scholarly journals Analytical Models for Seawater and Boron Removal through Reverse Osmosis

2021 ◽  
Vol 13 (16) ◽  
pp. 8999
Author(s):  
Michael Binns
Keyword(s):  
Reverse Osmosis ◽  
Numerical Models ◽  
Total Concentration ◽  
Transport Coefficients ◽  
Operating Conditions ◽  
Analytical Models ◽  
Boron Removal ◽  
Modelling Methodology ◽  
Membrane Modules ◽  
Similar Accuracy

Regarding the purification of seawater, it is necessary to reduce both the total concentration of salt and also the concentration of boron to meet purity requirements for safe drinking water. For this purpose reverse osmosis membrane modules can be designed based on experimental data supported by computer models to determine energy efficient configurations and operating conditions. In previous studies numerical models have been suggested to predict the performance of the removal with respect to difference pressures, pH values, and temperatures. Here, an analytical model is suggested which allows for both the simplified fitting of the parameters required for predicting boron transport coefficients and also the simple equations that can be used for the design of combined seawater and boron removal systems. This modelling methodology is demonstrated through two case studies including FilmTec and Saehan membrane modules. For both cases the model is shown to be able to predict the performance with similar accuracy compared with existing finite-difference type numerical models from the literature.

UV disinfection of water: the need for UV reactor validation

2003 ◽  
Vol 3 (4) ◽  
pp. 293-300 ◽  
Author(s):  
Y.A. Lawryshyn ◽  
B. Cairns
Keyword(s):  
Legionella Pneumophila ◽  
Uv Light ◽  
Numerical Models ◽  
Operating Conditions ◽  
Analytical Models ◽  
Human Consumption ◽  
Average Dose ◽  
Reactor Performance ◽  
Uv Reactor ◽  
Bioassay Data

Disinfection by ultraviolet light (UV) has received wide endorsement as an important contribution to the multiple barrier approach for protection of public health. UV can be used both to disinfect wastewater discharged to the environment, and to disinfect that water when it is picked up again for human consumption. UV readily blocks infectivity by such chlorine-resistant pathogens as Cryptosporidium parvum, Giardia lamblia and Legionella pneumophila. Multiple disinfectant use is now being discussed to broaden the spectrum of pathogens that can be inactivated by using disinfectants in their most strategically advantageous dose and function. Optimizing multiple barrier strategies requires attention to validation of the concepts and technologies involved. UV technology validation ensures that the equipment can deliver the target UV design dose, and that the monitoring/control technology modulates the dose appropriately with changes in water quality or operating conditions. The bioassay approach for UV reactor validation is recommended over analytical and numerical models. Analytical models, which provide an average dose estimate, have been shown to be inadequate. Numerical models, which utilize Computational Fluid Dynamics (CFD) and UV light intensity models to predict reactor performance, can be accurate when used by skilled professionals but require significant validation and/or calibration against bioassay data.

scholarly journals Performance Assessment of SWRO Spiral-Wound Membrane Modules with Different Feed Spacer Dimensions

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 692 ◽  
Author(s):  
A. Ruiz-García ◽  
I. Nuez
Keyword(s):  
Reverse Osmosis ◽  
Pressure Vessels ◽  
Operating Conditions ◽  
Solute Permeability ◽  
Permeability Coefficients ◽  
Water Permeability Coefficient ◽  
Seawater Reverse Osmosis ◽  
Membrane Modules ◽  
The Impact ◽  
Spiral Wound

Reverse osmosis is the leading process in seawater desalination. However, it is still an energy intensive technology. Feed spacer geometry design is a key factor in reverse osmosis spiral wound membrane module performance. Correlations obtained from experimental work and computational fluid dynamics modeling were used in a computational tool to simulate the impact of different feed spacer geometries in seawater reverse osmosis spiral wound membrane modules with different permeability coefficients in pressure vessels with 6, 7 and 8 elements. The aim of this work was to carry out a comparative analysis of the effect of different feed spacer geometries in combination with the water and solute permeability coefficients on seawater reverse osmosis spiral wound membrane modules performance. The results showed a higher impact of feed spacer geometries in the membrane with the highest production (highest water permeability coefficient). It was also found that the impact of feed spacer geometry increased with the number of spiral wound membrane modules in series in the pressure vessel. Installation of different feed spacer geometries in reverse osmosis membranes depending on the operating conditions could improve the performance of seawater reverse osmosis systems in terms of energy consumption and permeate quality.

