Distilled Water Production Research Articles

Computer modeling of employing binary/ternary organic blends in integrated HP-assisted HDH desalination systems

The global demand for potable water is rising, prompting the development of various energy systems for distilled water production. However, the significance of utilizing multicomponent working fluids in these systems has been largely overlooked. This study presents computer modeling of three HDH-based distillation units powered by two conventional heat pump cycles, namely, the simple and vapor injection heat pumps (first and second models) and an innovative heat pump cycle with an ejector expander (third model). The significance of the research lies in its pioneering investigation of utilizing two- and three-component mixtures in heat pump-based desalination units, which has not been previously explored. The study's primary aim is to determine whether using multicomponent working fluids instead of pure fluids or introducing structural modifications can more effectively enhance the performance of heat pump-based distillation units. The proposed models are simulated using EES and MATLAB software, with the study focusing on energetic, exergetic, exergoeconomic, and heat exchanger modeling to evaluate the feasibility of the configurations. The findings revealed that the structural modifications in the third scenario using R134a resulted in the highest GOR, with improvements of 44 % and 26.03 %, respectively, compared to the other scenarios. However, utilizing binary blend R22/R142b with different compositions improved the GOR of the first to three scenarios by 41.26 %, 29.06 %, and 11.87 %, respectively. Furthermore, in this case, the unit cost of distilled water for the first, second, and third scenarios increased by 12.87 %, 14.32 %, and 12.70 %, respectively. Finally, the first scenario has the highest NPV of 4.40 M$ and the shortest PP of 8.13 years. Therefore, utilizing the blend in a simple heat pump proves to be more efficient and cost-effective than implementing structural modifications.

Flat plate solar collector activated with alumina-silicon dioxide-copper oxide hybrid nanofluid: Thermal performance study

Flat plate collectors (FPC) play a crucial role in solar-powered desalination by harnessing sunlight to purify water. They are acclaimed for their simple yet efficient design, as their dark, flat surfaces effectively transfer heat to the desalination system, making them a preferred choice for sustainable water treatment. Nevertheless, the performance of FPC systems is hindered by the working fluid, which reduces the productivity of distilled water, particularly without the use of nanotechnology to enhance the fluid’s thermal properties. This study aims to enhance the performance of FPCs in desalination processes by integrating them with conventional still systems and employing hybrid nanofluids. These nanofluids, composed of alumina (Al2O3), silicon dioxide (SiO2), and copper oxide (CuO) nanoparticles at concentrations of 0.3 % in 50:50 combinations, namely Al2O3/SiO2, SiO2/CuO, and Al2O3/CuO, are introduced into the working fluid (water). The integration of these hybrid nanofluids is evaluated in terms of thermal behaviour, including thermal conductivity, outlet temperature, energy gain, water productivity, and thermal and exergy efficiency of FPC. Among the different combinations, the Al2O3/CuO hybrid nanofluid demonstrates the highest thermal conductivity, outlet temperature, energy gain, water productivity, as well as thermal and exergy efficiencies, reaching approximately 0.631 W/mK, 87.5 °C, 568.7 W, 124.3 ml/m2, 61.4 %, and 6.7 %, respectively. The Al2O3/CuO featured flat plate solar collector system has the potential for an optimum system of addressing the pressing global issue of water scarcity.

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.

Enhanced distilled water productivity using an innovative semi-cylindrical tent-shaped solar still coupled with evacuated tubes

Despite advances in enhancing the output of conventional solar stills, the pursuit of the most efficient solar distillation technique remains ongoing. Evacuated tubes, known for their superior thermal capacity compared to traditional single-basin solar stills, offer a promising solution for high-yield distillation. This study evaluates the performance of a semi-cylindrical tent-shaped solar still coupled with evacuated tubes (SCTSCET) against a conventional single-basin, single-slope solar still, used as a benchmark. Experiments conducted in Amman, Jordan, in May 2023, demonstrate that the SCTSCET significantly outperforms the conventional solar still in distilled water production. The SCTSCET achieved a daily yield of up to 9.7 liters, which is approximately 288 % higher than the 2.5 liters produced by the conventional still. This increased productivity is due to a 45.7 % enhancement in heat capacity provided by the evacuated tubes, which raised the water basin temperature to 61.4 °C, compared to 41.2 °C in the conventional still. This higher temperature facilitated a faster evaporation rate and improved water output. Additionally, the SCTSCET exhibited a 10 % higher hourly thermal efficiency and a peak exergy efficiency of 5.7 %, compared to 3.4 % for the conventional still, highlighting its superior ability to harness and utilize solar energy for distillation.

