Solar Distillation Research Articles

Identifying enhancement of double slope solar still performance by adding water cooling to walls

The object of this research is a double-slope solar still with the addition of water cooling on the wall (DSSS.WCW). The issue with solar stills is that the temperature of the cover glass is quite high, which consequently reduces the rate of evaporation. Methods to reduce the cover glass temperature involve water cooling, by flowing water and spraying it onto the cover glass. Both of these methods have been shown to reduce the temperature of the cover glass, but they still require additional energy and can decrease the solar radiation energy received by the absorber plate. This research proposes using a water cooling method on the wall that does not require additional energy and can prevent a reduction in the solar radiation energy received by the absorber plate. Experimental and theoretical research was conducted to study the effect of using DSSS.WCW. The results showed a 13.48 % reduction in the cover glass temperature, consequently increasing the temperature difference between the fins and the cover glass by 9.82 °C. The increase in temperature difference resulted in a 13.82 % increase in freshwater productivity theoretically by 2.80 kg/hour and a 13.10 % increase experimentally for the DSSS.WCW by 2.58 kg/hour. In addition, there was a theoretical increase in energy efficiency of 22.29 % and an experimental increase of 22.82 %, along with an increase in exergy efficiency of 15.71 %. The implementation of water cooling on the wall has been shown to enhance the efficiency of the double-slope solar still. In addition, the water cooling method on the wall does not reduce the solar radiation energy that can be received by the absorber plate and does not require additional energy. The results of this research can be applied in remote islands in Indonesia, particularly during the dry season

Brackish Water Phytodesalination by the Euhalophyte Sesuvium portulacastrum

In the Middle East and North Africa as well as in numerous countries in South America and Southeast Asia, water scarcity is a real concern. Therefore, water desalination has become a key solution and an important source of freshwater production. Solar stills are used for water desalination but they require low depth of sea or brackish water and sufficient solar radiation to evaporate water. In this investigation, a phytodesalinator is presented for the first time. The halophyte used in this work is Sesuvium portulacastrum L., a heat-tolerant euhalophyte. The presented phytodesalinator can replace basic solar stills during cold seasons if there is sufficient sunlight to ensure the transpiration process in the plant. The euhalophyte S. portulacastrum was tested for its ability to desalinate reject brine as grown for two subsequent phytodesalination cycles. Several factors were found to affect the productivity of the phytodesalinator, in particular, solar radiation, phytodesalination duration, and plant density. Nevertheless, it exhibited an average productivity of 2.44 kg/m2/d and showed several advantages in comparison with basic solar stills.

Experimental and computational modeling analysis of double slope solar still with a trapezoidal channel for preheating

In specific locations in India, water scarcity is an important issue, therefore several efforts are made to produce treated water so that rural and urban areas have access to safe and sustainable drinking water. The solar still method is the most affordable water purification option available in these hot areas. This research aims to enhance the performance of passive double-slope solar stills by analyzing the effects of preheated water on evaporation and yield rates. A new method was adopted to maintain the lowest water depth in the basin of a solar still by using a channel attachment to move the feed water. Additionally, the study investigates the impact of a trapezoidal channel attachment within the solar still, a first-time innovation, on its efficiency and yield rate. Computational fluid dynamics and experimental data collected on February 10, 2024, in Kattankulathur was analyzed to assess temperature variations and yield rates. A three-dimensional full-scale simulation was carried out using Ansys Fluent with a two-phase (evaporation and condensation) model, where the flow in the channels of the rate varied from 0.87 × 10-4 to 5.21 × 10-4 Ls−1 and the highest yield is achieved at flow rate of 1.74 × 10-4 Ls−1. The accuracy of the simulation technique was evaluated by comparing it to experimental data, and found a good match. The results demonstrated that solar still with trapezoidal channels significantly increased the overall yield rate. Optimal performance was achieved under specific environmental conditions, with a cumulative yield of 2.45 Lm−2 at a basin water depth of 10 mm, marking a 37.64 % increase over the conventional solar still. Economic analysis indicated a reduction in the payback period to 299 days, affirming the system’s cost-effectiveness. The trapezoidal channel design is limited to a cross-section of 10 mm2, and positioned at a 17° angle on the middle sidewall to minimize the shadow formation on the basin of still and maintain high yield and evaporation–condensation rates. The novelty of this work is to integrate trapezoidal channels on the double slope solar still and to optimize its design and flow rate to maximize the overall production.

