of cephalexin adsorption

The increasing need for sustainable methods to remove pharmaceutical contaminants like cephalexin and improve water desalination is critical. This study explores ZnO/nZVI nanoparticles synthesized with Jackfruit peel extracts as eco-friendly, cost-effective adsorbents, enhancing water purification in solar desalination systems. This work used a matte black paint coating within a double slope U-shaped solar distiller (DSUD) in a discontinuous experimental setting to examine potential improvements in solar distillation performance. Activated carbon (AC) and bioactive powdered nanoparticles of ZnO/nZVI (nano zerovalent iron), produced from jackfruit peel extracts (JP) were combined in a synergistic way. The effectiveness of cephalexin removal was assessed taking into account the JPAC solution parameters, reaction duration, ZnO/nZVI concentrations in the nanocomposite dosage, and initial nanocomposite concentration. The best conditions for cephalexin adsorption were found to be pH 5 and reaction time of 50 min, which resulted in high absorption efficiencies of 94.74% (nZVI) and 97.53% (ZnO) at room temperature with a JPAC dose of 2.50 g L⁻1. The efficiency of the eco-friendly adsorbent in getting rid of cephalexin was calculated using “pseudo-second-order kinetics” for nanocomposites, which is consistent with the “Langmuir” isothermal absorption process. The nanocomposites as absorbent materials in solar thermal desalination processes, efficient heat transmission and energy storage have been established. JPAC and the addition of steel balls (S) with a silver hue to the DSUD improved the internal heat transfer mechanisms. Thermodynamic of Gibbs free energy and the Laplacian method (TGL), two thermodynamic concepts, were used to extensively study the temperature dynamics of the DSUD with SJPAC components. For ZnO/JPAC, an exceptional distillate production rate was noted from 8:00 to 18:00, with a noteworthy 4.932 L/m2 output in winter and 5.833 L/m2 per day in summer. Using silver balls, ZnO/JPAC generated significant yields over a 24-h period: 8.957 L/m2 in summer and 7.253 L/m2 in winter, with an ideal energy efficiency of 51.05%. The unique advancements in TGL procedures and their environmental consequences are presented in this paper. The field of thermal energy transduction will advance if silver balls are used in DSUD for the synthesis of JPAC, ZnO/JPAC, and nZVI/JPAC, as supported by the theoretical insights presented here.

Enhancing the productivity of pyramid solar still utilizing repurposed finishing pads as cost-effective porous material

The primary objective of the current research is to augment the potable water yield of the solar still (SS). This objective is achieved by integrating a used brushed refinishing pad (BRP) as a porous material (PM) in the absorber basin. This integration maximizes the wet surface area due to the pad's porous nature, thereby enhancing photothermal absorption, which is the process where a material absorbs light and converts it into heat. An experimental investigation was conducted to analyze the effect of porous materials in a rectangular pyramid solar still (RPSS) regarding potable water yield and feasibility. The results were compared with those of the conventional solar still (CSS), revealing a noteworthy enhancement in the production of potable water with RPSS-PM, showing a 47.7 % increase on day one and a 48.1 % increase on the second day with a mere 10 % rise in basin water temperatures. The energy efficiency of RPSS-PM improved significantly by about 9 % on both days compared to CSS. From an economic perspective, this system's payback period (PBP) was 5.2 months, compared to 6.1 months for the CSS. Furthermore, the cost per liter (CPL) of potable water produced by the RPSS-PM was 16.6 % lower than that of the CSS. This innovative approach holds great potential for effectively addressing challenges related to water scarcity.

Mathematical Study of a Double-Slope Passive Solar Distiller with Water Heater Condenser

In this article, the inevitable condensation losses from the back-side glass cover of a passive single-basin double-slope distiller (PSDD) were recovered in heating water inside a glass solar water heater (SWH) to produce hot water as an auxiliary product of the distiller. The transient thermal performance of the PSDD-SWH was mathematically modeled and compared to a conventional PSDD in actual weather circumstances. Compared to a conventional PSDD, the results revealed that the thermal efficiency of the PSDD-SWH increased by 18% to 83% during the day. In addition, increasing the water mass inside the water heater from 3kg to 18kg increased the thermal efficiency of the PSDD-SWH by about 50% despite decreasing the total distillate by less than 1%. Moreover, the thermal performance of the PSDD-SWH, in terms of distillate production, hot water temperature, and thermal efficiency boomed in hot climates with high solar irradiation and high ambient temperatures. Furthermore, insulating the glass covers of the PSDD-SWH during off-sun hours significantly enhanced the thermal performance of the PSDD-SWH.

