Use of CFD Modeling for Designing Intake and Discharge Structures in a Discharge Canal

2010 ◽  
Author(s):  
Fangbiao Lin ◽  
George Pigg ◽  
Gerald Schohl
Keyword(s):  
Power Plants ◽  
Cooling Tower ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
The North ◽  
Cfd Models ◽  
Discharge Canal ◽  
Before And After ◽  
Pros And Cons

This paper presents a computational fluid dynamics (CFD) modeling approach for designing intake and discharge structures in a discharge canal for nuclear and fossil power plants. It discusses how the CFD models are developed, what types of results can be obtained from the CFD modeling study and how the results are used for developing designs of the intake and discharge structures. The pros and cons of the CFD modeling method for this type of application are also discussed. Intake and discharge structures for a “Helper Cooling Tower South” will be added to the discharge canal of the Crystal River Energy Complex (CREC). The CFD modeling was used to confirm suitable locations for the new intake and discharge structures to minimize potential recirculation and potential loss of cooling tower efficiency, and to evaluate the erosion of the banks on the north and south side of the canal due to the flow from the discharge structure. The CFD model was developed using FLUENT for the existing and future configurations of the discharge canal that consists of the existing intake, discharges, and the new intake and discharge structures. The CFD modeling runs were performed to investigate three-dimensional flow patterns, velocities and temperatures in the discharge canal under current and future operating conditions. Current and future conditions refer to those before and after installation of the Helper Cooling Tower South Intake and Discharge structures, respectively. Comparing the CFD results (streamlines, temperature and velocity distributions, etc.) for the future conditions to those for the existing conditions, the locations and designs of the new intake and discharge structures were assessed and developed. This study demonstrates that the new intake is not impacted by the new and existing discharge structures, and the existing intake will perform similarly as it performs before the construction of the new intake and discharges. The study also identifies some sections of the canal banks and bottom that may need to be protected from erosion due to the impacts of the high velocity water from the discharge structures.

scholarly journals Effect of Valve Opening Manner and Sealing Method on the Steady Injection Characteristic of Gas Fuel Injector

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1479
Author(s):  
Tianbo Wang ◽  
Lanchun Zhang ◽  
Qian Chen
Keyword(s):  
Steady State ◽  
Three Dimensional ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Fuel Injector ◽  
Injection Efficiency ◽  
Mixing Performance ◽  
Cfd Models ◽  
Valve Opening ◽  
Gas Fuel

The steady-state injection characteristic of gas fuel injector is one of the key factors that affects the performance of gas fuel engine. The influences of different injection strategies, such as different injection angles and different injection positions, on the mixing performance in gas-fueled engine have been emphasized in previous literatures. However, the research on the injection characteristics of the gas fuel injector itself are insufficient. The three-dimensional steady-state computational fluid dynamics (CFD) models of two kinds of injectors, in different opening manners, and the other two kinds of injectors, in different sealing methods, were established in this paper. The core region speed, stagnation pressure loss and mass flow rate were compared. Additionally, the effective injection pressure (EIP) concept was also used to evaluate the injection efficiency of gas fuel injector. The simulation results show that the jet speed of the pull-open injector is higher than the push-open injector under the same operating conditions. The injection efficiency of the pull-open valve is about 56.0%, while the push-open valve is 50.3%. In general, the steady-flow characteristic of the pull-open injector is better than that of the push-open one. The injection efficiency of the flat sealing injector is 55.2%, slightly lower than the conical sealing method.

Magnus-Effect Rotors for Solar Chimney Power Plants

2010 ◽  
Author(s):  
Mohamed A. Serag-Eldin ◽  
Mohammed A. Abdul Latif
Keyword(s):  
Power Plants ◽  
Operating Conditions ◽  
Circular Cylinders ◽  
Cfd Modeling ◽  
Solar Chimney ◽  
Magnus Effect ◽  
Expected Performance ◽  
Circular Track ◽  
Force Components ◽  
Axial Turbines

The paper proposes the use of spinning and rotating cylinders to replace the axial turbines of Solar Chimney power plants. A large number of circular cylinders are placed equidistant, on a circular track concentric with the solar chimney axis. The cylinders spin around their own axis while simultaneously rotating about the chimney axis. By virtue of the Magnus effect, Lift forces arise which create force components tangential to the track in the direction of motion of the cylinders; thus mechanical work is produced. Using CFD modeling, the paper analyzes the resulting flow pattern and presents the expected performance of the hypothetical design for different geometric parameters and operating conditions. It is demonstrated that the design is indeed promising, and worthy of further investigation and development. It is also revealed that good performance of the proposed rotor is highly dependent on the proper choice of operating parameters.