Coupled multi-DOF dynamic contact analysis model for the simulation of intermittent gear tooth contacts, impacts and rattling considering backlash and variable torque

2015 ◽  
Vol 230 (7-8) ◽  
pp. 1022-1047 ◽  
Author(s):  
C Spitas ◽  
V Spitas
Keyword(s):  
Numerical Models ◽  
Gear Tooth ◽  
Dynamic Contact ◽  
Spur Gear ◽  
Accurate Solution ◽  
Operating Conditions ◽  
Analytical Models ◽  
Analysis Model ◽  
Tooth Contact ◽  
Lateral Displacements

Variable torque conditions in geared powertrain applications are known to lead to tooth contact loss, contact reversal, tooth impacts, rattling vibration and noise. Displacements/ deflections dominate the low-torque high-vibration responses and, besides backlash, the real-time dynamic lateral deflections of the gear bodies and the occurrence of simultaneous double-sided tooth contact influence the instantaneous mesh excitation strongly. The faster deterministic and stochastic analytical models do not consider this coupling, whereas the numerical models that do so implicitly by simulating the contact of discretised tooth surfaces/ volumes are significantly limited by the accuracy and computational overhead of their discrete meshes. To provide a both fast and accurate solution of the contact problem, especially in displacement-dominated operating conditions, this work analyses the dynamic contact of gears starting from basic principles and derives an accurate analytical model for the coupling between the compliance, contact geometry, the backlash, and the torsional and lateral displacements and deflections in the general three-dimensional multi-DOF system. This serves as a foundation for a series of dynamical simulations of a single-stage spur gear transmission under different variable-torque excitations to predict tooth contact loss and contact reversal and the basic interactions that lead to impacts and rattling vibration. This approach can be used to predict critical torque fluctuation levels, beyond which these phenomena emerge.

scholarly journals Analysis of Boron Removal for Reverse Osmosis, Ion Exchange, and Capacitive Deionization

2021 ◽  
Vol 43 (10) ◽  
pp. 654-663
Author(s):  
Yu Chang Kim ◽  
Sungil Lim ◽  
Bangwoo Han ◽  
Sang Bok Kim ◽  
Inyong Park ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Ion Exchange ◽  
Reverse Osmosis ◽  
Ion Selectivity ◽  
Specific Energy Consumption ◽  
Operating Conditions ◽  
Feed Water ◽  
Carbon Electrode ◽  
Capacitive Deionization ◽  
Boron Removal

Objectives : This article provides a comparative analysis of boron removal for brackish water reverse osmosis (BWRO), boron selective ion exchange (IX), or capacitive deionization (CDI) processes. Permeate of 1st-Pass RO process has to be post-treated for additional boron removal. Hence, we experimentally analyzed the performance of boron removal and specific energy consumption (SEC) of three aforementioned processes and investigated whether the processes are suitable for 2nd pass process of RO desalination.Methods : Raw feed water was prepared using NaCl and B(OH)3. Semi-pilot scale RO and IX systems (over 1 m3/hr capacity) and bench scale CDI system (over 2.5 L/min) were tested for performance comparison. Boron concentration was measured using Azomethine-H method for feed and product water. Energy consumption was monitored by using power quality analyzer.Results and Discussion : Each process has its own operating conditions. The RO process required high pH of feed water for high boron removal rate, the IX process was operated below breakthrough point considering adsorption capacity of boron selective resin, and the CDI process didn’t remove boron because chloride ion has higher ion selectivity for carbon electrode than boron. In terms of SEC, the pressure-driven RO process showed the highest SEC among three processes. The CDI process based on electrical adsorption of carbon electrode showed a considerable energy consumption as well. On the other hand, the IX process was operated at low energy consumption because its removal is just based on adsorption-desorption mechanism.Conclusions : The RO and CDI processes have received a lot of attention as leading and emerging technology while the IX process was regarded as a stubborn process because of regeneration of resin and its several segmentalized steps. However, we found that the IX process has a better performance for boron removal and energy consumption.

