Active Solar Stills Research Articles

An experimental exploration of modified basin solar still performance through integration of flat plate collector and built condenser

AbstractThis study experimentally investigates the integration of a flat plate solar collector and a condensation chamber into a basin solar still. Three prototypes were designed and constructed for evaluation: a basin solar still coupled to both a solar collector and a condensation chamber, a basin coupled with a solar collector, and a simple basin solar still as a reference. The experiments, conducted from July 24 to 28, 2016, at the UDES site in Bouismail, Algeria, used seawater from the Fouka region. Solar radiation emerged as the primary influencer on the solar desalination system, with active solar stills, particularly those equipped with a flat plate collector, showing significant temperature increases. Daily cumulative production analysis revealed the condensation chamber as a significant contributor, representing 58% of total production. Incorporating a flat plate collector resulted in a 110% increase in daily production compared to the conventional solar still. Simultaneously incorporating both the flat plate collector and the condensation chamber showcased an impressive 176% increase in daily production. Daily production quantified at 5.9 kg/m2 for the active with a condensation chamber, 4.5 kg/m2 for the active solar still, and 2.1 kg/m2 for the simple solar still. Economic analysis indicated that the active solar still with the condensation chamber enables more cost‐effective freshwater production than the active solar still alone. Water analyses demonstrated the efficiency of solar distillation, converting high‐salinity saltwater (31.4%) into exceptionally pure distillate (0.00%).

Water desalination using PV panels based on boiling and evaporation

The annual share of water in Egypt has decreased to approximately 500 m3 per capita, while the annual water scarcity level is 1000 m3 per capita, which indicates that Egyptians are at a high risk of living. A domestic desalination unit based on solar energy was designed, built, and tested to solve this problem in remote areas that do not have access to fresh water or electricity but have access to salty water. The desalination unit has a new design that depends on boiling salty water using photovoltaic solar cells and then condensing the water vapor through a heat exchanger to obtain freshwater. This new design has not been implemented before and can compete with the solar stills used for domestic applications. The output of the developed unit was compared to those of passive and active solar stills that have been developed and built. The new desalination design produced almost the same amount of daily fresh water, 4 Liter/day, compared to the other solar stills (2–4.75 Liter/day), but the cost per unit volume of the new design, 31 $/m3, is less by 30% compared to the best performing solar still, 44.55 $/m3, which produces only 2 Liter/day. The price of the distilled water produced by the new design was 75% lower than the market price at the time of conducting the experiments. Converting a Solar still from a passive system, that is, operating only during sunlight, to an active system operating day and night improves the water productivity rate. However, this is not feasible because of the added accessories that increase the initial cost, consequently increasing the cost of desalination.

Comparison of simple and active solar stills for freshwater recovery during lithium brine mining

Lithium mining from brines raise environmental issues due to huge volumes of both saline and freshwater being constantly pumped in desertic environments. Data indicating the slow depletion of both underground water levels and lagoon surfaces in the regions where large lithium brine mining exploitations are located have recently being disclosed. Amongst different direct lithium extraction methodologies, DLE, for more sustainable lithium recovery, a few proposals aim at the recovery of freshwater from the high salinity brines. About 900 kg of freshwater could potentially be recovered per cubic meter of processed native brine. The water evaporation and freshwater production capabilities of a simple and an active solar still are compared in this work. These are two simple and relatively low-cost technologies that could be adapted to existing solar evaporation ponds. The two systems were thermodynamically modelled. Equations were derived which were fed with real meteorological data from the Olaroz salt lake location and brine properties derived from the Pitzer model for the said brine. Analysis of the heat fluxes show that the behavior of both systems is relatively similar with large heat losses that are responsible for neither of the systems reaching the evaporation rate of the evaporation ponds.

