Distilled Water Production Rate Research Articles

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.

Design and optimization of an integrated novel desalination system based on the temperature difference between the sea and mountain

As the world’s population and increasing urbanization continue to grow, freshwater needs have risen dramatically. A desalination process based on a natural vacuum and pipeline desalination method that can produce freshwater and transfer it simultaneously is designed and modeled comprehensively in this research. It has been demonstrated that the effect of compressibility is negligible for pressure and temperature ranges of the system, indicating that the first system model using incompressible flow assumption is valid. Solar thermal energy was also utilized to improve the system’s efficiency. The results are investigated for three scenarios for Bandar-Abbas and the adjacent mountain, Genu. The first, second, and third scenarios are associated with the initial model based on pipeline desalination, the model utilizing solar cooling to reduce the temperature in the condensation section, and the model using solar energy to increase the temperature in the evaporation section, respectively. The results show that the highest freshwater production is estimated at 125,842,962 and 21,101,132 kg per year for a tube diameter of 2 and 1 m, respectively. Furthermore, the annual production rate of distilled water in scenarios #2 and #3 increased by 13.85% and 139.1% compared to scenario #1, with a tube diameter of 2 m.

Single-stage tubular and multistage planar systems of passive permeate-side-heated solar membrane distillation

Scarcity of drinking water is a global problem and especially serious in rural areas of developing countries. Passive permeate-side-heated interfacial-heating solar membrane distillation has been shown recently as a promising system for off-grid distributed water and wastewater treatment. In this study, single-stage tubular systems were developed by giving the poly(vinylidene fluoride) (PVDF) membrane (pore size: 0.45 µm) a tubular structure with the outer surface (i.e., the permeate side) coated with carbon black NPs which absorbed solar thermal energy and evaporated the feedwater inside the membrane tube. Under natural sunlight, the vertical tubular system had a production rate of distilled water per footprint of 0.67‒2.06 kg m−2 day−1 throughout the year, 71% higher than the single-stage planar system on average. The three-stage planar systems were developed by overlapping three single-stage modules. Two adjacent modules shared a common copper sheet that serves as both the top of the condensation chamber of the preceding stage and the bottom of the feedwater chamber of the following stage. The copper sheet can partially transfer the condensation heat of the preceding stage to the feedwater of the following stage, thus enhancing the system energy efficiency (ƞsys) in producing distilled water. The ƞsys and distillate flux of the three-stage systems were 62% and 5.01 kg m−2 day−1, respectively, at the average daytime irradiance of 422 W m−2, 34% higher than the single-stage planar systems.

Investigational study on improving the yield from hybrid PV/T modified conventional solar still with enhanced evaporation and condensation technique - An experimental approach

ABSTRACT Renewable energy source is insisted in all areas of technology, especially the adaptation of solar power for various purposes. The present investigational study is carried out to improve the efficiency of PV/T solar still using enhanced evaporation and condensation technique. A DC-powered blower is fixed inside single slope solar still which increases the turbulence of evaporated vapor from the saline water inside the solar still while the condensation is improved using the cover cooling technique. The experiment is conducted on a constant water depth of 1 cm with three different blow rate periods (5 min, 10 min, and 15 min). The blower runs and stops for 30 seconds time period in all blow rates. To improve the efficiency of the photovoltaic system, an inorganic phase change material (PCM) (Glauber salt (Na2SO4.10H2O) is used underneath the PV panel for cooling the panel. To obtain a higher production rate of distilled water, a nickel-chromium (NiCr) heater is placed in the solar still which is powered by the integrated solar PV system. This proposed work helps to enhance the freshwater production process from saline water and also solar power production. From this investigation, it is observed that the proposed PV/T solar still gives an improved overall thermal and electrical efficiency of almost 12.5% and 11.5% respectively, and is superior as compared to the conventional solar still.

