Sensitivity Study of Lower Plenum Boron Injection in a BWR

2009 ◽  
Author(s):  
Jin Yan ◽  
Andrew Mallner
Keyword(s):  
Sensitivity Study ◽  
Operating Conditions ◽  
Second Phase ◽  
Cfd Model ◽  
Technical Approach ◽  
Test Program ◽  
Scale Test ◽  
Water Reactors ◽  
Two Phases ◽  
The Impact

Boiling water reactors (BWRs) are equipped with a standby liquid control system (SLCS). The SLCS is used to inject boron to shutdown the reactor from full power condition in the event that the control rods fail to insert. In order for the SLCS system to shut down the reactor, adequate mixing of the borated solution with the reactor coolant is necessary. In BWRs prior to BWR 5, the boron injection points are located in the lower plenum. The objective of this project is to evaluate the impact of the operating conditions on the boron injection based on the understanding of the behavior of multi-species flow in typical pre-BWR 5 reactors by using computational fluid dynamics (CFD). The project is divided into two phases. At the first phase, a CFD model based on the test configurations of GE 1/6 scale test program was established. The results were validated against measurements conducted by GE during the 1/6 scale test program performed in 1981. The validation shows that the CFD can give accurate predictions of the boron mixing. The technical approach employed in the CFD model was adequate to capture the boron mixing process in the BWR lower plenum. The second phase of the project is the sensitivity study based on the same technical approach developed in the first phase. However, a simplified BWR lower plenum model was used due to the time constrain. In the sensitivity study, the baseline case and four additional cases with different operating conditions were investigated using the same CFD approach.

scholarly journals Modeling Bacterial Regrowth and Trihalomethane Formation in Water Distribution Systems

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 463
Author(s):  
Gopinathan R. Abhijith ◽  
Leonid Kadinski ◽  
Avi Ostfeld
Keyword(s):  
Distribution Systems ◽  
Water Distribution ◽  
Mechanistic Model ◽  
Water Distribution Systems ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Growth Rate Constant ◽  
Model Parameters ◽  
Bacterial Regrowth ◽  
The Impact

The formation of bacterial regrowth and disinfection by-products is ubiquitous in chlorinated water distribution systems (WDSs) operated with organic loads. A generic, easy-to-use mechanistic model describing the fundamental processes governing the interrelationship between chlorine, total organic carbon (TOC), and bacteria to analyze the spatiotemporal water quality variations in WDSs was developed using EPANET-MSX. The representation of multispecies reactions was simplified to minimize the interdependent model parameters. The physicochemical/biological processes that cannot be experimentally determined were neglected. The effects of source water characteristics and water residence time on controlling bacterial regrowth and Trihalomethane (THM) formation in two well-tested systems under chlorinated and non-chlorinated conditions were analyzed by applying the model. The results established that a 100% increase in the free chlorine concentration and a 50% reduction in the TOC at the source effectuated a 5.87 log scale decrement in the bacteriological activity at the expense of a 60% increase in THM formation. The sensitivity study showed the impact of the operating conditions and the network characteristics in determining parameter sensitivities to model outputs. The maximum specific growth rate constant for bulk phase bacteria was found to be the most sensitive parameter to the predicted bacterial regrowth.

Fully Parametric High-Fidelity CFD Model for the Design Optimisation of the Cyclic Stagger Pattern of a Set of Fan Outlet Guide Vanes

2009 ◽  
Author(s):  
Andrea Milli ◽  
Olivier Bron
Keyword(s):  
Complex Geometry ◽  
Single Point ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
High Fidelity ◽  
Cfd Model ◽  
Design Optimisation ◽  
Guide Vanes ◽  
High Loss ◽  
Design Variables

The present paper deals with the redesign of cyclic variation of a set of fan outlet guide vanes by means of high-fidelity full-annulus CFD. The necessity for the aerodynamic redesign originated from a change to the original project requirement, when the customer requested an increase in specific thrust above the original engine specification. The main objectives of this paper are: 1) make use of 3D CFD simulations to accurately model the flow field and identify high-loss regions; 2) elaborate an effective optimisation strategy using engineering judgement in order to define realistic objectives, constraints and design variables; 3) emphasise the importance of parametric geometry modelling and meshing for automatic design optimisation of complex turbomachinery configurations; 4) illustrate that the combination of advanced optimisation algorithms and aerodynamic expertise can lead to successful optimisations of complex turbomachinery components within practical time and costs constrains. The current design optimisation exercise was carried out using an in-house set of software tools to mesh, resolve, analyse and optimise turbomachinery components by means of Reynolds-averaged Navier-Stokes simulations. The original configuration was analysed using the 3D CFD model and thereafter assessed against experimental data and flow visualisations. The main objective of this phase was to acquire a deep insight of the aerodynamics and the loss mechanisms. This was important to appropriately limit the design scope and to drive the optimisation in the desirable direction with a limited number of design variables. A mesh sensitivity study was performed in order to minimise computational costs. Partially converged CFD solutions with restart and response surface models were used to speed up the optimisation loop. Finally, the single-point optimised circumferential stagger pattern was manually adjusted to increase the robustness of the design at other flight operating conditions. Overall, the optimisation resulted in a major loss reduction and increased operating range. Most important, it provided the project with an alternative and improved design within the time schedule requested and demonstrated that CFD tools can be used effectively not only for the analysis but also to provide new design solutions as a matter of routine even for very complex geometry configurations.