Polymer‐based supporting materials and polymer‐encapsulated phase change materials for thermal energy storage: A review on the recent advances of materials, synthesis, and characterization techniques

AbstractPhase change materials (PCMs) can be classified as smart materials having its applications in varied fields like domestic and commercial refrigerators, solar absorption chillers, air conditioning, free and radiative cooling, solar air heaters, solar stills, solar absorption cooling, electric and electronic devices for cooling purposes and in textiles. Here, in this review, the various polymer‐based and encapsulated PCMs used for fulfilling the above applications are discussed along with their varied synthesis/fabrication methods. Furthermore, chemical characterization is discussed by FTIR for understanding the chemical structure along with functional groups present in the materials. The thermogravimetric analysis (TGA) is also critically discussed for understanding the thermal stability of the Polymer PCM or the phase change composites and the latent heat of PCM melting was also explored by differential scanning calorimetry (DSC) for various PCM which gives insight into the thermal energy storage capability and property. The inbuilt surface structure of the polymer PCM was also tried to be investigated by scanning electron microscopy (SEM) which when understood gives a clear picture about the structure–property relationship.Highlights Polymeric supporting materials and polymer encapsulation on PCM were reviewed. The materials used and the synthesis of polymeric PCM were studied in depth. Chemical characterization was reviewed for chemical structure. Thermal stability checks by TGA and latent heat prediction was done by DSC. Morphology was reviewed using SEM for the structure–property relationship.

Enhanced water production and improving solar water distillation efficiency of double-slope solar stills: Modeling and validation

Solar distillation is a promising technology for producing clean water using renewable energy, especially in regions with water scarcity and contamination. This study investigates the impact of design modifications on the efficiency of a double-slope solar still coupled with evacuated tubes and external reflectors. Using Matlab software analysis, key findings indicate that packing factors, temperature control, and solar radiation exposure all contribute to the system’s optimal performance. Solar radiation levels directly correlate with production rates, emphasizing the need for effective sunlight exposure. The system’s ability to rely on stored heat at night enhances its practicality. This study shows how to make solar stills more efficient at producing clean water. It is found that the best way to do this is to use PV cells with a packing factor of 0.25. A packing factor of 0.25 outperforms other factors, significantly increasing water production and system efficiency. With this optimal factor, the system achieved a remarkable thermal efficiency of 83.5 % and a maximum daily production of 19 L per square meter during peak solar radiation hours. The system’s overall efficiency is 94 % increased by 13 % over the highest value recorded in previous studies. Furthermore, the system’s productivity increased by 40 % from the highest value recorded in previous studies. The amount of electrical energy produced is directly proportional to the packing factor, by the power of 41.1 W-hours (Wh) at a PV cell with a packing factor of 0.25.

3E analysis of enhancing solar distillation performance through innovative wick convex stepped absorber, PCM, and evacuated tube solar water collector: Experimental investigation

Solar distillers have been developed to meet daily potable needs because they are simple to construct and easy to operate, especially in arid areas. Despite all this development, their efficiency and yield represent a challenge. Thus, the present study aims to improve the thermo-economic performance of stepped solar distillers via raising the rates of evaporation. This was achieved by shaping the absorber surface into the shape of a convex stepped absorber and incorporating it with the evacuated tube solar water collector as a first case, where different operating times were tested. After that, wick materials were added above the convex stepped absorber. Finally, in the third case, the reservoir of paraffin wax was added below the absorber as a latent storage medium. In all experiments, the performance indicators of the three cases are compared to those of classical solar distiller. As a result, incorporating all the proposed additives (third case) improved the productivity, thermal, and exergy efficiencies by 186.96 %, 44.52 %, and 171.15 %, respectively. In addition, all proposed additions reduced the cost of potable water per L by 16 %. The findings of this investigation demonstrated the sustainability, suitability, and economic viability of the suggested enhancements in the domain of solar distillation.

