CFD Modelling of Reverse Osmosis Channels with Potential Applications to the Desalination Industry

2011 ◽  
Vol 6 (2) ◽  
Author(s):  
S. Wardeh ◽  
Herve P. Morvan
Keyword(s):  
Reverse Osmosis ◽  
Large Scale ◽  
Middle Eastern ◽  
Membrane System ◽  
Design Parameters ◽  
Cfd Modelling ◽  
The United Kingdom ◽  
Through Flow ◽  
Potential Applications ◽  
The Cost

Desalination by reverse osmosis is receiving increasing attention due to recent improvements in membrane technology in particular. This technique is now used for small to very large scale applications, and has been identified as a key contributor to water treatment and provision not only in Middle Eastern countries but also closer to home in the United Kingdom for example. Computational Fluid Dynamics (CFD) is increasingly used for complex modelling applications in the chemical process and water industries. Previous work by the writers and others for spacer-filled desalination channels have yielded very good results in terms of modelling the flow and salt characteristics and history in the channels, as well as the overall performance of the membrane system. However, transient features imply that such simulations can be very costly and, if they can approximate experimental layouts with horizontal membranes, the investigation of a full desalination performance and operation remains a very distant prospect. CFD would therefore appear to be unsuited to industrial design at the present time. It is necessary to reduce the cost of the numerical simulations whilst maintaining high fidelity in key design parameters such as pressure loss, shear stress and salt concentration on the membrane, and through flow across the membrane for the method to be useful in design. A momentum loss approach based on a porous medium model is presented to this effect and benchmarked against detailed CFD results with success. It is shown to be capable of meeting key design parameters at a fraction of the full CFD cost.

scholarly journals Economic analysis of the implementation of autologous transfusion technologies throughout England

2005 ◽  
Vol 21 (2) ◽  
pp. 234-239 ◽  
Author(s):  
Simon Dixon ◽  
Virge James ◽  
Daniel Hind ◽  
Craig J. Currie
Keyword(s):  
Policy Development ◽  
Large Scale ◽  
Future Research ◽  
Cell Salvage ◽  
Autologous Transfusion ◽  
The United Kingdom ◽  
Intraoperative Cell Salvage ◽  
The Mean ◽  
The Cost ◽  
Preoperative Autologous Donation

Objectives:This study aims to provide the first estimates of the costs and effects of the large scale introduction of autologous transfusion technologies into the United Kingdom National Health Service.Methods:A model was constructed to allow disparate data sources to be combined to produce estimates of the scale, costs, and effects of introducing four interventions. The interventions considered were preparing patients for surgery (PPS) clinics, preoperative autologous donation (PAD), intraoperative cell salvage (ICS), and postoperative cell salvage (PoCS).Results:The key determinants of cost per operation are the anticipated level of reductions in blood use, the mean level of blood use, mean length of stay, and the cost of the technology. The results show the potential for considerable reductions in blood use. The greatest reductions are anticipated to be through the use of PPS and ICS. Vascular surgery, transplant surgery, and cardiothoracic surgery appear to be the specialties that will benefit most from the technologies.Conclusions:Several simplifications were used in the production of these estimates; consequently, caution should be used in their interpretation and use. Despite the drawbacks in the methods used in the study, the model shows the scale of the issue, the importance of gathering better data, and the form that data must take. Such preliminary modeling exercises are essential for rational policy development and to direct future research and discussion among stakeholders.

Global steel market will still face oversupply

2016 ◽  
Keyword(s):  
Latin American ◽  
Large Scale ◽  
Raw Materials ◽  
Emerging Market ◽  
Content Type ◽  
The United Kingdom ◽  
Steel Output ◽  
Steel Consumption ◽  
Steel Market ◽  
The Cost

Subject Slow cuts to global steel overcapacity. Significance In 2015, global steel output fell 2.8% compared to 2014, reaching 1.62 billion tonnes. China's production dropped by 2.3% to 804 million tonnes. In 2015, European benchmark steel prices fell by 27%, from 480 dollars/tonne to 350 dollars/tonne, while Chinese prices suffered a 41% drop, from 440 to 260 dollars/tonne. Margins at many steel-making groups contracted, as steel prices fell faster than the cost of raw materials. Large-scale job losses intensified in Europe, with the United Kingdom and Spain enduring the most of the capacity cuts. Impacts Latin American production could suffer from Asian competition unless sector-specific safeguards are introduced. Renewed dollar appreciation could make dollar-denominated debt unsustainable for many emerging-market steel-makers. BRICS exporters will suffer tariffs imposed by the US Department of Commerce. India will remain the industry's best hope for growth, due to its urbanisation and still low per capita steel consumption.

