Inlet Feed Research Articles

Desalination at ambient temperature and pressure by a novel class of biporous anisotropic membrane

Recent scientific advances have made headway in addressing pertinient issues in climate change and the sustainability of our natural environment. This study makes use of a novel approach to desalination that is environment friendly, naturally sustainable and energy efficient, meaning that it is also cost efficient. Evaporation is a key phenomenon in the natural environment and used in many industrial applications including desalination. For a liquid droplet, the vapor pressure changes due to the curved liquid–vapor interface at the droplet surface. The vapor pressure at a convex surface in a pore is, therefore, higher than that at a flat surface due to the capillary effect, and this effect is enhanced as the pore radius decreases. This concept inspired us to design a novel biporous anisotropic membrane for membrane distillation (MD), which enables to desalinate water at ambient temperature and pressure by applying only a small transmembrane temperature gradient. The novel membrane is described as a super-hydrophobic nano-porous/micro-porous composite membrane. A laboratory-made membrane with specifications determined by the theoretical model was prepared for model validation and tested for desalination at different feed inlet temperatures by direct contact MD. A water vapor flux as high as 39.94 ± 8.3 L m−2 h−1 was achieved by the novel membrane at low feed temperature (25 °C, permeate temperature = 20 °C), while the commercial PTFE membrane, which is widely used in MD research, had zero flux under the same operating conditions. As well, the fluxes of the fabricated membrane were much higher than the commercial membrane at various inlet feed temperatures.

Applying a new configuration for thermal integration of ethane cracking and CLC processes to enhance the ethylene and hydrogen productions

In this study, a new method for applying the chemical looping combustion (CLC) process instead of the furnace to provide the required heat for the ethane thermal cracking reactor has been suggested. It has been proposed that the new configuration of the ethane thermal cracking process be performed in the three separate series reactors. The structure of these new integrated reactors consists of three concentric cylinders. In the internal cylinder with a small diameter, the thermal cracking process is performed, while in the middle and external sides of new reactors, the oxidation and reduction processes of oxygen carriers are executed, respectively. The essential thermal energy for the endothermic ethane thermal cracking process is provided by the exothermic oxidation reaction in the air reactor. Furnace removal prevents nitrogen oxide emission, and a significant amount of carbon dioxide is recovered in the CLC process. According to the results of this new configuration, the ethylene and hydrogen production yields rise by about 12% and 15%, respectively, compared to the conventional ethane cracking reactor. Finally, the effects of design parameters such as inlet feed temperatures of the air, fuel and cracking reactors, as well as the mass flow rates of ethane and oxygen carrier on the performance of ethane thermal cracking have been investigated.

Unraveling the role of feed temperature and cross-flow velocity on organic fouling in membrane distillation using response surface methodology

Understanding the role of operating condition on fouling development in membrane distillation (MD) is critical for the further optimization of MD technology. In this study, organic fouling development in MD was investigated varying the feed inlet temperature from 35 to 65 °C and the cross-flow velocity from 0.21 to 0.42 m/s. The fouling layer thickness was estimated at the end of each experiment non-invasively with optical coherence tomography. The set of experiments was mined to model the initial flux decline, the near-stable flux, and the final foulant thickness responses by central composite design, a useful response surface methodology (RSM) tool. The results indicated a linear increment of the fouling thickness by increasing the feed inlet temperatures. Overall, the feed inlet temperature governed both the initial flux decline and the fouling deposition. The benefits in water productivity obtained by increasing the feed temperature were always offset by higher fouling deposition. Higher cross-flow velocities showed a positive effect on the initial flux, which however translated in larger values of the initial flux decline rate. On the other hand, the higher shear stress contributed to a decrease of the final steady-state fouling layer thickness. The proposed approach was proven to be a valuable tool to assess the role of the operating conditions on fouling and process performance in MD.

