Flow Distribution Analysis in the SOFC Stack Using CFD Technique

2017 ◽  
Author(s):  
Cheng Zhao ◽  
Cun Wang ◽  
Tao Zhang ◽  
Jian Pu
Keyword(s):  
Three Dimensional ◽  
Flow Distribution ◽  
Structure Design ◽  
Geometric Parameters ◽  
Channel Structure ◽  
Distribution Analysis ◽  
Flow Uniformity ◽  
Gas Distributor ◽  
Inlet Tube ◽  
Computational Fluid Dynamics Cfd

In this paper, a three dimensional solid oxide fuel cell (SOFC) model is constructed to investigate the gas distribution and the pressure variation in the external manifold stack by a computational fluid dynamics (CFD) approach. Several geometric parameters of external manifold stack, including the position of inlet tube, depth of the manifold and the channel resistance are optimized to achieve uniform gas distributions among the channels. Simulation results indicate that a gas distributor can enhance the flow uniformity effectively. Besides, with the increasing depth of the manifold, the flow tends to be more uniform in T-manifold but has a small impact on C-manifold stack. It is also shown that flow distribution is intensively enhanced with the raise of resistance, especially from 0Pa to 100Pa. Modeling results highlight the importance of manifold and channel structure design for external manifold stack and can be widely applied to design the geometric parameters.

Numerical Study of the Winter-Kennedy Method—A Sensitivity Analysis

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Binaya Baidar ◽  
Jonathan Nicolle ◽  
Chirag Trivedi ◽  
Michel J. Cervantes
Keyword(s):  
Boundary Conditions ◽  
Secondary Flow ◽  
Numerical Study ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Local Flow ◽  
Spiral Case ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Changes

The Winter-Kennedy (WK) method is commonly used in relative discharge measurement and to quantify efficiency step-up in hydropower refurbishment projects. The method utilizes the differential pressure between two taps located at a radial section of a spiral case, which is related to the discharge with the help of a coefficient and an exponent. Nearly a century old and widely used, the method has shown some discrepancies when the same coefficient is used after a plant upgrade. The reasons are often attributed to local flow changes. To study the change in flow behavior and its impact on the coefficient, a numerical model of a semi-spiral case (SC) has been developed and the numerical results are compared with experimental results. The simulations of the SC have been performed with different inlet boundary conditions. Comparison between an analytical formulation with the computational fluid dynamics (CFD) results shows that the flow inside an SC is highly three-dimensional (3D). The magnitude of the secondary flow is a function of the inlet boundary conditions. The secondary flow affects the vortex flow distribution and hence the coefficients. For the SC considered in this study, the most stable WK configurations are located toward the bottom from θ=30deg to 45deg after the curve of the SC begins, and on the top between two stay vanes.

Effects of Air Induct Structure to Flow Uniformity and Resistance for Primary Surface Recuperator of a Micro Gas Turbine

2010 ◽  
Author(s):  
Wei Qu ◽  
Shan Gao
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Loss ◽  
Air Flow ◽  
Flow Distribution ◽  
Structure Design ◽  
Flow Uniformity ◽  
Local Pressure ◽  
Pressure Losses ◽  
Micro Gas Turbine

Primary surface recuperator is important for micro gas turbines, the flow distribution and pressure loss are sensitive to the induct structure design significantly. The air induct structure for one recuperator is modelled and simulated. Several flow fields and pressure losses are obtained for different designs of air induct structure. The air induct structure can affect the flow uniformity, further influence the pressure loss a lot. For several changes of air induct structure, the non-distribution of air flow can be decreased from 67% to 13%, and the pressure loss can be decreased to 50% of the original. Considering the recuperator design and the gas turbine, one optimized structure is recommended, which has less local pressure loss and better flow distribution.

scholarly journals A CFD ANALYSIS OF THE INFLUENCE OF PLENUM CONFIGURATIONS ON GAS DISTRIBUTION IN A FLUIDIZED BED

2020 ◽  
Vol 50 (2) ◽  
pp. 83-88
Author(s):  
JOSE MIGUEL SORIA ◽  
TATIANA MARIEL AUSINA ◽  
GERMAN DELFOR MAZZA
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Fluidized Beds ◽  
Flow Distribution ◽  
Poor Quality ◽  
Cfd Analysis ◽  
Gas Distribution ◽  
Flow Uniformity ◽  
Computational Fluid Dynamics Cfd