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.

Theoretical investigation into saline optical properties for enhancing solar still performance: Mathematical modeling approach

This study investigates the dynamic optical properties of saline solutions, specifically transmissivity, absorptivity, and reflectivity, and their impact on the performance of solar stills. This research addresses the critical challenge of enhancing freshwater production through solar desalination, which is vital in water-scarce regions. Utilizing a validated mathematical model, the study examines how variations in saline depths (ranging from 5 mm to 40 mm), nanofluids, chemical additives, and dyes influence the optical properties and efficiency of solar stills. The results show that a depth of 20 mm emerges as optimal, providing a balance between high transmissivity, absorptivity, and low reflectivity, also a higher saline absorptivity, ranging from 0.014 to 0.021, significantly boosts solar still performance, while transmissivity, ranging from 0.26 to 0.95, affects instantaneous efficiency. The study reveals that the production of distilled water decreases from 6.77 to 4.87 L/m2 as the refractive index increases from 1.2 to 2.6, while higher extinction coefficients enhance production, reaching up to 6.96 L/m2 at 300 m−1. These findings demonstrate the importance of optimizing saline optical properties to improve solar still efficiency. The novelty of this work lies in its comprehensive analysis of the dynamic nature of saline optical properties and their practical application in enhancing solar desalination technology, going beyond previous efforts that assumed constant optical properties. This advanced understanding significantly contributes to the development of more efficient and effective solar desalination systems.

Performance enhancement by integrating concentrated inclined solar still for jaggery production

While unrefined sugar/jaggery consumption has various health benefits, unsustainable and inefficient production processes can negatively impact the environment and health. This study proposes a novel, sustainable approach to jaggery production using solar energy. The primary concentration is done in a VARS system, followed by the secondary concentration in a solar still field at low temperatures to maintain jaggery quality. The study presents experimental observations from the developed inclined solar still with external reflectors to preheat and concentrate the juice. In the absence of sun, the solar still field functions as an evaporation-condensation unit under auxiliary heating. By connecting several solar stills in series, the energy requirements from the PTC field can be reduced. The system is capable of producing a by product of distilled water, amounting to 169.78 kg/day, under varying solar radiation in April at Chennai, India. The overall energy efficiency of the system is 48.31 % under solar load, and 63.05 % under auxiliary heating. The system also leads to enhancement in CO2 mitigations, amounting to around 3134.7 tons of CO2 from dry bagasse combustion. Due to the added revenue from distilled water production, the system's payback period is reduced to as low as 4.89 years, depending on product selling price.

Primarily experimental study of the energy performances of a humidification-dehumidification seawater desalination system coupled with a heat pump

The study presented in this article explores a comprehensive analysis of a humidification-dehumidification (HDH) seawater desalination system integrating a heat pump for heating seawater intended for distillation, and incorporates additional condensation plates supplied with cold seawater. This system was the subject of an experimental investigation to simultaneously evaluate the energy performance of the heat pump and the thermal behavior of the desalination unit, focusing on seawater and condensation wall temperatures, as well as the stratification of temperatures of humid air inside the unit compared to the evaporation surface. Experimental results showed an average daily production of distilled water of approximately 32.75 kg/m² per day, with an electrical consumption of 37.68 kWh/day, which was reduced to 26.72 kWh/day through the integration of photovoltaic solar energy. Based on heat and mass balance equations of all the system’s components, the study used a detailed thermodynamic model. The system's energy performance was analyzed by calculating the coefficient of performance (COP), the specific energy consumption (SEEC), and the gain output ratio (GOR), reflecting the overall energy efficiency of the HDH system coupled with the heat pump, as well as the recovery ratio (RR), indicating the proportion of the recovered water compared to the input water.

