Specific Thermal Energy Consumption Research Articles

Multi-stage humidification–dehumidification system integrated with a crystallizer for zero liquid discharge of desalination brine

Desalination plants discharge a massive volume of brine every day, which negatively affects the ecosystem, particularly the subsurface ecology and marine life. To mitigate the brines' detrimental effects on the environment and facilitate the recovery of salt crystals and freshwater, the Zero Liquid Discharge (ZLD) approach was proposed. This study proposes four different configurations of multistage humidification dehumidification systems integrated with a crystallizer, exploring their energy and economic implications. Key findings from the study include the higher Gained Output Ratio (GOR) in series configurations due to lower temperature differences, resulting in lower heater energy consumption. The crystallizer significantly enhances water productivity, but it is a major consumer of both electricity (85%) and thermal energy (50.45–57.7%) in the system. Increasing the heat source temperature reduces the Specific Electrical Energy Consumption (SEEC) and the specific area while slightly increasing the Specific Thermal Energy Consumption (STEC). Elevated cooling water temperature raises SEEC and specific area but has negligible effects on STEC. Higher feed water flow rates increase SEEC but lower both STEC and specific area. Feed salinity elevation decreases productivity, SEEC, STEC, and specific area. The crystallizer constitutes 15.43–26.44% of the total capital cost, with series configurations incurring higher costs. Unit freshwater production costs, considering salt selling, range from 1.733 to 4.821 $.m−3. In a waste heat scenario, parallel configurations become profitable, where freshwater can be distributed at zero cost, while the produced salt crystals can be sold at an even lower price of $58.09 per tonne and $57.04 per tonne, respectively.

Productivity, selectivity, and energy consumption of pilot-scale vacuum assisted air-gap membrane distillation for the desalination of high-salinity streams

The implementation of air gap membrane distillation systems is limited by a lack of overall performance predictions which rely on few available pilot-scale studies. This study evaluates the productivity, energy consumption, and selectivity of a pilot-scale air gap membrane distillation system by combining experiments and modeling activities. The effect of operating conditions, i.e., applied vacuum, feed flow rate, and feed stream salinity, was investigated to identify regulating factors and quantify dependencies. Response surface methodology was applied to model the phenomena and provide statistical analysis. Increasing flow rates produced a near linear increase of productivity within the investigated range. Operating at higher applied vacuum also translated into enhanced productivity, though the distillate flux increased by a maximum of 10 % when vacuum increased from −100 mbar to −500 mbar. Flow rate and vacuum also governed the observed salt flux by a similar magnitude because salt flux resulted mainly from liquid pore flow phenomena. The trans-membrane pressure regulated the membrane rejection: increasing the pressure difference led to a lower rejection. Moreover, high feed stream salinity lowered both the productivity and the distillate quality. The productivity gains were typically achieved at the expense of an increase in specific thermal energy consumption; however, an interesting relation was observed with feed stream salinity, with a minimum of specific thermal energy consumption of roughly 300kWhth⋅m−3 identified in the treatment of a stream with a salinity of 150g/L.

Modeling and simulation of direct contact membrane distillation system integrated with a photovoltaic thermal for electricity and freshwater production

Energy drives the growth, transformation, and economic development of every nation. The vitality of human existence and progress hinges on the accessibility of both energy and water resources. As freshwater resources are diminishing, therefore, desalination needs have increased. In solar membrane distillation systems, the key challenge is maintaining the intake water temperature in the membrane distillation system with fluctuating solar radiation intensity which affects the distillate water quantity and quality. The objective of this study is to enhance and optimize a mathematical model for analyzing a cutting-edge solar-integrated PV/T-DCMD system. In this innovative integration, the direct contact membrane distillation intake water temperature is derived from the photovoltaic thermal output. The integration of direct contact membrane distillation with photovoltaic thermal systems represents a cost-effective and technologically advantageous concept. As the water temperature increases, there is a notable improvement in the evaporation efficiency of PV/T-DCMD systems, with an increase from 35.08% to 42.01%. Additionally, there is a reduction in specific thermal energy consumption, decreasing from 1,192 to 1,386 kWh/m3 as a consequence of the elevated feed water temperature.

