Thermal Desalination Technologies Research Articles

Emerging and Conventional Water Desalination Technologies Powered by Renewable Energy and Energy Storage Systems toward Zero Liquid Discharge

The depletion of fossil fuels has become a significant global issue, prompting scientists to explore and refine methods for harnessing alternative energy sources. This study provides a comprehensive review of advancements and emerging technologies in the desalination industry, focusing on technological improvements and economic considerations. The analysis highlights the potential synergies of integrating multiple renewable energy systems to enhance desalination efficiency and minimise environmental consequences. The main areas of focus include aligning developing technologies like membrane distillation, pervaporation and forward osmosis with renewable energy and implementing hybrid renewable energy systems to improve the scalability and economic viability of desalination enterprises. The study also analyses obstacles related to desalination driven by renewable energy, including energy storage, fluctuations in energy supply, and deployment costs. By resolving these obstacles and investigating novel methodologies, the study enhances the understanding of how renewable energy can be used to construct more efficient, sustainable, and economical desalination systems. Thermal desalination technologies require more energy than membrane-based systems due to the significant energy requirements associated with water vaporisation. The photovoltaic-powered reverse osmosis (RO) system had the most economically favourable production cost, while MED powered via a concentrated solar power (CSP) system had the highest production cost. The study aims to guide future research and development efforts, ultimately promoting the worldwide use of renewable energy-powered desalination systems.

Drinking Water Quality in the Kingdom of Saudi Arabia

The production and transmission system of the Saudi Water Authority (SWA) faces a number of challenges in maintaining the high quality of potable water. Produced desalinated water is transmitted for long distances and is mixed with ground and surface waters of varying quality. The SWA is also in the process of converting from thermal desalination to seawater reverse osmosis which typically gives higher total dissolved solids, requiring better control of species with possible impacts on system integrity or human health. The results of monitoring across the desalination plants and transmission systems of the SWA in 2020–2022 confirm an overall high quality of water, with levels of disinfection by-products and heavy metals low in comparison to public water supplies in high-income countries dependent on surface and groundwater rather than seawater desalination. The results also indicate that continued operational improvements are required with the transition from thermal desalination technologies to reverse osmosis in order to maintain chloride at a level to avoid corrosion in the distribution system and to maintain boron and bromate within acceptable regulatory limits. Significant improvement in bromate control was observed over the course of the study, and recent innovations in post-treatment suggest that this will improve further.

Innovative and efficient integrations of desalination plants coupled absorption, adsorption, and humidification-dehumidification desalination units employing external heat recovery techniques

Thermal desalination technologies have been developed recently to solve some pressing problems, such as high energy expenditure, increasing fuel costs, and environmental problems related to conventional plants. However, these technologies still need to be enhanced in terms of water production and gain output ratio (GOR). This paper presents innovative and efficient combined thermal desalination plants consisting of absorption (ABDS), adsorption (ADDS), and humidification-dehumidification (HDH) desalination units to enhance energy utilization, water production, and overall system performance. Four innovative combined desalination plants employing different external heat recovery scenarios are presented and compared. The result from each scenario is evaluated and compared with those of the standalone ABDS and with other studies found in the literature at the same heat source temperatures. The heat source is mainly utilized to drive the ABDS plant. The ADDS and HDH are driven by the heat rejection from the ABDS components with different external heat recovery scenarios. Results illustrated that the maximum freshwater production generated from the proposed scenarios ranges between 1.57 and 2.94 m3.day−1 with a GOR of between 1.38 and 1.75 at 120 °C. Raising heat source temperatures from 55 to 120 °C decreased the improvement in the water productivity from 618.5 to 224 % and decreased the enhancement in the GOR from 222.8 to 99 %. In scenarios where the ADDS and HDH are driven by the heat rejection from the absorption and condensation process of the ABDS, the maximum freshwater production results from the ABDS unit. On the other hand, in scenarios where the ADDS and HDH are driven by the outlet hot water from the ABDS-generator, the maximum freshwater production is obtained from the HDH unit. The finding provided that the proposed innovative scenarios have an effective improvement in overall system performance indicators.