Comprehensive analysis of design software application in solar distillation units

The use of solar stills in rural regions are becoming increasingly popular as it is an economical solution for drinking water from saline water sources. Many researchers have worked for the improvement of conventional solar still to enhance productivity. Costly and time-consuming processes of operation in solar stills encourage many scholars to analyze mathematical simulation. This paper presents comprehensive reviews of the application of different design software to solar still systems. Design software is essential for developing and analyzing the mathematical models and predicting the most suitable performance parameters for the enhanced production rate of distilled water for still systems. Numerical modeling of solar still systems is necessary to analyze and investigate air movement, temperature variation for knowing water temperature, and air temperature through software like CFD, MATLAB, FORTRAN, TRYNSYS AutoCAD. The simulation technique's application using CFD is made with TRNSYS, FLUENT, ANSYS, FORTRAN and MATLAB which are useful tools to develop such mathematical models for the prediction of flow parameters. Engineering Equation Solver (EES) package and COMSOL Multiphysics solve the differential energy balance equation. All newly developed software employed for the utility of still solar systems is discussed. This article provides a comprehensive overview of the various software tools used in solar still to help researchers, scientists, and academicians.

New solar still with energy storage: application to the desalination of groundwater in the Bou-Ismail region

Abstract This study aims to develop efficient desalination equipment that increases the distilled water production rate and enhances heat transfer in the evaporator. It focuses on the impact of equipment geometry and energy storage during the daytime and nocturnal period. In addition, the effects of the energy storage system, which is placed in two specific areas on the yield of the distillation process with and without energy storage, have been studied. The heat exchanger system provides the energy to the water to be treated in the daytime, while the concrete part provides the energy storage in the desalination evaporator at night time. The experimental test results showed that the increase of distilled water through the heating system is very important in comparison to the productivity of the conventional solar still. The obtained results indicate that the use of energy storage increases productivity by 50% in the nocturnal period. Indeed, the daily productivity of the concrete solar still, strongly affected by the heat transfer produced via concrete to the water evaporator, is presented in this study. It was found that the average daily distillate output of concrete solar still with energy storage is more significant than that of a solar still without energy storage.

Energy, Exergy Analysis, and Optimizations of Collector Cover Thickness of a Solar Still in El Oued Climate, Algeria

Researches in many laboratories on solar still desalination are concerned with increasing efficiency using only solar energy. One of the techniques is the difference in the thickness of the glass cover of the distiller. In order to see the influence of this parameter on efficiency, three similar stills with three different glass coverings were investigated. The flow of heat goes through the cover, and higher glass temperature leads to solar still productivity becoming lower. This paper presents an optimization of glass thickness ( G t ) of a conventional solar still (CSS) in El Oued climate, Algeria. Based on the experimental results, the distilled water production rate, energy, and energy efficiency of the CSS have been discussed. The results showed that the suitable G t of the CSS was 3 mm. The distilled water of around 3.15, 2.02, and 1.13 kg was produced by the CSS at energy efficiency of 30.71, 19.02, and 11.44% with the G t of 3, 5, and 6 mm, respectively. The daily average exergy efficiency of 2.46, 1.38, and 0.84% was calculated for the CSS at G t of 3, 5, and 6 mm, respectively.

Solar still desalination system equipped with paraffin as phase change material: exergoeconomic analysis and multi-objective optimization.

The current work is about analysis and multi-objective optimization (MOO) of weir-type solar still systems equipped with phase change material (PCM) regarding the exergetic and economic performance. To do so, the energetic and exergetic modeling of the suggested system is conducted then the substantial economic factors is applied to obtain the total cost rate of the considered SSDS. The total exergetic efficiency and total annual cost (TAC) is considered objective functions. Four parameters include mass of the PCM (mPCM), inlet brine water flow rate ([Formula: see text]), gap distance (d), and insulation width (xins) is chosen as decision variables. Moreover, a genetic algorithm-based MOO was applied to find the optimum states of evaluated solar still unit. The outputs represented that increasing the brine feed water mass flow rate does not affect the TAC while decreasing distilled water production rate. The scattered distribution of optimum states infers that the optimum value of PCM mass is about 1 kg. In addition, applied MOO reveals that with optimization of the studied system, the exergy efficiency increases about 1.47% and the annual distilled water increases 4.35% compared with the non-optimized system. The suggested system is capable to produce fresh water in remote areas without any pollution as well as in a low cost rate.