Parametric study of low‐temperature solar‐assisted flash evaporation desalination systems using two‐phase water–steam ejector

AbstractThis study aims to investigate a two‐phase subsonic ejector added to a flash evaporation desalination system to increase the system productivity of distilled water. The flash evaporation was of low‐temperature condition that it could be powered by a flat and evacuated tube solar water heater. A parametric study of superheat degree (range 5°C–25°C), back pressure (range 10–30 kPa of absolute pressure), primary fluid flow rate (range 1–3 L/min), nozzle diameter (range 1–3 mm), and salinity concentration (range 0%–7%) were investigated to examine the system productivity and the ejector performance in terms of its entertainment ratio under different operating conditions. Results show that the inclusion of the ejector led to an average of 99% improvement in system productivity, primarily through the efficient secondary flow. Moreover, the effect of the studied parameter was more pronounced in the considered flash evaporation desalination system as it has two places where flash evaporation occurs, compared with the normal system where the flash evaporation occurs at one place. All in all, the application of the ejector could enhance the system's productivity significantly under different operating conditions.

Experimental investigation of a sun tracking concentrated solar still with economic analysis

The current paper evaluated experimentally an innovative sun tracking concentrated solar still under Egyptian climatic conditions during the summer of 2022. The proposed system consists of a 120-cm-diameter parabolic reflector mirror that tracks the sun using a dual axis tracking system, a cylindrical solar still with a volume of 3.7 L positioned in its focal point, and a concentration ratio of 12.5. The performance of the concentrated solar still was investigated in the context of two critical parameters. First, three feed water salinity (17, 27, 37) ppt samples were evaluated, followed by four percentages of saline water filling ratio (26.5, 39.8, 53.1, 66.3)%. Increasing the salinity of the feed water had no effect on solar still productivity, but increasing the saline water filling ratio did. The daily cumulative productivity of the system was 6 kg/m2 with an optimal filling ratio of 53.1%, a daily efficiency of 42.88%, and an average cost of freshwater production of 0.0489 $/L. The proposed system also had the highest instantaneous efficiency of 61.77% and the highest distilled water productivity rate of 0.941 kg/h m2.

Solar-powered single-stage distillation and complex conductivity analysis for sustainable domestic wastewater treatment.

This study investigates the efficacy of a solar-powered single-stage distillation system for treating domestic wastewater, supplemented with complex conductivity analysis. Domestic wastewater samples were collected from a municipal manhole in El Jadida, Morocco, over a 24-h period. The single-stage distillation system, designed for domestic wastewater treatment, utilizes heat to vaporize the wastewater, followed by condensation to produce pure liquid water. The system demonstrated increased distilled water production with rising temperatures, with domestic wastewater outperforming seawater as a feed water source. Physical and chemical testing of the treated water revealed significant improvements in water quality, meeting, or exceeding Moroccan irrigation water standards. Reductions in parameters such as biological oxygen demand (BOD), chemical oxygen demand (COD), suspended matter, and heavy metals underscored the effectiveness of the distillation process. Complex conductivity analysis provided insights into the electrical properties of untreated wastewater and distilled water. Deconvolution of complex conductivity data using an equivalent electrical circuit model elucidated the electrochemical processes during treatment, highlighting the efficiency of the distillation process. The integration of solar energy addresses water scarcity while promoting environmental sustainability. Complex conductivity analysis enhances process understanding, offering avenues for monitoring and control in wastewater treatment.

Experiment of a stepped solar still water distillation divice combine with auxiliary condenser

At the present, there were many research and manufacture subjects the distilled water equipment by using solar energy in Viet Nam. Most of them were designed on traditional type which have a complex shape, cumbersome and low performance. With the aim of this study is to make a simpler, lighter equipment and enhanced production of distilled water, we fabricated a water distillation device which has ladder shape combine with a condensing auxiliary and using solar energy with an area of 1 m2 (evaporation area). The experimental study has established at inclined angles 200, 250, 300 ; circulate and does not circulate steam under conditions at Nha Trang City in 10/2023. The results showed that when the depth distilled water layer is 1cm at the inclined angle 250, the device gave the highest yield, production of distilled water reach 4.9l/m2 (from 7am to 17pm) corresponding to the average radiation of 635W/m2. The efficiency of the distillation equipment with circulation 7.1% higher than does not steam.