scholarly journals CFD Modeling to Predict Mass Transfer in Multicomponent Mixtures

2019 ◽  
Vol 14 (4) ◽  
Author(s):  
Mitra Sadat Lavasani ◽  
Rahbar Rahimi ◽  
Mortaza Zivdar ◽  
Mohammad Kalbassi
Keyword(s):  
Mass Transfer ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Ternary Mixtures ◽  
Cfd Modeling ◽  
Multicomponent Mixtures ◽  
Distillation Columns ◽  
Multicomponent Distillation ◽  
Interactive Nature ◽  
Two Phases

Abstract A novel three-dimensional computational fluid dynamics mass transfer (CMT) model in Eulerian–Eulerian frame work is deploys for investigating the concentration profiles, and trays efficiencies in multicomponent distillation columns. The proposed model is based on Maxwell Stefan equations, and CFD was employed as a powerful tool to model the hydrodynamics and mass transfer. The two phases are modelled as two interpenetrating phases with interphase momentum, heat and mass transfer. The Closure model is developed for mass interphase transfer rate in ternary mixtures. The predictability of the mass transfer behaviours of multicomponent can result in a more efficient and predictable design of distillation trays. Two non-ideal ternary mixtures were studied. The tray geometry and operating conditions are based on the experimental works of Kalbassi and the composition profiles, tray efficiencies, and point efficiencies of mixtures were presented. The obtained results were confirmed by the experimental data. The results indicate that the values of individual component tray efficiencies and point efficiencies for these multicomponent systems were considerably different which confirm the interactive nature of the mass transfer in multicomponent mixtures. These mixtures also illustrated different point efficiencies across the tray because of the composition dependency of these mixtures. The average relative error for the prediction of efficiencies is about 8 %, which indicates the accuracy of the model.

Computer Simulation of Transport Phenomena in Evaporative Cooling Towers

1988 ◽  
Vol 110 (2) ◽  
pp. 190-196 ◽  
Author(s):  
D. J. Benton ◽  
W. R. Waldrop
Keyword(s):  
Power Plants ◽  
Field Data ◽  
Cooling Tower ◽  
Operating Conditions ◽  
Cooling Towers ◽  
Governing Equations ◽  
Cooling Process ◽  
Transfer Processes ◽  
Finite Integral ◽  
Simultaneous Heat

A computer model of the simultaneous heat, mass, and momentum transfer processes occurring throughout an entire cooling tower is described in this paper. The model includes the flexibility to analyze the several configurations, fill arrangements, and flow distributions commonly used by the power industry. The fundamental governing equations are solved using a finite-integral technique to provide a quasi-two-dimensional description of the flow and cooling process within the tower. The model has been successfully compared with field data from cooling towers at three TVA power plants as well as data from other utilities. Each of these towers was significantly different in design, thereby demonstrating the versatility of the model for correctly predicting the cooling performance of mechanical and natural draft towers, as well as crossflow and counterflow orientations, for a range of meteorological and plant operating conditions.

A New 1.5-Stage Turbine Wheelspace Hot Gas Ingestion Rig (HGIR): Part I — Experimental Test Vehicle, Measurement Capability and Baseline Results

2013 ◽  
Author(s):  
Pepe Palafox ◽  
Zhongman Ding ◽  
Jeremy Bailey ◽  
Todd Vanduser ◽  
Kevin Kirtley ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Operating Conditions ◽  
Test Facility ◽  
Cfd Modeling ◽  
Test Vehicle ◽  
Steady State Condition ◽  
Measurement Capability ◽  
Hot Gas ◽  
Cfd Models ◽  
Exit Mach Number

An introduction is given to a new rotating wheelspace test vehicle known as the GE Hot Gas Ingestion Rig (HGIR). This scaled 1.5 stage turbine rig is configured similar to a current generation heavy duty gas turbine. It has a broad spectrum of measurement capability, including radial and circumferential ports for CO2 measurements that are used to measure the sealing effectiveness from candidate rim seal geometries. Engine-matched conditions are presented in a non-dimensional form that demonstrate the value of this fully capable test facility, including static pressure signatures at stage 1 nozzle exit, exit Reynolds number, exit Mach number and rotational Reynolds number. This paper also provides details of the operating conditions and assessment of a thermal steady-state condition achieved consistently throughout each test. Part I of this two-part paper focuses on the geometric details of this new state-of-the-art wheelspace rig, the measurement capabilities currently available and planned, and the results from the baseline geometry. The test data from this test vehicle are used to validate reduced order models, including unsteady CFD models. Details of the CFD modeling and validation are presented in the Part II paper Ding et al. [1]. Measurement uncertainties for all key parameters as well as the repeatability of the test rig to reproduce test conditions are presented to demonstrate the rigor taken in the design and operation of this testing facility.