Distilled water production with combination of solar still and thermosyphon heat pipe heat exchanger coupled with indirect water bath heater – Experimental study and thermoeconomic analysis

The aim of this study is to provide a solution for supplying distilled water used in indirect water bath heaters in the pressure reduction stations. A particular type of distilled water production system consists of a typical solar still and a heat pipe heat exchanger was constructed for recovering heat from the exhaust of an indirect gas heater. The system was tested under the climatic conditions of Semnan-Iran. Experimental results showed that in active type, the average daily production rate of distilled water would be 2.06 times higher than passive type. Also, in the proposed system, the average daily energy efficiency and the exergy efficiency would be 65.5% and 41% higher than the passive ones, respectively. The economic analysis showed that, the average CPL value and average exergoeconomic parameters for the active type was 32% higher and 15% lower than the passive ones, respectively. The exergoeconomic parameters for the passive and active types at the best case (5% interest rate, 20 years lifetime and 1 cm water depth), were 0.32 and 0.25 kWh/$ respectively. Furthermore, analysis showed that in average the active type mitigated 104% and 146% more CO2 compared to the passive type for environmental and exergoenvironmental parameters, respectively.

Development, evaluation, and multi-objective optimization of a multi-effect desalination unit integrated with a gas turbine plant

In this research study, a 40 MW gas turbine power plant, which is coupled with a multi-effect desalination system with thermal vapor compression, is investigated. The energy, exergy and exergoeconomic analyses of the integrated plant are presented. As the number of effects in a desalination system is a key parameter, the effect of number of effects on the system performance is investigated. The genetic algorithm-based multi-objective optimization is applied to determine the best decision variables.To achieve the best optimization states, different scenarios of multi objective optimization based on the total exergy destruction rate, unit electricity price, total cost rate, gain output ratio, distilled water cost, and total exergy efficiency are examined. Additionally, seven decision variables are compressor pressure ratio (rp), combustion temperature (T3), compressor isentropic efficiency (ηc), gas turbine isentropic efficiency (ηGT), top brain temperature (TBT), last effect temperature (LET), and ejector compression ratio (Cr). The parametric analysis results indicated that although increasing the number of effect enhance the distilled water production rate, it increases the total cost rate of the system. With motive steam flow rate of 14 kg/s, results showed that distilled water production rate is 12294m3/day. Additionally, with three different scenarios the optimal states of integrated system are introduced. The results of optimization scenarios suggested different optimal states that are best guide for designer to select the best system configuration.

Experimental Investigation and Performance Analysis of Double-Basin Solar Still Using CFD Techniques

Even though water is a renewable resource, most of the water present on the earth’s surface is not suitable for direct human consumption. Besides, due to increasing population, urbanization, environmental pollution and growth of industries, the requirement for pure water is found increasing day by day. Also, natural resources of water can meet freshwater demand to only to a limited extent. Hence, there is a need to find a way to purify saline water with the help of an effective water desalination technique. Solar still is one such method which makes use of naturally available sunlight to purify impure/saline water. In this paper, a double-effect passive solar still is designed for experimental investigations to determine the freshwater collected at the output channel. Also, a two-phase, three-dimensional model of the unit is developed in ANSYS FLUENT for the transient state to simulate various temperatures inside the solar still and to estimate the production rate of distilled water produced. The simulation was run for 8 h, and the results have been compared with the experiment performed. Experimental investigations show a total distilled output of 3.2 L/m2 collected in channel, whereas according to analysis results, 3.74 L/m2 output is observed. Here, simulation results follow the similar trend as the experimental results and show good agreement with each other.

Experimental studies on passive inclined solar panel absorber solar still

This manuscript aims to analyze the passive inclined solar panel basin (PISPB) still at diversified flow rate of water (mf). The freshwater collected from the solar still for different mf at 4.68, 7.56 and 10.08 kg h−1 is 3.7, 2.7 and 1.6 kg, respectively. Results showed that at higher flow condition, the still energy and exergy efficiency decreases and it is estimated as 36.06, 25.56 and 16.95% and 2.97, 1.91 and 1.01%, respectively, for flow rates of 4.68, 7.56 and 10.08 kg h−1. Results revealed that electrical, thermal and exergy efficiency of photovoltaic panel increases under higher flow condition and it is found as 8.05, 8.81 and 9.44%, 11.43, 20.8 and 22.17 and 19.38, 20.58 and 21.16% for mass flow rates of (mf) 4.68, 7.56 and 10.08 kg h−1, respectively. When the mf increases, there is a decrease in the PISPB still distilled water production rate, thermal and exergy efficiency, and there is an increase in power production, electrical, thermal and exergy efficiency through the photovoltaic panel.