Definition of Exergetic Efficiency in the Main and Emerging Thermal Desalination Technologies: A Proposal

Increasing attention is being given to reduce the specific energy consumption in desalination processes, which translates into greater use of exergy analysis. An exergetic analysis provides relevant information related to the influence of the efficiency of a single component in the global plant performance and in the exergy cost of the product. Therefore, an exergy analysis identifies the main improvement potentials in a productive thermodynamic process. Related to desalination technologies, many previous papers deal with the calculation of the parameters involved in the exergy analysis, the exergetic efficiency of different processes, plants, and technologies among them. However, different approaches for formulating the exergetic efficiency have been suggested in the literature, often without sufficient understanding and consistency. In this work, these formulations, applied to the main desalination components and processes, are compared and critically reviewed. Two definitions of exergy efficiency are applied to the desalination components of the three main thermal desalination processes (multieffect distillation–thermal vapour compression, multistage flash distillation, and direct-contact membrane distillation). The results obtained for the exergy efficiency of the MED-TVC, MSF, and DCMD processes for the input–output approach are 21.35%, 17.08%, and 1.28%, respectively, compared to the consumed–produced approach that presented 3.1%, 1.58%, and 0.37%, respectively. The consumed–produced approach seems to better fit the thermodynamic behaviour of thermal desalination systems.

Comparison of Desalination Technologies and Assessment of Their Sustainability

Water scarcity is a major issue in socioeconomic progress and a threat to livelihood. Overexploitation of freshwater resources threatens food security and sustainable water usage. Countries, therefore, are looking for new ways to ensure the long-term availability of drinking water sources, among which desalination has a prominent role. Several desalination technologies have been proposed during the last decade, which can be classified into two primary categories, i.e. thermal technologies, and membrane technologies. The former include Multi-Stages Flash distillation (MSF), Multi-Effect Distillation (MED), and Mechanical Vapor Compression (MVC), whereas the membrane technologies include Reverse Osmosis (RO), Electrodialysis (ED), and Forward Osmosis (FO). However, all these technologies are energy-intensive and can have significant environmental impacts. In this context, sustainable desalination technologies, such as solar desalination, are essential in solving this issue. The main objective of this paper is to compare the different desalination technologies based on their environmental, technical, and economic aspect. Based on the results, when considering energy consumption, water cost, and carbon dioxide emissions, membrane technology is the most promising option. However, thermal desalination technologies, particularly MED, coupled with Solar energy are technically more interesting compared to the RO.

Electricity and water cogeneration using a small PWR of 75 MW(th) coupled to a DCMD desalination plant with heat recovery

The use of a small PWR of 75 MW(th) coupled to a Direct Contact Membrane Distillation (DCMD) desalination plant with heat recovery, for cogeneration of electricity and water, is investigated here. Part of the heat used for desalination is waste heat from the power plant, as the desalination plant collects warm seawater from the power plant condenser instead of taking water directly from the sea. Two distinct coupling strategies are considered. In the first one, the additional heating required for the desalination process is obtained from steam extractions, taken at the low pressure turbine, after the extracted steam has already done a substantial amount of mechanical work. The second strategy is based on splitting the steam produced in the steam generator into two parallel Rankine cycles. The condenser at one of those cycles is set to operate just below atmospheric pressure in order to provide extra heating, at a higher temperature, for the desalination plant. Both strategies analysed in this work, relying on the use of waste heat and employing a DCMD desalination plant with efficient heat recovery, are shown to be competitive with other well established thermal desalination technologies currently used in nuclear cogeneration plants, such as MED and MSF.

Current Status and Advancement in Thermal and Membrane-Based Hybrid Seawater Desalination Technologies

Emerging hybrid technologies have better potential than conventional technology for diversifying the desalination industry, which is presently being dominated by thermal and membrane-based desalination. Notwithstanding the technological maturity of the desalination processes, they remain highly energy-intensive processes and have certain disadvantages. Therefore, the hybridization of thermal and membrane desalination processes holds great attention to mitigate limitations of individual processes in terms of energy consumption, quality and quantity of potable water, overall efficiency and productivity. This paper provides an oversight of conventional and developing desalination technologies, emphasizing their existing state and subsequent potential to reduce water scarcity. Conventional hybrid desalination systems (NF-RO-MSF, MED-AD, FO-MED, MSF-MED, RO-MED, RO-MSF and RO-MD) are briefly discussed. This study reveals that the integration of solar thermal energy with desalination has a great potential to substantially reduce greenhouse emissions besides providing the quality and/or quantity of potable water in cost-effective ways. Due to its abundant availability with minimal/no carbon footprint and the ability to generate both thermal and electrical energy, solar energy is considered better than other renewable energy technologies. The findings further suggest that hybrid desalination systems are technically sound and environmentally suitable; however, a significant study of the research process and development is still required to make this technology efficient and economically viable.

