Gained Output Ratio Research Articles

The optimum location of vapor compressor in multistage vacuum membrane distillation system

This paper investigates the performance optimization of a multistage vacuum membrane distillation (MSVMD) system integrated with a mechanical vapor compressor (MVC) for efficient water desalination. The conventional integrated MSVMD and MVC systems lack a detailed analysis regarding the optimal placement of the MVC, which can influence both productivity and energy efficiency. To address this gap, this study evaluates different compressor placements within the MSVMD setup, assessing their impact on productivity and the gained output ratio (GOR) under various operational parameters, including feed temperature, flow rate, number of stages, and vacuum pressure. The results reveal that the optimal MVC placement can increase system productivity by up to 28 % and enhance energy efficiency, achieving a GOR of about 13. Middle MVC placements maximize productivity, yielding freshwater production up to 500 L/h, while different placements, depending on the feed temperature, optimize the GOR. The parametric study demonstrates that increasing feed temperature significantly boosts productivity, particularly at lower numbers of stages, but reduces GOR due to the higher thermal losses. Additionally, higher feed flow rates improve productivity, with GOR stabilizing at the highest flow rates, and lower pressures in the permeate side increase productivity while keeping GOR consistent. The optimized MSVMD system thus offers a balanced approach, achieving substantial freshwater production with high energy efficiency

Theoretical and experimental investigation of a pilot-scale solar air-heated humidification dehumidification desalination system

Among the various humidification dehumidification desalination (HDD) system configurations, the air-heated cycle has demonstrated promising results in small lab-scale setup investigations, whereas pilot-scale studies are lacking. This study theoretically and experimentally investigates the performance of a pilot-scale flat-plate solar air collector-powered HDD unit. An optical-thermal model for a solar air collector and a transport model based on heat and mass transfer for the dehumidifier have been developed and validated using experimental data. The triangular-shaped turbulators on the absorber plate of a solar collector with relative roughness pitches of 2.3, 4.61, and 6.92 are built and optimized for maximum distillate yield. Perforated turbulators with open area ratios of 5.5 %, 12.25 %, and 21.8 % are evaluated. To reduce distillate production costs in the HDD system, naturally available wood apple shell with drilled holes is tested in the humidifier. Outdoor test results revealed that at an average solar intensity of 712 W/m2, the proposed system achieved a maximum distillate yield and gain output ratio of 17.34 kg/day and 0.65, respectively. Wood apple shell packing demonstrated better distillate yield, gain output ratio, and humidifier performance potential factor compared to the commercially available raschig ring and cascade mini-ring packings. Moreover, the optimal performance of the solar air collector with solid turbulators was obtained at a relative roughness pitch of 4.61 due to sufficient longitudinal space to effectively prevent flow separation and reattachment of the free shear layer. Turbulators with a 12.25 % open area ratio exhibited the highest Nusselt number and low friction factor.

Stacked solar distiller using water to storage heat for high-temperature evaporation

Solar stills can produce freshwater with low or even no carbonization to alleviate the problem of freshwater resource scarcity. However solar distiller's operation period is limited by the intermittence of solar energy, and the Gained-output ratio (GOR) is determined by operation temperature. To further develop efficient solar distillers, this paper investigates a stacked solar distiller with high evaporation temperature, utilizing water to storage heat. A mathematical model of a triple-stacked solar distiller (TSD) was established to describe the internal heat and mass transfer processes. Then an experimental device was built. The experiments under steady-heating and outdoor solar-heating have been conducted. The steady-heating testing results show that, when the evaporation temperature of TSD reaches 79.9 °C, the GOR reaches 2.00. The theoretical model can accurately predict the operating parameters of the distiller, with the deviation of the theoretical temperature from the experimental value within 0.9 °C and the GOR deviation ranging from 2.2 % to 21.0 %, under steady-heating testing. The outdoor testing results show that, at an average daily irradiance of 606 W/m2, the maximum evaporation temperature is above 90.0 °C, achieving a water yield rate of 2.53 kg/(h·m2) and the maximum instant GOR of system closing to 2.23. Combined with nighttime water yield attributing to heating storage, a water yield of 28.00 kg/(d·m2) can be achieved. This research may provide a good scheme for the scenario of small-scale distributed solar desalination demands.