Assessing performance of methane tri-reforming reactor using a parametric study on the fundamental process variables

This study represents a numerical investigation of the methane tri-reforming with full computational fluid dynamics and reaction mechanisms in an adiabatic fixed-bed reactor. A 2-D axisymmetric model over nickel-based catalysts is stablished to analyze the influence of relevant parameters. The attained results revealed that the feed composition, feed flow rate, inlet temperature, operating pressure and reactor geometry have important effects on the efficiency of the reactor. The observed temperature profile proves that the temperature peak increase with the inlet temperature. Moreover, the H2/CO ratio increases with decrement of O2/CH4 and CO2/CH4 and increment of H2O/CH4. As the feed flow rate rises, the CH4 conversion, CO2 conversion and the syngas ratio reduce. One of the most attractive results is the correlation between the pressure and the reactor performance. When the pressure falls, whereas less O2 is consumed, the CH4 and CO2 conversion rise due to the increase of the initial reaction rates. Finally, it is proved that the variations of the reactor diameter have a greater impact on the reactor performance compering with the reactor length.

Investigating the tolerance of nano-filtration for the treatment of wastewater

ABSTRACT The textile industries generate highly concentrated and toxic waste streams which are disposed of without any pretreatment leading to environmental imbalances. Therefore, such waste streams need to be treated before directly discharging. This study explores the nano-filtration (NF) approach for dye effluent remediation. Congo red dye is the widely used chemical that imparts red colour to fabric and is highly toxic when emitted in a very minute amount of 3 mg/L. Therefore, a polyamide-based NF HFT-150 was implemented for the removal of Congo red dye (CD), noting the influences of feed pressure (1–12 kg/cm2) and inlet concentration (10–100 mg/L) used for examining the permeate flux in the process. It was reported that 99.7% removal was obtained at a feed pressure of 6 kg/cm2 with permeate flux of 7.9 mL/min cm2 for an initial concentration of 10 mg/L. Moreover, the samples from a small scale textile industry from Pali, Rajasthan, were collected, and the physicochemical properties were evaluated, revealing the total dissolved salts of 8560 mg/L. The collected sample was treated by NF HFT-150, indicating that potentially strong discolouration was reported at 6 kg/cm2 feed pressure. Therefore, it can be suggested that nano-filtration could be efficiently implemented for textile effluent treatment.

Local Gas-Phase Current Contributions Influenced By Porous Media Properties and Geometric Features in PEM Electrolysis

To expand the commercialization of polymer electrolyte membrane water electrolysis (PEMWE) devices, it is beneficial to understand how cell geometry and porous media properties can impact cell performance. Due to the use of precious materials in PEMWE, particularly with an acidic membrane, it is cost-effective to simulate cell performance using a number of proposed designs to limit the number of prototypes. The use of three-dimensional (3-D) computational fluid dynamics (CFD) to simulate PEMWE 1 and alkaline 2 electrolysis operation has been previously demonstrated. This analysis sheds additional light on evaporation and the important role that it plays in facilitating the anodic and cathodic reactions.Evaporation rates in porous media vary immensely with changes in water content, which has been demonstrated experimentally. Zenyuk et al. 3 used computed tomography to quantify the liquid saturation and gas/liquid interfacial area inside a carbon gas diffusion layer. They linked these variables to evaporation rate using the injection feed pressure to adjust the liquid saturation. The authors determined that evaporation rates in fuel cells increase dramatically with a decrease in water content. Evaporation rate depends on the specific interfacial area (SIA). Measurements in porous media, namely sands and soils, have shown an increase in SIA with a decrease in liquid saturation. One may notice from Ouni et al. 4 that the SIA is indirectly proportional to liquid saturation when the maximum SIA is small and somewhat inversely proportional when the SIA is large. The nature of these relationships is considered in the present CFD model for evaporation in the porous transport layer (PTL) and catalyst layer.This study explores the effects of manifold geometry, flow field geometry, and properties such as PTL porosity, permeability, interfacial area, and anisotropy on local current density. Special emphasis is given to the contribution of the gas phase to the overall current and the conditions under which the gas-phase reaction is favorable. Changes in operating conditions, such as the feed temperature, feed rate, and cell potential, and how they impact local void fraction, relative humidity, and temperature at the anode are also investigated. The sensitivity of overall performance to material properties was found to be dependent on these operating conditions, primarily the anode inlet feed rate.References J. Lopata, Z. Kang, J. Young, G. Bender, J. W. Weidner, H-S. Cho, and S. Shimpalee, J. Electrochem. Soc., 168, 054518 (2021).J. S. Lopata, S-G. Kang, H-S. Cho, C-H. Kim, J. W. Weidner, S. Shimpalee, Electrochim. Acta, 390, 138802 (2021).I. V. Zenyuk, A. Lamibrac, J. Eller, D. Y. Parkinson, F. Marone, F. N. Büchi, and A. Weber, J. Phys. Chem. C, 120, 28701-28711 (2016).A. E. Ouni, B. Guo, H. Zhong, M. L. Brusseau, Chemosphere, 263, 128193 (2021). Figure 1