Improving the efficiency and productivity of solar distillation by creative design and heater and baffle integration

The hemispherical solar still (HSS) is a simple device used to desalinate saline water, but it has low productivity. This study aimed to enhance the evaporation rate of a hemispherical solar still (HSS) through several design modifications. The main innovation involved integrating an upper absorber with hanging wick cords, creating a modified system called the cords wick hemispherical solar still (CWHSS). Additionally, electric heaters powered by photovoltaic panels were incorporated to further boost performance, along with the introduction of squared baffles inside the CWHSS. Experimental results showed that the highest efficiency was achieved with the CWHSS incorporating baffles, heaters, and a condenser (CWHSS-B), leading to a 258% increase in distillate output and a 66.5% thermal efficiency. Under optimal conditions, the distillation rates were 4000 mL/m²/day for the HSS and 14,300 mL/m²/day for the CWHSS-B with heaters. Furthermore, the cost of water treatment was calculated at $0.022 per liter for the HSS and $0.016 per liter for the CWHSS-B, indicating significant cost benefits with the modified design.

Experimental Study on the Effects of Beeswax as Absorber for Solar Still

An experimental study on the effects of beeswax incorporated in the construction of the absorber for a solar still was conducted. As part of the study, two solar stills of the same geometry were constructed with the same water depth and volume. The one without a phase change material (PCM) was used as the control still, while the other with beeswax as a phase change material laid at the bottom of its basin to serve as an absorber was used as the experimental still. The experiments were conducted in the thermodynamic laboratory of JS Tarka University, Makurdi, Nigeria, between 10.00 am and 5.00 pm for two weeks. 16 litres of water were used for each still, corresponding to 100 mm depth. The stills were kept side by side and exposed to sunshine from 10.00 am to 5.00 pm for three days. Temperatures of the water at inlet and in the still were measured. HT-9815 digital thermocouple was used to determine the temperature of water in the basin and that of the inner glass cover. SM206 solar power meter was used to measure the amount of solar energy incident on the still’s collector. The results showed that the still with beeswax as phase change material (experimental still) has an improved thermal efficiency enhancement of 109.30% as compared to the still without a phase change material with a thermal efficiency enhancement of 86.1%. This implies that beeswax is a good phase change material for solar stills, and the use of beeswax should be encouraged as it is non-toxic and organic.

Integrated solar dryer and distillation system with PCM and injection, powered by PVT panels and solar concentrator

This research introduces a novel hybrid system integrating solar drying, solar distillation, and photovoltaic thermal panels, aimed at drying agricultural products, producing clean drinking water, and conserving energy. The system enhances the drying air temperature using thermal energy storage materials and a solar dish concentrator connected to a hot water storage tank, ensuring continuous operation even after sunset. The solar distiller, equipped with energy storage materials and an air injection system, is integrated with an external condenser to condense water vapor before expulsion, thereby increasing freshwater productivity. The results revealed that the developed system achieved an accumulative freshwater productivity of 87.1 L per day. The rates of water removal from dried potato slices ranged from 0.18 to 0.91 kg/h between 8:00 am and 10:00 pm. Additionally, the system achieved a gain output ratio of 1.38, indicating a significant improvement in energy efficiency. This innovative system offers practical solutions to address energy and freshwater scarcity, especially in remote regions of the Middle East and North Africa (MENA) region, which are characterized by high solar irradiance. The implementation of such hybrid systems could contribute to sustainable development by reducing reliance on conventional energy sources and mitigating environmental pollution.