Low-grade waste heat driven desalination with an open loop heat pipe

An innovative low-grade heat driven desalination system inspired by heat pipe is proposed in this work. The system utilizes siphon force to create vacuum environment for seawater evaporation at much lower temperature which can significantly reduce energy consumption. The capillary force of the NiO wick pumps the seawater to the evaporator and pushes the generated vapor to the condenser without using any additional mechanical equipment. Localized vaporization in the micro channels of the NiO wick's surface further improves the heat utilization efficiency. Experimental results show that nearly 3.88 kg/(m2·h) of distilled water production rate can be produced at the heat source temperature as low as 34 °C and this value can be increased to 55.25 kg/(m2·h) at the temperature of 60 °C. The corresponding heat-conversion efficiency is 65.2% and 90.7%, respectively, which is much higher than that of most conventional desalination techniques. With the very low temperature operation condition and high efficiency, this novel technology may provide an efficient approach to harvest low-grade heat for fresh water production.

Multi-objective optimization of two double-flash geothermal power plants integrated with absorption heat transformation and water desalination

Abstract Two configurations of double-flash geothermal power plants, one is combined with water desalination and one integrated with absorption heat transformation and water desalination, are proposed and investigated from the viewpoint of exergoeconomics. The main purpose of investigated systems is the simultaneous generation of electrical power and distilled water. A three-objective optimization procedure is performed to determine the optimal design points, considering for all configurations the decision parameters to be the pressures of low and high-pressure flash chambers and the temperatures of the evaporator and generator. The optimization aims to minimize the product unit cost, while maximizing the electric power generated and the production rate of distilled water. The Pareto frontiers for each configuration are drawn as part of the procedure. It is shown that, at constant and equal pressures of the high-pressure flash chamber, the product unit cost for the system combined with the absorption heat transformer is the lower of the two systems considered. In addition, under the optimized conditions, the product unit costs are approximately equal for the two studied configurations. However, the value of generated power for the system with an absorption heat transformer is about 17% greater than for the alternate system. Moreover, the system integrated with an absorption heat transformer has higher thermal and exergy efficiencies, at about 20% and 3%, respectively.

Solar assisted modified variable pressure humidification-dehumidification desalination system

Variable pressure humidification technology is proposed for seawater desalination through evaporation at pressure(s) less than atmospheric and subsequent condensation. Two sub-atmospheric humidification processes (process-I and II) utilizing solar heat are proposed and assessed theoretically. The desalinated water production rate, gained output ratio and an economical comparison between processes are made subject to similar operating conditions. It is deduced that, under similar conditions, pressure reduction from 0.9 bara to 0.1 bara leads to approximately 50% increase in the desalinated water production rate in each of the proposed processes. For humidifier pressures less than atmospheric pressure, the maximum gained output ratio for process-II is higher by 139.13% than that of process-I while the distilled water production rate is lower by 5.71%. Unlike other variable pressure desalination processes, there is no need to use compressor when the vacuum pump is present. To have a comprehensive study of the proposed systems and determine their feasibilities, a cost analysis is conducted. The result of cost analysis indicates that the total cost per liter of distilled water in two proposed process are 0.034 and 0.041 US $/L, respectively. This value is estimated to be reduced to 0.002 US $/L for an industrial scale variable pressure humidification-dehumidification plant.

Performance evaluation of photovoltaic/thermal–HDH desalination system

The efficiency of photovoltaic (PV) panel drops with increase in cell temperature. The temperature of the PV panel can be controlled with various cooling techniques. In the proposed work the PV panel is cooled by circulating water and the recovered heat energy is used to run a humidification and dehumidification desalination to produce distilled water from sea water (or) brackish water. This work deals with a detailed analysis of performance of combined power and desalination (Photovoltaic/Thermal–Humidification and Dehumidification) system. A mathematical model of PV/thermal–humidification dehumidification plant was developed and simulations were carried out in MATLAB environment. The performance of photovoltaic/ thermal desalination (Photovoltaic/Thermal–Humidification and Dehumidification) system was investigated under various solar radiation levels (800–1000 W/m2). For each solar radiation level the effect of mass flow rate of coolant water (30–110 kg/h) on water outlet temperature, PV efficiency, PVT thermal efficiency, distilled water production, and plant efficiency was studied. Results show that under each solar radiation level increasing coolant flow rate increases efficiency of PV panel and reduces the plant efficiency. The highest PV efficiency (16.598%) was reached under 800 W/m2 at mass flow rate of 110 kg/h and the highest plant efficiency (43.15%) was reached under 800 W/m2 at a mass flow rate of 30 kg/h. The maximum amount of distilled water production rate (0.82 L/h) was reached under 1000 W/m2 at water mass flow rate of 30 kg/h.

