Brine Flow Rate Research Articles

Low-Resistance Membrane vs. High-Resistance Membrane Performance Utilizing Electrodialysis-Evaporator Hybrid System in Treating Reject Brine from Kuwait Desalination Plants.

This work is an effort to mitigate the existing environmental issues caused by brine discharge from Kuwait's desalination plants and to find an economical and efficient way of managing reject brine from local desalination plants. Low- and high-resistance membranes (LRMs and HRMs, respectively) were used to produce salt and low-salinity water from brine effluent utilizing an electrodialysis (ED)-evaporator hybrid system. The effect of high current densities of 300, 400, and 500 A/m2 and brine flowrates of 450 and 500 L/h on the quality of produced salt and diluate were investigated for LRM and HRM. The recovered salt purity for LRM is up to 90.58%. Results show that the low-resistance membrane (LRM) achieved higher water recovery, energy consumption, desalination rate, operation time and ion removal rate than those of the high-resistance membrane (HRM) under the same operating conditions. The difference in concentration for 300 A/m2 between LRM and HRM increased from 0.93% at 10 min to 8.28% at 140 min. The difference in diluate concentration effluent is negligible for both membranes, whereas LRM produced higher concentrate effluent than HRM for all current densities and low flowrate (400 L/h). The maximum difference between LRM and HRM (with LRM achieving higher concentrations) is 10.7% for 400 A/m2. The permselectivity of LRM for monovalent cations decreased with current density, whereas the effect on permselectivity for HRM was insignificant for the current density values. The addition of a neutral cell was effective in reducing the buildup of divalent ions on the inner membrane of the cathode side.

A techno-economic assessment of conventional and modified Solvay processes for CO2 capture and reject brine desalination

The ongoing discharge of desalination reject brine and emission of carbon dioxide (CO2) into the environment pose a major threat to the ecosystem. In this context, the Solvay process presents a potential mitigation scheme for reducing reject brine salinity while simultaneously sequestering CO2. This work reports for the first time a systematic techno-economic assessment of the conventional (ammonia-based) and modified (calcium hydroxide-based and Potassium hydroxide-based) Solvay processes. The model evaluates the effect of reactor conversion, inlet CO2 weight%, inlet CO2 temperature, gas/liquid ratio, and brine flow rate on the CO2 and Sodium ions removal. In addition, the process cost associated with each parameter was analyzed, and the impact of implementing carbon tax on process profitability was investigated. Furthermore, the Solvay processes were evaluated using economic metrics including Net Present Value (NPV), economy of scale, and Levelized cost of water. The results suggest that the calcium hydroxide-based modified Solvay process outperforms other processes in terms of CO2 and Sodium ions removal. Moreover, for the studied parameters, the calcium hydroxide-based modified Solvay process demonstrated economic viability, yielding a decent annual profit. However, the conventional Solvay process requires a remarkable amount of expenses, yet after the implementation of 40 dollars per metric tons of CO2 as a carbon tax, the conventional Solvay reaches the break-even point. These findings underscore the importance of implementing environmentally friendly practices in the industry, as the modified Solvay process proves to be a promising solution for mitigating environmental threats and promoting sustainable operations.

Synergistic effects of electric and magnetic nanoparticles with electromagnetic energy in enhanced oil recovery

This study investigates the effect of electromagnetic energy implementation in the use of electric, magnetic, and hybrid nanofluids for enhanced oil recovery. The challenge lies in comprehending the intricate interplay of these factors to enhance the recovery factor (RF) of oil. We conducted a comprehensive analysis of parameters influencing oil recovery at its primary, secondary, and tertiary stages using finite-element-based simulations. Transitioning to the secondary stage, we observe a positive correlation between increasing brine flow rates and heightened RF. In the tertiary stage, a comparative assessment of nanofluids, including magnetite (Fe3O4), zinc oxide (ZnO), and copper oxide (CuO), reveals that enhancing nanofluid concentrations up to 0.001 % positively impacts RF, with Fe3O4 leading the pack at 22.20 %, followed by ZnO at 21.00 %, and CuO at 11.02 %. The introduction of electromagnetic field consistently augments RF for all nanofluids by a minimum of 4.8 %. Furthermore, this study explores the effect of hybrid nanofluids on RF, which tend to exhibit lower RF values. However, the introduction of electromagnetic energy significantly enhances RF for all hybrid nanofluids. The study offers valuable insights into the potential of nanomaterials and electromagnetic methods in the oil and gas industry.