Sustainable desalination through hybrid photovoltaic/thermal membrane distillation: Development of an off-grid prototype

Global freshwater scarcity is a critical challenge, particularly severe in remote Australian communities where seawater intrusion and aquifer salinisation exacerbate the need for alternative water resources. Conventional desalination technologies are energy-intensive and unsuitable for rural areas. This study introduces a novel, off-grid, sustainable desalination solution utilising solar-integrated membrane distillation (MD) technology. An innovative, stand-alone prototype combining a hybrid photovoltaic/thermal (PV/T) system with direct contact MD (DCMD) has been designed and developed. This fully integrated PV/T collector efficiently supplies the thermal and electrical energy required for the MD process. The photovoltaic panel generates the necessary electrical energy, while the heat from the PV panel warms the MD system’s feed solution, enhancing overall efficiency through the solar cell cooling effect. In addition, an innovative fan-cooled radiator equipped with two DC fans with a low power consumption rating was designed and customized to be applied as MD system cooling medium within the outdoor setting. The concept development and feasibility of the system are explored in detail through a comprehensive experimental investigation employing an innovative and practical approach to design and examine the integrated hybrid solar MD unit. This unique system was designed, constructed, and tested under dynamic outdoor conditions, during the summer season in Melbourne, to assess the integration strategy and evaluate its long-term operational performance. The performance of the integrated PV/T-MD system was evaluated using two commercial hydrophobic membranes with different pore sizes under various outdoor conditions and PV/T fluid flow rates. Key performance metrics analysed include solar irradiance intensity, temperature profiles of the PV/T panel and MD module, power, current and voltage profiles of the unit components, permeate flux, specific water productivity (SWP) and the thermal (ηthermPV/T) and electrical (ηelecPV/T) efficiencies, along with the gained output ratio (GOR). Comprehensive experimental assessments in indoor and outdoor settings were undertaken to confirm the technical viability of the system. The study demonstrates the feasibility of such systems through real-world trials and addresses key challenges in energy efficiency and internal heat recovery. The experimental trials demonstrated permeate flux values ranging between 8–16 kg/m2h outdoors, compared to 22–30 kg/m2h indoors, reflecting the impact of fluctuating environmental conditions. The system’s power consumption was measured 130–140 W, about one-third of the PV/T power rating. The maximum power generation reached 280 W in battery charging mode. achieving a maximum ηthermPV/T of 20 % and an ηelecPV/T of 18 %. Additionally, the cooling effect of the PV/T panel resulted in a 1.5–2 °C temperature reduction, improving electrical power output by 0.8–1.2 %. The findings highlight the significant potential of the system in providing reliable and efficient freshwater production in remote, off-grid communities, offering a scalable solution to address global water scarcity challenges.

Assessment of a pilot continuous freezing desalination system with vacuum-assisted brine extraction

Freezing desalination (FD) is considered a potential alternative that addresses the shortage in water resources. FD commercialization is limited due to the intermittent nature of the FD process. An experimental investigation is conducted to a pilot continuous freeze desalination unit that employs vacuum-assisted brine extraction. The system is regarded as a first step to realize a continuous freeze desalination process that can be then commercialized. The proposed pilot FD unit has multiple brine extraction stages to reach the desired water salinity. Four distinct feed water salinity are tested. The results show that the unit has the potential to produce low-salinity water without the need for washing or crushing which causes significant mass loss. The results indicate that water is obtained at a salinity of 393 and 1225 ppm NaCl at feed water salinities equal 10,000 and 40,000 ppm NaCl, respectively. Furthermore, the system produces an approximate constant volume equal 850 mL which is around 28 % of feed water volume. The gain output ratio (GOR) of the system is 3.07, 2.97, 2.99 and 2.98 for feed water with salinity 10,000, 20,000, 30,000 and 40,000 ppm NaCl respectively.