Parameter collaborative analysis and multi-objective optimization of a nanofluid filtered solar membrane distillation system using heat pump

The distributed solar powered membrane distillation (SPMD) system for water/electricity co-production is a valuable solution for relieving energy pressure in remote areas but it suffers from a complicated operation mechanism. This paper performs a comprehensive parameter analysis and user-oriented optimization on a nanofluid filtered solar membrane distillation system using heat pump to enhance its competitiveness. Response surface methodology is employed to examine the interactions of the influencing factors on the system performance, and the plots reveal significant interactions, particularly on equivalent specific thermal energy consumption (eSTEC). An artificial neural network is integrated with genetic algorithm to perform single and multi-objective system performance optimization. The results show that maximum system exergy efficiency, permeate flux and minimum eSTEC are 19.39 %, 35.8 kg·m−2·h−1 and 463.5 kWh·m−3, respectively. Furthermore, the technique for order preference by similarity to an ideal solution is utilized, based on performance indicator weight derived from the analytical hierarchy process, to offer a user-oriented optimal solution. It demonstrates that after optimization, the system exergy efficiency and permeate flux are improved by 9.9 % and 30.2 %, respectively, along with a reduction of eSTEC by 5.7 %. This research contributes to advancing solar-to-water/electricity efficiency and offering valuable insights for the development of SPMD systems.

Theoretical and experimental investigation of cylindrical air gap membrane distillation system and effect of the membrane support net on its performance.

In present study a cylindrical module is studied based on air gap membrane distillation configuration and studied for desalination purpose. A complete theoretical model was developed with consideration of design and operating parameters that enabled a Cylindrical Air Gap Membrane Distillation (CAGMD) module specific performance analysis. Theoretical model was verified with the literature as well as with the experimental results carried out on a lab scale CAGMD module. The effect of support nets which supports the membrane on the air gap side is also discussed on the performance. Support nets made up of four different thermal conductivities material- copper, aluminum, brass and polypropylene (PP) are considered for this study. The effect of feed temperature and flow rate, air gap width, cold flow rate, effect of thermal conductivities of support nets and height of the module was studied on the performance of CAGMD module. Permeate flux, Specific Thermal Energy Consumption (STEC) and the Gained output ratio (GOR) was selected as the performance indicators and the results for all the resulted parameters obtained from experimental and theoretical model falls in good agreement with only 6% deviation, that suggests that the proposed model is best suitable for predicting the behavior of any cylindrical AGMD module with great effectiveness. It is suggested that for better performance of the system feed flow rate, temperature and cold flow rate should be maintained at higher level. Maximum permeate flux achieved from the CAGMD module is 9.22kg/m2h.

Hybrid vacuum membrane distillation-multi effect distillation (VMD-MED) system for reducing specific energy consumption in desalination

This study focuses on the integration of vacuum membrane distillation into the multi-effect distillation (VMD-MED) system, incorporating heat recovery mechanisms to augment fresh water productivity and minimize the specific thermal energy consumption of the desalination process when compared to stand-alone vacuum membrane desalination systems. The hybrid system was devised by integrating the experimental output of VMD (permeate flux and hot brine) as heat source to MED. Two hybrid systems were investigated in this study: VMD/MED, wherein the heated brine from VMD served as a heat source for MED, facilitating the recovery of sensible heat from VMD; and VMD-HR/MED, where the latent heat of VMD vapor during condensation was utilized to pre-heat the feed water for MED. Based on the performance parameters, it was concluded that the VMD-HR/MED hybrid system outperformed both the stand-alone VMD and VMD/MED hybrid system in terms of efficiency. The latent heat recovery from the condenser of VMD in VMD-HR/MED hybrid system reduces the specific thermal energy consumption (STEC) to 38.42 kWh/m3, however, it enhanced the gain-output-ratio (GOR) and productivity of the system. Additionally, a rise in GOR and a simultaneous decrease in STEC were observed with increasing feed flow rates and vacuum pressure.

Influence of internal design on the performance of pilot vacuum-assisted air-gap membrane distillation modules for brine concentration with solar energy

Membrane distillation (MD) in batch operation is proposed for brine concentration with solar energy in zero liquid discharge (ZLD) desalination processes, but there are some research gaps yet. Energy efficiency is key for implementing the technology with solar energy and there is not enough experience and experimental results of operation of MD pilot modules at high salinity feeds. This research focuses on the experimental evaluation and comparison of two multi-envelope spiral wound commercial membrane distillation modules operating in vacuum-assisted air gap MD at the solar MD pilot facilities of Plataforma Solar de Almería in Spain. These modules have similar membrane area (24 and 25.9 m2) and residence time (large, to maximize thermal efficiency), but different internal design: 6 envelopes 5 m long and 12 envelopes 2.7 m long, respectively. This difference affects mostly the feed circulation velocity for equal feed flow rate. Performance parameters such as permeate production and specific thermal energy consumption (STEC) are compared and experimental models performed and validated for different feed salinities. Permeate quality and specific electrical energy (SEEC) consumption are also evaluated. The results show that the best module for batch operation is the one with a larger number of channels but of shorter length.

