Seawater Desalination System Research Articles

Theoretical analysis and auxiliary experiment of the optimization of energy recovery efficiency of a rotary energy recovery device

A rotary energy recovery device (RERD), as the energy saving equipment of seawater desalination system, has a great significance on reducing the energy consumption and permeate cost of the system. The high or low energy recovery efficiency directly determines whether the engineering application of the RERD can be widely used. In this paper, firstly, based on the calculation formula of energy recovery efficiency, the main impact factors of efficiency were analyzed theoretically, including processing capacity, the high and low pressure differentials, and the leakage of the device. Secondly, in order to carry out some required auxiliary tests smoothly, a new RERD was designed and manufactured, and a complete SWRO desalination system was also established. The results depicted that the energy recovery efficiency reached the maximum and the corresponding optimal processing capacity was about 12.15m3/h when the pressure of the low pressure seawater was 1.0bar, that of the high pressure brine was 60.0bar, and leakage of the device was 0.6m3/h. Furthermore, when processing capacity was kept 13m3/h constant and the efficiency was required to exceed 94%, under the existing operating conditions, the maximal leakage of the device was needed no more than 0.43m3/h.

Laminar flow and conjugate heat and mass transfer in a hollow fiber membrane bundle used for seawater desalination

A hollow fiber membrane-based bundle or humidifier (HFMH) is used for air humidification in the process of membrane type seawater desalination, where seawater flows inside the fibers and the process air stream flows across the fiber bundle. The HFMH has a staggered arrangement of cylindrical fiber tubes with equal transverse and longitudinal pitches. The forced convection heat and mass transfer in the cross-flow tube bundle under naturally formed boundary conditions are investigated numerically on a periodic computational cell. A membrane-based air humidification-dehumidification type sea-water desalination (MHDD) system is constructed and used to validate the model. The mathematical model proposed here takes into account of the fiber-to-fiber interactions. The typical velocity vector profiles, temperature contours as well as the concentration contours for both the air stream and saline water stream are plotted to disclose the heat and mass transfer mechanisms. The effects of air Reynolds numbers (ranging from 50 to 300) as well as the module packing fractions (ranging from 0.126 to 0.503) on the fluid flow and heat mass transfer properties of the module are investigated. A set of correlations are also proposed for the prediction of the friction factor, mean Nusselt numbers and Sherwood numbers in air side. These fundamental data is of interest for the design and optimization of the HFMH, a promising membrane type seawater desalination system.

Solar steam generation through bio-inspired interface heating of broadband-absorbing plasmonic membranes

Efficient solar-enabled evaporation plays a critical role in solar power-based concentration systems, photochemical plants, seawater desalination technologies, etc. However, traditional processes for solar steam generation usually depend on high-temperature heating of the bulk liquid, which requires highly concentrated solar power and suffers from high energy and optical losses. Therefore, the enhancement of solar steam generation by bio-inspired interface solar heating is proposed in this work. In this study, easy-to-prepare, flexible, and reusable plasmonic membranes (PMs) were fabricated for realizing the bio-inspired interface solar heating and continuous steam transportation through the micropores of the membranes. A solar steam generation efficiency of ∼85% was achieved at an illumination power of 10kWm−2. The effects of Au concentration in the membranes and optical power on the steam generation efficiency were systemically studied. The observed high evaporation rate and efficiency were attributed to three main factors: high (∼90%) and broadband solar absorption, efficient photo-thermal conversion due to high plasmon dissipation losses, and fast capillary flow in the membrane micropores. Finally, the application of PMs in a single basin solar still system for seawater desalination was investigated and the PMs exhibited great performance on enhancing the productivity of clean water.

Geothermal sea water desalination system (GSWDS) using abandoned oil/gas wells

Nowadays, the water crisis has turned to be a major problem in all over the world. Fresh water shortage and energy intensive process are the reasons underlying water crisis. Seawater desalination can be a solution for the fresh water shortage, but this process needs plenty of energy. Abandoned oil and gas wells are useless geothermal heat sources which can be used as a heat source for water desalination. Abandoned oil wells are capable of providing valuable amount of heat without the necessity to drill expensive deep wells. In this paper, the results of numerical simulation of an abandoned oil well in the Southern part of Iran, in “Ahwaz oil field”, is used for simulation of multi-effect seawater desalination process which uses oil well as a heat source and can approximately produce 565m3/day of fresh water. There are thousands of abandoned oil/gas wells in Iran that can be used as a heat source for this desalination system. This innovative use of abandoned wells is capable of not only solving the fresh water issues in Southern part of Iran, but also leading the country to go through sustainable developments. The process is environmentally-friendly, and significantly reduces the production of emissions, that are considered to be one of the main challenges in conventional desalination systems.