Comparative Analysis of Methods for Predicting Brine Temperature in Vertical Ground Heat Exchanger—A Case Study

This research was carried out to compare selected forecasting methods, such as the following: Artificial Neural Networks (ANNs), Classification and Regression Trees (CARTs), Chi-squared Automatic Interaction Detector (CHAID), Fuzzy Logic Toolbox (FUZZY), Multivariant Adaptive Regression Splines (MARSs), Regression Trees (RTs), Rough Set Theory (RST), and Support Regression Trees (SRTs), in the context of determining the temperature of brine from vertical ground heat exchangers used by a heat pump heating system. The subject of the analysis was a public building located in Poland, in a temperate continental climate zone. The results of this study indicate that the models based on Rough Set Theory (RST) and Artificial Neural Networks (ANNs) achieved the highest accuracy in predicting brine temperature, with the choice of the preferred method depending on the input variables used for modeling. Using three independent variables (mean outdoor air temperature, month of the heating season, mean solar irradiance), Rough Set Theory (RST) was one of the best models, for which the evaluation rates were as follows: CV RMSE 21.6%, MAE 0.3 °C, MAPE 14.3%, MBE 3.1%, and R2 0.96. By including an additional variable (brine flow rate), Artificial Neural Networks (ANNs) achieved the most accurate predictions. They had the following evaluation rates: CV RMSE 4.6%, MAE 0.05 °C, MAPE 1.7%, MBE 0.4%, and R2 0.99.

Development of strategies for continuous desalination of weak black liquor based on phase-behaviour analysis

This paper investigated different strategies to prevent salt deposition during weak black liquor (WBL) desalination under hydrothermal liquefaction conditions based on phase behaviour analysis. Phase equilibria of model salt solutions replicating the WBL composition were studied by high-pressure differential scanning calorimetry (HP-DSC) and different strategies to induce the Type 1 salt behaviour were applied. Two strategies led to an optimised salt separation: adjusting the concentrations of Type 1 salts, NaOH and NaHS, present in the WBL, and selectively exchanging carbonate from the model salt solution by replacing it with hydroxide. These strategies were tested in PSI’s continuous salt separation test rig, considering the recovering of salts. Although increasing the concentration of the Type 1 salts (NaOH and NaSH) impacted the precipitation temperature and extent of the salts, the strategy was not able to prevent it entirely. The HP-DSC results confirmed the efficiency of carbonate replacement by hydroxide since the Type 1 behaviour was observed after exchanging 75% of the carbonate. In the presence of organics, some salt accumulation and overflow into the desalinated stream occurred, which was addressed by optimising the brine flow rate.

The Flow Law of Brine and Sediment Particles in Gas-Driven Brine Drainage in the Sediments of Salt Cavern Gas Storage

The geological resources of salt cavern gas storage in China are mostly complex layered salt beds with many thin inter-layers and high insoluble matter content. In the process of cavity-building by water-solution method, the insoluble matters in salt layers and inter-layers are peeled off and deposited at the bottom of salt cavern, occupying more than one-third of the whole cavity volume. These sediments have a large pore volume and strong compressibility, and they are filled with brine; as a result, they have great potential for gas storage. The research on the flow law of brine and sediment particles in gas-driven brine drainage in the sediments of salt caverns is the basis of utilizing the void space of sediments for gas storage. In this paper, salt cores of salt cavern gas storage wells in the Jintan District were selected, and the physical characteristics of insoluble sediments of the salt cores were analyzed. Then, a laboratory simulation device and experimental method of the gas-driven brine drainage were presented. Using artificial composite sediments in the experimental device, the following was tested: (i) the flow rates of brine and particles in the vicinity of the brine drain pipe in the sediments under different nitrogen displacement pressures, (ii) the relationship between the sand extraction amount and nitrogen displacement pressure of different brine drain pipes, (iii) the sand extraction amount of different sizes of particles with brine drain time, (iv) the cumulative sand extraction amount of different brine drain pipes, and (v) the effect of brine flow rate on the sand extraction amount. The results show that quartz, plagioclase, and ankerite account for 45–94% and clay accounts for 3.3–14.4% of the insoluble minerals of the salt cores from the Jintan District. The particle size distribution of the sediments ranges from 0.04 mm to 6 mm and can be divided into four ranges: <0.5 mm, 0.5 mm~2 mm, 2 mm~4 mm, and >4 mm. The mass percentage of each range is 37.9%, 36.5%, 17%, and 8.6%, respectively. There is a threshold pressure of the gas-driven brine drainage, where the larger the diameter of the sieve hole, the lower the threshold pressure, and the easier the pipe is to sand out. The diameter of the sieve hole has a great influence on the flow rate of the sediment particles near the brine drain pipe. The increase in nitrogen displacement pressure has a positive correlation with the flow rate of sediments near the pipe with 5 mm diameter sieve holes, but has little effect on the flow rate of sediments near pipes with 1.5 mm or 0.5 mm diameter sieve holes. The sand extraction amount is affected by factors such as the nitrogen displacement pressure, diameter of sieve hole, brine drain time, and brine flow rate in the process of gas-driven brine drainage. A higher nitrogen displacement pressure and brine flow rate lead to more sand extraction. A screen pipe with 1 mm diameter sieve holes is suggested to be used for sand control, the sieve holes are recommended to be machined in the shape of a trumpet with a small inlet section (i.e., 1 mm) and a large outlet end (i.e., 1.5 mm), and the brine flow rate is suggested to be about 30 m3/h when the brine removal is carried out in the sediments of salt cavern, which depends on the actual operation on site.