A passive continuous flow pasteurisation process designed for solar application. Part I: Indoor experiments for thermal characterization and bacteria inactivation

Within the framework of the WHO's universal sanitation policy, water disinfection processes with low manufacturing and maintenance costs must be developed. This is the case with solar pasteurisation, the effectiveness of which, at 50–70 °C, has been already demonstrated in the literature. To be fully acceptable, the process must be appropriately energy efficient and be able to adapt to natural fluctuations in solar radiation. An experimental indoor test platform under controlled conditions, with thermal powers supplied similar to those of a future solar application with a standard thermal panel, was designed. Experimental results highlighted the specific thermal energy consumption (SECtherm), which is highly dependent on the effectiveness of a deliberately oversized heat recovery exchanger. The operation under both stationary and dynamic regimes underscored the role of the thermostatic valve which autonomously calibrated the flow of the fluid according to the injected available power. For the temperature range sufficient to inactivate microorganisms [50–70 °C], the specific thermal energy consumption reached values between 3.5 and 6 kWhtherm.m−3. The bacterial indicators, Escherichia coli and Enteroccocus, currently present in surface waters in the south of France, were no longer detected (<10 MPN.100 mL−1) after one-minute of pasteurisation at 55 °C and 60 °C, respectively.

Productivity and Thermal Performance Enhancements of Hollow Fiber Water Gap Membrane Distillation Modules Using Helical Fiber Configuration: 3D Computational Fluid Dynamics Modeling.

Although hollow fiber water gap membrane distillation (HF-WGMD) units offer certain advantages over other MD desalination systems, they still require enhancements in terms of distillate flux and productivity. Therefore, this work proposes a novel configuration by incorporating the helical turns of HF membranes within the water gap channel of the HF-WGMD modules. A fully coupled 3D CFD model is developed and validated to simulate the multifaceted energy conservations and diffusion mechanisms that are inherent to the transport phenomena in the proposed HF-WGMD module. Single and double helical HF membrane designs with different numbers of turns are compared to the reference modules of single and double straight HF membrane designs under various operational conditions. At a feed temperature of 70 °C, a noteworthy 11.4% enhancement in the distillate flux is observed when employing 20 helical turns, compared to the single straight HF membrane module. Furthermore, the specific productivity revealed a maximum enhancement of 46.2% when using 50 helical turns. The thermal performance of the proposed HF-WGMD module shows higher energy savings of up to 35% in specific thermal energy consumption for a one-stage module. Using three stages of single helical modules can increase the gain output ratio from 0.17 for the single stage to 0.37, which represents an increase of 117.6%. These findings indicate the high potential of the proposed approach in advancing the performance of HF-WGMD systems.

Experimental and numerical simulation of solar membrane distillation and humidification – dehumidification water desalination system

In this study, a novel solar hybrid air-gap membrane distillation and humidifier-dehumidifier desalination (AGMD-HDD) unit was designed and investigated. In this proposed system, photovoltaic panels were used as the source of electricity in the AGMD-HDD hybrid system. The present work was conducted to explore experimentally the hybrid system's performance within 12 months and simulated numerically using TRNSYS software. The simulated results were in good agreement with the measured values. The flowrate of produced purified water from the solar AGMD-HDD hybrid system were 21.29 kg/h and 11.76 kg/h in the summer and winter seasons respectively. The specific thermal energy consumption (STEC) varied from 60 kWh/m3 to 310 kWh/m3 in summer and 87.12 kWh/m3 - 605.2 kWh/m3 in winter. Freshwater cost estimation using the solar AGMD/HDH system showed a remarkable decrease in freshwater production up to USD 14.32/m3. The gained output ratio (GOR) and the system competence reached 5.33 and 91.03% in summer using a seawater flow rate of 600 kg/h. The total reduction in CO2 emissions was 32 tons in winter and 43 tons in summer seasons.

