Solar Distillation Research Articles

Synergetic integration of machining metal scrap for enhanced evaporation in solar stills: A sustainable novel solution for potable water production

The global water crisis necessitates innovative solutions for sustainable potable water production. Solar stills represent a promising technology for harnessing solar energy to meet this demand. However, solar stills often face limitations regarding yield and cost-effectiveness. This research addresses the pressing need to augment the performance of solar stills by introducing amendments such as utilizing black-coated metal scrap as a photothermal absorber in the absorber basin. These modifications aim to boost the absorption of solar radiation, thereby increasing potable water yield and improving the system’s economic viability. The study explores the utilization of black-coated metal scrap as a photothermal absorber to modify the absorber basin. Experimental results demonstrate a significant improvement in potable water yield, with a 129.85 % increase on day 1 and 127.21 % on day 2, reaching 3080 mL/m2 and 3090 mL/m2, respectively. Compared to conventional solar stills, the newly developed double slope solar still with an absorber basin featuring metal scrap exhibits a remarkable economic advantage, with a payback period (PBP) of 5.4 months, as opposed to 9.45 months for the traditional system. Additionally, the cost per liter (CPL) of potable water generated by the innovative system is 75.53 % lower than that of the conventional solar still system.

Numerical simulation of mezcal production using a Solar distiller, Compound Parabolic Collectors (CPC’s) and water as working fluid

Numerical simulation of mezcal production using a Solar distiller, Compound Parabolic Collectors (CPC’s) and water as working fluid

Effect of ten different physical parameters on solar still productivity: Theoretical modeling

AbstractSolar distillation using solar stills is widely recognized as a clean and cost‐effective method for producing freshwater. However, due to its straightforward design, solar still performance is greatly influenced by various physical characteristics. Many researches have evaluated solar still parameters, while only a few articles have concerned physical ones. Therefore, this article aims to investigate the effect of different physical parameters on solar still productivity through thermal modeling. The theoretical results were validated with those of a previous experimental model, showing a good agreement with each other. The results reveal that daily productivity experiences significant improvement with an increase in plate emissivity or insulation thickness. Conversely, an increase in water mass, glass absorptivity or insulation thermal conductivity leads to a substantial reduction in productivity. Notably, water transmissivity and plate absorptivity do not affect productivity. Modest enhancements in productivity can be achieved by reducing the effective emissivity between water and glass. While the initial temperature of water has a minor impact on productivity at low water mass, it exhibits a substantial improvement effect at high water mass. These results can be a good guidance for the designers and manufacturers to develop more efficient designs that maximize the production of clean water.

Development of sustainable energy: Performance investigation of the combined utilisation of a seawater electrolyser and single slope solar desalination still

The primary objective of this work is to investigate experimentally the desalination performance of seawater, hydrogen, and oxygen gas generation through the use of two identical single-slope solar stills. Seawater collected from “Bay of Bengal” was used as the fluid and analysis was conducted at a constant water depth of 20 mm. The system was constructed using mild steel and stainless steel 316 L was used as electrodes. A set voltage and current of 12 V and 40 A was supplied to the electrodes through switched-mode power supply (SMPS). The study investigated the impact of solar radiation and induction of electrolysis system on the performance of solar stills. The results demonstrate a significant positive correlation between solar radiation and still temperature, with 877.1 W/m2 of maximum solar radiation intensity resulting in a still temperature of 53.9 °C. The temperature of the basin water increased by an average of 4.25% upon the addition of an electrolyser. It was noted that with the introduction of electrolyser there was increase in productivity by 48 % than the still without the electrolyser. When the solar radiation was at its peak the maximum amount of hydrogen and oxygen were produced which is 0.44 kg/L and 0.24 kg/L respectively. It was noted that when the system with electrolyser is operated at its peak there was increase in solar still and exergy efficiency by 30.5 % and 9.32 % than the system operated without electrolyser. The economic analysis revealed that the hybrid system which possessed electrolyser has very short pay back period of 1.5 days which is approximately 90 days less than the still without electrolyser. The study shows the use of hybrid system reduces the carbon emission significantly which contributes for its sustainable utilisation. The study highlights the interaction between solar radiation, electrolyser induction, and overall efficiency in the context of seawater desalination and shows the system's strong performance.