EFFECT OF GEOMETRICAL AND OPERATIONAL PARAMETER ON OIL-WATER SEPARATION IN AXIAL INLET HYDROCYCLONE

To overcome the high water content in numerous oil fields, axial inlet hydrocyclone is considered an alternative device of oil-water separation technique that is used downfield. This type of hydrocyclone has a rare previous work compared to other vortex tube separators. Additionally, the accurate mechanism of the enhanced separation process by optimizing the separation technologies remains unclear. Therefore, an extensive study was conducted to expand the application range of the axial inlet hydrocyclone. This workpresents a literature review of the different separation technologies for the axial inlethydrocyclone. These are categorized into two groups: (i) geometrical parameters including, internal swirl element (ISE), swirl chamber, and (ii) operational parameters including, inlet flow rate, feed temperature, mixture fraction, and droplet size. The influence of these parameters on the velocity components profile and pressure drop were analyzed based on the separation performance parameters such as separation efficiency and pressure drop. This work could serve as an engineering tool that results in the enhanced economic workability of separation by hydrocyclone.

Analytical and numerical investigations of mixing fluids in microchannel systems of different geometrical configurations

AbstractThis work presents theoretical and numerical studies related to micromixing phenomena using two different shapes of microchannel systems (i.e., X‐ and Y‐shaped, respectively). In this study, we consider a system that consists of a primary fluid, an aqueous phase (Fluid A), and a secondary fluid (distributed phase), Rhodamine B, in water (Fluid B). In this study, a two‐dimensional closed‐form generalized analytical model is developed and solved using the method of separation variables to understand the fluid flow mixing behaviour under the influence of a convective–diffusive mass transport process. In addition, numerical simulations are also performed by solving the continuity, momentum, and mass transport equations for the two proposed microchannel systems under different flow conditions to understand the relative effects on micromixing phenomena resulting from the convection and diffusion mass transport. Results obtained from the numerical simulations evaluate the mixing performance by varying the inlet flow velocity of the secondary fluid stream (Fluid B: Rhodamine B in water). The numerical result in terms of the radial concentration distribution profile as a function of channel width based on the operating Reynolds number by varying inlet feed flow velocity (Fluid B) shows that more effective mixing has been carried out by the X‐shaped microchannel compared to the Y‐shaped microchannel. Moreover, the proposed generalized analytical model was validated with the obtained numerical results in terms of the normalized concentration distribution as a function of the normalized channel width. A good agreement between the analytical and obtained numerical results ( for both shapes of microchannel systems has been observed.