6E evaluation of an innovative humidification dehumidification solar distiller unit: An experimental investigation

This work aims to enhance the productivity, efficiency, energy utilization, feasibility, and environmental outcomes of solar desalination systems via representing an innovative humidification dehumidification solar distillation unit coupled with a built-in air solar heater and photovoltaic thermal unit. The air solar heater was further improved by the incorporation of copper chips as thermal energy-storing materials for extending the desalination process during the sun’s hours. Three distinct humidifier beds, including plastic waste (case A), wick materials (case B), and cellulose paper (case C) were tested and compared regarding system temperatures and hourly and daily drinkable water yield. Additionally, a 6E analysis was assessed and evaluated in terms of energy, exergy, economic, exergoeconomic, exergoenvironmental, and exergoenviroeconomic analysis for all the cases. According to the outcomes, the humidification dehumidification solar distiller with cellulose paper yielded the highest productivity and 6E outcomes where the daily drinkable water, thermal efficiency, and exergy efficiency were estimated as 7.78 L/m2, 73.45 %, and 5.3 %, outperforming the CSD by nearly 142.59 %, 144.02 %, and 229.19 %, respectively. Moreover, the price of drinkable water and the payback time decreased to 0.0099 $/L and 0.12 years, which represents a reduction of 68.27 % and 69.23 %, respectively, at an exergoeconomic factor of 4.19 kWh/$. Furthermore, the amount of CO2 reduced was increased to 3.92 tons, which is associated with earned credits of carbon of 56.78$. Finally, for this case, the HDH humidifier efficiency, dehumidifier effectiveness, and gain output ratio maximum and mean values were 96.66 and 84.5 %, 85.61 and 78.96 %, and 1.86 and 1.08, respectively.

Performance Analysis and Novel Cross-Flow Scheme of Low-Temperature Multi-Effect Distillation for Treating High-Mineralized Mine Water

Low-temperature multi-effect distillation (LT-MED) can be used to desalinate and demineralize highly mineralized mine water, facilitating the recycling and reuse of water resources. This study conducted a simulation of LT-MED technology for treating highly mineralized mine water using Aspen Plus and proposed a novel cross-flow optimization scheme. Initially, the impact of operational parameters such as process configuration, number of evaporation effects, and steam input on the gained output ratio (GOR) and scaling risk of a conventional LT-MED system was analyzed. It was found that the number of effects and heating steam flow rate had the most significant influence on GOR, while different processes exhibited limitations regarding GOR and scaling trends. To address these issues, this paper introduced a cross-flow operation process that combined forward, backward, and parallel flow. The simulation results indicated that, under conditions of eight effects, a maximum evaporation temperature of 70 °C, a temperature difference between adjacent effects of 4 °C, and a feed temperature of 45 °C, the cross-flow process—where the feed was introduced from the sixth effect—achieved the highest GOR and significantly reduced scaling risks compared to parallel and backward flow configurations. Finally, to further utilize low-pressure exhaust steam from the final effect of the cross-flow LT-MED system, mechanical vapor compression (MVC) and thermal vapor compression (TVC) were integrated into the LT-MED process. The thermodynamic performance of the coupled system was analyzed, and the simulations demonstrated that the coupled system outperformed the standalone use of either TVC or MVC, with the LT-MED-MVC-TVC system showing superior performance overall.

Experimental investigation of a humidifier-dehumidifier desalination system with a hybrid air heater (solar-electric) and vapor absorption refrigeration (VAR) system in the dehumidifier

This study focuses on the experimental investigation of the efficiency of a humidifier-dehumidifier (HDH) desalination process. The system employs a closed-air cycle, utilizing a hybrid (solar-electric) air heater to increase the air temperature before entering the humidifier. Additionally, a Vapor Absorption Refrigeration (VAR) system is employed to decrease the temperature of the water before it enters the dehumidifier. The system is suitable for deployment in regions with high temperatures and humidity levels. Tests have been conducted under prevailing weather conditions. Temperature and relative humidity at various stages of the cycle are measured and recorded using a dedicated sensor. This study examines the effects of different parameters, including air mass flow rate (MFR) and air temperature at the humidifier inlet, on fresh water production (FWP), coefficient of performance (COP), and gained output ratio (GOR). The results section presents the experimental findings, which show that the maximum COP, GOR, and FWP achieved values of 2.1, 4.1, and 200 g/h, respectively. Furthermore, an increase in air MFR corresponds to an increase in both COP and FWP, while GOR values show a decrease. Based on the eco-analysis conducted for this investigation, the cost per liter (CPL) was calculated to be 0.022 $ per kilogram.