Design of a Solar Distillation Still Model with Backup Heat from Biomass

Water borne pathogens caused series of diseases, and millions died each year. Therefore, availability of safe drinking water and good water sanitation is of great global importance, while this can be done through solar still distillation. The distillation process is one of the technologies for water processing and purification, and solar energy is the main source of energy that used to energize the process. Therefore, in this paper, a solar distillation still with back-up heat from Biomass has been designed with basin area of 1.045 m2 (1290 mm x 810 mm). However, various design equation were utilized during the design process. The energy requirement for evaporating water is 226 0kJ/kg. This implies that much heat energy is required to produce 1 litre of pure. For this reason, a collector of 1.044m2 area was used. This will provide sufficient energy for distillation process. The solution obtained from the Polymath 5.0 software, shows that, the day is not as intrinsic as the solution for the night. This might be due to supply of heat as concentrated heat unlike for the day when the heating increased relatively gently. It is hereby recommended that more of the machine should be develop and made available in the market to enhance a safer and more sanitize drinking water for the society.

Performance enhancement of solar distillation system with hemispherical projections and low-cost coating on absorber plate

Performance enhancement of solar distillation system with hemispherical projections and low-cost coating on absorber plate

Submerged nanoporous anodized alumina structure for solar-powered desalination.

Development of nanoporous structures utilizing a single step of anodization technique is well recognized as a cost-effective and straightforward approach for several applications. In the current work, anodized alumina was developed with nanoporous structure by utilizing oxalic acid as an electrolyte with a continuous voltage of 40 V. The formed nanoporous structure was subjected to desalination application because of its high absorbance of broadband solar spectrum energy. The desalination setup consists of two solar stills namely conventional and modified. The developed structure is placed in the modified still to examine its performance. It was observed that the structure distributing heat to surrounding water by absorbing photon energy from the sun through the nanopores and giving an efficient pathway to the water vapours for developing effective desalination. The nanoporous structure having ~ 45 nm average diameter. Furthermore, the band gap energy of nanoporous structure was found to be ~ 2.5 eV (absorption spectrum fitting) and ~ 2.8 eV (Tauc plot). The nanoporous structure possess the visible light spectra in solar region which helps the band gaps of nanoporous structure to provide an additional supply of energy for generating more water to evaporate. Moreover, the Urbach energy of the structure is 0.5 eV which reveals less defects in the modified still. The overall distillate yield of modified still was increased to 21% in contrast to conventional. Water quality analysis was also carried out before and after the desalination experiments, and the results were within acceptable limits set by World Health Organization (WHO).

Improving heat retention properties of steeped M-shape basin solar distillers utilizing paraffin RT50-enhanced silver nanoparticles and Manihot esculenta extracts

This research explores the development of phase change materials (PCMs) containing both organic and inorganic components in order to integrate thermal energy storage (TES) systems that are optimized for solar energy usage. The substantial interest in these materials has been sparked by the sporadic nature of solar energy consumption. Solar stills require improvements in distillate output, thermal efficiency, and lower distillate generation costs due to historically limited water production. The goal of this study is to improve these features in a steeped M-shaped basin single slope solar still (SMBSSS). The study specifically looks at the effects of a composite PCM as organic paraffin RT50 (PR) and silver nanoparticles (SN) from Manihot esculenta extracting solutions (ME), it's forming PRSNME nano-composites. It evaluates three modifications as TES materials and thermal property enhancers within SMBSSS. The key findings of the study come from SMBSSS that had 15% concentration of PRSNME installed. Notable results for the summer and winter include respectable thermal efficiency rates of 54.68 % in the summer and 44.46 % in the winter, as well as significant distillate production of 8.106 kg/m2/day and 6.357 kg/m2/day, respectively. PRSNME showed a 26 % increase in distillate yield at 15% concentration. The integration of SMBSSS with PRSNME demonstrated significant improvements in energy efficiency, with summer and winter concentrations of 7.4 % and 6.8 %, respectively, at 15 %. The incorporation of PRSNME proved to be highly effective, as evidenced by the notable 209 % increase in production when compared to the conventional solar still (CSS). An impact of 34.8 tons CO2 annually for SMBSSS was found through environmental calculations, indicating possible environmental advantages. Furthermore, cost study revealed that freshwater costs were greater for CSS (0.028 $/Litter) than for modified SMBSSS (0.014 $/Litter), indicating possible cost-effectiveness.