A novel analytical performance investigation of varying water depth in an active multi-stage basin solar still in addition to optimization of water depth in a single stage basin still

In the present research, active solar basin stills are studied and the effect of water depth on output productivity is evaluated analytically. In order to validate the reliability of the results of the proposed model, they have been compared with the available Karimi’s experimental data with an acceptable accuracy. Then, the temperature distribution of the basin, covers, the water in the basin and heat transfer coefficients between the water as well as covers in all stages are calculated. Then, the amount of fresh water as an output are derived for one and multistage units. With increasing the number of stages from one to four, the amount of fresh water was increased by 42%, 72% and 94%, respectively. In addition, the amount of yield water for the ratio of three stages to two stages and four stages to three stages was increased 20% and 13%, respectively. Moreover, in this article, a new approach is adapted based on the variation of water depth instead of considering it constant and because of this methodology, there is an optimum value for water depth, which leads to the maximum productivity. Due to the storage of energy in water as a function of water depth, with an increase in the amount of water in the basin of solar stills more than the optimum value, or even decreasing the water depth below the optimum value, one should expect to get the basin without water at the end of day. This may lead to have less fresh water in the output at the end of the day. Finally, a correlation has been provided to calculate the productivity of a single basin still based on the water depth in the basin.

A Review of a New Advance Technique for Energy Consumption Management by Using Active Solar Still (Nano and PCM Material)

This review aims to provide a comprehensive analysis of active solar stills, a promising technology for sustainable water purification. Active solar stills utilize external energy sources and the sun's energy to evaporate and condense water, thereby removing impurities and producing clean drinking water. However, existing reviews on active solar stills have certain limitations. This review addresses these limitations through consistent experimental setups and meta-analyses. Additionally, the review takes a holistic approach, considering not only productivity and efficiency but also practicality, maintenance requirements, and economic feasibility. The use of phase change material (PCM) in solar stills is a potential approach to entrap the heat and reduce the losses. The review provides practical guidelines and recommendations for optimizing the performance and feasibility of active solar stills. By integrating these novel aspects, this review offers valuable insights to advance the understanding, implementation, and adoption of active solar stills as a sustainable water purification solution.

Exergy, energy, and economic analyses of pyramid solar still integrated with solar water heater

ABSTRACT One of the top priorities in the development of solar stills is productivity enhancement. The present study experimentally investigates both passive and active pyramid solar stills. In active mode, the pyramid solar still is integrated with a solar water heater. The tests were carried out with conventional pyramid solar still (CPSS) and active pyramid solar still (APSS) at 1, 2, and 3 cm of water depth, respectively. The experimentation has been carried out in Nagpur (Longitude 21.124042, Latitude 79.002211) from April – May 2022. The finding shows that the pyramid solar still coupled with a solar water heater at a water depth of 1 cm produces the highest productivity of 7.99 L/m2.The hourly thermal efficiency is to be inversely related to the absorber area and the exergy efficiency is inversely related to the absorber area and directly proportional to the still output. Hence exergy and thermal efficiency of CPSS at 1 cm water depth is enhanced by (107.59%) and (49.36%) as compared to APSS, respectively. The cost per liter of fresh water obtained from conventional pyramid solar still and active pyramid solar still are 0.0139$/L and 0.00751$/L respectively. Based on the study, lower basin water depths and secondary heating enhance the solar still’s productivity.

Techno-Economic and Enviroeconomic Analysis Review of Distinct Passive and Active Solar Distillation Still

Water scarcity is an issue that stems from the overconsumption and misuse of fresh water supplies, which leads to shortages and decreased quality of life. It most affects developing countries that do not have the infrastructure in place to mitigate these factors. Solar still become most suitable method for water purification in these types of places due to its cheapness and easily made from locally available materials. Current paper concentrate on a detailed techno-economic and enviroeconomic analysis of distinct configurations of active and passive solar distillation stills. Distilled water production, cost per litres, environmental cost comparison has been done between different types of passive and active solar still. Active solar still has a higher system cost compared to passive solar due to the addition of thermal energy by different components and mechanisms. Based on the results, minimum cost per litre is obtained for passive conventional solar still with the spherical ball as heat storage material and in case of active solar still, with PV module, reflectors, air-cooling technique are 0.0136 $/l and 0.0092 $/l, respectively. On the basis of energy, the highest environmental cost was found for AMSSFS air-cooled with evacuated mode (1456.38 $), while the lowest was found for active solar stills with N - Flat Plate Collectors (44 $).