Recycling brine water of reverse osmosis desalination employing adsorption desalination: A theoretical simulation

Intake, pretreatment and brine disposal cost of reverse osmosis sea water desalination systems represent about 25% of total cost of the desalinated water. The present study investigates effect of reverse osmosis brine recycling employing adsorption desalination on overall system desalinated water recovery. The adsorption desalination produces dual useful effects which are high quality potable water and cooling effect. Reverse osmosis desalination is simulated by engineering equation solver (EES). The brine leaving reverse osmosis system is fed to adsorption desalination system. The adsorption desalination is driven by a low temperature heat source such as solar energy. The adsorption desalination system has been simulated by MATLAB. Results show that the proposed combination system recovery increases and permeate salinity decreases. In addition to system performance improvements, a cooling effect is generated and can be utilized for cooling applications.

The salinity gradient power generating system integrated into the seawater desalination system

Seawater desalination is an important way to solve the problem of fresh water shortage. Low energy efficiency and high cost are disadvantages existing in seawater desalination. With huge reserve and the highest energy density among different types of marine energy, salinity gradient energy has a bright application prospect. The promotion of traditional salinity gradient power generating systems is hindered by its low efficiency and specific requirements on site selection. This paper proposes a salinity gradient power generating system integrated into the seawater desalination system which combines the salinity gradient power generating system and the seawater desalination system aiming to remedy the aforementioned deficiency and could serve as references for future seawater desalination and salinity gradient energy exploitation. The paper elaborates on the operating principles of the system, analyzes the detailed working process, and estimates the energy output and consumption of the system. It is proved that with appropriate design, the energy output of the salinity gradient power generating system can satisfy the demand of the seawater desalination system.

Experimental study of a stand-alone solar-wind-powered reverse osmosis seawater desalination system

Experimental study of a stand-alone solar-wind-powered reverse osmosis seawater desalination system

Economic Prospective of Small/Medium Nuclear reactors for Hybrid Seawater Desalination Systems

Economic Prospective of Small/Medium Nuclear reactors for Hybrid Seawater Desalination Systems

Study on the Wind and Solar Hybrid Desalination for Water-Saving Society Development of Shandong Province

The seawater desalination technology provides an effective way to solve the shortage issue of freshwater resources. This paper describes current water resource situation of Shandong Province which calls for a seawater desalination system serve itself continuously. Having analyzed the current situation of wind and solar energy recourses in Shandong, this article bring up reverse osmosis desalination using wind and solar hybrid power, and theoretical design and matching calculation in the process also has been carried out. Additionally, economic calculation was conducted. The results show that the combination use of wind and solar power in seawater desalination has certain economic benefits, as well as improving the proportion of unconventional water’s usage.

Evaluation of energy consumption of gas hydrate and reverse osmosis hybrid system for seawater desalination

Evaluation of energy consumption of gas hydrate and reverse osmosis hybrid system for seawater desalination

Combined Solar Chimney Power Plant and Solar Still

This study presents solar chimney power plantintegrated with seawater desalination system. A simplemathematical model is based on the conservation of massand energy. The results show that the integrated system ofsolar chimney power plant and solar still can achievesimultaneously. The analysis is performed for bothsummer and winter at latitude 30oN. It’s noted that thewater layer thickness is of a significant effect on the freshwater productivity while the dimensions of solar chimneyand the solar collector are of a minor effect. Theproductivity of fresh water and output power for summerare the highest. The present work is compared withexperimental data of the other work and showed a goodagreement.

Implementation of dynamic working condition seawater desalination system optimization and simulation model

Freshwater is an increasingly important research topic in the 21st century, similar to the importance of coal and oil in the 19th and 20th centuries, respectively. To expand expertise on desalination systems, this study aims to design a set of seawater desalination systems with dynamic working conditions based on the visualized development platform LABVIEW. The optimization searched for the optimal working conditions and formed the seawater desalination refinement process control technology and solution. A scaled dynamic load working device safety and protection solution was obtained, and an ideal scenario compared with the real operation environment was reproduced to assist people in operating and running the system.