Experiments’ feasibility study of solar stills in Indonesia, using evaporator covers and cornerless solar collectors

Desalination is a pivotal method for purifying water, offering a reliable means to obtain clean, potable water. Its operational simplicity and utilization of solar energy render desalination a promising technology. In desalination, condensation is the final stage for collecting purified water. However, the persistent challenge of high evaporator glass temperatures significantly impacts the nucleation rate and subsequent condensate release. This research aims to enhance the efficiency of the desalination system by focusing on increasing the rate of condensate water collection. The methodology involves a seven-day direct testing period using a single slope model desalination device featuring dimensions of 1 m2 and an evaporator glass tilt angle of 35°. Solar energy is the primary energy source, absorbed by a collector comprising 3/4-inch diameter copper pipes (14 pipes, 1 m in length) designed without slope. The glass cover is insulated with Styrofoam covered by aluminum foil to mitigate heat ingress from the sun, thereby reducing the temperature of the inner glass surface and accelerating nucleation rates. The maximum water temperature in the evaporator reached 68.7 °C, with the system absorbing energy at a rate ranging from 1048.40 W/m2 to 289.19 W/m2. The energy efficiency of the desalination system was measured at 39.82 %. The highest freshwater production during testing reached 2.33 L/day, with a daily average of 1.52 L/day. Overall, the solar test results still have the potential to be utilized and continue to be developed due to low-cost materials that can overcome the clean water crisis, especially in remote areas.

Enhanced solar desalination with photothermal hydrophobic carbon nanotube-infused PVDF membranes in air-gap membrane distillation

This work aims to increase the efficiency of the solar powered-air gap membrane distillation (SP-AGMD) process; a desalination method driven by solar energy, providing an eco-friendly and sustainable approach to addressing global water shortages. The innovation lies in integrating photothermal hydrophobic multiwalled carbon nanotubes (h-MWCNTs), in varying weight percentages from 5 % to 60 %, into polyvinylidene fluoride (PVDF) membranes using the phase inversion membrane fabrication technique. The h-MWCNTs were synthesized through oxidation and functionalization with oleylamine (OL) to improve their photothermal properties. Their successful integration was confirmed via scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The h-MWCNTs-based SP-AGMD membranes were further evaluated for wettability, liquid entry pressure (LEP), surface temperature, and solar absorbance, demonstrating significant solar light absorption and localized surface heating. This generated the necessary driving force for the AGMD process. Performance metrics such as vapor flux, salt rejection, specific thermal energy consumption, photothermal efficiency, and temperature polarization (TP) coefficient were significantly improved, especially with a 20 % h-MWCNTs addition, which tripled the solar-energy-driven flux and increased photothermal efficiency by 326 % under standard solar conditions, compared to unmodified membranes. All h-MWCNTs-based SP-AGMD membranes achieved over 99 % salt rejection. Lastly, the membranes were tested with real seawater to confirm their applicability for desalination. This photothermal approach offers a scalable, sustainable solution for water purification, making a significant advancement in membrane distillation technology.

Effect of charcoal balls on distillation productivity in hemispherical solar stills: Experimental investigation and performance analysis

This study investigates the enhanced performance of hemispherical solar stills by integrating charcoal balls. The method showcases improved efficiency by augmenting heat transfer mechanisms and enhancing solar radiation absorption. Reducing the surface tension of basin water is a solution to increase its heating, enhancing the softwater yield of solar stills. The novelty of the research lies in the innovative integration of charcoal balls to improve the performance of hemispherical solar stills. This method presents a unique approach to enhancing heat transfer and evaporation dynamics, potentially revolutionizing the efficiency of solar desalination systems. Therefore, the impact of charcoal balls at a diameter of 1 cm on the performance of distillation productivity was studied. A hemispherical solar still containing charcoal balls (HSS-CB) was compared with a simple hemispherical solar still (SHSS) in the same conditions. Experiments were conducted at El-Oued-Algeria in June 2024. The method employed in this research offers distinct advantages, primarily in its ability to enhance solar still efficiency by incorporating charcoal balls. These advantages stem from the increased surface area for heat transfer, improved solar radiation absorption, and potential enhancement of evaporation and condensation processes. Cumulative return results for SHSS and HSS-CB are 4.80 and 6.20 L/m2/day, respectively. The rate of improvement in the cumulative return was 29.16 % for SHSS using the quantity of coal powder. It is recommended that charcoal balls be used to boost solar stills productivity.