Techno-economic investigation of an entirely solar-powered hybrid HDH/RO desalination plant for moderate water demand under various operating conditions

The study presented a scalable, entirely solar-powered hybrid desalination system suitable for moderate demand and valid for various water salinities. The system merged two desalination techniques: HDH (humidification-dehumidification) and RO (reverse osmosis). The required power for all components was obtained from a photovoltaic (PV) system. The experiments were conducted to evaluate the separate units' and hybrid system's performances under different conditions, including various sprayed hot water (to the HDH) temperatures, RO feed water temperatures, air velocities, and water salinities. Based on the recorded data, the techno-economic analyses were conducted to assess the gain output ratio (GOR), recovery ratio (RR), specific energy consumption (SEC), the total amount of dissolved solids (TDS), and production cost. As a result, the RO unit's productivity increased almost linearly with feed temperature, showing a maximum hourly yield of 60 L/m2. In contrast, HDH productivity showed exponential growth with feed temperature, achieving a maximum hourly yield of 18 L/m2. The SEC of the RO unit decreased from 1.1 kWh/m³ to 0.63 kWh/m³ when using the rejected HDH's hot brine. The hybrid system's accumulated productivity reached 535 L/m2, significantly higher than the standalone HDH (58.5 L/m2) and standalone RO (368 L/m2). Additionally, the hybrid system demonstrated substantial improvements in GOR and RR, with daily values of 11.15 and 55.73 %, respectively. Economically, the yielded water cost was significantly lower, at 0.63 $/m³ for the HDH/RO system compared to 3.51 $/m³ for the standalone HDH.

New hybrid system of PV/T, solar collectors, PEM electrolyzer, and HDH for hydrogen and freshwater production: Seasonal performance investigation

A new hybrid energy system of PV/T, flat plate collector, PEM electrolyzer, and humidification-dehumidification desalination is introduced here. A comprehensive mathematical model for the system seasonal performance is constructed and solved numerically using MATLAB software. A year-round comparison between the traditional PV/T performance and its concentrated counterpart indicates that the latter performs better compared to power, hydrogen, and freshwater production and system overall efficiency. The maximum monthly achieved PV/T efficiency, electrolyzer efficiency, desalination system Gain Output Ratio, and overall system efficiency are 52 %, 62 %, 4.8 %, and 44 %, respectively at a concentration ratio of 4 and maximum allowable PV temperature. The system produces 82,200 kWh of energy annually and provides 77,700 kWh and 1500 kWh to the electrolyzer and the electric heater, respectively. Moreover, the system produces an annual freshwater production of about 52,700 kg, out of which approximately 10,000 kg are consumed in the electrolysis process, and an annual hydrogen production of approximately 1120 kg.

Techno-economic process design of multi-stage flash- reverse osmosis for water and power production using solar-wind resources

This paper introduces a newly developed hybrid power plant design that combines renewable energy sources to produce both electricity and freshwater. The design offers a higher gain output ratio (GOR) and improved efficiency in power and freshwater production, all at a lower cost compared to existing research papers. To generate power, the power plant incorporates a range of technologies, such as a horizontal-axis wind turbine (WT), photovoltaic panels (PV), parabolic trough collectors (PTC), a steam Rankine cycle, a multi-stage flash (MSF) desalination unit that cleverly harnesses excess heat from the Steam Rankine cycle, and an Reverse osmosis (RO) unit. With the assistance of ASPEN Plus, ASPEN Economic, and HOMER PRO software, the process parameters undergo significant improvement. According to the results, the power plant has the capacity to generate 57.63 MW of electricity and produce 2505 m3h of freshwater. Additionally, it has a GOR of 9.09 and utilizes 7285 m3h of seawater, which has a renewability factor of 97.6 %. In addition, the efficiency of the steam Rankine cycle stands at 32 %, providing notable energy savings. The production costs for electricity and freshwater are 0.037 $kW and 1.38 $m3, respectively, indicating their affordability. The economic analysis reveals promising results for the project, with an anticipated annual profit of 41 % and a relatively short capital payback period of 2.4 years. By implementing the proposed hybrid cogeneration power plant, the region can tackle its water and energy scarcity issues with a sustainable and long-lasting solution.