scholarly journals Physics-Based Simulations of Flow and Fire Development Downstream of a Canopy

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 683
Author(s):  
Gilbert Accary ◽  
Duncan Sutherland ◽  
Nicolas Frangieh ◽  
Khalid Moinuddin ◽  
Ibrahim Shamseddine ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Forest Canopy ◽  
Prescribed Burning ◽  
Second Phase ◽  
Flow Conditions ◽  
Developed Turbulence ◽  
Large Eddy ◽  
Long Time ◽  
Two Phases ◽  
The Impact

The behavior of a grassland fire propagating downstream of a forest canopy has been simulated numerically using the fully physics-based wildfire model FIRESTAR3D. This configuration reproduces quite accurately the situation encountered when a wildfire spreads from a forest to an open grassland, as can be the case in a fuel break or a clearing, or during a prescribed burning operation. One of the objectives of this study was to evaluate the impact of the presence of a canopy upstream of a grassfire, especially the modifications of the local wind conditions before and inside a clearing or a fuel break. The knowledge of this kind of information constitutes a major element in improving the safety conditions of forest managers and firefighters in charge of firefighting or prescribed burning operations in such configurations. Another objective was to study the behavior of the fire under realistic turbulent flow conditions, i.e., flow resulting from the interaction between an atmospheric boundary layer (ABL) with a surrounding canopy. Therefore, the study was divided into two phases. The first phase consisted of generating an ABL/canopy turbulent flow above a pine forest (10 m high, 200 m long) using periodic boundary conditions along the streamwise direction. Large Eddy Simulations (LES) were carried out for a sufficiently long time to achieve a quasi-fully developed turbulence. The second phase consisted of simulating the propagation of a surface fire through a grassland, bordered upstream by a forest section (having the same characteristics used for the first step), while imposing the turbulent flow obtained from the first step as a dynamic inlet condition to the domain. The simulations were carried out for a wind speed that ranged between 1 and 12 m/s; these values have allowed the simulations to cover the two regimes of propagation of surfaces fires, namely plume-dominated and wind-driven fires.

scholarly journals Adrian Cowell e a Amazônia Brasileira

2021 ◽  
Author(s):  
Filipe Freitas Chaves
Keyword(s):  
Conflicts Of Interest ◽  
Road Construction ◽  
Indigenous Populations ◽  
Second Phase ◽  
Hydroelectric Dams ◽  
The People ◽  
Rubber Tappers ◽  
Gold Miners ◽  
Two Phases ◽  
The Impact

This article aims to examine two phases of the English director Adrian Cowell (1934-2011), who documented the Brazilian Amazon for 50 years. The first phase that we intend to examine is when he arrives in the country and meets the Villas Bôas brothers, filming the attempt by the sertanista brothers to attract isolated Indians into the interior of the Xingu National Park, in order to save them from civilization. The second phase we want to analyze is when he returns to the country, in 1980, after a season abroad, and films for a decade what would become his most famous series: The Decade of Destruction. Adrian Cowell followed the entire process of development and destruction of the Amazon, conflicts of interest, the impact of major projects, advances in agriculture and livestock, colonization projects, road construction and hydroelectric dams and their consequences in daily life of the people who live in the region: indigenous populations, rubber tappers, farmers, loggers, gold miners and others. The study of his films is extremely important to encourage debate and awareness about socio-environmental issues, aiming at the preservation of the largest forest in the world.