Fluidized beds are widely used in many industries. The fluidization quality of these units is strongly related to the characteristics of the plenum and distributor (grid). In this work, the effect of different plenum geometries, and gas entrance sizes and locations on the velocity profile above the distributor was analyzed by Computational Fluid Dynamics (CFD). The results showed that flow uniformity above the distributor improved with an increase in the gas inlet diameter and the plenum height. Channeling was observed for the bottom central inlet. Additionally, simulations for plenum heights predicted by one of the frequently used correlations (Litz correlation) were also carried out and showed, especially for a bottom central gas inlet, a poor quality flow distribution. This behavior indicated that Litz correlation tends to underestimate the plenum height for obtaining a uniform flow downstream the distributor.

Design considerations for the volutes of centrifugal fans and compressors

1999 ◽  
Vol 213 (4) ◽  
pp. 401-410 ◽  
Author(s):  
D Pan ◽  
A Whitfield ◽  
M Wilson
Keyword(s):  
Three Dimensional ◽  
Flow Distribution ◽  
Internal Flow ◽  
Area Ratio ◽  
Design Flow ◽  
Centrifugal Fan ◽  
Flow Conditions ◽  
Design Considerations ◽  
Centrifugal Fans ◽  
Computational Fluid Dynamics Cfd

The initial conceptual design of centrifugal fan and compressor volutes is considered and extended to accommodate overhung volute designs often used in process and turbocharger compressors. The initial passage design is then developed through the application of a commercial computational fluid dynamics (CFD) code.’ Based on the experimental data of a turbocharger compressor volute, three-dimensional, compressible, steady flow computations were carried out for alternative volute designs. Detailed internal flow data in both a conventional and a modified volute design, at both design and off-design flow conditions, are presented. The design investigation showed that enlarging the flow passage area near the tongue region, but without changing the exit-inlet area ratio of the volute, led to an improvement in the internal flow distribution at off-design flow conditions.

Flow distribution analysis by helical scanning in polysulfone hemodialyzers: Effects of fiber structure and design on flow patterns and solute clearances

2006 ◽  
Vol 10 (4) ◽  
pp. 380-388 ◽  
Author(s):  
Claudio RONCO ◽  
Nathan LEVIN ◽  
Alessandra BRENDOLAN ◽  
Federico NALESSO ◽  
Dinna CRUZ ◽  
...  
Keyword(s):  
Flow Distribution ◽  
Flow Patterns ◽  
Distribution Analysis ◽  
Fiber Structure ◽  
Structure And Design

Assessment of Unsteady Flows in Turbines

1992 ◽  
Vol 114 (1) ◽  
pp. 79-90 ◽  
Author(s):  
O. P. Sharma ◽  
G. F. Pickett ◽  
R. H. Ni
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Research Activities ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Impact

The impacts of unsteady flow research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations that identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

The Effect of Bench Arrangements on the Natural Ventilation of a Multispan Greenhouse

2013 ◽  
Author(s):  
Sunita Kruger ◽  
Leon Pretorius
Keyword(s):  
Fluid Dynamics ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Low Velocity ◽  
Lower Velocity ◽  
Cfd Models ◽  
Temperature Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Plant Level

In this paper, the influence of various bench arrangements on the microclimate inside a two-span greenhouse is numerically investigated using three-dimensional Computational Fluid Dynamics (CFD) models. Longitudinal and peninsular arrangements are investigated for both leeward and windward opened roof ventilators. The velocity and temperature distributions at plant level (1m) were of particular interest. The research in this paper is an extension of two-dimensional work conducted previously [1]. Results indicate that bench layouts inside the greenhouse have a significant effect on the microclimate at plant level. It was found that vent opening direction (leeward or windward) influences the velocity and temperature distributions at plant level noticeably. Results also indicated that in general, the leeward facing greenhouses containing either type of bench arrangement exhibit a lower velocity distribution at plant level compared to windward facing greenhouses. The latter type of greenhouses has regions with relatively high velocities at plant level which could cause some concern. The scalar plots indicate that more stagnant areas of low velocity appear for the leeward facing greenhouses. The windward facing greenhouses also display more heterogeneity at plant level as far as temperature is concerned.