Spray Drying Optimization for Rice Bran Protein (RBP) Powder Using Response Surface Methodology (RSM)

Rice bran is a by-product of the rice milling process which contain a high concentration of protein. It’s are often used as a feed cattle, fertilizer, and fuel. Its application as a source of human nutrition is rare due to high lipid concentration. This lipid concentration can be reduced through the extraction process. After the extraction process, the rice bran extract needs to be converted into powder form through a drying process for the quality preservation. In this study, spray drying is utilized as drying technique. The aims of this study were to optimize the spray drying parameter; inlet temperature, feed flowrate and air flowrate for rice bran protein (RBP) powders production. Box Behnken Design (BBD) model in response surface methodology (RSM) are utilized in this study to maximize the RBP powder yield and protein concentration. Raw rice bran (RRB) was extracted using thermal water-based extraction method before the drying process. The optimum condition suggested by the model are at the inlet temperature of 120oC, feed flowrate of 18.38% and air flowrate of 670 L/hr which produced RBP powder yield of 19.42 g RBP/100g RRB and protein concentration of 17.32 mg/ml. The model obtains in this study show a low error between the predicted value and experimental data at 1.68 % and 1.14 % for RBP powder yield and protein concentration respectively. The model can be used to evaluate the process characteristic and understanding.

Digitalized turbulent behaviors of air and rice husk flow in a vertical suspension furnace from computational fluid dynamics simulation

AbstractThe knowledge of fluid–particle flow behavior is necessary. Unfortunately, computational fluid dynamics (CFD) studies are mostly focused on developing numerical methods in detail. Instead, the CFD studies should also subtly shift to become a tool for digitalizing fluid science to guide the practical industrial aspects. Therefore, this simulation study intends to reveal the air and rice husk flow behaviors in a vertical suspension furnace, complete with presenting digital simulation data, aiming to alleviate the escape particle amount. According to this study, the escaped particle amount was suppressed under more sphere particle, smaller particle size, and feed inlet pipe that sunk into the burner. The properties change from rice husk to ash, along with temperature escalation (as in combustion phenomena), enlarging the escaped particle amount, so the cyclone should be installed to handle it. In addition, the results of digital turbulent data from CFD simulation have succeeded in intriguing and revealing the fluid–particle flow behavior in the vertical suspension furnace. The data show a close match to the real phenomena occurring inside this furnace which reflects the standard k–ε model can conclusively predict fluid–particle flow behavior without conflicting Newton's second law of particle motion.

Effect of Teflon-Coated PVDF Membrane on the Performance of a Solar-Powered Direct Contact Membrane Distillation System

The present study dealt with the generation of freshwater through the direct contact membrane distillation (DCMD) technique, powered by an evacuated tube solar collector (ETSC). The major objective of the present work was to determine the optimum conditions of fluid flow rate and temperature for maximum freshwater productivity across both the feed and permeate sides of the membrane module. A flat hydrophobic membrane composed of polyvinylidene fluoride (PVDF) coated with Teflon was utilized for the DCMD process. The rate of freshwater production was examined with the variation in the feed/permeate flow rates (from 3 to 7 LPM) and feed temperature (from 45 °C to 75 °C) for a constant permeate-side temperature of 30 °C. The experimental results indicated that a maximum freshwater productivity of 45.18 kg/m2h was achievable from the proposed system during its operation with a high solar heated inlet feed temperature of 75 °C and mass flow rates of 7 LPM across both sides of the membrane. Further, a detailed assessment of the performance parameters indicated that the present solar-powered DCMD system exhibited a maximum evaporative efficiency of about 80% and temperature polarization coefficient (TPC) of 0.62 respectively.

Heat transfer enhanced surfaces for horizontal tube falling film evaporator characterized using laser interferometry