Experimental investigation of distilled water production performance of conventional solar stills using CaCl2·6H2O phase change material reinforced with SrCl2·6H2O and graphene-based nanoparticles

This study aims to enhance the performance of conventional single-slope basin-type solar stills by integrating phase change materials (PCMs) and nanoparticles. Calcium chloride hexahydrate, known for its high heat storage capacity, was selected as the primary PCM. Strontium chloride hexahydrate was added as a nucleating agent to address the supercooling tendency. Additionally, graphene oxide (GO) and graphene nanoplatelets (GNP), which have not been previously used in solar stills or compared for their performance, were incorporated into the PCM to utilize their photothermal properties and enhance solar energy absorption. The integration of GO and GNP with the PCM-nucleating agent combination resulted in daily total distilled water productions of 5424ml/m2 and 5032 ml/m2, respectively. The integration of GO with the PCM-nucleating agent combination provided the most significant improvement in efficiency, with a 54.44 % increase compared to the standard still, a 15.4 % increase compared to the still using only the nucleating agent, and an 8 % increase compared to the still incorporating GNP.

Improving the solar ethanol distillation system by combining the heat pipe and parabolic trough collector

This research examines the advantages of utilizing heat pipe technology with parabolic trough collectors in solar ethanol distillation systems. The goal of this work is to optimize the ethanol yield and concentration generated from the distillation of the ethanol–water mixtures from various types of feedstock. Laboratory experiments were conducted to analyze the effect of charged concentrations (2 % to 10 % v/v) and the properties of feedstock (pineapple, sticky rice, and molasses) on the distillation. The results indicate the feedstock types and charged concentration significantly affected the rate of output and ethanol yield. The amount and concentration of distilled ethanol from molasses (385 ml, 70 % v/v) was higher than that of sticky rice (375 ml, 68 % v/v) but highest from pineapple (395 ml, 72 % v/v). Even though pineapple resulted in the highest overall distillated ethanol, pineapple and sticky rice are costly feedstock, as well as increasing complexity in the ethanol production process, which could result in a reduction of value added investments. Implementing renewable solar energy yield ethanol for reduced operating cost or better benefit overall production to underpin a sustainability aspect of agriculture compared to standard conventional distillation. This research contribution to the solar ethanol distilling process, production of biofuels, and interest in renewable fuel sources.

Exergo and enviro-economic analysis of thermal energy storage assisted finned solar still

The current investigation focuses on improving the performance of a single slope solar still integrated with Phase Change Material as energy storage media. The problem of low thermal conductivity of PCM which hinders the energy storage capability has been addressed by incorporating fins with different profiles into the energy storage unit. Initially, an experimental investigation was conducted and analyzed to assess the effective performance of a Conventional Single Slope Solar Still (CSS) using various water depth levels: 1–4 cm. The optimal basin water depth for testing solar still with energy storage material along with fins was identified as 2 cm. Subsequently, the CSS was subjected to performance enhancement investigation under three different conditions: Case 1 – Solar Still (SS) with PCM storage unit, Case 2 – SS with fins at the PCM storage unit, and Case 3 – SS with fins at the storage unit and a parallel plate attached to the other end of the fins. The experimental results demonstrated the production of fresh water and efficiency improvements are as follows 26.95%, 55.86%, 69.14% and 24.34%, 52.83%, 68.83% for cases I, II, and III, respectively. Further, it was observed that Case III exhibited a lower cost of water production and a shorter payback period compared to CSS. The enviro-economic analysis revealed that the net CO2 emissions (NCEM) and Carbon Credits Earned (CCE) for Case III were 15.60 tons and 312.07 USD respectively against 9.22 tons and 184.31 USD for CSS.