A Pressure-Based Multiphase Flowmeter: Proof of Concept.

Multiphase flowmeters (MPFMs) measure the flow rates of oil, gas, and brine in a pipeline. MPFMs provide remote access to real-time well production data that are essential for efficient oil field operations. Most MPFMs are complex systems requiring frequent maintenance. An MPFM that is operationally simple and accurate is highly sought after in the energy industry. This paper describes an MPFM that uses only pressure sensors to measure gas and liquid flow rates. The design is an integration of a previously developed densitometer with an innovative Venturi-type flowmeter. New computing models with strong analytical foundations were developed, aided by empirical correlations and machine-learning-based flow-regime identification. A prototype was experimentally validated in a multiphase flow loop over a wide range of field-like conditions. The accuracy of the MPFM was compared to that of other multiphase metering techniques from similar studies. The results point to a robust, practical MPFM.

Diffusion of point source pollutants in the tee structure

Abstract The tee structure is an integral part of the water distribution system, and pollutants diffuse in complex ways within the structure. In this paper, the diffusion pattern of contaminants in the tee structure was examined using a combination of numerical simulations and experiments. The coefficient of variation was chosen as an evaluation indicator, and the uniform diffusion length (LU) was defined to quantify the location of uniform diffusion of pollutants in the structure. Several factors were used to investigate pollutant diffusion in the pipe, including pipe diameter, break location, inlet Reynolds number, outlet flow ratio, brine flow rate, and brine density. Results show that the inlet Reynolds number, outlet flow ratio, and pipe diameter all significantly affect pollutant diffusion. The LU increased as the inlet Reynolds number, outlet flow coefficient, and pipe diameter increased. In addition, equations for calculating LU were fitted using dimensional analysis and can be used to predict LU under other conditions as well.

Red Fruit Juice Concentration by Osmotic Distillation: Optimization of Operating Conditions by Response Surface Methodology.

Osmotic distillation (OD) was implemented at laboratory scale to concentrate a red fruit juice produced from a blend of blood orange, prickly pear, and pomegranate juice. The raw juice was clarified by microfiltration and then concentrated by using an OD plant equipped with a hollow fiber membrane contactor. The clarified juice was recirculated on the shell side of the membrane module, while calcium chloride dehydrate solutions, used as extraction brine, were recirculated on the lumen side in a counter-current mode. The influence of different process parameters, such as brine concentration (20, 40, and 60% w/w), juice flow rate (0.3, 2.0, and 3.7 L min-1), and brine flow rate (0.3, 2.0, and 3.7 L min-1) on the performance of the OD process in terms of evaporation flux and increase in juice concentration, was investigated according to the response surface methodology (RSM). From the regression analysis, the evaporation flux and juice concentration rate were expressed with quadratic equations of juice and brine flow rates, as well as the brine concentration. The desirability function approach was applied to analyse the regression model equations in order to maximize the evaporation flux and juice concentration rate. The optimal operating conditions were found to be 3.32 L min-1 brine flow rate, 3.32 L min-1 juice flow rate, and an initial brine concentration of 60% w/w. Under these conditions, the average evaporation flux and the increase in the soluble solid content of the juice resulted in 0.41 kg m-2 h-1 and 12.0 °Brix, respectively. Experimental data on evaporation flux and juice concentration, obtained in optimized operating conditions, resulted in good agreement with the predicted values of the regression model.