Productivity prediction of a spherical distiller using a machine learning model and triangulation topology aggregation optimizer

Solar stills offer a sustainable and environmentally friendly solution to water scarcity in remote areas, but their limited productivity hinders their wider adoption. This study proposes innovative modifications to the spherical solar distiller to address this challenge. We introduce a rotating spherical ball within the distiller and investigate its impact on productivity at various speeds (0–2 rpm) with and without a wick. Additionally, we explore the effectiveness of preheating feed water to different temperatures (45–70 °C) and its interaction with the rotating ball mechanism. Moreover, six machine learning models were employed to predict the water productivity of the distillers under different working conditions. The employed models were standalone long short-term memory (LSTM), LSTM optimized by reptile search algorithm, LSTM optimized by grey wolf optimizer, LSTM optimized by dwarf mongoose optimization algorithm, LSTM optimized by manta ray foraging optimizer, LSTM optimized by triangulation topology aggregation optimizer. The results showcased that with an optimal rotation speed of 0.5 rpm and 1 rpm for configurations with and without wick, respectively, we achieved productivity increases of 62 % and 55 %. Notably, preheating feed water to 65 °C further boosted the new distiller performance, surpassing the conventional solar still by 91 %, achieving an impressive output of 6000–6200 mL/m2.day compared to 3000–3250 mL/m2.day for the conventional distiller. Moreover, the thermal efficiency of the new distiller configuration reached 62 %, almost doubling that of the conventional distiller (32 %). Moreover, the triangulation topology aggregation optimizer outperformed other models in predicting water productivity with a high R2 range of 0.953–0.999.

An experimental comparison for thermos-economic performance of five different designs of solar stills

Five different solar stills (SSs) have been tested in this experimental study. Hemispherical SS, tubular SS, pyramid SS, double slope SS, and conventional SS are the five SS systems. The primary goal is to determine which SS will perform more effectively at the testing location. Initially, the SSs were evaluated with no changes and the outcomes were contrasted with those of the conventional SS. Secondly, exterior reflectors have been added to four SSs. Third, hemispherical SS and tubular SS with reflectors have been utilized with phase change material (PCM) combined with Ag-Nanoparticles. Lastly, tests using reflectors, fan, and external condensers have been conducted on the hemispherical SS and tubular SS. The findings showed that the increase in productivity for hemispherical SS, tubular SS, pyramid SS, and double slope SS without modifications are 107 %, 97 %, 66.5 %, and 30 % greater than that of conventional SS, respectively. Furthermore, the results depicted that employing reflectors improved the productivity rise for tubular SS, hemispherical SS, pyramid SS, and double slope SS to be higher than conventional SS's productivity by 168 %, 153 %, 113 %, and 85 %, respectively. Besides, the effect of employing PCM-Ag with hemispherical SS and tubular SS (with reflector) is increasing their productivity to be 202 % and 212 % higher than conventional SS's production, respectively. Also, the hemispherical SS and tubular SS with reflector, fan, and a condenser showed 217 % and 236 % higher productivity than conventional SS. The actual cost of producing water for the conventional SS, hemispherical SS, and tubular SS with reflectors and fan is 0.0244, 0.012, and 0.013 $/L, respectively.

