Reverse Osmosis Unit Research Articles

Thermodynamic evaluation of a novel renewable energy system that simultaneously provides electricity, freshwater, and syngas using a multiobjective optimization approach

AbstractThis research entails the simulation and thermodynamic evaluation of a combined solar‐powered system that is intended to achieve the energy necessary to construct factories in areas where other sources of energy are not available. The system comprises five major circuits: (1) a parabolic trough that collects solar energy and passes it to downstream circuits via an evaporator, (2) an organic Rankine cycle that generates electricity for devices and factories, (3) a proton exchange membrane electrolysis unit that produces hydrogen from pure water, (4) a methanation unit that produces gas by combining hydrogen and carbon dioxide, and (5) a reverse osmosis (RO) unit that purges seawater to produce freshwater. This investigation studies the efficiency of energy and exergy, the destruction rate of exergy, and the economic value of system components as a whole. The system is represented by the technical equation solver, and the results are obtained as a result. This research employs the genetic algorithm and Technique for Order of Preference by Similarity to Ideal Solution method to locate the most effective point. The achieved outcomes include a maximum total system efficiency of 54.935% and a minimum total cost of 2.578 $/GJ. Dated to the optimal point, the power generated is 305.5 kW, the required power of a single‐cell electrolyzer is 293.8 W, the mass flow rate of methane and hydrogen production is 448.92 and 225.64 kg/h, respectively. The water volume generated by RO is 35.25 m3/h, and the total cost of the investment is 85.57 $/h.

Comprehensive analysis and optimization of a low-carbon multi-generation system driven by municipal solid waste and solar thermal energy integrated with a microbial fuel cell

Abstract In this article, a novel multi-generation plant is addressed and assessed from the energy, exergy, exergoenvironmental and exergoeconomic points of view. The multi-generation plant is composed of two main units: one unit for energy production and another unit for carbon capture and methanol synthesis. Biomass fuel, solar energy and seawater are the main nutrients in the plant. Steam, Brayton, organic Rankine and Kalina cycles have been employed to generate electricity. A linear Fresnel collector-driven solar farm is considered as an auxiliary heat source. In addition, an integrated desalination unit based on a multi-effect desalination unit, a microbial fuel cell and a reverse osmosis unit has been installed in the multi-generation plant. The proposed structure for the offered multi-generation plant is designed under a new configuration and layout that had not been reported in the publications. From the outcomes, the multi-generation plant can produce 69.6 MW of net electricity, 0.53 kg/s of methanol, 0.81 kg/s of oxygen gas, 73.8 kg/s of fresh water and ~0.015 kg/s of hydrogen gas. Under such performance, the offered multi-generation plant can be 51.72 and 27.5% efficient from the points of view of energy and exergy, respectively. Further, the total cost rate and environmental impact of the plant are ~3378 US$/h and 294.1 mPts/s, respectively. A comparative analysis is developed to exhibit the superiority of the planned multi-generation plant. A five-objective optimization is also developed to achieve the optimum design data and outcomes of the plant.

Advanced Exergy Analysis of Cascade Rankine Cycle‐Driven Reverse Osmosis System

A novel solar‐assisted cascade Rankine cycle‐driven reverse osmosis (RO) system is proposed and evaluated using conventional and advanced exergy analysis. The system comprises a solar collector as a heat input, steam Rankine cycle (SRC), and organic Rankine cycle (ORC) to generate turbine work and RO units for brackish water treatment. Water and R1233zd(E) are used as the working fluid in the SRC and ORC, respectively. The RO system is proposed to produce 1 m3 h−1 of permeate water from each RO unit. Conventional exergy analysis shows that the solar collector exhibits the highest exergy destruction of 0.798 kW, followed by the RO unit. However, advanced exergy analysis reveals that only 16.16% of the avoidable exergy in solar collectors can be reduced due to technical constraints. Advanced exergy analysis identified that endogenous avoidable exergy destruction contributes 24% of overall exergy destruction, which can be reduced by optimizing operating parameters and making technical improvements. The RO unit has a higher exogenous avoidable exergy, potentially suggesting improvements in other system component parameters. The advanced exergy analysis also prioritized the components for improving system performance in a sequence of RO high‐pressure pumps, RO modules, solar collector, ORC condenser, evaporative condenser, ORC expander, and SRC turbine.