Improvement of low-cost solar-powered desalination technologies in low-light intensity

Enhancing the efficiency of low-cost solar-powered desalination technologies, such as solar stills (SS), is essential for ensuring continuous access to freshwater in remote, water-stressed areas, particularly during cloudy or rainy days when the performance of conventional SS systems is compromised. This study introduces an innovative stepped solar still design, optimized for ease of operation, maintenance, environmental compatibility, and improved efficiency, especially under low-light conditions. The impact of the inlet mass flow rate on the desalination process was investigated to enhance distilled water production. Light absorption and step hot spot temperatures were further improved by incorporating natural and cost-effective absorbers, such as carbon, and an innovative soil-carbon combination. The synergy of this soil-carbon combination, enhancing light absorption, heat transfer, and storage through increased surface contact during radiation exposure and its distribution during shutdown, led to a 12.8% and 3% increase in distilled water production over the 4-hour test duration, compared to the baseline and carbon-only tests, respectively. This innovative design, combined with the use of a soil and carbon mixture, significantly improves the performance of solar distillation systems. These findings contribute to the development of sustainable, low-cost, and energy-efficient solutions for freshwater provision in remote areas, addressing both water scarcity and energy conservation challenges.

Experimental comparison investigation on the performance analysis of desert crystal sand roses and sand grain as natural effective heat storage materials in conical solar distillers: 4E and sustainability analyses

Conical solar distillers represent one of the most important technologies for producing low-cost freshwater in remote areas. However, its drawback is its limited freshwater production due to heat loss, so the present study aims to use natural effective heat energy storage materials to reduce heat loss, improve productivity, and avoid the higher cost of producing freshwater. To achieve this goal, comparison investigations on the performance analysis of Desert Crystal Sand Roses and Sand Grain as natural effective heat storage materials in conical solar distillers to improve freshwater productivity and at the same time avoid the high cost of producing freshwater. To achieve this goal experimentally, three identical conical solar distillers were built and tested in El Oued, Algeria. The first is the classical conical solar distiller (CCSD). The second is the conical solar distiller with the Natural Desert Crystal Sand Roses (CSD-SR). The third is a conical solar distiller with the Natural Desert Sand Grain (CSD-SG). The experimental results demonstrated that incorporating the Desert Crystal Sand Roses as natural storage materials in the distiller basin represents an innovative design that is characterized by serving as corrugated surfaces to enhance the absorbed rates of solar rays and interface surface area with the basin water, in addition to representing effective heat energy storage materials. Where using the Desert Crystal Sand Roses (CSD-SR) increases the cumulative productivity to 9.29 L/m2 per day with an improvement of 95.58 % compared to CCSD. Also, the use of Desert Crystal Sand Roses (CSD-SR) improved the energy efficiency, exergy efficiency, and sustainability index by 94.45, 227.45, and 2.9 % compared to CCSD. Also, the exergo-economic analysis indicated that the annual energy and exergy outlets were 94.48 and 227.42 %, respectively. Additionally, the cost per liter of produced freshwater from CSD-SR was reduced by 48.61 % compared to CCSD.

Ultra-high freshwater production in multistage solar membrane distillation via waste heat injection to condenser

Passive solar membrane distillation (MD) is an emerging technology to alleviate water scarcity. Recently, its performance has been enhanced by multistage design, though the gains are marginal due to constrained temperature and vapor pressure gradients across the device. This makes condenser cooling enhancement a questionable choice. We argue that condenser heating could suppress the marginal effect of multistage solar MD by unlocking the moisture transport limit in all distillation stages. Here, we propose a stage temperature boosting (STB) concept that directs low-temperature heat to the condensers in the last stages, enhancing moisture transport across all stages. Through STB in the last two stages with a heat flux of 250 W m−2, a stage-averaged distillation flux of 1.13 L m−2 h−1 S−1 was demonstrated using an 8-stage MD device under one-sun illumination. This represents an 88% enhancement over the state-of-the-art 10-stage solar MD devices. More notably, our analysis indicates that 16-stage STB-MD devices driven by solar energy and waste heat can effectively compete with existing photovoltaic reverse osmosis (PV-RO) systems, potentially elevating freshwater production with low-temperature heat sources.