Experimental and analytical examinations of a single-glazed solar still desalination with a spray-feeding water system with an artificial neural network

Using solar stills to desalinate salt water effectively provides clean water in remote areas at affordable prices. It is well-established that a crucial factor in enhancing the efficiency of solar desalination systems is increasing brackish water's surface evaporation rate by minimizing surface tension and boosting thermal energy. However, recent studies and proposed ideas indicate a limited and insufficient focus on this aspect. As a response, this research introduces a novel approach to raising the temperature of saline water. This is achieved through a system that involves simultaneous saline water spraying and circulation, affecting all factors and effectively reducing the surface evaporation rate. This approach impacts factors influencing surface evaporation rates and offers advantages such as low thermal inertia, reduced surface tension, and enhanced thermal energy within the desalination system. Therefore, the main goal of this study will be to improve the performance of the solar desalination system through circulating preheated salt water spray and using artificial neural networks and machine learning algorithms to obtain the function of predicting the amount of fresh water produced. The results of this study show that the evaporative heat transfer coefficient of the introduced system is significantly larger than that of the conventional solar still unit, with an average difference of about 43.98%. Also, the results of daily water output in both systems show a significant increase and superiority of 28.75% in freshwater production for the modified system. Also, the efficiency of the improved system is 65.18% higher than that of the passive solar distillation system, and the cost per liter was 0.059 ($/L/m2). The results of this study highlight the effectiveness of the saltwater spraying technique in enhancing the performance of solar desalination systems, making it a valuable prospect for future industrial applications in desalination systems and into energy systems for smart cities as a sagacious strategy towards clean and sustainable process.

Enhanced water production in hemispherical solar stills via solar collector and thermal storage integration: experimental validation

ABSTRACT In arid regions that face water scarcity, solar distillation offers hope by meeting the increasing need for clean drinking water. This study investigates the integration of a hot water storage system, heated by a flat plate solar collector, into a hemispherical solar still. Placing the storage tank below the still's absorber enhances heat input and efficiently stores excess daytime thermal energy. Conducted in Bouismail from December 2022 to October 2023, the study yielded significant results: the modified solar still outperformed the conventional one, with production increases of 157% in winter and 207% in summer. Moreover, the modified still demonstrated remarkable efficiency improvement in summer, reaching 37.42% compared to 20.38% for the conventional still. The orientation of the fins within the storage tank, with respect to the hot water entrance orifice, significantly impacted water production, with alterations of the angle resulting in decreases of up to 25%. Increasing saltwater depth led to reduced distilled water output, with declines of up to 37.08% for the modified still. Economic analysis showed a slightly higher cost per liter of water produced by the modified still ($0.1897) compared to the simple one ($0.1446).

Experimental optimization of conical solar distillers using graphite pin fins as sensible heat storage materials: Energy, exergy, and exergo-economic approach

Fresh water and energy are essential for the development and prosperity of societies. Solar stills are easy to build, operate, and maintain, but their disadvantage is low daily productivity. This work aims to optimize and enhance the performance of conical solar stills by integrating innovative graphite pin fins that function as extended surfaces and sensible energy storage in the distillation basin. Graphite is inexpensive, available locally, natural properties, and has good thermal characteristics and heat capacity. Four different alternates spacing between the graphite pin fins ranging from 10 to 70 mm have been investigated and optimized to achieve maximum daily water production. Three identical conical solar distillers were designed, manufactured, and tested, under the same weather conditions in El Oued city, Algeria (33.3676◦ N and 6.8516◦ E). Energy, economy, exergy, and exergo-economics approach were performed to evaluate the economic feasibility of modified conical distillers. The results showed that reducing the distance between the pin fins leads to a decrease in the productivity of the distiller due to the increase in the shadow area. Among the pin fin distances evaluated, the 50 mm distance achieved the highest daily water production with reasonable economic feasibility. Adding graphite pin fins to conical distiller basin increases daily productivity and thermal efficiency by 52.16–90.78% and 33.44–63%, respectively. The production cost and payback time of the modified conical distillers with pin fins are reduced by 35.49–79.72% and 35.48–79.72%, respectively compared to the traditional conical stiller.