Mathematical model of thermal water concentration

Thermal spring water is currently widely used as a finished product in the form of a spray and as an important component of effective dermatological and cosmetic products. In the Russian Federation, nitrogensilicon thermal waters (ASTW) are widespread in the Far East, especially in Kamchatka, which means they are significantly removed from the enterprises of mainland Russia that produce dermatological and cosmetic products. The high cost of delivery to processing sites leads to higher prices for drugs containing thermal water as a component. The purpose of the research was to concentrate thermal water of a certain composition using reverse osmosis. The results showed that concentrating water using the reverse osmosis method retained its original properties and the percentage of macro and microelements. High concentration capacity and cost-effectiveness were demonstrated by the use of Desal®TFM roll-type reverse osmosis elements in experiments. A mathematical model of the process of concentrating thermal water from Kamchatka (Nizhne-Paratunsky springs) using a reverse osmosis unit by repeatedly passing it through a membrane is proposed. An original mathematical formula was obtained to determine the rational degree of concentration in order to minimize the total costs of concentration and transportation of the resulting concentrate.

Optimal design of a solar-driven Kalina system for combined power and desalination purposes

This research study presents a thermodynamic simulation and exergy analysis of a solar-powered Kalina cycle that is integrated with a reverse osmosis desalination (RO) module and a thermoelectric generator (TEG) system. A parabolic through solar collector (PTSC) provides the required heat to drive designed plant. The thermodynamic simulation and exergy examination of the proposed system are carried out using the Engineering Equation Solver (EES). A parametric study of the presented plant to show the primary parameters impacts on the system operation is conducted. The system in this study generates 212.7 kW of electrical power and 44.46 m3/h. The total energy efficiency of the plant is 24.3 %. The inlet thermal energy from PTSC is 876.5 kW. In addition, the thermoelectric module generates 7.26 kW electrical power. Carried out analyses show that the recuperator has the most significant exergy destruction rate among all system components, with 303.2 kW. The unit responsible for the second major exergy destruction value associated with the RO unit, which accounts for 74.22 kW. To examine the influence of influences of parameters like direct normal irradiance (DNI), turbine inlet pressure, and mass flow rate of the Kalina cycle the system case study is presented. It can be observed that increasing DNI parameter from 750 W/m2 to 1000 W/m2 leads in a net output power increment from 279.1 kW to 372.1 kW and increasing fresh-water production from 41.64 m3/h to 48.09 m3/h. Moreover, the calculation shows that increasing DNI has a positive impact on the TEG unit output power too. Enhancing the inlet turbine pressure increases both net output power and fresh-water production by reverse osmosis unit while this increment diminishes the thermoelectric unit electrical output. It can be observed that increasing turbine inlet pressure from 110 kPa to 200 kPa, increases net output power and fresh-water production by about 6.08 % and 3.5 %, respectively.

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.

What is the carbon footprint of reverse osmosis in water treatment plants? A systematic review protocol.

"Carbon footprint" (CF) is a direct measure of greenhouse gas emissions caused by a defined activity and can demonstrate global warming effects. The emissions of Greenhouse gases (GHGs) in water projects start from the primary water sources, followed by transportation, construction, and operation phases in the final treatment plants. Due to their possible environmental impacts, the water treatment plants equipped with Reverse Osmosis (RO) units will be investigated for their carbon footprint. The research question is "What is the carbon footprint of reverse osmosis in water treatment plants?". The literature search in this study will be divided into two sequential sections; in the first section, the search will be limited to Scopus, Science Direct, EMBASE, and PubMed databases. The keywords of water, "water treatment plants", "water purification", desalination, "reverse osmosis", RO, "carbon emission", "carbon dioxide/CO2 emission", "carbon footprint", "Life Cycle Assessment" and, LCA will be used. The carbon footprint of RO will be expressed based on the direct and indirect effects based on RO capacity. In the second section, the internet and specialist search will be done, and the search will be updated. No date limitation will be considered, and the main search will be done in English. When the search is completed, the screening will be performed. After removing duplicates, the title and abstract will be examined. The full text will be read if the title and abstract are not helpful for decision-making. In addition, the bibliography and references will proceed after the full-text screening. The Collaboration for Environmental Evidence (CEE) Critical Appraisal Tool will be used for risk of bias checking and study validity assessment. After full-text evaluation, data will be collected and categorized by two authors. If there is enough data, meta-analysis will be performed. Systematic review registration PROSPERO CRD42022327572.