Surfactant pretreatment as a novel fouling mitigation strategy for membrane distillation

Membrane distillation (MD) has emerged as a promising thermal desalination technology for hypersaline wastewater reclamation. However, the practical implementations of MD face a critical challenge of membrane fouling. Conventional strategy to address membrane fouling is to emphasize the progress in developing composite MD membranes, but these membranes are commercially unavailable. In this study, we introduce a new operation strategy to mitigate fouling by using surfactant pretreatment. We demonstrate that after being pretreated by 0.05 mM Triton X-100 feed solution for 10 min, a commercial polyvinylidene fluoride (PVDF) membrane can exhibit outstanding fouling resistance in MD process. Further, we elucidate the underlying working mechanism using quartz crystal microbalance (QCM) experiments, oil contact angle measurements, and force spectroscopy determinations. Specifically, in the pretreatment process, the amphiphilic surfactant adsorbs onto the hydrophobic membrane, altering the membrane surface to be hydrophilic. During the MD operations, a hydration layer forms on the hydrophilic surface, eliminating the foulant-membrane interaction and thereby achieving fouling mitigation. For effective fouling mitigation, a surfactant exhibiting a moderate hydrophilic-lipophilic balance (HLB) value (e.g., Triton X-100 with an HLB of ∼14) is required. As an easy-to-implement but effective strategy to mitigate membrane fouling, surfactant pretreatment can substantially improve the fouling resistances of commercial hydrophobic membranes, greatly facilitating the practical applications of MD and membrane contactor technologies.

Energy analysis of a small-scale multi-effect distillation system powered by photovoltaic and thermal collectors

Powering thermal desalination technologies by renewable energy is believed to be a viable solution to overcome the worldwide freshwater scarcity problem without causing more damage to the environment. In this paper, a multi-effect distillation system (MED) with mechanical vapor compression is powered by the generated electrical power of photovoltaic/thermal collectors and assisted by the by-product thermal power generated. The system is sized according to thermal power needed and designed for small-scale application and weather conditions of Alexandria, Egypt. Excess electricity is injected into the grid and hot water storage tank is used as a back-up to compensate low and fluctuating radiation. Results show that, at a saturation temperature of MED’s heating steam of 55 °C, freshwater production is 11.1 m3/day in 10 hours of operation, system specific power consumption is 9.72 kWh/m3, specific area is 317.04 m2s/kg, and performance ratios of the desalination unit is 3.33 and 6.97 for the overall system. However, at T = 65 °C the system’s electrical energy is totally absorbed by the compressor, and the system’s performance decreases.

Thin‐Film Composite Membrane with a Hydrophobic Substrate for Robust Membrane Distillation

AbstractMembrane distillation (MD) is a promising thermal desalination technology, but its application is largely limited by membrane wetting. This study introduces a thin‐film composite (TFC) membrane comprising a polyamide (PA) surface layer, a polydopamine (PDA) interlayer, and a hydrophobic polyvinylidene fluoride (PVDF) membrane substrate for anti‐wetting MD operations. With a PDA reaction time of 1 h, a compact and hydrophilic PDA interlayer forms on the PVDF membrane substrate, facilitating the subsequent formation of the PA surface layer. With 2 cycles of interfacial polymerization process, a dense PA surface layer forms on the PDA interlayer, rendering a TFC membrane with robust wetting resistance. From diffusion experiments and breakthrough pressure measurements, the TFC membrane exhibits excellent wetting resistance because the dense PA surface layer can prevent the wetting contaminants from reaching the hydrophobic membrane substrate due to the combination of the size exclusion effect and capillary effect. The results from this study shed lights on a new approach for the fabrication of robust MD membranes for practical applications.