Innovative configurations for spherical solar distillation: Ball rotation and preheating for improved productivity

Solar stills are acknowledged as an environmentally friendly desalination method that addresses water scarcity issues in remote areas; however, they contend with a productivity challenge. This work presents a combination of novel arrangements for the spherical solar distiller (RBSD) to augment its productivity. Rotational sphere was anticipated. The influence of speed for RBSD (0, 0.5, 1, 1.5, and 2 rpm) with and without wick was tested. Also, the effect of utilizing a preheater to supply the RBSD with hot feed water under various preheating temperatures, specifically 45, 50, 55, 60, 65, and 70 °C with and without condenser was investigated. Results revealed that the optimized speed is 0.5 rpm and 1 rpm for the RBSD with and without wick, respectively, where the productivity rise reached 62 % and 45 %, respectively. Also, the best preheating temperature that provided the highest performance for RBSD was 65 °C, where the CSD produced 3250 mL/m2.day, while, at 0.5 rpm and 65 °C, the RBSD with a preheater produced 6200 mL/m2.day with an increase in productivity by 91 %. When integrating the external condenser to RBSD with wick and preheater, the productivity of RBSD (6800 mL/m2.day) was augmented by 116 % over that of the CSD (3150 mL/m2.day). Also, the thermal efficiency of CSD and RBSD with wick, preheater and condenser was 32 % and 62 %, respectively. Finally, the cost of distilled water for CSD, RBSD with wick, RBSD with wick and preheater, and RBSD with wick, preheater, and condenser was found to be 0.220$/L, 0.075$/L, 0.055$/L, and 0.030$/L, respectively.

Potable water production through alow-cost single chamber solar still in north India.

The main aim of this study is to evaluate the performance of a single slope solar still and to assess the effect of nanofluid on its performance. A single basin single slope solar still was designed and fabricated at the Department of Chemical Engineering, IET Lucknow. Its performance was assessed in terms of theyield of potable water. The effect of various climatic parameters was also studied. Al2O3 nanofluid was used to enhance theyield of the solar still. In the presence of nanofluid, the total yield of the solar still improved by 16.6%. Its economic feasibility was analyzed and reported. The portability of thesmall size of solar stills, itsbetter economics, easy fabrication, and good performance make them very useful for industrial as well ashousehold purposes.

Techno-economic evaluation of solar distillation system for essential oil extraction from medicinal plants

Techno-economic evaluation of solar distillation system for essential oil extraction from medicinal plants

Assessing the Economic Viability of Solar Distillation Employing a Rotating Hollow Cylinder

Assessing the Economic Viability of Solar Distillation Employing a Rotating Hollow Cylinder

Examining the effect of water and glass surface temperature on the rate of generation and heat transfer in triangular double-slope single-basin solar still in Kerman province

Freshwater is a fundamental ingredient and its shortage is a serious issue. High evaporation rates of some regions can be exploited for freshwater production using solar stills. Meanwhile, Kerman province in the south of Iran has a hot and dry climate and suffers from water shortages and drought. On the other hand, Iran has a lot of access to salt and open water and has a high evaporation capacity in many areas and has the facilities and technical knowledge in the field of using solar water desalinators. Therefore, in this research, the effect of temperatures of salty water and glass surfaces on the rate of freshwater production in Kerman province is investigated. A numerical approach is used in this study and experimental research is used as validation reference. Moreover, the grid independency study is performed with proper accuracy and an adequate number of meshes. In addition to, the rate of water production and average Nusselt number (Nuave) in different cases, temperature, mass fraction, streamlines and velocities are examined for evaluation of results. The results show that by increasing the glass surface and salty water temperatures and raising the difference between the salty water and glass temperatures, which is accompanied by an increase in the density gradient, the rate of freshwater production increases. Also, the highest rate has occurred at the water temperature of Tw = 65 °C and glass temperature of Tg = 61 °C.