An adaptive power management approach for hybrid PV-wind desalination plant using recurrent neural networks

In hybrid Photovoltaic (PV)-wind desalination plants, power management is necessary because renewable energy sources such as PV and wind are highly variable. An optimal power management system also helps extend the equipment's life by preventing overloading or underloading of the system. This paper proposes a recurrent neural network (RNN) based power management for a desalination plant. In the proposed work, renewable energy sources like solar and wind are utilized to power the reverse osmosis (RO) desalination unit. The developed RNN model optimizes renewable energy sources while maintaining a stable function of the desalination process. The RNN power management module utilizes historical data to predict the power generation of the PV and wind sources and then adjusts the system's output to meet the power demand of the desalination plant while considering the limitations of the RO unit and the water profile requirements. The developed model was implemented in MATLAB tool, and the results are estimated. Simulation outcomes demonstrate that the developed model improves the hybrid system's performance in terms of resource and battery storage utilization and minimizes energy loss.

Performance of a solar hybrid desalination plant integrated with photovoltaic-thermal collectors for remote regions: Experimental and modeling investigation

Energy and freshwater are the most prioritized needs for any nation nowadays, especially for arid areas. Giving attention to renewable energy sources like solar energy is a must towards a cleaner environment and a world with no need of temporary sources like fossil fuels. Also, a solution to lower the power requirements and costs of desalination hybrid systems should be investigated to overcome the water problem. The present study aims to design and build a novel hybrid desalination plant working with the highest productivity and lowest power consumption. This was done by incorporating a reverse osmosis desalination unit with the conventional solar distiller. The photovoltaic/thermal collectors were utilized to produce electricity as well as a heating unit in addition to the evacuated tube solar collectors, to preheat the hybrid desalination plant feed water. The results presented that the use of photovoltaic/thermal panels and evacuated tube solar collectors as preheating units improved water recovery by 46% and reduced power consumption by 38.34% for the small reverse osmosis unit but the salt rejection decreased by 4%. Cooling the photovoltaic panel increased its electricity production by 24.1% on average. Moreover, the combination of the solar distiller with the reverse osmosis unit on the feed line represents the best configuration which improves the solar distiller’s productivity by 98.32% as compared to separate solar distillers. The cost of freshwater produced is 0.719 $/m3 which is cost competitive compared to previous solar desalination systems.

Improving the operation of small reverse osmosis plant using Pelton turbine and supplying emergency electric loads

ABSTRACT This study focuses on improving the operation of reverse osmosis (RO) with Pelton turbine in different circumstances. In the integrated RO system, the Pelton Turbine is used instead of a PX due to its significantly lower cost. The RO system is studied at different pressures ranging from 6.5 to 8.5 bar. Additionally, the influence of feed water TDS and temperature on the RO permeate and retentate was also studied. The experimental results showed that increasing the RO pressure led to an increase in the permeate flow rate. The permeate was heightened by approximately 72% once the pressure was increased from 6.5 to 8.5 bar. However, it was observed that increasing the pressure by 30% resulted in a significant decline in turbine power, which decreased by approximately 71.8%. Furthermore, the study found that raising the salinity led to an increase in RO permeate TDS, while increasing the feed water temperature resulted in a decline in productivity TDS. To control the high-pressure pump and supply emergency loads, an Arduino program circuit was used, providing a convenient and flexible way to manage the system. The theoretical modeling developed in the study was found to be in better agreement with the real findings, with a deviance of 3.51%. This indicates the accuracy and reliability of the model in predicting the operation of the integrated RO unit. Finally, the cost of the produced water was 0.26 $/m3.