Advanced design techniques in passive and active tubular solar stills: a review.

Clean water production using green energy supply plays a significant role in the globe's health and economic development. In recent years, so much importance is given on developing the advanced designs of solar stills to improvise the productivity of conventional solar stills. Tubular solar stills (TSSs) are one of the emerging areas to improve clean water productivity. This paper's main aim is detailed review of passive and active tubular solar still design specifications and highlighting the specific merit of each design. The common tube materials in passive and active TSS are glass, stainless Steel 304, vinyl chloride, flexi glass, poly carbonate, and poly ethylene with variation in thickness from 0.07 to 2.5mm. Diameter of the tube varied from 50 to 280mm in both the cases. Also, the monetary analysis of TSS is discussed, and the average price of water for passive and active tubular solar still is $0.022 and $0.027 per liter of water. Future perspectives also included in the conclusion section for the possible design and material improvements one can do to enhance the performance of the TSS for the benefit of researches. The excellent cover material for TSS is polythene film when compared to the vinyl chloride sheet. TSS with PCM, wick materials, and corrugated absorber enhance productivity during night time. Multi-effect tubular stills performed 28.70% better in comparison to single-effect stills, and TSSs with horizontal axis are 19.12% more productive than vertical axis tubular stills.

Clean Water Production Enhancement through the Integration of Small-Scale Solar Stills with Solar Dish Concentrators (SDCs)—A Review

The conventional solar still, as a water treatment technique, has been reported to produce water at a low working temperature where various thermal resistance pathogens could survive in their distillate. In this work, the reviews of previous research on the quality of water produced by passive solar stills and their productivities in initial basin water temperatures were first presented and discussed. The next review discussed some recent studies on the performances of small-scale solar stills integrated with SDCs (with and without sun-tracking systems (STSs)) to observe the operating temperatures from early hours until the end of operations, daily water yield, and cost per liter. Based on these findings, it was revealed that SDCs with STSs indicated an instant increase in the absorber water temperature up to 70 °C at the starting point of the experiments in which this temperature range marked the unbearable survival of the pathogenic organisms and viruses, particularly the recent SARS-CoV-2. Furthermore, disinfection was also observed when the absorbers’ water temperature reached beyond the boiling point until the end of operations. This indicates the effectiveness of SDCs with STS in reflecting a large amount of sun’s rays and heat to the small-scale absorbers and providing higher operating absorbers temperatures compared to immobile SDCs. Daily productivities and costs per liter of the SDCs with STSs were found to be higher and lower than those of the other previous passive and active solar stills. Therefore, it is recommended that small-scale absorbers integrated with SDCs and STS can be used as a cost-effective and reliable method to produce hygienic pathogen-free water for the communities in remote and rural areas which encounter water scarcity and abundant annual bright sunshine hours.

An Exhaustive Review on a Solar Still Coupled with a Flat Plate Collector

In recent years, producing energy and potable water has become a contemporaneous issue in all areas, especially in rural and remote areas. It is due to the limitation of fossil fuels in generating energy and the daily increase of potable water topic pollution due to various development activities in the industries. Gradually, the use of renewable energies has been suggested as far as humans focus on using these energies in various activities, which is gratis and accessible in more areas without having negative anthropogenic hazards. Solar radiation has an important position in renewable energies and has played a significant role in the desalination process due to the convenience in applying and abundance in the areas with potable water shortages. However, one of the active solar stills is the coupling of conventional solar still with a flat plate collector. In this type, a flat plate collector is used to raise the temperature of saline water which increases the productivity. In this research, the solar still coupled with a flat plate collector is reviewed as the active solar still and the affecting parameters on its performance and efficiency are discussed. First, a summary of working research and their research of flat plate collectors is reviewed to be more familiar with flat plate collectors, their details, and technology. Then, solar still coupled with a flat plate collector is extensively reviewed and discussed in detail. Four types of studies on solar still coupled with a flat plate collector were done, including energy analysis, exergy analysis, economic analysis, and productivity evaluation.