Mathematical modeling and experimental analysis of the double-effect DCMD-heat pump integrated system

High energy consumption represents one of the hindrances in enabling large scale application of membrane distillation. In this work, experimental and simulation studies of a double-effect direct-contact membrane distillation integrated with a single-stage vapor-compression heat pump (DE-DCMD-HP) were carried out for concentrating tap water with the aim to evaluate the energy saving of the integrated system. It was found during our experiments that an auxiliary cooler must be added to remove the excess heat from HP to enable the integrated system to reach the steady-state condition. The temperature-heat flux plots were first utilized to analyze how HP and DE-DCMD affected each other and reveal their coupling mechanism. The simulation results showed that the increase in the first-effect feed inlet temperature, Tfi,1 and the flow rate, V caused the thermodynamic cycle line of refrigerant shift to higher temperature, which led to the increase of the input power of the compressor and the auxiliary cooler, ultimately affecting the water production mass rate, ṁd, the coefficient of performance, COP, the gain output ratio, GOR, and the specific energy consumption, SEC. The experimental and simulation results revealed that increasing Tfi,1 and V increased the permeate flux Nh and GOR and reduced the SEC. The performances for three different DCMD configurations were furthermore evaluated via experiments at constant feed temperature whereby the SEC decreased from 2168 kWh·t−1 for single-effect DCMD to 1085 kWh·t−1 for DE-DCMD to 257 kWh·t−1 for DE-DCMD-HP.

Comprehensive performance analysis and optimization of an ORC-HDH system for power and freshwater production driven by marine exhaust gas

Freshwater serves as a vital energy source for ships, underscoring the paramount importance of research into desalination systems in facilitating diverse and reliable energy supply for maritime vessels. Aiming at numerous waste heat of marine engines and the shortage of freshwater resources on board, this paper designs an innovative waste heat recovery (WHR) system. It includes an organic Rankine cycle, a compression refrigeration cycle, and a humidification-dehumidification (HDH) desalination system to recover waste heat from exhaust gases in cascades, which can effectively produce power, cooling, and freshwater, respectively. A parametric study of the co-generation system in terms of the freshwater production, gained output ratio (GOR), cost per unit of freshwater production, net power output, and per unit of output power cost, are conducted to identify the key operating parameters. A set of operating parameters is determined for the HDH system with a temperature of the humidifier outlet of 358.15 K and a mass flow rate ratio (MR) of seawater to humid air of 4.5. The effect of the relative humidity and temperature of the humid air, as well as the salinity and temperature of the seawater, on the performance of the HDH subsystem are analyzed. And the optimal operating conditions of the co-generation system are obtained through multi-objective cuckoo search optimization. The results demonstrate that the co-generation system can produce an output-power of 1479.8 kW, 500 kW, and 0.49 kg/s for cooling and freshwater production by using the working-fluid R365mfc/Cyclopentane with a mixing ratio of 33:67 under optimal conditions. The GOR and cost per unit of HDH subsystem are 1.62 and 1.70 $/m3, with a capital payback period of 4.18 years. The equivalent output-power of the co-generation system is 9.5 % higher than that of an ORC system.

Investigating the impact of nanofluids and exergy metrics for integrated solar-biomass SCO2 power and desalination cycles

Several strategies have emerged for utilizing waste heat across diverse sectors. Yet, integrated systems that merge power generation with freshwater production, especially those leveraging renewable energy, remain relatively unexplored. Addressing this gap, a novel solar biomass-driven system is under development for power generation and desalination facilities. In the suggested system, rather than wasting the energy of a supercritical CO2 power cycle, a bottoming cycle is proposed to augment energy utilization factor (EUF). By integrating humidification-dehumidification, thermal vapor compression, and reverse osmosis (HDH-TVC-RO) with a multi-effect distillation (MED) unit, freshwater production rate is significantly enhanced. The outcomes reveal a freshwater output of 29.36 kg/s, a gained output ratio (GOR) of 17.36, and the EUF of 3.372. Various nanofluids have been assessed for the solar collector and due to superior total exergy efficiency and less corrosion effects, Cu- and carbon-based nanoparticles are recommended. Sensitivity analysis indicates that increasing the pressure ratio of compressors boosts the total GOR. Furthermore, adjustments to both the parameters of pressure of steam fed to HDH-TVC, and the compressor pressure ratio demonstrate a linear effect on EUF behaviour.