Integration of 3D-CFD Component Simulation Into Overall Engine Performance Analysis for Engine Condition Monitoring Purposes

2018 ◽  
Author(s):  
C. Klein ◽  
F. Wolters ◽  
S. Reitenbach ◽  
D. Schönweitz
Keyword(s):  
Performance Analysis ◽  
Condition Monitoring ◽  
Guide Vane ◽  
Engine Performance ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Inlet Guide Vane ◽  
Cfd Model ◽  
The Impact ◽  
Engine Condition

For an efficient detection of single or multiple component damages, the knowledge of their impact on the overall engine performance is crucial. This knowledge can be either built up on measurement data, which is hardly available to non-manufacturers or –maintenance companies, or simulative approaches such as high fidelity component simulation combined with an overall cycle analysis. Due to a high degree of complexity and computational effort, overall system simulations of jet engines are typically performed as 0-dimensional thermodynamic performance analysis, based on scaled generic component maps. The approach of multi-fidelity simulation, allows the replacement of single components within the thermodynamic cycle model by higher-order simulations. Hence, the component behavior becomes directly linked to the actual hardware state of the component model. Hereby the assessment of component deteriorations in an overall system context is enabled and the resulting impact on the overall system can be quantified. The purpose of this study is to demonstrate the capabilities of multi fidelity simulation in the context of engine condition monitoring. For this purpose, a 0D-performance model of the IAE-V2527 engine is combined with a CFD model of the appropriate fan component. The CFD model comprises the rotor as well as the outlet guide vane of the bypass and the inlet guide vane of the core section. As an exemplarily component deterioration, the fan blade tip clearance is increased in multiple steps and the impact on the overall engine performance is assessed for typical engine operating conditions. The harmonization between both simulation levels is achieved by means of an improved map scaling approach using an optimization strategy leading to practicable simulation times.

Experimental and Numerical Investigation of the Flow in a Low-Pressure Industrial Steam Turbine With Part-Span Connectors

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Markus Häfele ◽  
Christoph Traxinger ◽  
Marius Grübel ◽  
Markus Schatz ◽  
Damian M. Vogt ◽  
...  
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Numerical Study ◽  
Three Dimensional ◽  
Low Pressure ◽  
Operating Conditions ◽  
Engineering Practice ◽  
Cfd Model ◽  
Wide Range ◽  
The Impact

An experimental and numerical study on the flow in a three-stage low-pressure (LP) industrial steam turbine is presented and analyzed. The investigated LP section features conical friction bolts in the last and a lacing wire in the penultimate rotor blade row. These part-span connectors (PSC) allow safe turbine operation over an extremely wide range and even in blade resonance condition. However, additional losses are generated which affect the performance of the turbine. In order to capture the impact of PSCs on the flow field, extensive measurements with pneumatic multihole probes in an industrial steam turbine test rig have been carried out. State-of-the-art three-dimensional computational fluid dynamics (CFD) applying a nonequilibrium steam (NES) model is used to examine the aerothermodynamic effects of PSCs on the wet steam flow. The vortex system in coupled LP steam turbine rotor blading is discussed in this paper. In order to validate the CFD model, a detailed comparison between measurement data and steady-state CFD results is performed for several operating conditions. The investigation shows that the applied one-passage CFD model is able to capture the three-dimensional flow field in LP steam turbine blading with PSC and the total pressure reduction due to the PSC with a generally good agreement to measured values and is therefore sufficient for engineering practice.

Assessment of wind power capacity credit in Morocco: Outlook to 2020

2019 ◽  
Vol 44 (2) ◽  
pp. 196-207
Author(s):  
Yassir El Karkri ◽  
Aboubakr El Makrini ◽  
Hassane El Markhi ◽  
Tijani Lamhamdi ◽  
Hassan El Moussaoui
Keyword(s):  
Wind Energy ◽  
Wind Farm ◽  
Electric Energy ◽  
Wind Farms ◽  
Electricity Production ◽  
Second Phase ◽  
Energy Integration ◽  
Production Network ◽  
Two Phases ◽  
The Impact

The present article focuses on the calculation of the wind capacity credit by integrating the Moroccan project on the wind energy of 1000 MW in 2020. After an introduction to the Moroccan Integrated Wind Energy Project, a wind capacity credit assessment program will be implemented on Matlab software including the whole information about “installed capacity, number of plants, failure rate, types of installed units, peak demand etc.” This program will be used to calculate the safety rate of an electrical system as well as the capacity credit of Morocco’s electricity production network. This section will be built in two phases: the first phase will examine the impact of TAZA wind farm with an installed power of 150 MW, while the second phase will focus on the generalization of this study on all the wind farms that will be injected to the Moroccan grid in 2020. The research provides conclusion according to comments and assessment of the impact of this electric energy integration based on the wind generation.

scholarly journals The impact of non-accessible library and information science journals on research productivity in Pakistan

2016 ◽  
pp. 40-57
Author(s):  
Shamshad Ahmed ◽  
Awais Uzair
Keyword(s):  
Social Networking Sites ◽  
Research Productivity ◽  
Information Science ◽  
Citation Rate ◽  
Journal Citation Report ◽  
Library And Information Science ◽  
Second Phase ◽  
Mixed Method Research ◽  
Two Phases ◽  
The Impact