A non-nuclear inline densitometer for multiphase flows

Multiphase flowmeters are used in the oil-and-gas industry to measure real-time flow rates of oil, gas, and brine, flowing simultaneously as a non-homogeneous mixture, in a pipeline from wellhead to separator. Since these flow rates cannot be measured directly, they are inferred from other measurements including mixture density. Mixture density is commonly measured using nuclear densitometers which can be problematic in terms of safety and maintenance. This paper details the development—concept and experimental validation—of a non-nuclear inline densitometer that measures multiphase mixture density using pressure sensors. A comprehensive flow-loop test was conducted at a commercial facility to evaluate the technology under a wide range of flow conditions—flow rates 1000 to 10000 bpd, gas fractions 0% to 96%, water cuts 0% to 100%, with a synthetic oil as liquid hydrocarbon, methane as gas medium, two water salinities—totaling nearly 300 test points. The results from this experimental validation—specifically, the technology’s accuracy and operating envelope—point to a groundbreaking practical solution to a long-standing problem.

Dynamic modelling and simulation of industrial scale multistage flash desalination process

Multistage Flash (MSF) desalination process is still a dominant process, especially in the Gulf region, to produce high quality freshwater. Although there has been energy price surge in recent years, MSF process will continue to operate in that region for some foreseeable future. The key challenge is how to make such processes still profitable. Understanding the dynamics of any processes under uncertainty and disturbances is very important to make a process operationally feasible and profitable. The main aim of this work is to understand the dynamics of industrial scale MSF process using high fidelity and reliable process model. For this purpose, a detailed dynamic model for the MSF process incorporating key and new features is developed and validated against the actual data of a large-scale seawater desalination plant. The model is then used to study the behaviour of large scale MSF processes for disturbances in steam temperature, feed temperature and the recycle brine flow rate. The simulation results show that the last stage requires a longer time to settle compared to the preceding stages. In addition, steam temperature shows insignificant influence on the performance ratio compared to the inlet seawater temperature and recycle brine flow rate. Furthermore, it is found that the productivity of plant can increase in the winter compared to that in the summer. However, this benefit comes at the expense of increased steam consumption in the winter, resulting in a low performance ratio.

Working fluid selection for the geothermal-solar hybrid cycle at Olkaria II power plant in Kenya

At Olkaria II power plant located in Kenya, the brine from the separator is re-injected back into the ground. This study analyzes a flash geothermal-solar hybrid cycle using the working fluids n-butane, n-pentane, cyclopentane, hexamethyldisiloxane and toluene in order to utilize the brine. The studied working fluids have no potential to deplete the ozone or cause global warming. The working fluids were analyzed in terms of net power output and pump power required. This was done by heating Therminol VP-1 fluid to a maximum temperature of 400 °C using the parabolic trough solar collector and varying the working fluids mass flow rate, Therminol VP-1 flow rate and pressure, and the brine pressure and flow rate. They were varied to investigate their effect on the power output of the Organic Rankine Cycle. The working fluid with higher net power output was selected as a suitable working fluid for the hybrid cycle. The selected working fluid was used to determine the average hourly power output in each month of the hybrid system using the irradiance of Olkaria II power station. N-butane showed the best results in net power output hence it was selected as a suitable working fluid as compared to the other working fluids. When the hybrid system was analyzed using n-butane to obtain the hourly average power output in each month, the results revealed that the month of February has the highest hourly average power output where the Steam Turbine has an average hourly power output of 10.48 MW and Binary Turbine net power output of 18.56 MW. The minimum average hourly power output was obtained in the month of June where the Steam Turbine has an average hourly power output of 9.08 MW and Binary Turbine net power output of 16.88 MW.