Integrated solar dryer and distillation system with PCM and injection, powered by PVT panels and solar concentrator

This research introduces a novel hybrid system integrating solar drying, solar distillation, and photovoltaic thermal panels, aimed at drying agricultural products, producing clean drinking water, and conserving energy. The system enhances the drying air temperature using thermal energy storage materials and a solar dish concentrator connected to a hot water storage tank, ensuring continuous operation even after sunset. The solar distiller, equipped with energy storage materials and an air injection system, is integrated with an external condenser to condense water vapor before expulsion, thereby increasing freshwater productivity. The results revealed that the developed system achieved an accumulative freshwater productivity of 87.1 L per day. The rates of water removal from dried potato slices ranged from 0.18 to 0.91 kg/h between 8:00 am and 10:00 pm. Additionally, the system achieved a gain output ratio of 1.38, indicating a significant improvement in energy efficiency. This innovative system offers practical solutions to address energy and freshwater scarcity, especially in remote regions of the Middle East and North Africa (MENA) region, which are characterized by high solar irradiance. The implementation of such hybrid systems could contribute to sustainable development by reducing reliance on conventional energy sources and mitigating environmental pollution.

Optimization of vacuum membrane distillation and advanced design of compact solar water heaters with heat recovery

With the escalating global population, freshwater scarcity has become a pressing challenge. To address this issue, this paper presents a novel compact solar water heater (CSWHT) system incorporating heat recovery and submerged-membrane filtration. The research aims to develop an efficient desalination method that reduces water production costs and maximizes output. The system comprises a feed storage tank, a vacuum membrane distillation (VMD) system positioned atop the submerged CSWHT, a liquid ring vacuum pump (LRVP) utilizing waste heat from the outlet to preheat the feed, and hollow fiber membranes.Three critical parameters, namely the mass of the feed in the storage tank, the number of hollow fiber membrane rows, and the feed volumetric flow rate, were optimized using a multi-objective non-dominated sorting genetic algorithm II (NSGA II) to minimize water production cost (WPC) while maximizing water production. Subsequently, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was employed to identify the optimal scenario from among the selected best solutions.For Mediterranean seawater and a 6 m2 solar collector area, the multi-objective NSGA II algorithm identified 20 membrane rows per collector, 334.4 kg feed mass in the storage tank, and 0.027 kg.s−1 feed mass flow rate as the optimal system parameters. Under these optimized conditions, the system exhibited a daily production capacity of 92.5 kg water, 4.6 kg chloride, and 0.03 g bromide, while achieving a production cost of 12.2 USD.m−3 and a gain output ratio (GOR) of 1.6. These results highlight the system's remarkable potential for desalination with high efficiency and low cost. Future research should focus on scaling up the system and exploring its applicability in various geographical locations.

Utilization of waste hot air of medical oxygen plant in solar desalination unit employing jet impingement air heater for water production

ABSTRACT Many oxygen plants have been established specially during COVID-19 period and they are still serving for medical needs. The objective of the present work is to utilize solar and waste thermal energy of medical oxygen plants for water production. Humidification–dehumidification desalination (HDD) has been found suitable for this objective due to low temperature energy need during the process. The layout of an HDD unit has been presented to utilize waste heat, specially when solar energy is not much effective or absent. The system has been configured with a jet impingement solar air heater and a packed bed humidifier. A mathematical model has been developed and validated with the results of experiments. A comparative study of the proposed unit (HDD-O2) and a conventional unit has been performed in terms of yield and gained output ratio (GOR). The optimum flow rates of working fluids found in the range 0.03–0.04 kg/s and the temperature of air and water resulted in a continuous gain in yield. The average yield and GOR of the HDD-O2 unit were found to be 8.5 kg/d and 1.1 that could reach up to 11 kg/d and 1.4, respectively. The HDD-O2 unit provided yield at the cost of 0.04 $/kg with a payback period of 1.73 years. The findings of the present work indicated the suitability of the HDD-O2 plant for water production.