A study on heat and mass transfer analysis of solar distillation system

The solar stills were developed to fulfil the freshwater need of the growing population. The paper presents the recent modifications made in still to improve their productivity like the application of phase change materials (PCM), connecting flat-plate collector (FPC), use of nanoparticles, stepped solar still, and attaching separate condenser in the still. Active solar stills are found more productive than passive ones and the thermal efficiency of active solar stills lie in the range of 50–70%, which is far better than passive still having 20–55% thermal efficiency. According to the literature studied in the paper, the maximum productivity of active solar still is 10 litres per day and in passive solar stills, it is 6 litres per day. The different approaches used to carry out the heat and mass transfer analysis of single and double slope active and passive solar stills are also discussed in the paper.

Utilization of ensemble random vector functional link network for freshwater prediction of active solar stills with nanoparticles

This study introduces an Ensemble Random Vector Functional Link Networks (EnsRVFL) to predict the yield of active solar stills with nanoparticles. The active solar still system composed of a conventional solar still (RSD) integrated with a suction fan and an external condensation system. The addition of two different nanoparticles of Cu2O and Al2O3 into the basin of the solar still was investigated. The yield of the active solar still (MSD) was enhanced by about 140% and 100% when using Cu2O and Al2O3 respectively compared with that of RSD. In addition, using the fan increased the efficiency of the active solar still with Cu2O and Al2O3 to be 36.02% and 32.82%, respectively. Besides, the thermal efficacy of the passive solar still was kept almost constant at around 20.5%. Then, the proposed EndRVFL method was used to anticipate the hourly yield of the solar stills. Real experimental data were used to train and test the developed model. To assess the accuracy of the proposed model, the predicted results by EnsRVFL as well as standalone RVFL were compared with the experimental ones using different statistical assessment criteria. The coefficient of determination (R2) ranges between 0.942 and 0.978 for RVFL and 0.982 and 0.991 for EnsRVFL for all investigated cases, which reveals the outperformance of EnsRVFL over standalone RVFL.

A review on various designs of solar still

The availability of drinking water is reducing day by day, whereas the freshwater necessity is tremendously increasing. There is a need for some sustainable water distillation (purification) to overcome this problem. Solar desalination is a technique used to convert brackish or saline water into potable water, and solar still is a useful device to distil brackish water for drinking purposes. Numerous designs of the solar still system have been developed worldwide. Many researchers outlined mathematical terms, performed experiments and validated the outcome from the various types of solar stills by varying the design and operating parameters. In this article, a review of the active and passive solar stills' performance has been carried out.

Study of analytical observations on energy matrix for solar stills

The extraordinary amount of solar irradiative energy all around the Earth has one of the motivational factors to work with such systems that utilize these for the services towards the benefits of mankind and its progressive growth, and that makes a powerful society and commendable nation. However, in the current era an unavoidable problem for the scarcity of potable water is going on, as brackish water keeps increasing faster than the approachable fresh water resources. For this, solar still systems for water treatment are one of the best solutions that utilize the solar energy as a prime source of working to the system. Out of those systems, energy matrix is one of the important performing factors that indicate the overall usability, payout characteristics, life cycle performing efficiency, etc. of the system. The current presentation reflects that active parameters undertaken in previous studies especially based on the energy matrix for active solar stills. A comparative result has been shown that results better in favor of nanoparticles and lower embodied energetic systems. Based on the overall performances and influencive parameters, a discussion and focused concluding remarks has been framed that suitably justifies the development towards this technology.