Investigation of salt precipitation dynamic in porous media by X-ray and Neutron dual-modality imaging

In this work, a new dual modality monitoring technique is presented to demonstrate its interest to investigate the salt precipitation dynamics induced by gas flow-through drying. It consists of imaging simultaneously a core flood using both Neutron and X-ray beams. A method to calibrate and process the two signals is presented. It takes advantage of the difference in attenuation between the two ionizing radiations to quantify the different phase saturations and compositions as well as the reduction of porosity caused by salt precipitation. A set of experiments has been conducted at the NeXT-Grenoble beamline of the Institute Laue-Langevin facilities (ILL, France). Experiments were conducted on a homogeneous rock sample of Bentheimer sandstone using dry nitrogen and a 100 g/L KBr brine. The two first experiments aimed to calibrate the dual modality for the different phases. The last two experiments have been conducted with a brine capillary contact maintained at the gas outlet. Experimental data have given new insights into the organization of the three phases (the brine, the gas, and the precipitated salt) when a salt bank is formed in the sample. These quantities computed using dual-modality imaging show great similarities with published work. The salt accumulation was used to estimate the flow rate of brine pumped through the capillary contact to compensate for the brine evaporation in the gas phase. Observations have shown that a reduction of the initial porosity in some sections of the sample by 12–14% was enough to trigger a gas draw-down characterized by the migration of the salt toward the gas inlet. In some conditions (low gas inlet pressure for example), the rise of the water could be fast enough to form a second salt bank higher in the sample. It has been observed that the formation of the second salt bank could spread the precipitated salt in a less damaging configuration for the gas flow, triggering a phase of gas build-up characterized by the withdrawal of the water. These phases of gas draw-down and build-up could alternate until the sample clogs.

Influence of Operational Strategies for the Recovery of Magnesium Hydroxide from Brines at a Pilot Scale.

The continuous depletion of minerals caused by land mining and the increase in their demand have pushed the development of novel sustainable technological processes for mineral recovery from unconventional sources. In this context, magnesium (Mg) has gained considerable attention for its peculiar properties and high relevance of its compounds, such as magnesium hydroxide, Mg(OH)2. In the present work, the influence of several operating conditions on the Mg(OH)2 precipitation process was thoroughly investigated by adopting a novel multiple feed-plug flow reactor. The influence of (i) initial Mg2+ concentrations in the feed stream; (ii) brine and alkaline flow rates; and (iii) the product recycling strategy (seeded crystallization) was considered. The results marked the possibility of improving sedimentation and filterability properties of Mg(OH)2 suspensions by adopting the recycling strategy to overcome industrial issues associated with the production of Mg(OH)2 suspensions using NaOH solutions.

Multiphase Flow Analysis Using Piezoelectric Leaf-Cell Sensor Array

The composition of the multiphase flow rates from hydrocarbon reservoirs has direct impact on the programs to optimize hydrocarbon production and for the identification of problems with production. However, the accurate measurement of the flow rates of oil, brine, and gas in three-phase regimes remains an intractable problem for current state-of-the-art sensor technologies. Here, we describe a piezoelectric acoustic leaf-cell sensor array providing an in situ real-time measurement of the distribution in three-phase flow fluid density over the wellbore cross section. The sensor array measurements are evaluated from experimental three-phase flow loop test data under a range of flow regimes comprised of 0–95% gas volume fraction and water/liquid volume ratio between 0 and 100%. The experimental data include three-phase flow transitions well into the nonlinear subsonic gas velocity region predicted by the Wood equation and show an average absolute error in three-phase fluid density prediction less than 0.05 g/cc over the entire test regimen.

Application of reservoir exergy profile analysis by wellbore simulation on Olkaria Domes geothermal field

Geothermal is the energy for the future and is eco-friendly. Exergy analysis of geothermal power plants has been referenced based on wellhead and surface environment conditions. Previous studies have not linked the surface and sub-surface in Olkaria and other geothermal fields worldwide. The wellbore simulator connected the wellhead, and the reservoir simulated pressure and temperature logs for Olkaria Domes in Olkaria, a liquid-dominated geothermal field. The simulation results enabled the calculation of exergy values at any depth using the pressure and temperature between the reservoir and wellhead. Obtained results of the research used to interpret heat transfer between geothermal reservoir layers and the location of the reservoir. This study takes the exergy analysis to the source of geothermal brine under saturated conditions. The paper presents exergy profiles of geothermal wells at Olkaria Domes. The field data input parameters were wellhead pressure, mass flow rates of steam and brine, wellbore diameter, and the reservoir depths (deeper/second and shallow). A wellbore model developed in 1988 was used to simulate temperature-pressure profiles. The thermodynamic parameters (temperature and pressure) from the wellbore simulator were input parameters in the Engineers Equation Solver (EES) code to calculate entropy, enthalpy, and specific exergy. The wellbore exergy profiles show estimated feed zone depths of -1000 - (-) 2800 m.a.s.l for two-directional and three vertical wells. The profiles predicted convective and conductive heat transfers points. For wellhead temperatures of between 182 -205°C, the reservoir temperatures from the wellbore simulator are high at 292°C. The formation pressures were between 3,978 to 7,710 kPa. Exergy wellbore simulation of the geothermal reservoir predicted the reservoir and heat transfers in the sub-surface. The study demonstrates the importance of connecting the reservoir and wellhead via a wellbore simulation and exergy profiles.