Communicating Public Health Advice After a Chemical Spill: Results From National Surveys in the United Kingdom and Poland

2013 ◽  
Vol 7 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Julia M. Pearce ◽  
G. James Rubin ◽  
Richard Amlôt ◽  
Simon Wessely ◽  
M. Brooke Rogers
Keyword(s):  
Public Health ◽  
United Kingdom ◽  
Large Scale ◽  
Hazardous Substance ◽  
Crisis Communications ◽  
Public Health Preparedness ◽  
The United Kingdom ◽  
The Cost ◽  
And Coping ◽  
The Impact

AbstractObjectiveThe aim of this study was to enhance public health preparedness for incidents that involve the large-scale release of a hazardous substance by examining factors likely to influence public responses to official guidance on how to limit their exposure.MethodsAn online demographically representative survey was conducted in the United Kingdom (n = 601) and Poland (n = 602) to test the strength of association of trust in authorities, anxiety, threat, and coping appraisals with the intention to comply with advice to shelter in place following a hypothetical chemical spill. The impact of ease of compliance and style of message presentation were also examined.ResultsParticipants were more likely to comply if at home when the incident happened, but message presentation had little impact. Coping appraisals and trust were key predictors of compliance, but threat appraisals were associated with noncompliance. Anxiety was seen to promote behavioral change. UK participants were more likely to comply than Polish participants.ConclusionsSuccessful crisis communications during an emergency should aim to influence perceptions regarding the efficacy of recommended behaviors, the difficulties people may have in following advice, and perceptions about the cost of following recommended behaviors. Generic principles of crisis communication may need adaptation for national contexts. (Disaster Med Public Health Preparedness. 2013;7:65-74)

scholarly journals Subsidising the spread of COVID-19: Evidence from the UK’S Eat-Out-to-Help-Out Scheme*

2021 ◽  
Author(s):  
Thiemo Fetzer
Keyword(s):  
Large Scale ◽  
The Core ◽  
Mobility Data ◽  
The United Kingdom ◽  
Notable Increase ◽  
Alcoholic Drinks ◽  
Lower Infection ◽  
Causal Impact ◽  
The Cost ◽  
Active Record

Abstract This paper documents that a large-scale government subsidy aimed at encouraging people to eat out in restaurants in the wake of the first 2020 COVID-19 wave in the United Kingdom has had a significant causal impact on new cases, accelerating the subsequent second COVID-19 wave. The scheme subsidised 50% off the cost of food and non-alcoholic drinks for an unlimited number of visits in participating restaurants on Mondays–Wednesdays from 3–31 August 2020. Areas with higher take-up saw both a notable increase in new COVID-19 infection clusters within a week of the scheme starting and a deceleration in infections within two weeks of the program ending. Similarly, areas that exhibited notable rainfall during the prime lunch and dinner hours on the days the scheme was active record lower infection incidence—a pattern that is also measurable in mobility data—and non-detectable on days during which the discount was not available or for rainfall outside the core lunch and dinner hours.

scholarly journals Adjoint-Based Aerodynamic Design of Complex Aerospace Configurations

2016 ◽  
Author(s):  
Eric J. Nielsen
Keyword(s):  
Large Scale ◽  
Design Research ◽  
Design Parameters ◽  
Aerodynamic Design ◽  
Cfd Simulations ◽  
Sensitivity Derivatives ◽  
Computational Fluid Dynamics Cfd ◽  
Langley Research Center ◽  
The Cost ◽  
Derivatives Of

An overview of twenty years of adjoint-based aerodynamic design research at NASA Langley Research Center is presented. Adjoint-based algorithms provide a powerful tool for efficient sensitivity analysis of complex large-scale computational fluid dynamics (CFD) simulations. Unlike alternative approaches for which computational expense generally scales with the number of design parameters, adjoint techniques yield sensitivity derivatives of a simulation output with respect to all input parameters at the cost of a single additional simulation. With modern large-scale CFD applications often requiring millions of compute hours for a single analysis, the efficiency afforded by adjoint methods is critical in realizing a computationally tractable design optimization capability for such applications.