A Review on ImprovementTechniques of Freshwater Productivity for Solar Distillation Systems

Solar desalination is known as a method used to turn brackish into potable water owing to high population density and automation, consumable water demand continues to increase. and the system used for desalination is known as a solar still. The main types of solar stills include active and passive solar stills fresh water is obtained from passive solar stills without the use of high-grade energy(electrical energy). several researchers framed mathematical expressions, performed experiments, and confirmed the outcome of the different types of solar stills This paper analyzed the methodologies used in previous years to enhance the efficiency of active and passive solar stills. using types of absorbent materials, reflectors, and a sun tracking device is introduced the solar energy intensity is maximum and thus improves absorption production by 380%, an overall increase in efficiency of 2% will increase production to around 22% in some research, Through this study, The results showed that the use of wire nets and sand in the container increases the daily output of freshwater by about 3.1%, 13.7% in winter, about 3.4% and 14.1% in summer. It also turns out that the productivity of distillation is 20 L / m2 over the inverter compared to 5 kg / m2 in the conventional system. Results also show that the efficiency of the solar still is affected by the kinds, design, and heat storage system.

Solar distillation of impure water from four different water sources under the southwestern Nigerian climate

Abstract. The enormous problems caused by the scarcity of potable water and the transmission of waterborne diseases such as cholera, dracunculiasis, hepatitis, typhoid and filariasis in some parts of Nigeria have created a public health concern. Every day thousands of lives are lost due to contact with waterborne diseases. The insufficient medical resources available in developing countries are deployed towards the treatment of waterborne diseases that can easily be avoided if potable water can be made available. This study seeks to investigate the purification of four different water samples (namely water from flowing rivers, freshly dug well or groundwater, rainwater from the rooftops and heavily polluted dirty water) consumed by the people in the local community using a solar desalination method. A single basin solar still was constructed, and experimental studies were carried out to determine the influence of solar insolation and temperature variations on the yield of the distillate for both the passive and active solar stills tested. The quality of the distillate was tested by measuring the total dissolved solid (TDS) and electrical conductivity (EC) and later comparing it to the World Health Organization (WHO) standard for drinkable water. The values obtained after desalination fall within the acceptable/tolerable range for TDS and EC, in accordance with the WHO standard for drinkable water. This analysis provides an indigenous distillation method to enhance the production of drinkable water at a low cost.

Experimental investigation of a double slope active solar still: Effect of a new heat exchanger design performance

Heat exchanger design is one of the most important design parameters, which affects the performance of active solar stills equipped with heat exchanger. However, up to the present, there is a limited number of experimental studies investigate the impact of this parameter. The present work aims to study the integration of a novel designed multi-scale heat exchanger to active solar still coupled with a parabolic trough collector experimentally. This novel design is based on the practical implications of the constructal theory. The performance of the proposed heat exchanger is then compared with the conventional ones such as parallel channels and serpentine heat exchangers. Total distillate production of active solar still integrated with new heat exchanger is 34.1% and 30.4% higher than the stills integrated with parallel channels and serpentine heat exchangers, respectively.Furthermore, the highest overall energy efficiency of 39.4% was obtained utilizing the novel design heat exchanger. The enhancement in distillate production and efficiency for the still with the new design heat exchanger is in fact due to the higher brine temperature, the higher temperature difference between brine (i.e. evaporation surface) and the condensing surface, lower pressure drop, and consequently higher volumetric flow rate of heat transfer fluid.