Productivity, energy, and exergy analyses of a water desalination system-based vortex tubes with different configurations: An experimental implementation

The present implementation explores the use of vortex tubes (VTs) as an alternative thermal technology for water desalination systems (WDSs). VTs are utilized to provide hot air for evaporating salt water in the evaporator, while simultaneously supplying cold air to condense the water vapor in the condenser. The study investigates the influence of a number of operating parameters, including inlet water temperature (Ti,w), cold mass ratio (CR), and vacuum pressure (pvac) on the performance of WDS-based VTs through experimental analysis. Different configurations of VTs are tested for WDS applications, including WDS-based single vortex tube (VT), WDS-based two series vortex tubes (2SVTs), and WDS-based two parallel vortex tubes (2PVTs). Performance metrics such as the evaporation heat (QEvap), desalinated water production (DWP), gain output ratio (GOR), and exergy performance are evaluated for each configuration. Results show that the WDS-based 2SVTs exhibits the highest QEvap; while the WDS-based 2PVTs demonstrates the lowest value. Correlations are proposed to predict DWP for different configurations of WDS based on pvac, Ti,w, and CR with a maximum deviation of ±12.2 %. Furthermore, the WDS-based 2SVTs achieves the best GOR of 2.5 at an inlet water temperature of 80 °C, representing a significant improvement compared to the WDS-based VT and 2PVTs. The exergy efficiency (ηex) increases with higher CR, and the WDS-based 2SVTs ensures the best exergy performance, and its maximum overall ηex equals 78.2 %.

Integrated membrane distillation and absorption chiller driven by solar energy: Concept and analysis

Solar energy linked to absorption chiller system is used to supply the heating and cooling energies to membrane distillation (MD) process. The heating load is taken directly from the solar energy system. The cooling load is provided by the absorption chiller system, which converts the solar energy into refrigeration power. Using a solar collector area of 60 m2 and MD feed flow rate of 600 kg/h, the maximum distillate production for a single MD can reach 61.5 kg/h, which corresponds to a recovery ratio of 10.2% and a gain output ratio (GOR) of 3.2. Increasing the MD feed flow rate necessitates enlarging the solar collector area to meet the escalating energy demand. An additional MD unit was also integrated and powered by the internal energy of the absorption chiller system. The total distillate production approaches 83 kg/h and the GOR enhances to 4.5. The condenser stream of the two integrated MD units is quenched by the refrigeration power of the absorption chiller system under split and joint scenarios. The split scenario was found to outperform the joint option in terms of providing higher average distillate production over the period of daily sunshine hours. However, the joint scenario can activate both MD units only if a larger solar collector of 100 m2 is employed and the condenser of the absorption chiller system is operated at 40 °C. Similarly, the split scenario can activate the two MD units only if split ratio equal or higher than 60% is enforced.

Simulation of vacuum membrane desalination within an enhanced design of compact solar water heaters

Vacuum Membrane Distillation stands out as a solar desalination method utilizing membrane pressure differentials to evaporate seawater and collect it as fresh water. On the other hand, the new design of compact (or integrated) solar water heaters can be very suitable for Vacuum Membrane Distillation use. In the new design of solar system, its upper part, which is under buoyancy pressure, can have a very suitable space for installing the Vacuum Membrane Distillation system. The purpose of this research is to simulate the proposed design and a dynamic time-domain model was developed for comprehensive simulation, encompassing absorber plate characteristics, collector dimensions, mass flow rate, vacuum pressure reduction, the influence of increasing membrane rows, and seawater concentration. Simulation results showcase the system’s potential, yielding 57.12kg/m2/day of freshwater daily with an average gain output ratio exceeding 1.1. The estimated water production cost is 0.039USD.L-1, along with the generation of 4.3kg.kg/m2/day of chlorine and 0.037g.kg/m2/day of bromine from Mediterranean seawater. For super saline water, the projections indicate a daily production of 104.46kg.kg/m2/day of freshwater with a production cost of less than 0.01 USD/L, a GOR of 1.7, and a daily production of 37.8kg.kg/m2/day of chlorine for a collector area of 6 m2. These outcomes underscore the efficiency and economic viability of the proposed design, positioning it as a promising solution for seawater desalination challenges.