Design and performance a novel hybrid membrane distillation/humidification–dehumidification system

Water shortage is a burden on governments with the significant increase in population and industrial activities. There is an urgent need to devise innovative systems for providing potable water with low production costs. The availability of seawater around the world with the presence of desalination technologies can offer various solutions. A novel air gap membrane/humidification-dehumidification (AGMD/HDH) hybrid system was designed and implemented to produce distilled water. The influence of operational parameters on the hybrid process was studied in detail. Freshwater productivity gained output ratio (GOR), energy efficiency, specific thermal energy consumption (STEC), and feasibility study was investigated to optimize the process. Air flowrate, seawater feed temperature, and water flow rate were ranged from 100 kg/h to 250 kg/h, 40 °C, 65 °C, and 240 L/h to 600 L/h, respectively. The hybrid system produced freshwater of 24.4 kg/h at optimum conditions. The leading performance indicators were 6.8 for GOR, energy efficiency (80%), and 240 kWh/m3 for STEC. Humidification-dehumidification (HDH) system was mainly powered by low-grade energy power, so the proposed hybrid system was able to recover heat loss from the operation of the air gap membrane desalination (AGMD) unit. The cost estimation of distilled water is 9.34 US $/m3 with an annual production rate of 210.62 m3/year. The proposed hybrid air gap membrane distillation/humidification–dehumidification units showed remarkable improvement in total water productivity at a low cost.

Performance enhancement of a nanofluid filtered solar membrane distillation system using heat pump for electricity/water cogeneration

Membrane distillation (MD) assisted by heat pump exhibits a favorable energy performance in water production, but it consumes huge precious electricity. In this work, a nanofluid filtered concentrating photovoltaic/thermal (CPV/T) technology is proposed to integrate with heat pump membrane distillation (HPMD) system for electricity/water cogeneration. Solar energy cascade utilization is considered in the system where electricity generated by CPV/T powers heat pump for MD heat recovery, and the collected thermal energy is used to heat seawater. A comprehensive study is carried out by establishing models of the receiver, direct contact membrane distillation (DCMD) and heat pump to investigate the performance of the nanofluid filtered solar membrane distillation system using heat pump. Results show that the seawater of 350.3 K is fed to the DCMD module while the electrical efficiency is above 12.2%. MD parametric analysis and equivalent specific thermal energy consumption (eSTEC) optimization are performed. We found that HPMD operates at the lowest eSTEC of 607.8 kWh·m−3 at heating temperature of 338 K and feed flow rate of 0.04 kg s−1. An overall system efficiency of 61% is obtained, and the comparison of permeate flux and energy consumption demonstrates advantages of the proposed system over other hybrid MD technologies.

Energy and economic performance assessment of a solar-assisted regenerative vacuum membrane desalination system

Vacuum membrane water desalination is a promising technology for freshwater production with the advantages of low conduction heat loss and mass transfer resistance, compared to other membrane technologies. Such systems can be driven by solar thermal collectors for green water production, yet there is a lack of dynamic system simulations in the literature to comprehensively assess the energy and economic system performance and evaluate the impact of brine recirculation as a method of regeneration, especially under hot desert climates where solar resources are abundant, but freshwater resources are scarce (e.g., the northern coast of Egypt, considered as the case study here). In this study, a dynamic system simulation model is developed in TRNSYS, where a new “Type” is introduced for the vacuum membrane module. Initial sizing of the system with ∼20 % solar fraction resulted in annual average gained output ratio and specific thermal energy consumption of 2.51 and 133.5 kWh/m3, respectively, with levelized cost of water and payback period of 14.7 USD/m3 and 1.53 years, respectively. By increasing the solar collectors’ area from 8 to 16 m2, the levelized cost of water increased by 14.54 %. The storage volume was highly influential on the solar fraction, which increased by 101.39 % as the volume increased from 0.3 to 0.7 m3. Increasing the membrane area from 0.3 to 0.5 m2 increased the gained output ratio by 76.75 % while decreasing the levelized cost of water by 14.79 %. Internal heat regeneration through brine recirculation enhanced the system performance at lower recirculation ratios. Without recirculation, the levelized cost of water increased by 117.41 % and the system met the daily distillate water demand for only 90 days of the year.