Solar Desalination Based on Micro Gas Turbines Driven by Parabolic Dish Collectors

2019 ◽  
Author(s):  
David Sánchez ◽  
Miguel Rollán ◽  
Lourdes García-Rodríguez ◽  
G. S. Martínez
Keyword(s):  
Gas Turbine ◽  
Reverse Osmosis ◽  
Gas Turbines ◽  
Waste Heat ◽  
Distillation Unit ◽  
Design Parameters ◽  
Small Scale ◽  
Micro Gas Turbine ◽  
The Cost ◽  
The Impact

Abstract This paper presents the preliminary design and techno-economic assessment of an innovative solar system for the simultaneous production of water and electricity at small scale, based on the combination of a solar micro gas turbine and a bottoming desalination unit. The proposed layout is such that the former system converts solar energy into electricity and rejects heat that can be used to drive a thermal desalination plant. A design model is developed in order to select the main design parameters for two different desalination technologies, phase change and membrane desalination, in order to better exploit the available electricity and waste heat from the turbine. In addition to the usual design parameters of the mGT, the impact of the size of the collector is also assessed and, for the desalination technologies, a tailored multi-effect distillation unit is analysed through the selection of the corresponding design parameters. A reverse osmosis desalination system is also designed in parallel, based on commercial software currently used by the water industry. The results show that the electricity produced by the solar micro gas turbine can be used to drive a Reverse Osmosis system effectively whereas the exhaust gases could drive a distillation unit. This would decrease the stack temperature of the plant, increasing the overall energy efficiency of the system. Nevertheless, the better thermodynamic performance of this fully integrated system does not translate into a more economical production of water. Indeed, the cost of water turns out lower when coupling the solar microturbine and Reverse Osmosis units only (between 3 and 3.5 €/m3), whilst making further use the available waste heat in a Multi Effect Distillation system rises the cost of water by 15%.

Solar Desalination Based on Micro Gas Turbines Driven by Parabolic Dish Collectors

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
David Sánchez ◽  
Miguel Rollán ◽  
Lourdes García-Rodríguez ◽  
Gonzalo S. Martínez
Keyword(s):  
Reverse Osmosis ◽  
Gas Turbines ◽  
Waste Heat ◽  
Economic Assessment ◽  
Integrated System ◽  
Energy Utilization ◽  
Design Parameters ◽  
Small Scale ◽  
Parabolic Dish ◽  
The Cost

Abstract This paper presents the preliminary design and techno-economic assessment of an innovative solar system for the simultaneous production of water and electricity at small scale, based on the combination of a solar micro gas turbine (mGT) and a bottoming desalination unit. To assess this system, a design model is developed to select the main design parameters for two different desalination technologies, reverse osmosis (RO), and multi-effect distillation (MED), aiming to exploit the available electricity and waste heat from the turbine, respectively. The results show that, from a thermodynamic standpoint, it is possible to exceed 65% solar energy utilization if both electricity and waste heat are used to produce fresh water. Nevertheless, the better thermodynamic performance of the fully integrated system does not translate into a more economical production of water. Indeed, the cost of water turns out lower when coupling the solar microturbine and reverse osmosis units only (between 3 and 3.5 €/m3), while making further use of the available waste heat in a multi-effect distillation system rises the cost of water by 15%.

Membrane-Less Hydrogen Iron Redox Flow Battery

2018 ◽  
Vol 16 (1) ◽  
Author(s):  
Kyamra Marma ◽  
Jayanth Kolli ◽  
Kyu Taek Cho
Keyword(s):  
Porous Electrode ◽  
Membrane System ◽  
Design Parameters ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Ohmic Losses ◽  
Battery Systems ◽  
A Cell ◽  
The Cost ◽  
New System