Effect of a black paint coated double layer cellulose sponge as an absorber in a solar interfacial distillation: an experimental investigation

ABSTRACT In the recent past, direct solar energy-based distillation for the production of freshwater has been the subject of extensive research. Nevertheless, the outdoor experimental study did not thoroughly investigate the incorporation of the interfacial absorber concept in conventional solar distillation. Therefore, the impact of a simple black paint spray coated double-layer cellulose sponge on the freshwater yield of a solar distillation system is examined in this work. The modified top layer of the cellulose sponge exhibited an increase in the average absorbance of solar radiation from 27.59% to 86.88% in the wavelength range of 200–2400 nm. The maximum freshwater yield of the black paint-coated cellulose sponge-based floatable interfacial absorber (Unit II) was found to be 3.85 L/m2/day, which was 29.27% higher than that of the conventional solar distillation unit (Unit I) upon 4 days of experimental investigation. Comparably, Unit-II outperformed Unit I with an overall evaporation efficiency of 46.08%, which was 10.22% higher than Unit I. Furthermore, Unit II attained an exergy efficiency of 64.24%, surpassing Unit I by 28.5%. Therefore, in order to address the water shortage in rural areas of society, this work would assist researchers in designing and developing an effective interfacial absorber.

Development and Performance Evaluation of an Economical Solar Still for Water Purification

Aim: The study aims to address the global challenge of clean water scarcity by exploring a cost-effective and efficient solar still for purifying various types of contaminated water using solar energy. Methodology: An experimental investigation was conducted using a solar still designed with acrylic sheets, an inner mirrored surface, and aluminum fins. The study evaluated the solar still's performance in purifying seawater, brackish water, and polluted water, comparing input and output water quality. The experiments were carried out with and without aluminum fins, using a solar still with an area of 0.25 m². Results: The solar still successfully reduced the total dissolved solids (TDS), salinity, and pH of the input water. For seawater with an initial TDS of 14,700 PPM, salinity of 18.13 PSU, and pH of 9.15, the output values were 15 PPM TDS, 0.01 PSU salinity, and a pH of 7.4. The highest water volumes were achieved with aluminum fins: 410 ml for seawater, 380 ml for brackish water, and 380 ml for polluted water, compared to 170 ml without fins. The maximum water yield of 1.64 l/m2 was achieved for sea water using this solar still. Conclusion: The study demonstrates that the solar still, particularly when equipped with aluminum fins, effectively transforms high-TDS, high-salinity, and high-pH water into clean, potable water. The findings suggest that solar distillation is a viable solution for producing safe drinking water from contaminated sources.

The efficiency of solar stills with copper-coated sponge cubes for water desalination: A comparative study

Water scarcity within the world may be an enormous threat to living beings. Potable water can be produced by renewable energy using solar desalination. In the quest for efficient water desalination methods, researchers have turned to solar stills as a promising solution. One approach to enhancing the productivity of solar stills is the utilization of copper-coated sponge cubes. These cubes, when integrated into the still, provide extended heating periods, leading to higher temperature differences. This, in turn, improves freshwater production by improving the performance of the modified still. In this work, three basin-type solar stills of each 0.5 m2 area have been studied experimentally in the location of Coimbatore, Tamil Nadu. Comparative studies were done between the solar still modified with sponge materials and the modified solar still with sponges coated with copper powder. In these experimental studies, the various performance characteristics related to solar still efficiency have been examined. The sponges were placed inside the water of the basin. The commercially available copper powder was prepared like a paste and coated in the sponges, and it was increased in size to 0.005 m on all sides. The sponges pasted with copper powder reduce the energy losses from the still due to its high thermal conductivity and the evaporation rate also increased by the capillary action of the sponge. High heat transfer to water also occurred due to the addition of copper powder. From the comparative studies, the solar still with sponge materials coated with copper powder gives a higher yield. The proposed solar still with modifications improves efficiency. The solar still without modification gives a yield of 1.3 kg/day, the modified still with sponges gives an output of 1.5 kg/day and the modified still with copper-coated sponges gives an output of 2.35 kg/day. The copper-coated sponge cubes placed still produced an efficiency of 60.07%.