Development of a Design Approach for the Optimization of Steam Turbine Exhaust System Performance Through CFD Modelling

2021 ◽  
Author(s):  
Tommaso Diurno ◽  
Stella Grazia Tomasello ◽  
Tommaso Fondelli ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
...  
Keyword(s):  
Power Plants ◽  
Fluid Dynamic ◽  
Renewable Energy Sources ◽  
Computational Cost ◽  
Great Influence ◽  
Computational Effort ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Geometrical Parameters ◽  
Exhaust Hood

Abstract Nowadays, the ever-increasing world electricity generation by renewable energy sources has brought about changes in conventional power plants, especially in those ones where large steam turbines work, which were widely used to meet the world’s energy needs by operating mostly at fixed conditions. Now, instead, they have to be capable to operate with greater flexibility, including rapid load changes and quick starts as well, in order to make the most of the renewable resources while guaranteeing the coverage of any shortcomings of the latter with traditional fossil fuel systems. Such service conditions are particularly challenging for the exhaust hoods, which have a great influence on the overall turbine performance, especially at off-design conditions. In fact, the complex and high rotational 3D flow generated within the diffuser and the exhaust hood outer casing can cause an increase in aerodynamic losses along with the detriment of the hood recovery performance. For these reasons, an optimized design and adequate prediction of the exhaust hood performance under all the machine operating conditions is mandatory. Since it has been widely proven that the exhaust hood flow strongly interacts with the turbine rear stage, the necessity to model this as well into a CFD modeling becomes crucial, requiring a remarkable computational effort, especially for full transient simulations. Even if adopting simplified approaches to model the last stage and exhaust hood interfaces, such as the so-called Frozen Rotor and the Mixing Plane ones, helps to keep the computational cost low, it can be not for an exhaust hood optimization process, which requires a significant number of CFD simulations to identify the most performing geometry configuration. For these reasons, a simplified model of the exhaust hood must be adopted to analyse all the possible design variants within a feasible time. The purpose of this work is to present a strategy for the exhaust hood design based on the definition of a simplified CFD model. A parametric model has been developed as a function of key geometrical parameters of both the exhaust hood and the diffuser, taking into account the strong fluid-dynamic coupling between these components. A periodic approximation has been introduced to model the exhaust hood domain, thus allowing to augment the number of the geometrical parameters of the DOE, while keeping the computational effort low. A response surface has been achieved as a function of the key geometrical parameters, therefore an optimization method has allowed identifying the best performing configuration. A 3D model of the optimized periodic geometry has been then generated to assess the effectiveness of the procedure here presented. Finally, the presented procedure has been applied in several off-design operating conditions, in order to find out an optimal geometry for each operating point, evaluating how much they differ from that one got for the design point.

CFD Modeling of the Performance of a Prechamber for Use in a Large Bore Natural Gas Engine

2005 ◽  
Author(s):  
Allan Kirkpatrick ◽  
Gi-Heon Kim ◽  
Daniel Olsen
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Combustion Process ◽  
Three Dimensional ◽  
Cfd Modeling ◽  
Main Chamber ◽  
Gas Engine ◽  
Natural Gas Engines ◽  
Natural Gas Engine ◽  
Cfd Models

The topic of this paper is the performance of a prechamber for use in a large bore two stroke natural gas engine. With increased regulation of emissions from stationary natural gas engines, there has been interest in modification of the combustion process, such as extending the lean limit, to reduce NOx emissions. One promising combustion technique uses an ignition prechamber. CFD models of a prechamber and the cylinder were developed in order to simulate the performance of a prechamber ignition system. The modeling included a full three dimensional transient analysis with scavenging, moving piston, and main chamber fuel injection. The CFD analysis included the fuel injection into the prechamber, pressurization by the inflowing main chamber gases, spark ignition, combustion, and flame propagation into the main combustion chamber. The computations indicated that the prechamber is more well mixed than the main engine chamber, with the prechamber mixture close to stoichiometric for better ignition. There is a strong, well-organized vortex in the prechamber induced by the incoming jet from the main chamber. The combustion flame in the prechamber travels in the direction of the gas vortex along lines of increasing equivalence ratio. The flame then propagates across the main cylinder in a very uniform fashion, indicating that there is sufficient energy to ignite the lean, partially mixed mixture in the main chamber. The orientation of the prechamber nozzle was also investigated, and an orientation of twenty degrees relative to the main chamber was found to produce a flame that did not impinge on the piston.