scholarly journals The Efficiency of a Fence of Tidal Turbines in the Alderney Race: Comparison between Analytical and Numerical Models

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 892
Author(s):  
Jérôme Thiébot ◽  
Nasteho Djama Dirieh ◽  
Sylvain Guillou ◽  
Nicolas Guillou
Keyword(s):  
Numerical Models ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Analytical Models ◽  
Yield Potential ◽  
Hydrodynamic Characteristics ◽  
Energy Yield ◽  
Three Dimensional Model ◽  
Lower Efficiency ◽  
Array Efficiency

Assessing the efficiency of a tidal turbine array is necessary for adequate device positioning and the reliable evaluation of annual energy production. Array efficiency depends on hydrodynamic characteristics, operating conditions, and blockage effects, and is commonly evaluated by relying on analytical models or more complex numerical simulations. By applying the conservations of mass, momentum, and energy in an idealized flow field, analytical models derive formulations of turbines’ thrust and power as a function of the induction factor (change in the current velocity induced by turbines). This simplified approach also gives a preliminary characterization of the influence of blockage on array efficiency. Numerical models with turbines represented as actuator disks also enable the assessment of the efficiency of a tidal array. We compare here these two approaches, considering the numerical model as a reference as it includes more physics than the analytical models. The actuator disk approach is applied to the three-dimensional model Telemac3D in realistic flow conditions and for different operating scenarios. Reference results are compared to those obtained from three analytical models that permit the investigation of the flow within tidal farm integrating or excluding processes such as the deformation of the free surface or the effects of global blockage. The comparison is applied to the deployment of a fence of turbines in the Alderney Race (macro-tidal conditions of the English Channel, northwest European shelf). Efficiency estimates are found to vary significantly from one model to another. The main result is that analytical models predict lower efficiency as they fail to approach realistically the flow structure in the vicinity of turbines, especially because they neglect the three-dimensional effects and turbulent mixing. This finding implies that the tidal energy yield potential could be larger than previously estimated (with analytical models).

Investigations of Road Wear Caused by Studded Tires

2014 ◽  
Vol 42 (1) ◽  
pp. 2-15
Author(s):  
Johannes Gültlinger ◽  
Frank Gauterin ◽  
Christian Brandau ◽  
Jan Schlittenhard ◽  
Burkhard Wies
Keyword(s):  
Traffic Safety ◽  
Test Bench ◽  
Operating Conditions ◽  
Test Method ◽  
Analytical Models ◽  
The Road ◽  
Driving Speed ◽  
Major Factors ◽  
Tire Friction ◽  
Variable Operating Conditions

ABSTRACT The use of studded tires has been a subject of controversy from the time they came into market. While studded tires contribute to traffic safety under severe winter conditions by increasing tire friction on icy roads, they also cause damage to the road surface when running on bare roads. Consequently, one of the main challenges in studded tire development is to reduce road wear while still ensuring a good grip on ice. Therefore, a research project was initiated to gain understanding about the mechanisms and influencing parameters involved in road wear by studded tires. A test method using the institute's internal drum test bench was developed. Furthermore, mechanisms causing road wear by studded tires were derived from basic analytical models. These mechanisms were used to identify the main parameters influencing road wear by studded tires. Using experimental results obtained with the test method developed, the expected influences were verified. Vehicle driving speed and stud mass were found to be major factors influencing road wear. This can be explained by the stud impact as a dominant mechanism. By means of the test method presented, quantified and comparable data for road wear caused by studded tires under controllable conditions can be obtained. The mechanisms allow predicting the influence of tire construction and variable operating conditions on road wear.