Scrutiny of a Bi-evaporator poly-generation system includes distilled water production unit: Comparative study and Bi-objective optimization

While geothermal energy is typically associated with beneficial environmental effects, it is crucial to acknowledge that it can lead to greenhouse gas emissions. Therefore, the implementation of geothermal systems should include an environmental assessment. This study presents and evaluates an innovative geothermal-powered bi-evaporator poly-generation system from seven perspectives: thermodynamic, extended-environmental, exergoenvironmental, exergoeconomic, net present value, and bi-objective optimization. The designed ploy-generation system comprises a desalination unit, a unit for extracting hydrogen, and a modified organic flash cycle, all integrated with a single geothermal flash cycle. These subsystems work in unison to create a comprehensive and integrated system for simultaneously generating purified water, green hydrogen, electricity, and meeting refrigeration load requirements. Regarding the findings at the base mode, the designed system is able to generate net power, refrigeration load, distilled water, and H2 production rates of 244.9 kW, 741.4 kW, 0.4443 kg/s, and 1.062 kg/h, respectively. By employing NSGA-II optimization, the values of commodities are substantially increased, which enhanced the poly-generation system product cost and energetic efficiency by 7.13 % and 30.48 %. Also, the net electricity selling price significantly affects NPV, so the payback period reduces to 8.56 years.

Removal of the veterinary antibiotics oxitetracycline from contaminated water by solar distillation

Veterinary oxytetracycline (OTC) is a persistent contaminant to conventional water treatments. The present study aims to remove OTC from contaminated water through an alternative technology that is distillation via solar energy, being a promising solution in regions with a high incidence of solar radiation. The experimental research was carried out at the State University of Paraíba (UEPB). A cascade-type solar distiller was used to treat the contaminated water, which was collected in an artesian well and combined with the antibiotic at a concentration of 30.0 mg.L−1. Meteorological parameters were evaluated, and temperature profiles obtained. The heat transfer coefficients were determined. After the distillation process, the presence of the OTC substance was no longer detected, which indicates removal of at least 99.67 % and the distilled water productivity reached 2282.05 mL.m−2.day−1. Moreover, considering the physical chemical analyzes of the contaminated and distilled waters, reductions were achieved for pH values, electrical conductivity, turbidity, apparent color and chlorides, and a maximum reduction level of 100.0 % for total hardness, sodium and potassium in distilled water. This shows that the solar distillation process is suitable for obtaining quality water that meets current legislation in Brazil and the world. It is concluded that the solar distillation system used has a real capacity for veterinary OTC removal and water production.

Modifying performance of solar still, by using slices absorber plate and new design of glass cover, experimental and numerical study

By utilizing novel techniques on the absorber plates as well as the glass cover, this effort attempts to increase the distilled water productivity of a modified pyramid solar still. Under the climatic conditions of Iraq, the use of basin absorber plates with slices along its length, and a W-shaped glass cover was investigated experimentally and numerically. In this work, two comparable solar stills with basin absorber plates of 1 m2 have been planned and built using regional resources. Two absorber plates made of stainless steel were produced, first one was solid and the second was sliced. Two covers made of glass were produced one has a pyramid-shaped glass cover and the other a W-shape. According to experimental and numerical findings, forming slices and changing the glass cover resulted in a 20 % increase in the amount of distilled water. when compared to a pyramid glass cover and a standard sort of absorber plate.

Modified evacuated tube collector basin solar still for optimal desalination of reverse osmosis concentrate

This study focused on the optimal production feasibility of distilled water from the concentrate of a reverse osmosis device using an evacuated tube collector basin solar still. The characteristic effect of the device's condenser on the produced freshwater volume was evaluated to improve the performance of the solar still, resulting in productivity enhancement. The direct contact of two faces of the cubic condenser with water vapor results in the doubling of the effective surface area. However, freshwater production was decreased by eight times compared to the case where only one face of the condenser is in contact with water vapor. This reduction was attributed to the shorter path taken by the condensed droplets. At the bottom of the evacuated tube collector, some building mineral pumice was used to prevent the formation of large water vapor bubbles. According to this methodology, the average daily production of distilled water from the concentrate of the reverse osmosis unit with a total dissolved solids of 15200 ppm was achieved at 4.58±0.12L.m−2. The quality of produced distilled water revealed that solar desalination using an evacuated tube collector basin solar still can be a notable and economical solution for the concentrate treatment of reverse osmosis.