Analysis of water gap membrane distillation process with an internal gap circulation propeller

A novel propeller-aided water gap membrane distillation (P-WGMD) system has been investigated through detailed mathematical modeling, and its performance was compared with that of a baseline/conventional WGMD system. The proposed system contains a rotating propeller blade, which improves mass and heat transfer within the gap space. The installed propeller and its modeling within the gap chamber represent the novelty of the present work. The influences of various design variables, including propeller diameter, propeller material, propeller thickness, position of the propeller, and the thickness of the gap on the distillate production and the specific thermal energy consumption (STEC) of the proposed propeller-aided P-WGMD system, are investigated. In addition, the effects of different operating parameters such as feed water temperature, coolant temperature, feed water flowrate, and coolant flowrate on the performance of the baseline WGMD and propeller-aided P-WGMD processes were examined. Results revealed that propeller material and propeller thickness showed marginal effects on the system's performance, especially when the thermal conductivity of the propeller material exceeded 100 W/m K. The propeller position has a strong influence on the system performance, and placing the propeller away from the membrane surface improves the system performance. Larger propeller diameters and higher propeller speeds exhibit better system performance. Propeller speed and propeller diameter are found to be the most dominant design factors affecting the performance of the proposed system. Furthermore, the P-WGMD system exhibits superior performance over the baseline WGMD system under the same operating conditions, where the flux of the P-WGMD system could reach a maximum value of 322 kg/m2h at a feed flowrate of 10 L/min, propeller speed of 1000 rev/min, feed temperature of 70 °C, coolant temperature of 20 °C, and coolant flowrate of 2.5 L/min. The presence of a propeller within the gap chamber reduces the resistance to heat transfer from about 0.002057 m2K/W to 0.0001144 m2K/W, reflecting the enhancement gained in the proposed system. Freshwater costs from the proposed system vary between 8.243 $/m3 and 11.57 $/m3 while those from the baseline system fall between 9.971 $/m3 and 21.11 $/m3.

Multipass hollow fiber membrane modules for membrane distillation

Membrane distillation (MD) is an interesting process for desalination; however high thermal energy consumption remains one of the main obstacles in its widespread adoption. The current study presents multipass hollow fiber membrane modules to improve thermal efficiency of MD process. Fundamentally three module designs are considered: conventional one shell and one tube (fiber) pass (A), 1 shell and multiple tube passes (B/C) and equal but multiple shell and tube passes (D). The performance of the proposed designs is analyzed as a function of length of each pass, number of passes and operating conditions by using Aspen Plus simulator. The results demonstrate that the traditional design A yields the highest flux — up to 92 % higher than the multipass design D. On the other hand, the multipass design D is the most energy efficiency and shows up to 35 % less thermal energy consumption than the conventional single pass design of the same length. Single shell and multiple tube pass designs (B/C) show higher flux than D; however, their specific thermal energy consumption remains the highest among all the designs investigated. The pressure drop in multipass modules was marginally (1.5 %) higher than the conventional single pass modules.

Energy and exergy analysis of multi-stage vacuum membrane distillation integrated with mechanical vapor compression

Membrane distillation (MD) is a promising candidate for desalinating hypersaline brine, but its poor energy efficiency has remained a major barrier for widespread application. One possible solution to this issue is to recover the latent heat in the process. In this work, a multi-stage vacuum MD (MSVMD) was integrated with a mechanical vapor compressor (MVC) to enhance the latent heat recovery, and the energetic and exergetic performance of this integrated process was examined. A comprehensive energy and exergy analysis is provided to compare MSVMD and MSVMD-MVC processes for desalination of hypersaline brine. This analysis was conducted by examining the effect of the compression ratio on the energetic and exergetic performance, and the findings are reported in terms of specific thermal energy consumption (STEC), specific electricity consumption (SEC), and exergetic efficiency. The energy analysis shows that thermal energy consumption can be reduced as the compression ratio increases, due to the enhancement of latent heat recovery. The MSVMD-MVC process can be operated in a steady-state condition, without the need for thermal heat input; with STEC and SEC of 0 and 49 kWh/m3 at the feed temperature of 50 °C and MVC compression ratio of 2.14. Moreover, exergy analysis demonstrates the efficacy of the eNRTL model in exergy calculation. Exergy destruction can be greatly reduced by increasing the compression ratio to an optimal value. For high salinity brine (124 g/L), MSVMD-MVC achieved a higher exergetic efficiency of 6.85%, compared to 2.42% in MSVMD. The result suggests that the application of MVC can intensify the energy efficiency and exergetic efficiency of the MSVMD system, although this process cannot outperform the current desalination technologies from the standard primary energy point of view.