Dynamic analysis of a helical gear reduction by experimental and numerical methods

2020 ◽  
Vol 68 (1) ◽  
pp. 48-58
Author(s):  
Chao Liu ◽  
Zongde Fang ◽  
Fang Guo ◽  
Long Xiang ◽  
Yabin Guan ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Fourth Order ◽  
Numerical Models ◽  
Helical Gear ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lumped Mass ◽  
Gear Mesh

Presented in this study is investigation of dynamic behavior of a helical gear reduction by experimental and numerical methods. A closed-loop test rig is designed to measure vibrations of the example system, and the basic principle as well as relevant signal processing method is introduced. A hybrid user-defined element model is established to predict relative vibration acceleration at the gear mesh in a direction normal to contact surfaces. The other two numerical models are also constructed by lumped mass method and contact FEM to compare with the previous model in terms of dynamic responses of the system. First, the experiment data demonstrate that the loaded transmission error calculated by LTCA method is generally acceptable and that the assumption ignoring the tooth backlash is valid under the conditions of large loads. Second, under the common operating conditions, the system vibrations obtained by the experimental and numerical methods primarily occur at the first fourth-order meshing frequencies and that the maximum vibration amplitude, for each method, appears on the fourth-order meshing frequency. Moreover, root-mean-square (RMS) value of the acceleration increases with the increasing loads. Finally, according to the comparison of the simulation results, the variation tendencies of the RMS value along with input rotational speed agree well and that the frequencies where the resonances occur keep coincident generally. With summaries of merit and demerit, application of each numerical method is suggested for dynamic analysis of cylindrical gear system, which aids designers for desirable dynamic behavior of the system and better solutions to engineering problems.

Novel Magnetic Resonance Measurements of Fouling in Operating Spiral Wound Reverse Osmosis Membrane Modules

2021 ◽  
Vol 196 ◽  
pp. 117006 ◽  
Author(s):  
Nicholas W. Bristow ◽  
Sarah J. Vogt ◽  
Szilard S. Bucs ◽  
Johannes S. Vrouwenvelder ◽  
Michael L. Johns ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Reverse Osmosis ◽  
Reverse Osmosis Membrane ◽  
Membrane Modules ◽  
Spiral Wound

scholarly journals Gaining a better understanding of the extrusion process in fused filament fabrication 3D printing: a review

2021 ◽  
Author(s):  
Bahaa Shaqour ◽  
Mohammad Abuabiah ◽  
Salameh Abdel-Fattah ◽  
Adel Juaidi ◽  
Ramez Abdallah ◽  
...  
Keyword(s):  
3D Printing ◽  
Numerical Models ◽  
Extrusion Process ◽  
Analytical Models ◽  
Limiting Factor ◽  
Fused Filament Fabrication ◽  
Promising Tool ◽  
Relevant Work ◽  
3D Printing Technique ◽  
Required Quality

AbstractAdditive manufacturing is a promising tool that has proved its value in various applications. Among its technologies, the fused filament fabrication 3D printing technique stands out with its potential to serve a wide variety of applications, ranging from simple educational purposes to industrial and medical applications. However, as many materials and composites can be utilized for this technique, the processability of these materials can be a limiting factor for producing products with the required quality and properties. Over the past few years, many researchers have attempted to better understand the melt extrusion process during 3D printing. Moreover, other research groups have focused on optimizing the process by adjusting the process parameters. These attempts were conducted using different methods, including proposing analytical models, establishing numerical models, or experimental techniques. This review highlights the most relevant work from recent years on fused filament fabrication 3D printing and discusses the future perspectives of this 3D printing technology.

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