Experimental and theoretical investigation of thermal efficiency and productivity of single slope basin type solar distillation system using honey-comb

The aim of current research was to improve water quality by constructing a single slope basin type solar water distillation system with honeycomb, as well as to increase distilled water pro-ductivity. In this investigation, honeycomb structure of 2.25 cm and a diameter of 6 mm in a square section (100 cm ×100 cm) have been proposed to enhance the efficiency of the solar still. An experimental analysis was done to investigate the performance of the honeycomb structure. Thermal efficiency of the standard solar distillation system was obtained approxi-mately 18.48%, while the thermal efficiency and productivity of the solar distillation system with honeycomb was obtained 25.45% and 749.58 ml/m2 respectively. It was concluded that, the solar distillation system with honeycomb structure was more efficient that a simple con-ventional solar distillation system. The addition of honeycomb structure in simple solar de-salination system increased the productivity and efficiency by 35.36% and 37.71% respectively.

Investigation of structural parameters for inclined weir-type solar stills

The solar still, in which saline or brackish water is converted into freshwater using renewable solar energy, can be an effective solution to water scarcity. Inclined solar stills are well-known due to their high production yields compared to other types of solar stills. In this study, an inclined weir-type solar still was developed as a modified inclined solar still with an emphasis on the effect of structural parameters, such as weir height, distance between weirs, and distance between the absorber plate and the condenser cover, on distilled water production. The optimal values of structural parameters for the maximum freshwater production were specified by the response surface methodology and a quadratic model derived from a Box-Behnken design model. The results showed that the operational variables of the inclined weir-type solar still system significantly impacted the water production volume. Using a weir height of 2 cm, a distance of 3.5 cm between weirs, and a distance of 15 cm between the absorber plate and the condenser cover, the maximum water production volume was achieved at 6.474 kg m−2.day−1. The selected model had R2, Radj2 and Rpred2 values of 0.9978, 0.9939, and 0.9756, respectively. The maximum and minimum volumes of the produced water were obtained as 6.64125 and 1.79792 kg m−2. day1, based on the multiple response prediction of the variables. According to the validation tests, the model’s accuracy in prediction of the maximum amount of freshwater production was notable (97.49%).

A novel design of a twin-chimney solar power plant for power and distilled water production

This work suggests an innovative and distinctive solar twin-chimney power plant (STCPP) design. The proposed unique design consists of a solar chimney power plant, upgraded with a secondary low-cost chimney. Unlike other solar chimney power plants, the proposed design attaches the secondary chimney directly to the collector to maximize water output while having a high energy density and utilization. Several solar chimney power plants designed with water desalination have been proposed in the literature. However, in all the proposed designs, the water desalination occurs mainly at the primary (inner) chimney. In contrast, water desalination occurs at the secondary chimney of the STCPP. The secondary chimney provides a larger surface area than the primary one, hence more water desalination and higher utilization.According to the findings, the novel method produced 1,111,754 kWh of energy annually, 2.9 times more than a conventional solar chimney power plant (384,092 kWh). The findings also revealed that the new design generated 209,165 tons of distilled water instead of nothing with the traditional solar chimney. Additionally, the results showed that the proposed design could reduce CO2 emissions by 658318.5 kg annually, with a 0.650 utilization factor. Furthermore, the comparative study with similar designs showed that the proposed design outperformed all other methods regarding utilization, energy production, water production, and CO2 reduction.

A hybrid study of a 4-stage compressed solar distiller based on experimental, computational and deep learning methods

In the present study, a hybrid technique is employed to demonstrate the thermal performance of a 4-stage compressed solar distiller with hydrophilic evaporators (CSDHE) regarding the role of natural convection in the air gap domain. Initially, the test is conducted under simulated solar radiation of 2.13 W·m−2 over 5400 s. A thermodynamic model incorporating diffusion is developed for the next step to analyze internal transient temperatures. In the third step, a 3D single-phase natural convection model of the CSDHE is simulated to achieve the research objectives. Based on experimental, thermal modeling, and computational results, a dual deep neural network is developed to predict the thermal behavior of the system and the variation of convection heat transfer coefficient for different air gap thicknesses over 10,000 s. The experimental results revealed a distilled water production rate of 3.806 kg·m−2h−1 with a gained output ratio (GOR) of 112 %. Moreover, the findings demonstrate that conduction accounts for 84.23 % of total heat transfer, while convection accounts for 6.36 % during 5400 s. We also found that, by employing a convolutional neural network (CNN) and directly harvesting data from pre-defined contours, the hybrid training dataset for deep forward neural network (DFNN) is trained 28.35 % faster than conventional methods.