Harnessing fluorescence resonance energy transfer for improved solar still performance with zinc oxide nanoparticles and activated carbon

The Single Slope Corrugated Wick type Solar Distillers (SWS) have attracted significant research funding owing to their simple preparation process and excellent durability against heat and moisture. However, there is a recognized need to enhance their solar energy conversion efficiency. The utilization of ZnO nanoparticles (Z) in SWS is limited by their light absorption capacity, resulting in suboptimal thermal energy conversion and solar energy absorption. In this investigation, we propose an innovative method known as Fluorescence Resonance Energy Transfer (FRET), combining crystallized Z with activated carbon (AC) derived from areca nut shells. This novel approach substantially boosts the thermal efficiency of solar energy utilization in SWS by facilitating efficient energy transfer from ZAC to water.The FRET technique enables the effective transfer of energy from ZAC to water and is comprehensively analyzed. By utilizing Z as donors and AC as acceptors, the photoluminescence emitted by ZAC can be absorbed by both components, thereby increasing the carrier population as of Corrugated Wick-type towards the condenser face within SWS. The evaporation rate from water to the condensing surface is significantly higher in SWS with ZAC compared to conventional wick-type solar stills (CWS), attributed to the efficient heat transfer facilitated through multi-dimensional heterojunctions within ZAC. The energy and charge transfer processes are optimized for both summer and winter operating conditions. The ZAC-based SWS exhibits exceptional resilience in various ambient conditions, resulting in a substantial 33.989 % enhancement in distillation efficiency during summer and a notable 31.199 % improvement in winter. The incorporation of ZAC elevates the production of distillate water to 6.325 liters/m2 per day in summer and 5.840 liters/m2 per day in winter (24 h). The energy distribution among particle components is extensively scrutinized using the FRET mechanism.

Development of characteristic equations of conical solar still by incorporating N identical concentrator collectors with/without photovoltaic panel: A comparative investigation

This paper focuses on the development of characteristic equations and performance analysis of a conical solar still (CSS) connected to N identical compound parabolic concentrator (CPC) collectors, with or without photovoltaic thermal (PVT) integration. The objective is to achieve sustainable solar distillation in line with the United Nations' sustainability goals. The thermal model is developed by formulating energy balance equations for each part followed by its experimental validation considering N=0and1. A fair agreement between analytical and experimental results is observed having correlation coefficients as 0.996, 0.993, 0.992, and 0.97, 0.98, 0.99 for water temperature, yield, and glass temperature for N = 0 and 1, respectively. The study considers three cases: CSS integrated with N identical partially covered PVTCPCs (case (i)), CSS integrated with N identical fully covered PVTCPCs (case (ii)), and CSS integrated with N identical CPCs (case (iii)). The performance of these cases is compared using climate conditions in New Delhi on a typical day in June. The findings indicate that the mean value of instantaneous efficiency for case (i) is higher by 67.75 % than case (ii), however lower by 22.22 % than case (iii). The study also investigates the influence of variations in mass-flow rate and N on the output of the active CSS.

Experimental investigation of a solar still system with a preheater and nanophase change materials

Solar desalination systems are crucial for generating fresh water, particularly in regions with water scarcity. They harness renewable solar energy, making them sustainable and cost-effective in remote areas. Solar desalination addresses water scarcity challenges with a sustainable, decentralized, and efficient approach. The objective of this study is to analyze the impact of varying depths of basin water on the overall productivity of distillate in a solar distillation system. The research specifically investigates three distinct scenarios, focusing on the concentration of freshwater at different depths. The investigation extends to the analysis of temporal variations in heat transfer loss for three different phase change materials (PCMs) namely paraffin wax + nano CuO, paraffin wax, and lauric acid. This study also examines the impact of varying depths of basin water on the overall productivity of distillate in three distinct scenarios. In all instances, it has been observed that the more concentrated form of freshwater can be found at a depth of 20 mm. The water basin temperature lowered by 44.78% for paraffin wax + nano CuO composite, in comparison to paraffin wax (45.31%) and lauric acid (47.37%) when the water depth was increased from 20 mm to 60 mm. The equations pertaining to energy conservation and heat transfer in the solar distillation system are presented. The investigation also encompassed the analysis of temporal variations in heat transfer loss for three unique PCMs. The study recorded an increase in the total distillate freshwater of 3480, 1248.5, and 2637 ml/m2/day for paraffin wax + nano CuO, lauric acid, and paraffin wax correspondingly. Lauric acid has exhibited a level of performance in terms of total distillate.