CFD Studies on Burner Secondary Air Flow

2004 ◽  
Author(s):  
Anil K. Purimetla ◽  
Jie Cui ◽  
Stephen Idem ◽  
Sastry Munukutla
Keyword(s):  
Power Plants ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Scale Model ◽  
Cfd Modeling ◽  
Navier Stokes ◽  
Dust Deposition ◽  
Navier Stokes Equations ◽  
Secondary Air ◽  
The Individual

In many fossil power plants operating today, there is insufficient means to assure the proper balancing of the secondary airflows between the individual burners of wall-fired units in addition there is a problem of dust deposition on the floor. This mismatch leads to decreased boiler efficiency and increased emissions. In this study, a Computational Fluid Dynamics (CFD) modeling of a fossil power plant wind box scale model is performed using the commercial software CFX5.6. The model solves the three dimensional Reynolds averaged Navier-Stokes equations with the K-epsilon turbulence model. The CFD results are validated by the experimental data taken from a 1/8th scale model of a wall fired fossil unit. Simulations under various flow conditions are obtained to identify the optimum design in terms of the equalization of the secondary airflow through the burners.

scholarly journals CFD Modeling of Syngas Combustion and Emissions for Marine Gas Turbine Applications

2016 ◽  
Vol 23 (3) ◽  
pp. 39-49 ◽  
Author(s):  
Nader R. Ammar ◽  
Ahmed I. Farag
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Alternative Fuels ◽  
Flame Temperature ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Ansys Fluent ◽  
Gas Fuel

Abstract Strong restrictions on emissions from marine power plants will probably be adopted in the near future. One of the measures which can be considered to reduce exhaust gases emissions is the use of alternative fuels. Synthesis gases are considered competitive renewable gaseous fuels which can be used in marine gas turbines for both propulsion and electric power generation on ships. The paper analyses combustion and emission characteristics of syngas fuel in marine gas turbines. Syngas fuel is burned in a gas turbine can combustor. The gas turbine can combustor with swirl is designed to burn the fuel efficiently and reduce the emissions. The analysis is performed numerically using the computational fluid dynamics code ANSYS FLUENT. Different operating conditions are considered within the numerical runs. The obtained numerical results are compared with experimental data and satisfactory agreement is obtained. The effect of syngas fuel composition and the swirl number values on temperature contours, and exhaust gas species concentrations are presented in this paper. The results show an increase of peak flame temperature for the syngas compared to natural gas fuel combustion at the same operating conditions while the NO emission becomes lower. In addition, lower CO2 emissions and increased CO emissions at the combustor exit are obtained for the syngas, compared to the natural gas fuel.

Wind Effects on Air-Cooled Condensers for Power Plant Cooling

2010 ◽  
Author(s):  
John S. Maulbetsch ◽  
Michael N. DiFilippo ◽  
Michael Owen ◽  
Detlev G. Kroger
Keyword(s):  
Water Conservation ◽  
Power Plants ◽  
Field Measurements ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Electric Power Plants ◽  
Extensive Field ◽  
Air Cooled Condensers ◽  
And Performance ◽  
Utility Scale

The use of large, air-cooled condensers (ACC’s) for the cooling of turbine exhaust steam at steam/electric power plants is chosen more frequently as concerns over water conservation and water-related environmental issues become more prevalent. While dry cooling achieves significant reductions in plant water consumption, it does so at increased cost and reduced plant efficiency and output when compared to the more commonly used closed-cycle wet cooling systems. Maintaining full cooling capability under all operating conditions is crucial to the efficiency and economic viability of the plant. The effect of wind on ACC performance is the most significant challenge associated with ACC specification, design and performance. Extensive field measurements have been made on five utility-scale ACC’s to determine their operation and performance under varying wind conditions. The primary wind-related effects are shown to be hot air recirculation and degraded fan performance. The total effect on performance plus the relative importance of the two mechanisms are related to wind conditions and ACC configurations. Brief comparisons of field data to the results of CFD modeling are discussed.

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