Synergistic cotreatment of cooling tower blowdown and produced waters: Modeling strategies for a comprehensive wastewater treatment simulation

Cooling tower blowdown from thermoelectric power plants and produced water from hydraulic fracturing may soften when mixed due to the complimentary chemistry of the two wastewaters. The potential benefit of low effort softening warrants the investigation of a cotreatment process concerning these industrial wastewaters. The synergy is expected to lessen chemical demand for softening and further enable sustainable practices such as designing for a zero-liquid discharge (ZLD) process. The treatment process may then provide a treated effluent suitable for use as blowdown makeup. In this study, the feasibility and effectiveness of a cotreatment train is explored through simulation of chemical softening, filtration, reverse osmosis (RO), multi-effect distillation (MED), and electrolysis unit operations within a comprehensive process model. Innovative modeling strategies are necessary to result in a meaningful process model when considering the significant complexity of the water chemistry for this treatment train. Through the methodology described in this work, a feasible process design is presented as a base case for treatment of experimentally characterized blowdown and produced water samples obtained in the northern Appalachian region. Thereafter, the base case also establishes a platform for more detailed process analyses of different scenarios in future work. Detailed descriptions of modeling methodologies, process design decisions, and simulation results are provided as a perspective on comprehensive modeling of multi-technology treatment trains for complex feedwaters. With the results of the cotreatment simulation, it is determined that the total water recovery of the process may serve to completely makeup the blowdown rate and partially make up the evaporative losses of a theoretical thermoelectric plant's water demand. This complete recovery is evaluated to require 18,343.531 kW of a chemical energy equivalent, 1184.971 kW of electricity, and 68,126.291MJh−1 of power plant steam to result in 408.532m3h−1 of treated water effluent at a quality of approximately 0.135gL−1 total dissolved solids for the base case design.

Improved efficiency in an integrated geothermal power system including fresh water unit: Exergoeconomic analysis and dual-objective optimization

The single-flash geothermal cycle (SFGC) is not without its limitations, featuring drawbacks like diminished efficiency, restricted power generation capacity, and the incapability to yield multiple outputs concurrently. Furthermore, the SFGC requires a substantial water supply, potentially leading to adverse environmental consequences. In a concerted effort to enhance overall performance and facilitate the concurrent production of multiple valuable products, this study introduces a multigeneration system (MGS). By integrating additional subsystems into the SFGC framework, including a branched GAX cycle enabled by a thermoelectric generator (TEG), a domestic water heater (DWH), and a reverse osmosis unit, the objective is to surmount these limitations effectively. A thermodynamic and exergoeconomic analysis of the system is conducted and a bi-objective optimization is employed to minimize system cost and maximize exergy efficiency. The parametric study reveals that when degassing ranges are in the range of 0.2–0.37, the system product cost varies from $27.07/MWh to $28.44/MWh. In the optimized scenario there is a decrease of 67.7% in cooling provided by the system. This leads to an increase of 3.5% in generated electricity and a 3% increase in water purification compared to the base scenario. Through optimization the exergy efficiency of the system improves from 61.84% to 62.90% while the multigeneration gain output ratio (MGOR) decreases from 1.40 to 1.38.