Concurrent hydrogen and water production from brine water based on solar spectrum splitting: Process design and thermoeconomic analysis

This paper presents a novel process for high efficiency production of hydrogen and desalination of brine water based on the concept of solar spectrum splitting. The advantage of this system is concurrent production of hydrogen and distilled water using a sustainable process at large scale. The harvested energy from the separated solar spectral bands is used to supply the required energy for high temperature steam electrolysis and a double-stage flash distillation system. The integrated solar system is designed to reduce the energy conversion deficiencies, considerably. In order to investigate the performance of this system, a process simulation code is developed. An exergy analysis is conducted and the economic feasibility of the plant is evaluated. The sensitivity of the integrated cycle performance on solar insolation, electrolyzer temperature, and pressure is analyzed, and the results indicate that utilization of concentrator cells, with a multi-band gap mirror can increase the productivity of the cycle, drastically. It is observed that hydrogen and distilled water production rate can be increased by more than 1.6 times, when the harvested solar power increases from 28 MW to 55 MW. It is concluded that the maximum energy and exergy efficiencies of the integrated solar cycle is about 45%.

Proposal and performance assessment of novel combined ORC and HDD cogeneration systems

In this paper, four combined cogeneration systems including the Humidification-Dehumidification Desalination (HDD) and Organic Rankine Cycle (ORC) are investigated from thermodynamic and economic viewpoints. In the first scenario, the outlet water flow of ORC condenser enters the HDD directly as feed water. In the second scenario, the temperature of ORC condenser outlet water rises in a heat exchanger by the ORC evaporator heat source outlet flow before entering the HDD. In the third scenario, the ORC evaporator heat source outlet flow passes through a heat exchanger to heat the HDD feed water. The fourth scenario is a combination of scenarios (I) and (III) so that it contains both of them in one configuration. In all the scenarios the ORC waste heat either from its condenser or evaporator is utilized. Results show that the ORC with toluene produces more power and that scenarios (IV) and (II) produce more desalinated water compared to the other scenarios. It is also observed that, compared to seven working fluids, using n-heptane as a working fluid in these two scenarios results in the highest distilled water production rate. It is concluded that the least distilled water unit cost is achieved by the scenarios (I) and (II), respectively and that using n-heptane, among the other working fluids, brings about the least unit cost for produced distilled water.

Experimental study of waste concentration by mechanical vapor compression technology

To study the concentration characteristics of mechanical vapor compression (MVC) technology on the wastewater concentration process, a single-effect MVC system for concentrating dimethylacetamide wastewater was investigated. The performance of the MVC experimental system was evaluated under different levels of distillation pressure and concentrations of the raw solution. We demonstrated that under conditions of atmospheric distillation (evaporating temperature was 100°C), the COP and distilled water production rate of the experimental system reached 20.17 and 70.80kg/h, respectively. In the distillation operating cycle, the DMAC solution was concentrated from 6% to 83.5%. In addition, when the system was under vacuum conditions (evaporating temperature was 55.8°C), the COP and distilled water production rate were 5.44 and 18.2kg/h, respectively, and the concentration of the DMAC dilute solution was only 0.2%.

Design and Performance Analysis of a Modified Vacuum Single Basin Solar Still

Water is essential to life. The origin and continuation of mankind is based on water. The supply of drinking water is an important problem for the developing countries. Among the non-conventional methods to desalinate brackish water or seawater, is solar distillation. The solar still is the most economical way to accomplish this objective. Tamilnadu lies in the high solar radiation band and the vast solar potential can be utilized to convert saline water to potable water. The sun’s energy heats water to the point of evaporation. When water evaporates, water vapour rises leaving the impurities like salts, heavy metals and condensate on the underside of the glass cover. Sunlight has the advantage of zero fuel cost but it requires more space and generally more equipment. Solar distillation has low yield, but safe and pure supplies of water in remote areas. In this context, the design modification of a single basin solar still has been discussed to improve the solar still performance through increasing the production rate of distilled water. The attempts are also made to increase the productivity of water by using different absorbing materials, depths of water, heat storage medium and also by providing low pressure inside the still basin. They greatly improve the rate of evaporation and hence the rate of condensation on the cooler surface. The theoretical results agree well with the experimental ones.