Mechanism and Flow Control on the Mismatching of Impeller and Vaned Diffuser Caused by Inlet Prewhirl for Centrifugal Compressors

2016 ◽  
Author(s):  
Qiangqiang Huang ◽  
Xinqian Zheng ◽  
Aolin Wang
Keyword(s):  
Flow Control ◽  
Control Method ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Vaned Diffuser ◽  
Inlet Distortion ◽  
Computational Fluid Dynamics Cfd ◽  
Stagger Angle ◽  
Good Agreement ◽  
Matching Relation

Air often flows into compressors with inlet prewhirl, because it will obtain a circumferential component of velocity via inlet distortion or swirl generators such as inlet guide vanes. A lot of research has shown that inlet prewhirl does influence the characteristics of components, but the change of the matching relation between the components caused by inlet prewhirl is still unclear. This paper investigates the influence of inlet prewhirl on the matching of the impeller and the diffuser and proposes a flow control method to cure mismatching. The approach combines steady three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations with theoretical analysis and modeling. The result shows that a compressor whose impeller and diffuser match well at zero prewhirl will go to mismatching at non-zero prewhirl. The diffuser throat gets too large to match the impeller at positive prewhirl and gets too small for matching at negative prewhirl. The choking mass flow of the impeller is more sensitive to inlet prewhirl than that of the diffuser, which is the main reason for the mismatching. To cure the mismatching via adjusting the diffuser vanes stagger angle, a one-dimensional method based on incidence matching has been proposed to yield a control schedule for adjusting the diffuser. The optimal stagger angle predicted by analytical method has good agreement with that predicted by computational fluid dynamics (CFD). The compressor is able to operate efficiently in a much broader flow range with the control schedule. The flow range, where the efficiency is above 80%, of the datum compressor and the compressor only employing inlet prewhirl and no control are just 25.3% and 31.8%, respectively. For the compressor following the control schedule, the flow range is improved up to 46.5%. This paper also provides the perspective of components matching to think about inlet distortion.

scholarly journals Three-Dimensional Navier–Stokes Analysis and Redesign of an Imbedded Bellmouth Nozzle in a Turbine Cascade Inlet Section

1996 ◽  
Vol 118 (3) ◽  
pp. 529-535 ◽  
Author(s):  
P. W. Giel ◽  
J. R. Sirbaugh ◽  
I. Lopez ◽  
G. J. Van Fossen
Keyword(s):  
Three Dimensional ◽  
Navier Stokes ◽  
Experimental Measurements ◽  
Inlet Section ◽  
Turbine Cascade ◽  
Blade Cascade ◽  
Inlet Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Transonic Turbine ◽  
Flow Nonuniformity

Experimental measurements in the inlet of a transonic turbine blade cascade showed unacceptable pitchwise flow nonuniformity. A three-dimensional, Navier–Stokes computational fluid dynamics (CFD) analysis of the imbedded bellmouth inlet in the facility was performed to identify and eliminate the source of the flow nonuniformity. The blockage and acceleration effects of the blades were accounted for by specifying a periodic static pressure exit condition interpolated from a separate three-dimensional Navier–Stokes CFD solution of flow around a single blade in an infinite cascade. Calculations of the original inlet geometry showed total pressure loss regions consistent in strength and location to experimental measurements. The results indicate that the distortions were caused by a pair of streamwise vortices that originated as a result of the interaction of the flow with the imbedded bellmouth. Computations were performed for an inlet geometry that eliminated the imbedded bellmouth by bridging the region between it and the upstream wall. This analysis indicated that eliminating the imbedded bellmouth nozzle also eliminates the pair of vortices, resulting in a flow with much greater pitchwise uniformity. Measurements taken with an installed redesigned inlet verify that the flow nonuniformity has indeed been eliminated.

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