Characteristics of dissolved organic matter in point-source wastewaters at a petrochemical plant: Molecular constituents and contributions to the influent of wastewater treatment plant

Dissolved organic matter (DOM) in point-source petrochemical wastewaters (PCWs) from different operating units is closely linked to the efficiency of wastewater treatment plant (WWTP). However, systematic studies on DOM characters of point-source PCWs and their influences on WWTP influents were seldom conducted. In this study, DOM in three low-salinity point-source PCWs and four high-salinity point-source PCWs at a typical petrochemical plant were comprehensively characterized at a molecular level. Orbitrap mass spectrometry results indicated that point-source PCWs had diverse DOM constituents tightly related to the corresponding petrochemical processes. Phenols in oily wastewaters (OW), phenols and N-containing compounds in coal partial oxidation wastewater (POXW), and naphthenic acids (NAs) and aromatic acids in crude oil electric desalting unit wastewater (EDW) were characteristic DOM constituents for low-salinity point-source PCWs. While S-containing compounds (mercaptans, thiophenes) and NAs in spent caustic liquors (SCL), alcohols and esters in butanol-octanol plant wastewater (BOW), high molecular weight aromatic ketones in phenol-acetone plant wastewater (PAW), and oxygenated NAs as well as short chain N-containing compounds in concentrate from reverse osmosis unit (ROC) were characteristic DOM constituents for high-salinity point-source PCWs. Spearman correlation analysis indicated that though with relative low pollutant contents (OW) and discharge volume (EDW), N/O/S-containing compounds of OW and EDW greatly contributed to the polar DOM constituents of low-salinity influent in WWTP (R > 0.5, P < 0.001). While N-containing compounds of ROC mainly contributed to the polar DOM of high-salinity influent (R > 0.5, P < 0.001). Though N-/S-containing species in PAW had low contents, they also posed obvious impacts on DOM constituents of high-salinity influent. Interestingly, some O-/S-containing species were newly formed during the confluent process of high-salinity point-source PCWs. The results strengthened the combined contributions of pollutants contents, discharge emission and DOM constituents of point-source PCWs to the water matrix of WWTP influents, which would provide reference for the management of PCW streams.

Optimizing Solar Energy Harvesting through Integrated Organic Rankine Cycle–Reverse Osmosis Systems: A Techno–Economic Analysis

When it comes to seawater desalination in the small- to medium-electricity ranges, the organic Rankine cycle (ORC) powered by solar energy stands out as the most energy-efficient technology currently available. Various solar techniques have been developed to capture and absorb solar energy. Among them, the parabolic trough collector (PTC) has gained recognition as a low-cost solar thermal collector with a long operating life. This study investigates the thermodynamic performance and economic parameters of a PTC-powered ORC using Dowtherm A and toluene as working fluids for the solar cycle and ORC cycle, respectively. Thermo-economic multi-objective optimization and decision-making techniques are applied to assess the system’s performance. Four key parameters are analyzed for their impact on exergy efficiency and total hourly cost. Using TOPSIS decision-making, the best solution from the Pareto frontier is identified, featuring an ORC exergy efficiency of 30.39% and a total hourly cost of 39.38 US$/h. The system parameters include a mass flow rate of fresh water at 137.7 m3/h, a total output net power of 577.9 kJ/kg, and a district heating supply of 1074 kJ/kg. The cost analysis reveals that the solar collector represents approximately 68% of the total hourly cost at 26.77 US$/h, followed by the turbine, thermoelectric generator, and reverse osmosis (RO) unit.

Innovative desalination system driven by a solar micro gas turbine for off-grid applications

Past work by the authors has suggested that Solar micro Gas Turbines (SmGTs) can be used cost-effectively to produce electric power and heat for freshwater production through desalination, mainly in off-grid locations. This is further studied in this work, providing an exhaustive modelling procedure and methodology. Additionally, a comprehensive analysis of system performance under both design and part-load conditions is provided along with the complete set of characteristics of the components of the SmGT and the desalination unit. To this end, the SmGT is assessed first, incorporating innovative solutions that enable better off-design performance: Variable Inlet Guide Vanes (VIGVs) in the compressor and Variable Nozzle Guide Vanes (VNGVs) in the turbine. The implementation of these features brings significant advantages in part-load operation, leading to a considerable increase in solar-to-electric efficiency and rangeability, particularly under certain ambient conditions; in particular, using these features yields 5% higher efficiency at the minimum load of the original engine (without variable geometry) and, from this load setting downwards, 15% lower minimum stable load is enabled. Furthermore, a sensitivity analysis to control strategies and ambient conditions has been included, exploring their impact on system performance.The water treatment system is comprised of two elements. A Reverse Osmosis (RO) desalination unit is driven by the electric power produced by the SmGT. Considering the emphasis on flexibility and part-load operation enhancement addressed in this work, a moderate recovery rate is proposed for this unit. The RO unit produces brine with high salt concentration to be partially treated further in a Zero Liquid Discharge (ZLD) unit driven by the exhaust gases of the microturbine (at about 250–300 °C), where the sensible heat of this stream is harvested by the ZLD unit to “dry” and concentrate the effluent. Finally, the potential and the operational limitations of the ZLD system are discussed, complemented with results from an experimental proof of concept where the feasibility of the concept is verified.