New graphite fins efficacy on conical solar distiller performance: Experimental study with thermal, exergy, economic, and sustainability analysis

The pressing issue of freshwater scarcity in remote areas has stimulated the development of the performance of solar distillers as a means of desalinating saltwater. This was done by incorporating efficacy new graphite fins with basin of the conical solar distiller. The new graphite fins are characterized by their high thermal properties, so they represent thermal storage materials and are used to increase the surface area to absorb solar radiation and transfer heat. To get the optimal height of new graphite fins that achieve highest freshwater production, four different heights 1, 2, 3, and 4 cm of the new efficacy graphite fins were studied. To achieve this, three conical distillers were built with the same dimensions, the first is a classical conical distiller (CCD), and the second and third are the modified conical distiller with graphite fins (MCD-GF). The results presented that incorporating the new efficacy graphite fins that have 3 cm height with the basin of conical solar distiller represents a good choice, that causes improves the freshwater production, energy efficiency, exergy efficiency, and sustainability index by 97.37, 94.37, 574.1, and 18.6 % as compared to CCD. In addition, it reduces the cost of producing fresh water by 48.26 %.

Performance study for single slope solar still integrated with different types of solar collectors

The demand for consumed pure water continues to rise due to the increase in population density. Solar desalination is a process of converting brackish water into potable water. Solar distillation is one of the techniques used in desalination of raw water. Solar stills represent the common method for applying the principle of distillation process for obtained of pure water. Active and passive are the main categories of solar stills. In this study increasing the evaporation process inside the still is experimentally implemented with the help of two type of solar collector (finned tube solar collector and flat plate solar collector) integrating to conventional stills enhance productivity. The results show that the yields of conventional solar still, conventional with flat plate solar collector and conventional with finned tubes solar collector are (2.886, 3.853 and 4.766) L/m2.day respectively. Hence, the productivity is improved by 65.12 % and 33.49 % when using finned tubes and flat plate solar collectors respectively, as compared to that of conventional solar still. The cost analysis for the three solar still models for 1 Litter of yield is performed and the indication is that the lowest cost is form conventional still with finned tubes collector.

Exergoeconomic assessment of a multi-section solar distiller coupled with solar air heater: Optimization and economic viability

This study focuses on optimizing the solar distiller and provides a foundation for future research and development in solar distillation technologies. This paper does an exergoeconomic analysis of a multi-section solar distiller (MS-SS) system that is combined with a solar air heater (SAH). Therefore, its objective is to determine the most effective operational and design parameters while taking into account the system's lifespan and interest rate. This will offer significant knowledge for improving the MS-SS. Key parameters examined in the study include exergoeconomic indicators, exergy production factor (EPF), exergy-based loss rate, exergy efficiency, and water cost. Variations in exergy loss rate across different seasons were observed, with implications for system efficiency. The exergoeconomic analysis demonstrates the impact of interest rates on the system's economic viability, with corresponding effects on water costs. The key findings suggest varying daily output and exergy efficiency, with the lowest values recorded in winter and the highest in summer. Summer demonstrates superior output exergy, averaging of 145 × 103 Wh per month. In the normal case of output salinity between 0 and 500 ppm, the cost was reduced by 96.7 %, and by 96.3 % in the case of four interior sections. Water cost reduction is also observable at the same output salinity, with 54.1 % at 0 ppm and 62.4 % at 200 ppm between number of interior sections = 0 and 4.

Distillation of treated dairy effluent using integrated solar dish collector and solar still: A case study of distillate output enhancement

A solar thermal distillation system was designed to be compatible with electrically powered conventional laboratory distillation assembly. Its efficacy was checked in converting the treated dairy effluent into distilled water. The experimental setup comprised of a solar parabolic dish collector (aperture area 4.15 m2) and a solar still (basin area 1 m2) and was designed such that both can be used separately or in the combination. The study was conducted during March – June 2023. The solar dish collector was tested with two receivers with different bottom materials viz., stainless-steel and brass, thereby an average daily yield of 6.5 litres and 6.9 litres were obtained for both receivers, respectively. Simultaneously, solar still produced 2.08 litres of water individually per day. Thus, the highest yield obtained for whole setup was 8.9 litres per day considering individual performances of both the systems. The daily average thermal efficiency of dish collector for was found 65.59 % with steel receiver and 63.33 % with brass receiver. Similarly, thermal efficiency of solar still was 35 %. The quality of distillate was analysed on 10 parameters viz., pH, TDS, TSS, COD, BOD, Oil & Grease, SPC, Coliform count, electrical conductivity, and chloride content which showed promising results.