A comprehensive review of solar thermal desalination technologies for freshwater production

<abstract> <p>This review is inspired by the increasing shortage of fresh water in areas of the world, and is written in response to the expanding demand for sustainable technologies due to the prevailing crisis of depleting natural water resources. It focuses on comprehending different solar energy-based technologies. Since the increasing population has resulted in the rising demand for freshwater, desalination installation volume is rapidly increasing globally. Conventional ways of desalination technologies involve the use of fossil fuels to extract thermal energy which imparts adverse impacts on the environment. To lessen the carbon footprint left by energy-intensive desalination processes, the emphasis has shifted to using renewable energy sources to drive desalination systems. The growing interest in combining solar energy with desalination with an emphasis on increasing energy efficiency has been sparked by the rapid advancements in solar energy technology, particularly solar thermal. This review paper aims to reflect various developments in solar thermal desalination technologies and presents prospects of solar energy-based desalination techniques. This paper reviews direct and indirect desalination techniques coupled with solar energy, and goes on to explain recent trends in technologies. This review also summarizes the emerging trends in the field of solar thermal desalination technologies. The use of nanoparticles and photo-thermal materials for localized heating in solar desalination systems has decreased energy consumption and enhanced the efficiency of the system. Solar power combined with emerging processes like membrane distillation (MD) has also a recent resurgence.</p> </abstract>

Performance Analysis of an Eductor-Based Membrane Distillation Unit

Thermal desalination technologies involve two primary processes: vapor generation from saline water, and effective recovery of the resulting condensate. Membrane distillation (MD) systems are among the emerging thermal desalination technologies which use a hydrophobic membrane to recover condensate through either direct or indirect contact (with the cooling fluid) condensation. The specific process technology (for thermal energy transfer and condensate recovery) depends on the type of MD. Direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD) are two significant MD processes, with DCMD having the advantage of direct condensation and simple design, while VMD systems have high yield through sub-atmospheric vapor generation. This work focuses on developing an eductor-based MD process incorporating the strengths of both DCMD and VMD. It is an experimental study with a water jet eductor replacing the vacuum pump and condenser in a typical VMD system for active permeate vapor transfer and condensation. Unlike the exiting VMD systems, the proposed design recovers condensate by direct contact condensation. The sub-cooled water acts as a motive flow which entrains the secondary vapor into the stream, causing mass transfer via condensation at the interface. The modified VMD was found to have achieved better flux compared to the conventional VMD system. The performance of the eductor, sensitivity to parameters, and the practicality of the technology have been analyzed.

Performance enhancement of a hybrid multi effect evaporation/membrane distillation system driven by solar energy for desalination

The development of novel and energy-efficient desalination technologies has been inspired by the global water shortage and rising fossil oil prices. The current study aimed to incorporate solar energy into a hybrid water desalination set up including thermal desalination and membrane distillation (MEE-MD) technologies. This technology was demonstrated utilizing multi-effect evaporation (MEE) and air-gap membrane distillation (AGMD) structures. The performance of the hybrid desalination system with heat recovery (MEE-HR/MD), which is powered by an evacuated tube heat pipe solar collector, was evaluated outdoors under a variety of climatic conditions. Results showed that hybrid MEE/MD configurations surpassed the standalone multi-effect evaporation unit. The performance ratio of the hybrid system is 45% higher than the standalone MEE. The hybrid proposed system has a fresh potable water production capacity of 159,84 m3 per year at a cost of US $ 5.37/m3 and minimizes carbon dioxide emissions by 189 tons per year.

Energy and water without carbon: Integrated desalination and nuclear power at Diablo Canyon

A seawater reverse osmosis (SWRO) desalination plant collocated with an existing nuclear plant would have low electricity costs, could share the power plant’s seawater intake and outfall, and would have zero carbon footprint during operation. Unlike thermal desalination technologies, electrically-driven SWRO is ideal for retrofitting existing power plants because the turbines and condensers would not need expensive modifications. Here, we evaluate the techno-economic feasibility of collocating a large-scale SWRO plant with an existing nuclear power plant, specifically the 2.2 GWe Diablo Canyon Nuclear Power Plant on California’s central coast. The seawater that cools the nuclear plant’s condensers provides the feed water for desalination. The desalination brine is diluted with the remaining condenser coolant before being discharged to the ocean. A brushed-screen intake structure, serving both the nuclear power plant and the desalination plant, can comply with strict California regulations protecting marine organisms. This coproduction arrangement has a significant cost advantage relative to a stand-alone desalination plant. The levelized cost of water (LCOW) ranges from US$0.77 to US$0.98 per m3 of fresh water, with water distribution to offtakers adding US$0.02 to US$0.21 per m3 over 20–185 km. In comparison, California’s largest desalination plant, in Carlsbad, has an LCOW of about US$1.84 per m3. These cost savings result from reduced power costs (about US$0.054 per kWh) and from sharing some expensive infrastructure. Further, nuclear electricity allows a Carlsbad-size SWRO to avoid 47 kt/y of CO2 emissions relative to grid electricity. Examination of substantially larger desalination plants introduces additional considerations. This study is the first to show that collocated SWRO and nuclear power are strongly coupled and have a significant economic advantage over seawater desalination at other sites. These benefits should apply to dozens of existing nuclear power plants worldwide.