PERFORMANCE EVALUATION OF TWO DEFFERENT ACTIVE SOLAR STILLS

The main goal of this work is evaluating the performance of two solar desalination systems under active mode using an integrated solar flat plate collector (FPC). The first one included a glass covered pyramid solar still (PSS) combined with FPC, whilst the second is consists of a greenhouse solar still (GSS) with the same area of brine basin and provided with transparent acrylic cover and connected to another similar FPC. The two systems were fully powered by solar energy using photo voltaic (PV) system. The pre-experiment was performed to evaluate the thermal performance of FPC to determine the optimum hot water flow rate to be used in the main experiment. The main experiment aims to investigate the performance of the two active solar stills under different brine depths and salinity levels. The effect of using basin auxiliary materials including black wick clothes (BWC) and black rubber mat (BRM) on the performance of solar stills was studied with taking into consideration the performance indicators. The obtained results revealed that, the water flow rate of 0.30 l/min achieved the highest values of maximum and average thermal efficiency for the solar FPC. Furthermore, there was no remarkable difference in the hourly productivity and accumulated yield for active PSS and GSS under the best operating condition of brine depth 1cm, salinity level 10000 ppm using BWC and water flow rate 0.30 l/min. Nevertheless, the instantaneous efficiency of active PSS was higher than active GSS, particularly at noon. The cost of distilled water unit is approximately equal for both stills. In conclusion, the two designs of stills proved a good performance with advantages of lightweight, durability and formability for the transparent acrylic cover of GSS over the fragile glass cover of PSS.

Energy-matrices, exergy, economic, environmental, exergoeconomic, enviroeconomic, and heat transfer (6E/HT) analysis of two passive/active solar still water desalination nearly 4000m: Altitude concept

In spite of numerous valuable researches for evaluating the effect of different parameters for analyzing exergy/environmental/economic/energy-matrices/heat transfer of solar stills; the effect of high altitude (highlands) on these parameters and comparing two active/passive systems was not performed. This paper conducted a meticulous analysis of two active and passive solar stills at different altitudes (Tochal: 3964 m and Tehran: 1171 m) during seven consecutive days between 24.07.2018 and 30.07.2018. The geometry of solar stills in both experiments is similar and for active type, the system utilized with thermoelectric (Peltier) modules and powered by a photovoltaic panel. Results revealed that altitude has a direct effect on the exergy of solar stills where the summit-located solar stills (passive and active) have higher exergy efficiency. Furthermore, higher evaporative exergy is obtained by both active solar stills at the Peak of Tochal Mountain and the center of Tehran. Likewise, heat transfer analysis showed that the highest and lowest heat transfer coefficients are obtained by active solar still at the Peak of Tochal Mountain and passive solar still in Tehran respectively. However, due to the higher glass temperature, the highest radiative heat transfer coefficients are obtained by Tehran-located systems. Economic results showed that the highest and lowest cost of water with 0.0079 and 0.0372 $/L are assessed by passive solar still in Tehran and active solar still at the Peak of Tochal Mountain respectively. Energy-matrices indicated that the lowest and highest energy payback time based on energy and exergy with 1.57 and 52.75 years attained by passive solar still in Tehran. Also, Environmental analysis showed that higher CO2 mitigation obtained by active solar stills rather than passive types in both locations. Also, enviroeconomic as well as exergoeconomic (based on energy) parameters showed that both passive and active SSs at the city of Tehran have higher values rather than that of solar stills at the summit because of higher days of operation during the year.

Application of simultaneous thermoelectric cooling and heating to improve the performance of a solar still: An experimental study and exergy analysis

The performance of solar stills is affected by various parameters (e.g. solar radiation, water depth, thermal insulation, and the temperature difference between glass and water). There are two alternatives to increase the temperature difference between glass and water: increasing the water or reducing the glass temperatures. The present study aims to investigate the effect of simultaneous thermoelectric cooling and heating on the performance of a solar still. The experiments were conducted during 8 days in Tehran, Iran (35°41′N, 51°19′E). The setup consisted of a double-slope solar still and a thermoelectric enhancing system that was used to cool the glass cover and heat the water, simultaneously. The cold side of the thermoelectric modules cools a water stream which passes on the glass cover. On the other side (hot side) of the thermoelectric modules, there flows another water stream passing through a helical coil heat exchanger which is located inside the solar still in the water. The obtained results, compared to the passive solar still, indicated that this modification improves the productivity by 2.32 times and generates 76.4% of the efficiency. Moreover, it is observed that the maximum exergy efficiency in the conventional and modified solar stills is about 1.48% and 0.8%, respectively. Also, the economic analysis showed that the price of the produced water for active and passive solar stills were about 0.105 and 0.176 $/L/m2 respectively.