In this study, a new type of redox flow battery (RFB) named “membrane-less hydrogen-iron RFB” was investigated for the first time. The membrane is a cell component dominating the cost of RFB, and iron is an abundant, inexpensive, and benign material, and thus, this iron RFB without the membrane is expected to provide a solution to the challenging issues of current battery systems such as high cost and safety concerns. The research focus in this study was placed on defining key design parameters to make this new system promising as an RFB. Crossing rate of reactants over carbon porous electrode (CPE) was controlled by modifying its pore structure with Teflon impregnation, and the effects of the Teflon on crossover, kinetic, Ohmic, and mass transfer was investigated by cell-based test and one-dimensional computational model. It was found that the cell performance (i.e., charge and discharge polarization) of the new membrane-less system was equivalent to that of the conventional membrane-system (i.e., RFB having a membrane). Especially, the Ohmic properties of the new system were constant and stable, while in the conventional membrane system, they were significantly varied and deteriorated as cell tests were continued, indicating that degradation or contamination of membrane affecting Ohmic properties could be mitigated effectively in the membrane-less system, which was found first in this research. The modeling analysis provided insight into the system, showing that the effect of reactant crossover on performance decay was not significant, and Teflon impregnation in the CPE caused significant kinetic and Ohmic losses by impeding ion transport and reactant access to reaction sites. From this study, it was found that the membrane-less H2-iron system is feasible and promising in resolving the challenge issues of the conventional systems. And the results of this study are expected to provide guidelines for research and development of flow battery systems without having a membrane.

Characterization of seawater reverse osmosis fouled membranes from large scale commercial desalination plant

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Reverse Osmosis ◽  
Large Scale ◽  
Retention Rate ◽  
Local Level ◽  
Microscopic Analysis ◽  
Transmembrane Pressure ◽  
Hydraulic Permeability ◽  
Seawater Reverse Osmosis ◽  
A Chain

The objective of this work is to study the ageing state of a used reverse osmosis (RO) membrane taken in Algeria from the Benisaf Water Company seawater desalination unit. The study consists of an autopsy procedure used to perform a chain of analyses on a membrane sheet. Wear of the membrane is characterized by a degradation of its performance due to a significant increase in hydraulic permeability (25%) and pressure drop as well as a decrease in salt retention (10% to 30%). In most cases the effects of ageing are little or poorly known at the local level and global measurements such as (flux, transmembrane pressure, permeate flow, retention rate, etc.) do not allow characterization. Therefore, a used RO (reverse osmosis) membrane was selected at the site to perform the membrane autopsy tests. These tests make it possible to analyze and identify the cause as well as to understand the links between performance degradation observed at the macroscopic scale and at the scale at which ageing takes place. External and internal visual observations allow seeing the state of degradation. Microscopic analysis of the used membranes surface shows the importance of fouling. In addition, quantification and identification analyses determine a high fouling rate in the used membrane whose foulants is of inorganic and organic nature. Moreover, the analyses proved the presence of a biofilm composed of protein.

Cost- und Monitoring-Projekt: Zwei neue forstliche Meinungsumfragen im Vergleich | The Cost- and Monitoring-Projects: A Comparison of Two New Forestry Opinion Polls

2000 ◽  
Vol 151 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Stephan Wild-Eck ◽  
Willi Zimmermann
Keyword(s):  
Large Scale ◽  
Forest Policy ◽  
Forest Economics ◽  
Positive Attitudes ◽  
Federal Institute ◽  
Swiss Confederation ◽  
Institute Of Technology ◽  
The Cost ◽  
Near Future ◽  
Opinion Polls

Two large-scale surveys looking at attitudes towards forests, forestry and forest policy in the second half ofthe nineties have been carried out. This work was done on behalf of the Swiss Confederation by the Chair of Forest Policy and Forest Economics of the Federal Institute of Technology (ETH) in Zurich. Not only did the two studies use very different methods, but the results also varied greatly as far as infrastructure and basic conditions were concerned. One of the main differences between the two studies was the fact that the first dealt only with mountainous areas, whereas the second was carried out on the whole Swiss population. The results of the studies reflect these differences:each produced its own specific findings. Where the same (or similar) questions were asked, the answers highlight not only how the attitudes of those questioned differ, but also views that they hold in common. Both surveys showed positive attitudes towards forests in general, as well as a deep-seated appreciation ofthe forest as a recreational area, and a positive approach to tending. Detailed results of the two surveys will be available in the near future.

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