Evaluating energy consumption of air gap membrane distillation for seawater desalination at pilot scale level

Abstract This study aimed to optimise an air gap membrane distillation (AGMD) system for seawater desalination with respect to distillate production as well as thermal and electrical energy consumption. Pilot evaluation data shows a notable influence of evaporator inlet temperature and water circulation rate on process performance. An increase in both distillate production rate and energy efficiency could be obtained by increasing the evaporator inlet temperature. On the other hand, there was a trade-off between the distillate production rate and energy efficiency when the water circulation rate varied. Increasing the water circulation rate resulted in an improvement in the distillate production rate, but also an increase in both specific thermal and electrical energy consumption. Given the small driving force used in the pilot AGMD, discernible impact of feed salinity on process performance could be observed, while the effects of temperature and concentration polarisation were small. At the optimum operating conditions identified in this study, a stable AGMD operation for seawater desalination could be achieved with specific thermal and electrical energy consumption of 90 and 0.13 kW h/m 3 , respectively. These values demonstrate the commercial viability of AGMD for small-scale and off-grid seawater desalination where solar thermal or low-grade heat sources are readily available.

Alternatives for vacuum generation in unconventional seawater desalination systems

Seawater desalination is a viable option to reduce water shortage problems. As a consequence, the development of technologies that can guarantee the availability of water resources is essential. This article primarily focuses on the study and theoretical analysis of a vacuum generation system for a modular desalination unit with low-enthalpy geothermal energy as power source. This desalination unit, currently in the Research & Development stage, aims to be an effective, low-cost and marketable product, fulfilling the need of water in regions that have both, the energy source, and the lack of drinking water, such as northwestern Mexico. Based on the dissertation presented, the use of a hydroejector is proposed, discussing the feasibility of the use of steam or air as working fluid.

Evaluation of economic feasibility of reverse osmosis and membrane distillation hybrid system for desalination

AbstractThis study seeks to evaluate the economic feasibility of membrane distillation (MD) and reverse osmosis (RO)-MD hybrid system for seawater desalination. A theoretical cost model was applied to analyze the effects of flux, recovery, membrane properties, and energy price on RO, MD, and RO-MD hybrid system. The simulation results showed that MD stand-alone system and RO-MD hybrid system can be cost-competitive compared with RO systems when the recovery and flux of MD system are higher than those of RO system and the steam cost is relatively cheap. It is also revealed that the water costs of RO-MD hybrid system and RO system are same under similar operating conditions, but the water cost of MD stand-alone system is higher. The effect of thermal energy cost on water cost for MD and RO-MD systems was also analyzed. Based on these results, guidelines for an analysis of economic feasibility of MD and RO-MD were suggested.

Seawater desalination with solar-energy-integrated vacuum membrane distillation system

This study designed and tested a novel type of solar-energy-integrated vacuum membrane distillation (VMD) system for seawater desalination under actual environmental conditions in Wuhan, China. The system consists of eight parts: a seawater tank, solar collector, solar cooker, inclined VMD evaporator, circulating water vacuum pump, heat exchanger, fresh water tank, and brine tank. Natural seawater was used as feed and a hydrophobic hollow-fiber membrane module was used to improve seawater desalination. The experiment was conducted during a typical summer day. Results showed that when the highest ambient temperature was 33 °C, the maximum value of the average solar intensity was 1,080 W/m2. The system was able to generate 36 kg (per m2 membrane module) distilled fresh water during 1 day (7:00 am until 6:00 pm), the retention rate was between 99.67 and 99.987%, and electrical conductivity was between 0.00276 and 0.0673 mS/cm. The average salt rejection was over 90%. The proposed VMD system shows favorable potential application in desalination of brackish waters or high-salt wastewater treatment, as well.