Optimization of convection-enhanced evaporation (CEE) using generalized cost ratios

Brine is a byproduct of desalination plants and several industrial processes which can have an adverse impact on the environment if not managed properly. Conventional brine management technologies are energy intensive and costly which limit their adoption. This study presents the first cost optimization of convection-enhanced evaporation (CEE) system to achieve a modular, cost-effective brine management and on-site treatment option for decentralized desalination plants and small-volume industries. CEE involves evaporating water from saline liquid films, released on evaporation surfaces, by the difference in vapor pressure created by forced air convection. The optimization identifies the optimal operating settings (brine flow rates, brine temperatures, and air speeds) and enables comprehensive investigation of the effect of various operational decisions on operating (energy) cost, capital cost, and footprint area. The objective functions are formulated using two cost ratios that relate material, thermal, and electrical energy costs, effectively generalizing the optimization results to be independent of location-specific cost parameters. The optimization reveals two distinct operation modes, “all-electric mode” and “heating mode”. The “all-electric mode” corresponds to a lower total specific cost, ranging from $1.4 to $5 per m3, and higher footprint area, ranging from 0.5 to 1.8 m2 per m3 of evaporated volume. The “heating mode” corresponds to a higher total specific cost, up to $6.5 per m3; at low energy cost ratios, a compact footprint area ranging from 0.072 to 0.5 m2 per m3 of evaporated volume is achieved. Proposed designs were found to have lower costs than technologies available in the literature.

Variable operation of a renewable energy-driven reverse osmosis system using model predictive control and variable recovery: Towards large-scale implementation

Powering Reverse Osmosis (RO) systems with Renewable Energy (RE) is essential for decarbonising water production. Integration of RE requires large-scale RO plants to operate efficiently using variable power. Nevertheless, variable operation (involving matching the RO load to available power without battery back-up) has only been implemented for small-scale systems. This paper presents a variable-speed operation technique suitable for large-scale RO systems using an optimised operational strategy and a Model Predictive Controller (MPC). The technique was validated using a laboratory test rig having comparable performance to large-scale systems. A dynamic plant model was used to design the operational strategy and control system. Several operational strategies were explored for varying the operating parameters according to power available from a RE source. An advanced control system based on MPC was designed and compared to a conventional Proportional-Integral-Differential controller. The results showed that operation at variable recovery with constant brine flowrate delivered the lowest specific energy consumption and widest operation range for a system with an isobaric pressure exchanger. The MPC controller improved the settling time for a 10% step-change in permeate flowrate by 47%. Moreover, it improved energy utilisation, giving a 2.35% increase in hourly permeate production for a defined power input time-series.

Performance assessment of an inclined stepped solar still integrated with PCM and CuO/GO nanocomposite as a nanofluid

Providing potable water for buildings through a reliable technique using sustainable and renewable energies is crucial for saving fossil fuels. Desalination systems could afford fresh water using solar energy. Nanofluids have been applied in solar stills to enhance their productivity. In this study, an inclined stepped solar still with baffles is fabricated to investigate the effect of CuO/GO nanocomposite wt. %, volume ratio of individual nanoparticles in the nanocomposite, presence of paraffin wax as a phase change material (PCM), and input brine flow rate on the distillate yield, glass, brine and bottom temperatures. The results showed that 0.03 wt % CuO and GO boosted the freshwater yield by 48.12 and 81.59%, respectively. A nanocomposite with volume ratio of 30/70 for CuO/GO increased the volume of the freshwater by 81.59%. Additionally, it has been found that decreasing the brine flow rate from 30 to 8 L h−1 increased the freshwater production and conversely increasing to 68 L h−1 caused reduction of the distillate yield. Finally, application of paraffin wax as PCM under the steps of solar still caused an increase of 32.8% in distillate yield. Generally, it is revealed that the nanocomposite of CuO/GO is a hopeful candidate for application in solar stills to enhance their productivity.

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.