The purpose of this paper is to identify: (a) Non-accessible library and information science journals from HEC National Digital Library (DL) Subscribed databases, (b) Approaches adopted by the LIS researchers to acquire non-accessible articles, and (c) The impact of non-accessible articles on their research endeavor. A sequential exploratory strategy of mixed method research was applied to identify the impact of non-accessible LIS journals on research. This study was completed in two phases. In the first phase, an online surfing of all HEC subscribed databases was conducted and a list of openly accessible, partially accessible and non-accessible LIS journals was prepared. Impact factor of journals was checked from the list of Journal Citation Report by Thomson Reuter, 2013. In the second phase, a structured questionnaire was prepared to identify the approaches adopted by the researchers to acquire non-accessible articles and their impact on research productivity. Findings of the study show that (a) Emerald, (b) Science Direct, (c) JSTOR, (d) Project Muse, (e) Taylor & Francis, (f) Wiley-Blackwell Journals, and (g) University of Chicago Press, are the HEC subscribed databases which have LIS journals. Study reveals that there are 18 % non-accessible and 37 % partially accessible LIS journals on the HEC subscribed databases. Researchers tried to acquire non-accessible articles through friends, social networking sites (SNS) Groups, BDD and by requesting to authors etc. Respondents agreed that non-accessible journals do impact on research productivity. As a result, citations of non-accessible articles decreases, which negatively impact the quality and quantity of both authors and researchers' work. The outcomes of this study are significant for LIS researchers to become aware of the current situation of non-accessible journals and its impact on their research endeavors. It will also guide the HEC and research institutions to redesign their policy for the subscription of relevant databases that will enable complete access to journals on LIS discipline. It will also help to increase the quality of researchers' work and citation rate of authors' articles. This study may then be replicated in other fields and countries also. There is not enough work analyzing the impact of non-accessible journals on research productivity.

scholarly journals Impact of Twitter Sentiment Related to Bitcoin on Stock Price Returns

2020 ◽  
Vol 26 (6) ◽  
pp. 60-71
Author(s):  
Feda Hassan Jahjah ◽  
Muhanad Rajab
Keyword(s):  
Exchange Rate ◽  
Financial Markets ◽  
Stock Price ◽  
Second Phase ◽  
Digital Currency ◽  
Two Phases ◽  
Negative Sentiment ◽  
The Impact ◽  
Deep Learning Model ◽  
Positive Effect

Twitter is becoming an increasingly popular platform used by financial analysts to monitor and forecast financial markets. In this paper we investigate the impact of the sentiments expressed in Twitter on the subsequent market movement, specifically the bitcoin exchange rate. This study is divided into two phases, the first phase is sentiment analysis, and the second phase is correlation and regression. We analyzed tweets associated with the Bitcoin in order to determine if the user’s sentiment contained within those tweets reflects the exchange rate of the currency. The sentiment of users over a 2-month period is classified as having a positive or negative sentiment of the digital currency using the proposed CNN-LSTM deep learning model. By applying Pearson's correlation, we found that the sentiment of the day (d) had a positive effect on the future Bitcoin returns on the next day (d+1). The prediction accuracy of the linear regression model for the next day's revenue was 78%.

Location and hierarchical allocation disaster with combined ε-constraint and simulation-based optimization approach

SIMULATION ◽  
2021 ◽  
pp. 003754972110639
Author(s):  
Sogol Mousavi ◽  
Seyed Mojtaba Sajadi ◽  
Akbar AlemTabriz ◽  
Seyyed Esmaeil Najafi
Keyword(s):  
Second Phase ◽  
Optimization Approach ◽  
Allocation Model ◽  
Location Allocation ◽  
Medical Centers ◽  
Simulation Based ◽  
Simulation Based Optimization ◽  
Two Phases ◽  
The Impact ◽  
Hierarchical Allocation

The increasing frequency of natural disasters and the necessity of proper planning to minimize the impact and casualties of such crises have always been matters of great concern to human societies. In this study, a hybrid mathematical-simulative location-allocation model is proposed to carry out disaster management (DM) efforts with maximum coverage in the immediate aftermath of an earthquake. The proposed model consists of two phases: determining the optimal location of the temporary emergency stations (TECs), followed by optimal and hierarchical allocation of casualties to said temporary medical centers (TMCs). Given the contradictory nature of the model’s two objectives, that is, minimizing the cost of setting up TMCs and the time taken to transfer casualties to TMC. In the second phase, a simulation-based optimization approach is employed to simulate casualties’ behavior at the onset of the disaster and to determine the optimal capacity of the medical centers. The findings indicate that the costs and distance traveled by casualties during the earthquake have been reduced by 15%.

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