The falling film evaporators are a class of heat exchanger that is widely studied. The research for improving the efficiency is still of prime importance because of its widespread applications in many industries such as desalination, food processing, nuclear energy, refrigeration etc. Our motive in this work is to investigate the potential use of heat and mass transfer enhanced surfaces for horizontal tube falling film evaporator to scale up its effectiveness. Four different tube surfaces viz. bare copper tube, Al2O3 thermal spray coated tube, Al2O3 + TiO2 thermal spray coated tube and open cell copper metal foam wrapped tube were taken for the study. Scanning electron microscope, 3D surface profilometer, contact angle metre and energy-dispersive X-ray spectroscopy were utilized to study the surface texture, surface roughness, wettability and composition, respectively. Out of these four surfaces, a total of eight configurations were realized by varying the coating thickness, surface roughness and porosity. A new prototype of horizontal tube falling film evaporator was designed and fabricated with fully wetted flow. An in house developed novel method based on laser interferometry was utilized for the experimental investigation. This non-invasive technique was capable of measuring falling film thickness and falling film interface temperature simultaneously with unprecedented circumferential span. For the film thickness evaluation, an optical shadow method incorporating Otsu’s algorithm with precise interface tracking features was used. Mach–Zehnder Interferometer was employed to visualize the isotherm formation and to quantitatively infer the interface temperature. A 2D CFD study based on VOF model was carried out and found to be in good agreement with experimental as well as theoretical results. Further, the effect of flow rate, feed inlet water and body temperature were explored in detail and analysed statistically.

Screening of forward osmosis membrane potential to treat produced water

AbstractThe produced water is considered one of the largest waste streams in the oil and gas industries. Untreated produced water discharge damages the environment. Forward osmosis utilizes a dilute solution to concentrate contaminated streams to treat produced water. This paper tried to shed some light on forward osmosis‘s potential in treating produced water, measuring forward osmosis commercial membrane‘s effectiveness in treating produced water feed taken from two different points in an oil and gas facility in Malaysia. The rejection for chemical oxygen demand and boron was greater than 80 %, and a considerable decrease in forward osmosis flux was observed. The corrugated plate interceptor‘s inlet feed decreased by 73 % relative to the initial flux, while it decreased by 52.5 % for equalization tank feed. Design expert® was used to optimize the process using a one‐factor experimental design. The regression models indicated a good fit of model. The R2 was 0.9393 and 0.9888 for corrugated plate interceptor‘s inlet, and the equalization tank produced water, respectively. The optimization results concluded a 20 % draw solution concentration with the desirability of 0.927 and 0.987 for two feed waters.

Analysis of Air Flow Rate in Bulkhead Reactors on Struvite Mineral

Struvite is a white crystalline chemical known as magnesium ammonium phosphorus hexahydrate (MgNH4PO4.6H2O). Struvite is soluble in acidic conditions and slightly soluble in neutral and alkaline conditions. In industry, struvite is known as scale in pipes. Urinary stones can be called struvite because struvite crystals can form easily in the urine of animals and humans infected with ammonia organisms produced in the urine. Struvite can potentially be formed by alkaline urine and high magnesium excretion due to a high magnesium plant- based diet. The formation of struvite minerals is carried out in an insulated reactor by mixing a solution of MgCl2, NH4OH, and H3PO4 in a ratio of 1:1:1. The treatment of struvite mineral formation was carried out with a feed inlet rate of 35 ml/minute, the temperature at the reactor was carried out at 30oC while the intake air rate was carried out in the range of 0.25-1.25 liters/min. The pH of the solution was kept at a value of 9. The process was carried out until a steady state was reached. The formation of struvite minerals using an insulated column reactor was obtained at conditions of pH 9, operating temperature of 30oC and air rate of 1.25L/min.

Computational fluid dynamics based numerical simulations of heat transfer, fluid flow and mass transfer in vacuum membrane distillation process

Abstract In this study, we developed a comprehensive two-dimensional computational fluid dynamics (CFD) model using COMSOL™ Multiphysics to describe and simulate heat transfer, mass transfer and fluid flow in the flat sheet vacuum membrane distillation (VMD) under laminar flow conditions. A combination of Knudsen and Poiseuille flow was applied to study mass transfer across the membrane. The effect of variation of Reynolds number, inlet feed temperature and degree of vacuum on different parameters (mass flux, temperature polarization coefficient- TPC, concentration polarisation, heat transfer coefficient) was studied. There was a positive impact of the Reynolds number (50–200) on mass flux (13.15%), heat transfer coefficient (2.64%) and TPC (1.42%), while CPC decreased by 56.63%. The increment in the heat transfer coefficient was due to fluid mixing on the feed side, while the increment in the TPC was due to a higher temperature gradient across the membrane surfaces. The increment in the feed temperature (323–343 K) resulted in an increase in mass flux by 132.9%, while TPC decreased from 0.98 to 0.90. The degree of vacuum (640–750 mm Hg) increased mass flux and heat transfer coefficient by 72.52 and 425.83%, respectively, while the TPC decreased by 8.81%. The feed temperature was the most sensitive parameter with respect to mass flux. The developed CFD model was validated with in-house experimental results with reasonable accuracy.