Heat transfer innovations and their application in thermal desalination processes

<h2>Summary</h2> The familiarity of mature thermal technologies for brine concentration and crystallization is likely to sustain their widespread deployment despite their high capital and operational (i.e., energy) costs relative to emerging non-thermal alternatives. This critical review and analysis evaluates the potential for recent innovations in manufacturing devices for improved heat and mass transfer to demonstrably reduce the lifecycle costs of these thermal desalination technologies. We identify three promising innovation applications, including novel heat transfer geometries enabled by additive manufacturing, emerging surface engineering methods to promote dropwise condensation, and new polymer-/polymer-composite-based heat transfer components. Based on the estimated cost and performance impacts of these material and process modifications, we find that polymer-/polymer-composite-based heat transfer devices have the largest potential to reduce the unit cost of water in the near term. Throughout the review, we also highlight remaining research gaps and unmet technoeconomic targets that would benefit from future investigation and collaboration between the heat transfer and desalination communities.

A systematic construction of water-electricity cogeneration and thermal membrane coupling desalination technology using the waste heat in steel industry

The widespread use of fossil energy emits a large amount of carbon dioxide, leading to the greenhouse effect and global warming. The essence of reducing carbon emissions is to achieve higher-quality sustainable development. The recycling of waste heat in the iron and steel industry is of great significance to reducing carbon emissions. Aiming at the problem of insufficient utilization of gas in iron and steel industry and the development of seawater desalination industry, a water-electricity cogeneration and thermal membrane coupling technology is established. Low-temperature multi-effect distillation seawater desalination device is directly connected with steam turbine generator, which uses gas to generate electricity. After generating electricity, negative pressure exhaust at the end of steam turbine is used for seawater desalination. The thermal efficiency of the system is increased to over 80%, the waste heat is effectively utilized, and the carbon emission in the thermal desalination process is reduced. At the same time, the high-efficiency removal and resource utilization of salt in concentrated seawater are realized. The recovery ratio of freshwater is over 55%, the salt content of freshwater is below 500 mg/L, and the salt content of seawater concentrated by membrane method can reach 79,450 mg/L. A new comprehensive utilization and recycling system of seawater has been constructed to realize efficient recycling of energy resources and promote the development process of carbon emission reduction.

Characteristics of Desalination Brine and Its Impacts on Marine Chemistry and Health, With Emphasis on the Persian/Arabian Gulf: A Review

At a time when worldwide water shortage is increasing, seawater is being viewed as an inexhaustible supply of freshwater via the process of seawater desalination. As a result, seawater desalination is becoming more popular, especially in areas where freshwater is scarce, such as the Middle East and North Africa (MENA), which accounts for half of all global saltwater desalination activities. To enhance the efficiency of saltwater desalination, thermal and membrane-based desalination technologies are continually being developed and hybridized systems established. Brine is an unavoidable product of seawater desalination and is commonly disposed of in oceans and seas, where it has negative effects on the surrounding marine environment and its biodiversity due to the resultant increased salinity and temperature, as well as the presence of chemicals. Furthermore, the quality and amount of brine are influenced by several parameters, including the input quality and quantity, the desalination process, and the discharge method. The intensity of brine’s influence on the marine biota is determined by a number of factors; nevertheless, marine species differ in their tolerance to brine’s effects. Desalination technology is improving to maximize water recovery and reduce the volume of brine produced, with the objective of eventually reaching zero liquid discharge and limiting harmful effects on the marine environment. Meanwhile, proper systems for analyzing the effects of seawater desalination facilities on the marine ecology must be implemented. This review study will look at all of the factors that determine the physicochemical features of desalination brine, with a focus on its impact on marine chemistry and biodiversity. More crucially, the most cutting-edge brine management methods will be investigated for long-term desalination and a healthy marine ecosystem.