Investigation into design parameters in seawater reverse osmosis (SWRO) and pressure retarded osmosis (PRO) hybrid desalination process: a semi-pilot scale study

AbstractThe performance of a seawater reverse osmosis and pressure retarded osmosis (SWRO-PRO) hybrid system for power generation and seawater desalination was investigated using a pilot-scale system. The draw and feed solutions of the PRO process were SWRO brine and permeate, respectively. The PRO system performed better, meaning it had a higher energy recovery rate, at higher draw solution salinities. The PRO performance was further improved by increasing the flow rate of the draw solution as this reduced the concentration polarization effect in the PRO membrane. The performance of the PRO module was investigated experimentally, and the results were compared with simulations. The maximum power density of the PRO membrane module was 14 W/m2 at 28 bar using a solution with 70,000 mg/L of sodium chloride (NaCl) and draw and feed solution flow rates of 20 LPM and 4 LPM, respectively. We estimated the performance of the PRO membrane module using a simulation that incorporated the temperature of the draw solu...

Pressure Retarded Osmosis (PRO): Past experiences, current developments, and future prospects

Pressure Retarded Osmosis (PRO) has attracted worldwide attention with respect to its salinity gradient energy production potential, and low energy desalination applications. PRO processes, which use Seawater Reverse Osmosis (SWRO) brine as draw solutions, have a higher potential of being applied to any new, and existing membrane based seawater desalination systems, as an energy production and/or conservation process. Hydraulic pressure is applied on a high salinity draw solution, and the hydraulic pressure of the high salinity draw solution can be kept relatively constant during operation, even though the volumetric flow rate is to be increased. Therefore, the draw side of the PRO process can be considered near-isobaric, in most cases. The harvested Gibbs free energy of mixing, and the volumetric expansion can explain this near-isobaric behavior of the draw side in the PRO process. Thus, PRO can be used to multiply the internal energy of the draw solution with respect to the ratio of the permeated water flux. Even though PRO has very high theoretical potential for energy production and/or recovery, there are several shortcomings, which should be answered before the realization of the scale up applications, such as; thermodynamic process optimization, high power density membranes, and high efficiency hydraulic pressure conversion and recovery systems. This review gives detailed information about the PRO process including; (1) theoretical background, (2) membranes for PRO, (3) experimental and large scale applications, and (4) economic feasibility of PRO applications.

Pilot-Scale Investigation of Forward/Reverse Osmosis Hybrid System for Seawater Desalination Using Impaired Water from Steel Industry

This paper was focused on the investigation of a forward osmosis- (FO-) reverse osmosis (RO) hybrid process to cotreat seawater and impaired water from steel industry. By using this hybrid process, seawater can be diluted before desalination, hence reducing the energy cost of desalination, and simultaneously contaminants present in the impaired water are prevented from migrating into the product water through the FO and RO membranes. The main objective of this work was to investigate on pilot-scale system the performance of the combined FO pretreatment and RO desalination hybrid system and specifically its effects on membrane fouling and overall solute rejection. Firstly, optimization of the pilot-scale FO process to obtain the most suitable and stable operating conditions for practical application was investigated. Secondly, pilot-scale RO process performance as a posttreatment to FO process was evaluated in terms of water flux and rejection. The results indicated that the salinity of seawater reduced from 35000 to 13000 mg/L after 3 hrs using FO system, while after 6 hrs it approached 10000 mg/L. Finally, FO/RO system was tested on continuous operation for 15 hrs and it was demonstrated that no pollutant was detected neither in draw solution nor in RO permeate after the end of operating time.

Mathematical modeling assisted investigation of forward osmosis as pretreatment for microbial desalination cells to achieve continuous water desalination and wastewater treatment

Coupling forward osmosis (FO) with microbial desalination cells (MDCs) can lead to some synergistic benefits, i.e. simultaneous water recovery, desalination and removal of COD (chemical oxygen demand). Herein, an FO-MDC system was developed and examined in a continuously-operated mode. It achieved 70.6% COD removal from a synthetic wastewater and 94.0% conductivity decrease in a salt solution containing 35gL−1 NaCl. The flow rates of both wastewater and salt water exerted strong effects on the system performance. At a draw flow rate of 0.02mLmin−1, the effluent TDS (total dissolved solids) reached 315mgL−1, lower than the maximum contaminant levels of the National Secondary Drinking Water Regulations. A mathematical model was developed for the first time through integrating FO model with MDC model. This model could well predict the key performance parameters such as current generation and desalination effectiveness and rate. When further tested with actual domestic wastewater amended with glucose and NaHCO3, the FO-MDC system generated a desalinated effluent containing 1130mgTDSL−1. The results of this study suggest that proper coordination of the treatment capacity of the two membrane-based treatment processes could create a potentially effective system for wastewater reuse and seawater desalination.