An integrated and continuous downstream process for microbial virus-like particle vaccine biomanufacture.

In this study, we present the first integrated and continuous downstream process for the production of microbial virus‐like particle vaccines. Modular murine polyomavirus major capsid VP1 with integrated J8 antigen was used as a model virus‐like particle vaccine. The integrated continuous downstream process starts with crude cell lysate and consists of a flow‐through chromatography step followed by periodic counter‐current chromatography (PCC) (bind‐elute) using salt‐tolerant mixed‐mode resin and subsequent in‐line assembly. The automated process showed a robust behavior over different inlet feed concentrations ranging from 1.0 to 3.2 mg ml−1 with only minimal adjustments needed, and produced continuously high‐quality virus‐like particles, free of nucleic acids, with constant purity over extended periods of time. The average size remained constant between 44.8 ± 2.3 and 47.2 ± 2.9 nm comparable to literature. The process had an overall product recovery of 88.6% and a process productivity up to 2.56 mg h−1 mlresin −1 in the PCC step, depending on the inlet concentration. Integrating a flow through step with a subsequent PCC step allowed streamlined processing, showing a possible continuous pathway for a wide range of products of interest.

A 3D Transient CFD Simulation of a Multi-Tubular Reactor for Power to Gas Applications

A 3D stationary CFD study was conducted in our previous work, resulting in a novel reactor design methodology oriented to upgrading biogas through CO2 methanation. To enhance our design methodology incorporating relevant power to gas operational conditions, a novel transient 3D CFD modelling methodology is employed to simulate the effect of relevant dynamic disruptions on the behaviour of a tubular fixed bed reactor for biogas upgrading. Unlike 1D/2D models, this contribution implements a full 3D shell cooled methanation reactor considering real-world operational conditions. The reactor’s behaviour was analysed considering the hot-spot temperature and the outlet CH4 mole fraction as the main performance parameters. The reactor start-up and shutdown times were estimated at 330 s and 130 s, respectively. As expected, inlet feed and temperature disruptions prompted “wrong-way” behaviours. A 30 s H2 feed interruption gave rise to a transient low-temperature hot spot, which dissipated after 60 s H2 feed was resumed. A 20 K rise in the inlet temperature (523–543 K) triggered a transient low-temperature hot spot (879 to 850 K). On the contrary, a 20 K inlet temperature drop resulted in a transient high-temperature hot spot (879 to 923 K), which exposed the catalyst to its maximum operational temperature. The maximum idle time, which allowed for a warm start of the reactor, was estimated at three hours in the absence of heat sources. No significant impacts were found on the product gas quality (% CH4) under the considered disruptions. Unlike typical 1D/2D simulation works, a 3D model allowed to identify the relevant design issues like the impact of hot-spot displacement on the reactor cooling efficiency.

Modeling and Simulation of TiO2/Se Sensor for Detection of CO Gas Using Comsol Multiphysics