Desalinating a real hyper-saline pre-treated produced water via direct-heat vacuum membrane distillation

Membrane distillation (MD) is an emerging thermal desalination technology capable of desalinating waters of any salinity. During typical MD processes, the saline feedwater is heated and acts as the thermal energy carrier; however, temperature polarization (as well as thermal energy loss) contributes to low distillate fluxes, low single-pass water recovery and poor thermal efficiency. An alternative approach is to integrate an extra thermal energy carrier as part of the membrane and/or module assembly, which can channel externally provided heat directly to the membrane-feedwater interface and/or along the feed channel length. This direct-heat delivery has been demonstrated to increase single-pass water recovery and enhance the overall thermal efficiency. We developed a bench-scale direct-heated vacuum MD (DHVMD) process to desalinate pre-treated oil and gas “produced water” with an initial total dissolved solids of 115,500 ppm at a feed temperature ranging between 24 and 32 °C. We evaluated both water flux and specific energy consumption (SEC) as a function of water recovery. The system achieved a 50% water recovery without significant scaling, with an average flux >6 kg m–2 hr–1 and a SEC as low as 2,530 kJ kg−1. The major species of mineral scales (i.e., NaCl, CaSO4, and SrSO4) that limited the water recovery to 68% were modeled in terms of thermodynamics and identified by scanning electron microscopy and energy-dispersive X-ray spectroscopy. In addition, we further developed and employed a physics-based process model to estimate temperature, salinity, water transport and energy flows for full-scale vacuum MD and DHVMD modules. Model results show that a direct-heat input rate of 3,600 W can increase single-pass water recovery from 2.1% to 3.1% while lowering the thermal SEC from 7,800 kJ kg−1 to 6,517 kJ kg−1 in an unoptimized module. Finally, the scaling up potential of DHVMD process is briefly discussed.

Integration of waste heat in thermal desalination technologies: A review

Desalination is increasingly becoming a crucial method for providing fresh water globally. However, most of the desalination technologies are energy-intensive and driven by fossil fuels that are contributing to climate change and other environmental problems. In this vein, renewable energy and energy efficiency are promising pillars of sustainable energy production and consumption, and the recovery of waste heat helps to augment the energy efficiency of a system. Based on the temperature (T) of the heat source, waste heat can be classified into three categories: low temperature (T&lt;100°C), medium temperature (100°C£T&lt;300°C) and high temp-erature (T³300°C). There is scarcity of review work on the integration of waste heat in desalination technologies. In this study, the progress in the utilisation of waste heat to drive thermal desalination processes has been investigated. It is found that 63% of waste heat streams are of low grade, which is still satisfactory for thermal desalination technologies that run on low-temperature heat sources. As of 2018, there was only one known thermal desalination plant driven by waste heat. Lack of data on waste heat, especially in developing countries, has been identified as a major challenge to the advancement of desalination technologies driven by this source of thermal energy. Other constraints are presented and discussed in this paper.

A multi-objective optimisation framework for MED-TVC seawater desalination process based on particle swarm optimisation

Owing to the high specific energy consumption associated with thermal desalination technologies such as Multi Effect Distillation (MED), there is a wide interest to develop a cost-effective desalination technology. This study focuses on improving the operational, economic, and environmental perspectives of hybrid MED-TVC (thermal vapour compression) process via optimisation. Application of particle swarm optimisation (PSO) in several engineering disciplines have been noted but its potential has not been exploited fully in desalination technologies especially MED-TVC in the past. A multi-objective non-linear optimisation framework based on PSO is constructed here. Two of our earlier models have been used to predict the key process performance and cost indicators. The models are embedded within the PSO optimisation algorithm to develop a new hybrid optimisation model which minimises the total freshwater production cost, total specific energy consumption and brine flow rate while maintaining a fixed freshwater production for a given number of effects and seawater conditions. The steam flow rate and temperature are considered as control variables of the optimisation problem to achieve the objective function. The PSO has successfully achieved the optimum indexes for the hybrid MED-TVC process for a wide range of number of effects. It also shows a maximum reduction of freshwater production cost by 36.5%, a maximum energy saving by 32.1% and a maximum reduction of brine flow rate by 38.3%, while maintaining the productivity of freshwater.