Modular operation of renewable energy-driven reverse osmosis using neural networks for wind speed prediction and scheduling

Operating reverse osmosis (RO) systems with renewable energy (RE) can contribute greatly to water security. However, the stochastic and intermittent nature of renewables means that most large-scale RO relies on fossil fuels via a grid connection. Modular operation by connecting and disconnecting RO units is promising to power multi-unit RO entirely from RE. Nevertheless, it may lead to excessive start-ups/shutdowns, especially when using wind energy. This paper proposes using neural networks for wind speed prediction and scheduling to improve the modular operation of wind-powered RO. A modular operation technique was developed for a three-unit RO system with variable water output. To estimate the number of operating units, a neural network was designed to predict wind speed 24 hrs ahead, giving a correlation (R = 0.64) and a RMSE of 1.54 m/s against real data. Two approaches, high- and low-output scheduling, were defined to either maximise production or minimise unplanned shutdowns during modular operation. The high- and low-output scheduling reduced the number of start-up/shutdown cycles by 37.5 % and 75 % compared to unscheduled operation, leading to a 1.9 % and 2.3 % improvement in specific energy consumption, respectively. Overall, scheduled RO operation minimised unplanned shutdowns and delivered stable performance while following recommended operating procedures.

A novel solar-powered thermal desalination unit coupled with a reverse osmosis plant to increase overall water recovery

The global water crisis could be alleviated by converting saline water to potable water through desalination technologies. Reverse osmosis is the dominant technology in the market. However, its brine disposal is challenging. This paper proposes and investigates a novel hybridization between a solar-driven reverse osmosis plant and a solar-driven thermal desalination unit to enhance the water recovery ratio (freshwater produced/feed saline water). The thermal desalination unit combines an adsorption cycle, ejectors, and a humidification-dehumidification cycle. The brine from the reverse osmosis unit is used as a feed for the thermal desalination unit to produce higher amounts of freshwater. The extra-high saline water discharged from the proposed system can be used for salt extraction in a solar pond as a byproduct. Theoretical and economic models are developed to evaluate the performance and cost of the proposed system. It is found that the recovery ratio of standalone reverse osmosis and the proposed hybrid desalination plant is 40.8% and 70.5%, respectively, having a feed salinity and brine salinity limit of 32,500 ppm and 110,000 ppm. The recovery ratio of the hybrid system could reach 84%, with brine disposal of 220 ppm (which is valid for salt crystallization processes). The reduction in freshwater cost by using the hybrid plant is 23% to 27% compared to the standalone reverse osmosis plant for 40,000 to 50,000 ppm feed salinity and 10 m3 plant capacity. The suggested system can produce freshwater of 83 and 47 m3 per ton of silica gel per day at the gained output ratio of 2.71 and 2.6 in June and December, respectively.