Testing the performance of tubular solar still with flat basin, cords wick basin, and various angle of inclinations

Freshwater scarcity is a growing concern due to population expansion and industrial development. Solar stills offer a solution for generating potable water, although production volumes are limited. This research aims to address this challenge by improving the yield, thermal efficiency, and cost-effectiveness of freshwater production in tubular solar stills (TSS). We propose a novel approach that incorporates wick materials within the TSS design. This method involves creating a specific number of cuts (cracks) in a secondary basin liner positioned 2.5 cm above the original liner within the still. The upper liner is extended with wick, and wicking cords are suspended from edges and openings of this liner. These cords continuously remove saltwater, ensuring a consistently moist wick surface. The design of the wick cords optimizes water utilization and minimizes energy waste. The cords extract precisely the amount of saline water needed for evaporation, eliminating the loss or overflow of hot water. This approach maximizes wick efficiency without sacrificing freshwater production. The study investigates the performance of the TSS using 32 wick cords in conjunction with jute wick material. This modification to the conventional TSS offers a simple and cost-effective method to enhance productivity. Additionally, the glass cover of the still is tilted at an angle to facilitate the collection of distilled water droplets. ICWTSS was used as a code name for the modified TSS. After that, three distinct inclination angles (2°, 4°, and 6°) were examined, and the effectiveness of ICWTSS at each angle was contrasted with that of CSS. With a 6° angle of inclination, the ICWTSS showed a 67 % thermal efficiency and a 257 % increase in production over CSS.

Experimental investigation of the effect of angled fins on the energy and exergy efficiencies of solar stills: A comparison between double slope and pyramid solar stills under Tunisia weather conditions

Solar stills play a crucial role in addressing the scarcity of potable water, particularly in remote areas. However, traditional solar still designs are often inefficient, with limited productivity and high energy consumption. One approach to enhancing the efficiency of solar stills is to use finned absorber plates, which can increase the heat transfer area and improve heat transfer rates, thereby enhancing evaporation and overall productivity. This study investigates the impact of different configurations of angled fins on the energy and exergy efficiencies of solar stills, focusing on Pyramid Solar Still (PSS) and Double Slope Solar Still (DSSS) designs. Energy efficiency was calculated over several days to determine the effect of the number of angled fins ((3 × 3), (3 × 5), and (3 × 7) fins) on the performance of both solar stills and to compare the two configurations. The most favorable results were obtained using an absorber plate featuring (7 × 3) angled fins in PSS. The desalination systems equipped with finned absorber plates with (7 × 3) angled fins achieved approximately 43.22 % and 46.25 % greater productivity for the PSS and DSSS, respectively, compared to absorber plates without fins. In this configuration with (7 × 3) angled fins, the PSS system recorded an energy efficiency of 37.84 %, while the DSSS system achieved a rate of 31.93 %. The PSS desalination system with an absorber plate without angled fins achieved an energy efficiency of 26.18 %, while the similarly equipped DSSS system attained an energy efficiency of 22.39 %. Regarding exergy efficiency, the PSS showed an average daily exergy efficiency without angled fins of 1.94 %, but using (7 × 3) angled fins boosted this to 2.66 %, the highest value observed. Likewise, the DSSS’s exergy efficiency started at 1.54 % without fins but reached 2.15 % with (7 × 3) fins. Overall, though, the PSS consistently outperformed the DSSS in terms of both energy and exergy efficiency across the various absorber plate configurations. These findings underscore the effectiveness of using finned absorber plates to enhance the evaporation rate and improve the overall efficiency of solar stills.