Experimental and Theoretical Study on Mechanical Performance of a Sustainable Method to Simultaneously Generate Power and Fresh Water

Many regions around the world have limited access to clean water and power. Low-grade thermal energy in the form of industrial waste heat or non-concentrating solar thermal energy is an underutilized resource and can be used for water desalination and power generation. This paper experimentally and theoretically examines a thermoelectric-based simultaneous power generation and desalination system that can utilize low-grade thermal energy. The paper presents concept design and the theoretical analysis of the proposed system followed by experimental analysis and comparison with the theoretical estimations. Experiments were carried out at three heat loads 50, 100 and 150 W to achieve varying temperature gradients across thermoelectric generators. During the experiments, thermoelectric generators were maintained at a hot to cold side temperature difference between 20 to 60 °C. The experiments showed that the power generation flux and freshwater mass flux increased with the increase in the thermal energy source temperature. The power flux varied between 12 to 117 W/m2 of thermoelectric generator area, while freshwater mass flux varied between 4.8 to 23.7 kg/m2⋅h. The specific thermal energy consumption varied between 3.6 to 5.7 MJ/kg of freshwater; this is comparable to the single-stage conventional distillation system.

Performance enhancement of permeate gap membrane distillation system augmented with impeller

This research presents an assessment of a novel permeate gap membrane distillation (i-PGMD) desalination system. The investigated i-PGMD module involved the installation of an impeller inside the condensation chamber to promote turbulent dissipation rate and enhance mass and heat transfer characteristics of the system. The performance of the impeller enhanced PGMD unit (i-PGMD) is compared with the conventional PGMD without the installed impeller (PGMD). Results showed that the installed impeller greatly improved the system’s energy efficiency and flux. The i-PGMD unit recorded the best flux, gained output ratio (GOR), and specific thermal energy consumption (STEC) of 181.08 kg/m2h, 0.59, and 1129.27 kWh/m3, respectively, while the PGMD unit attained the best flux, GOR, and STEC of 94.01 kg/m2h, 0.51, and 1302.6 kWh/m3, respectively. Furthermore, the impeller speed greatly influenced the performance of the i-PGMD system. Large gap width was found to have a negligible adverse effect on the i-PGMD module performance. The i-PGMD unit was found to be less sensitive to the salinity of the feed when compared to the PGMD configuration.

Experimental investigation of membrane distillation with bubble column dehumidifier system for water desalination

The performance of a new integrated system of single-stage sweeping gas membrane distillation module and a bubble column dehumidifier (SGMD-BCD) was experimentally investigated. The productivity and energy consumption of the system is evaluated under different operating conditions. The SGMD module acts as a humidifier to produce high-quality distilled and the bubble column dehumidifier is an effective condenser for improved performance. The sweeping air stream is created in two different ways; using a vacuum pump and compressed air. Results showed that the integrated system yields higher permeate flux, better gained output ratio (GOR), and lower specific thermal energy consumption (SEC) when the vacuum pump is used. Increasing the feed temperature from 50 to 80 °C increased the flux by 175%, on average. Doubling the sweeping air flow rate from 1 to 2 SCFM resulted in flux enhancement of 49% and 25% for the vacuum pump and the compressed air supply, respectively. Operating the system with the vacuum pump and without cooling the bubble column dehumidifier showed a marginal reduction in flux but resulted in significant improvements in GOR and SEC values of 0.76 and 909 kWh/m3, respectively, at an optimum dehumidifier water column height of 9.5 cm.

Thermo-economic assessment of forward osmosis as pretreatment to boost the performance and sustainability of multi-effect distillation for seawater desalination

This work presents the thermodynamic and techno-economic assessment of a forward osmosis – multi-effect distillation (FO-MED) system able to improve the thermal performance of the MED seawater desalination process and reduce its environmental impact. Energy, exergy and techno-economic analyses have been carried out to identify the best boundary conditions that enhance the process efficiency and water cost, predicting the scale formation with the Ryznar index. Results show that using FO pretreatment in a 100 m3/d MED plant of 8 effects at 65 °C allows increasing the heating steam temperature up to 100 °C and the number of effects to 16 without increasing the risk of scaling. This results in 44 % reduction of the specific thermal energy consumption and 21 % decrease in the specific heat transfer area. The volume of saline water rejected to the sea is reduced 40 % and the water footprint 36 %. The exergy analysis reveals that the MED is the component with the highest exergy destruction. Finally, the levelized cost of water of the FO-MED is higher (7.6 $/m3) than the standalone MED process (4.6 $/m3). If high-performing and cost-effective membranes are used, the product cost could be reduced 33 % (5.1 $/m3).