Performance and control of a reverse osmosis unit integrated with Pelton Wheel to supply emergency electric loads under various operating conditions

Nowadays, the whole world is moving very quickly into the field of seawater desalination. This is because the world suffers from a lack of potable water. Water and energy are adjoining linked fields. The present work aims at investigating the performance of a reverse osmosis (RO) plant integrated with Pelton Wheel under various operating conditions. The main reason for using Pelton turbine instead of the pressure exchanger (PX) is the low cost of Pelton compared to that of PX. The RO system integrated with the Pelton Wheel was tested under various operating pressures of 650, 700, 750, 800, and 850 kPa. Changing the feed water pressure affects the pressure of the reject entering the Pelton wheel and this, in turn, affects the velocity of the water jet. Also, the impact of varying the feed water salinity (total dissolved solids (TDS) = 400, 500, 600, 700, and 850 ppm) and temperature (20–39 °C) on the permeate and reject of RO was tested. In addition, a theoretical modeling was built to predict the performance of the RO system. The permeate flow rate was increased by raising the RO operating pressures. The permeate flow rate was augmented from 2.5 to 4.3 L min−1 when increasing the operating pressure from 650 to 850 kPa, respectively. Therefore, the permeate flow rate is enhanced by around 72% when increasing the operating pressure by only 30%. Besides, increasing the pressure by 30% (from 650 to 860 kPa) decreased the generated power of the Pelton Wheel by approximately 72% (from 960 to 270 W, respectively). Also, increasing the feed water salinity leads to raise the salinity of RO permeate, and vice versa. The RO permeate salinity is raised from 165 to 285 ppm when increasing the operating pressure from 650 to 850 kPa, respectively. As well, the more the increase in feed water temperature, the more improve in the permeate flux and salinity. The permeate TDS was decreased from 140 ppm at feed-water temperature 20 °C to 56 ppm at feed water temperature 39 °C. In this study, the Arduino program circuit was used to supply the required emergency loads by controlling the pressure values of high-pressure pump due to easy and open code program. Finally, the theoretical modelling results are in good correspondence with the experimental results. The average deviation among the theoretical and experimental results was 3.5%.

Techno-economic modeling of a novel poly-generation system based on biogas for power, hydrogen, freshwater, and ammonia production

In the current study, a new poly-generation energy system run by biogas steam reforming is proposed and assessed. To dissect the techno-economic feasibility of the offered system, energy, exergy, and sum unit cost of the products (SUCP) are considered as robust indicators for the system appraisal. Also, to acquire enhanced thermodynamic efficiencies, the system has benefited from the careful design of the biogas steam reforming unit, modified Rankine cycle, ammonia synthesis unit, hydrogen generation equipment as well as reverse osmosis unit. It is uncovered that the prepared poly-generation system is qualified to provide 687.4 kW of power, 0.9662 kg/s of freshwater, 0.15 kg/s of hydrogen, and 1.149 kg/s of ammonia. Besides, the energy and exergy efficiencies of the system have been calculated at about 18.9% and 16.9%, respectively with a total exergy destruction rate of 51020.78 kW. Also, following the results of the thermodynamic appraisals, the biogas steam reforming reactor and ammonia synthesis reactor have the highest contributions to inefficiencies happening in the system. Furthermore, from a sweeping sensitivity investigation, the optimum performance of the system appears in a biogas steam reforming reaction temperature of 1050K. Also, the SUCP decreases by about 21 $/GJ by increasing the Biogas Steam Reforming reactor pressure.

Evaluating the Efficiency of Magnetic Treatment for Feed Water in Reverse Osmosis Processes.

The paper presents a new methodology for short-term (5-25 min) benchtop tests to evaluate the effectiveness of magnetic treatment of feed water for reducing mineral scaling on a reverse osmosis (RO) membrane. Scale deposition is measured at a controlled level of salt supersaturation in water flowing through an RO unit in once-through mode. A magnetic water conditioner is tested in a transient flow regime when variations of the permeate flux along the flow path are insignificant. Scale formation under these conditions is governed by salt crystallization on the membrane surface. The proposed method was implemented to investigate the influence of magnetic treatment on gypsum deposition on RO membranes in supersaturated aqueous CaSO4/NaCl solutions. The effects of magnetic water treatment on scale formation under our experimental conditions were found to be statistically insignificant with a confidence level of 95%. However, this outcome should not be considered to negate the potential efficiency of magnetic water treatment in specific applications. The proposed methodology of testing under a controlled level of salt supersaturation will also be useful for evaluating the efficiency of other water treatment technologies.