Performance optimization and comparative study of a conical solar distiller with optimized construction of aluminium balls as energy storage materials

This study seeks to find the ideal size of aluminum balls to improve the effectiveness of conical solar stills for storing energy, due to the increasing demand for drinking water and the high costs of getting portable drinking water. To achieve this, three comparable conical solar distillers were made using aluminum balls of various diameters (1 cm, 1.5 cm, 2 cm, and 2.5 cm) at a 4 cm center spacing. Two days were spent on the experiments. The first distiller had no metal balls on the first day, whereas the second and third had 41 1 cm and 1.5 cm aluminum balls uniformly dispersed at the bottom. On the second day, the first distiller had no metal balls, but the second and third had 41 2 cm and 2.5 cm balls. The water basin depth was consistently maintained at 2.5 cm. The results revealed that the distiller with 2 cm diameter aluminum balls achieved the highest productivity, yielding 840 mL/m2, compared to the distillers with aluminum balls of 1 cm, 1.5 cm, and 2.5 cm diameter, as well as the conventional distiller without any storage materials, which yielded 645 mL/m2, 695 mL/m2, 755 mL/m2, and 570 mL/m2, respectively. The ideal diameter for the aluminum balls was found to be 2 cm, leading to a significant 47.37 % enhancement in water productivity. Conical solar stills using 2 cm diameter aluminum balls as an economical energy storage material provide the best answer.

ANSYS Fluent-CFD analysis of a continuous single-slope single-basin type solar still

The present study endeavours to substantially contribute towards alleviating the global water scarcity problem. The task entailed designing a computational model of a renewable energy-based evaporator. Using ANSYS Fluent, the CFD simulations of a three-dimensional conventional continuous single slope, single basin solar still were carried out in summer at 23.79°N, 86.43°E coordinates. With the optimized inclination condensation angle of 29° and water depth at 1 cm, the solar still recorded the highest hourly drinking water, about 1.5 kg m−2, at 11:00 h. The continuous production resulted in a water collection rate of 8.6 kg m−2 day −1, encompassing the production of all previous models. Additionally, compared with the literature correlation for solar still simulated mass, the Power model calculation was the closest, with a 12.4% variation. Furthermore, the study showcases that CFD is an economical, efficient, and easily diagnosable technique for designing solar stills.

Optimal orientation of efficacy metal fins to enhanced freshwater generation in solar distillers: An experimental study

The pressing issue of water scarcity in remote regions has stimulated the search for simple desalination techniques. Solar distillers represent one of the most important solutions in remote regions for producing freshwater, but they have low productivity. The efficient iron fins represent an effective solution to improve their freshwater productivity. However, due to the negative effect of the shadow resulting from the metal fins, the present study aims to obtain the optimal orientation of efficacy metal fins that achieves the highest productivity for solar stills. To achieve this, three solar distillers were designed and built with identical dimensions. The first distiller has vertically oriented iron fins incorporated with its basin. The second distiller has 45° inclined iron fins incorporated with its basin. But the third distiller is devoid of any iron fins and represents the reference case. Our findings revealed that the inclusion of iron fins, particularly inclined ones, significantly enhanced the yield of the solar still by 48.94 %. In contrast, the enhanced distiller with vertical fins showcased a 33.84 % increase in productivity compared to the reference distiller. Based on these results, we recommend adopting the 45° inclined metal fins to mitigate shading effects and achieve the highest productivity.

Development of a mathematical model of productivity for conventional and stepped solar stills using RSM

Solar stills play a vital role as devices for utilizing solar energy to generate drinkable water, especially in dry regions where obtaining clean water poses a considerable challenge. This research concentrates on the expansion of a comprehensive mathematical model for anticipating and enhancing the performance of both conventional and stepped solar stills, employing Response Surface Methodology (RSM). The study investigates the influence of key design parameters, for instance, water depth (mm), mass flow rate (kg/h), and glass thickness (mm), on the productivity of conventional and stepped solar stills. The experimental setup involves the systematic collection of data from both conventional and stepped solar stills under varying operational conditions. Through the application of RSM, a predictive mathematical model is established, capturing the complex interdependencies among the input variables and their impact on the distilled water output, called productivity. This model serves as a valuable tool for understanding and optimizing the performance of solar stills in diverse operating conditions.