Effect of square and perforated fins on improving the efficiency of the classic pyramidal solar still

A practical study was conducted to improve the performance of traditional pyramidal solar stills by using fins with square shapes and a circular diameter on the inside, as well as an internal mirror with a pyramid angle of 55 degrees for the improved and 45 degrees for the traditional. The fins were inserted into the base of the solar still, and a glass mirror was installed on each of the still's four sides to compare its performance to that of a typical device. The experimental findings acquired from the pyramidal and enhanced solar systems revealed the following for the first system: Combining the classic pyramidal with the inner-mirror pyramidal demonstrated the results of traditional distillation at 1250 ml/hour with a 47.6% efficiency. Regarding the modified pyramidal still, distillation data revealed an increase of up to 1500 ml/hour with an efficiency of 56.9%. The second system consisted of a traditional pyramid with a 45-degree angle and an enhanced one with a 55-degree angle, square fins, and an internal mirror, which generated more distillate products than the traditional one under all conditions tested. The daily productivity of the enhanced pyramid was 2200 ml/hour, with a 90% efficiency, whereas the original pyramid's daily output was 1675 ml/hour, with a 59.5% efficiency. Furthermore, the use of fins enhanced daily distillate production.

Black glass balls as thermal enhancers in conical solar distillation: performance optimization and comparative insights

Black glass balls as thermal enhancers in conical solar distillation: performance optimization and comparative insights

Innovative solar distillation system with prismatic absorber basin: Experimental analysis and LSTM machine learning modeling coupled with great wall construction algorithm

Enhancing the vaporization surface area of the solar distillers through the implementation of a novel configurations based solar distiller represents a cost-efficient strategy for maximizing the distilled water output of conventional solar stills. The study introduces a pioneering wicked prismatic-shaped solar distiller equipped with wick materials and feed spaying nozzles, aimed at augmenting vaporization rates inside the still trough and, consequently, increasing the yield of freshwater. Two solar distillers with double slope covers are constructed and tested include a modified solar still with a prismatic basin, two incline covers, and spraying nozzles (MSS) and a reference double slope solar still (RSS). Furthermore, we have constructed a hybrid artificial intelligence framework, integrating a long short-term memory (LSTM) neural network fine-tuned through the utilization of great wall construction algorithm (GWCA). This model has been designed for the purpose of forecasting both the saltwater temperature and the associated freshwater product within the two examined solar distillers, whereas, the time, solar flux, wind velocity, and ambient temperature are considered as inputs. GWCA is effectively employed to optimize the LSTM model by determining the optimal parameter values to enhance its performance. The experimental results revealed that the daily freshwater production for the MSS reached 7.94 kg/m²/day, while the RSS achieved 5.31 kg/m²/day. This represents a substantial 49.53% improvement when compared to the RSS. Additionally, the daily energy efficiency of the MSS and RSS was assessed at 57.40% and 39.80%, respectively, whereas the daily exergy efficiency was 3.80% and 2.20%, respectively, signifying a notable 44.23% and 72.74% increase the energetic and exergetic efficiencies over RSS. Furthermore, the prediction findings demonstrated that during the testing phase, the coefficient of determination for saltwater temperature prediction of the MSS was calculated at 0.996 for LSTM-GWCA and 0.963 for LSTM. In the case of freshwater product prediction, these values were 0.983 for LSTM-GWCA and 0.922 for LSTM, respectively.