Metal oxide sensors are being used from past three decades. They still suffer from some disadvantages, such as high operating temperature, high power consumption, sensor stability, and cross sensitivity. Since the cost of development of these sensors is high, it is important to develop a mathematical model to economically predict the behavior of these sensors. In this context, research work focused on evaluating the performance of these sensors using numerical analysis software. In this work, modeling and simulating the gas sensing properties of Titanium dioxide/Selenium (MOS) sensor material to detect carbon monoxide (CO) gas using Comsol Multiphysics software has been proposed. The gas sensing simulation was performed using ‘Reaction engineering,’ ‘Transport of diluted species,’ ‘Surface reactions,’ and ‘Laminar flow’ interfaces of Comsol Multiphysics software on Titanium dioxide/Selenium material. Two kinds of simulations, space independent and space dependent simulation, was performed on this material in a constant volume gas chamber. The geometry was created in space dependent node, Comsol. The carbon monoxide gas was injected through gaussian pulse feed inlet at different concentrations (1 ppm, 5 ppm, 10 ppm, and 15 ppm) into the gas chamber and MOS sensor layer was allowed to reach steady state. The adsorption simulation on sensor layer exposed to carbon monoxide (CO) gas shows the change in surface concentration of the adsorbed CO molecules on the sensor layer.

Dynamic behavior of CO2 adsorption from CH4 mixture in a packed bed of SAPO-34 by CFD-based modeling

Abstract In this work, a dynamic non-isothermal adsorption process of CH4 and CO2 in a fixed bed of SAPO-34 particles was modeled by coupled DEM-CFD. This Euler–Lagrange method gives access to specification of each adsorbent pellet including location, temperature and concentrations, and facilitates study of phenomena like adsorption. Transport phenomena including heat and mass transfer in fluid and between solid and gas were taken into account. Eventually the model was validated by experimental results of breakthrough curve. Especially near wall channeling effect and the role of inlet feed velocity on the bed efficiency were addressed in this work. Local and bulk porosity values calculated using DEM model showed an acceptable agreement with previous empirical equations. Results indicated that this coupled method can be applied as a promising tool to study the mass transfer zone and efficiency of the adsorption process. The results revealed that as the feed continues to flow into the column, the lower layers of the adsorbent particles become practically saturated and then the mass transfer zone starts moving upward to a region of fresher adsorbent in the column. Also, the results showed that, at a low inlet velocity with a low Peclet number (Pe = 0.195), channeling effect is reduced and the diffusion mechanism controls the mass transfer. However, HETP enhances with increase in the feed gas velocity (Pe = 2.25) as well as increase in deviation from plug flow regime, and consequently the adsorption efficiency decreases. HETP decreases drastically at the beginning with increase in interstitial velocity. Increase in the interstitial velocity beyond a particular value of 0.5 cm s−1 leads to increase in the HETP value. This trend and presence of a minimum in this graph were explained based on Van Deemter concept.

Long-Term Treatment of Highly Saline Brine in a Direct Contact Membrane Distillation (DCMD) Pilot Unit Using Polyethylene Membranes.

Membrane distillation (MD) is an attractive separation process for wastewater treatment and desalination. There are continuing challenges in implementing MD technologies at a large industrial scale. This work attempts to investigate the desalination performance of a pilot-scale direct contact membrane distillation (DCMD) system using synthetic thermal brine mimicking industrial wastewater in the Gulf Cooperation Council (GCC). A commercial polyethylene membrane was used in all tests in the DCMD pilot unit. Long-term performance exhibited up to 95.6% salt rejection rates using highly saline feed (75,500 ppm) and 98% using moderate saline feed (25,200 ppm). The results include the characterization of the membrane surface evolution during the tests, the fouling determination, and the assessment of the energy consumption. The fouling effect of the polyethylene membrane was studied using Humic acid (HA) as the feed for the whole DCMD pilot unit. An optimum specific thermal energy consumption (STEC) reduction of 10% was achieved with a high flux recovery ratio of 95% after 100 h of DCMD pilot operation. At fixed operating conditions for feed inlet temperature of 70 °C, a distillate inlet temperature of 20 °C, with flowrates of 70 l/h for both streams, the correlations were as high as 0.919 between the pure water flux and water contact angle, and 0.963 between the pure water flux and salt rejection, respectively. The current pilot unit study provides better insight into existing thermal desalination plants with an emphasis on specific energy consumption (SEC). The results of this study may pave the way for the commercialization of such filtration technology at a larger scale in global communities.