• Proceedings of the KSME Conference
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• 2003.04a
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• pp.585-590
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• 2003

The distributions of mass flow rate and pressure are major factors to deside the performance of a proton exchange membrane fuel cell (PEMFC). These factors are affected by channel configuration of air plate. In this paper. structural analysis is performed to investigate deformation of porous media. Two kind of models are suggest for flow analyses. Deformed porous media and undeformed porous media are considered for air plate model. The Numerical flow analysis results with deformed porous media and undeformed porous media had some discrepancy in pressure distribution. The pressure and velocity in a working condition are numerically calculated to predict the performance of the air plates. Distributions of the parameters in the PEMFC are analyzed numerically under steady-state conditions.

• Journal of the Korean Society of Visualization
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• v.2 no.2
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• pp.32-37
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• 2004

In this paper the numerical method with a zonal embedded grid system for an incompressible flow within a semi-circular container is presented. The algorithm is validated by its application to some typical flow models including the spin-up flow inside a semi-circular geometry. Flow visualization for the spin-up flows was used by PIV. The results show that at high Reynolds numbers the cyclonic cell at the left-hand side region moves along the circular wall and merges with the cell at the right-hand side region.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.161-163
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• 2008

The paper deals with a inverter control scheme to apply feeder flow control in the hybrid system consisted of a photovoltaic system and a fuel-cell system. The inverter operation modes and a feeder control reference is changed by changing of the loads. Simulation results using the PSCAD/EMTDC are presented to establish a inverter control method for a Feeder flow control mode.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.3
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• pp.243-254
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• 1996

The main purpose of this study is to investigate the collection efficiency characteristics of a cylindrical ESP. To do that, it is necessary to analyze the electric field, gas flow field, and mechanism of particle movement by numerical simulation based on EHD model. For a gas flow field, Navier-Stokes equation involving the electric source term was solved by SIMPLE algorithm. In case of the electric field, the current continuity and electric field equations were solved by S.O.R. method. The analysis of particle movement was performed on the basis of PSI-CELL model from the Lagrangian viewpoint. The results showed that the influence on the gas flow field by the electric field is almost negligible in a cylindrical ESP. The particle drift velocity $V_P$ toward the collection surface is increased continuously by the electrostatic force due to the rise of particle charge as the particle is moving to the flow direction and the particle size becomes larger. The collection efficiency is to quitely higher with the increase of applied voltage for the same particle size, while becomes smaller as the inlet velocity is increased.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1329-1332
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• 2003

Stepwise dechlorination of 1,2,4-trichlorobenzene was observed at a glassy carbon electrode in dimethylformamide containing 0.1 M tetraethylammonium perchlorate. Especially, dechlorination to dichlorobenzene and further to monochlorobenzene or benzene was successfully demonstrated with a porous reticulated vitreous carbon electrode. Electrochemical dechlorination of polychlorobenzenes employing a flow cell with a reticulated vitreous carbon working electrode is also described. Preliminary experiments with a flow cell showed that dechlorination of trichlorobenzene to dichlorobenzene was partially completed while dechlorination to benzene or monochlorobenzene was not successful, suggesting that a flow rate and electrolysis time should be further optimized for the complete electrolysis.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.2
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• pp.45-50
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• 2008

Molecular flows inside a guide block in the OLED(organic luminescent emitting device) deposition process have been simulated using DSMC(direct simulation Monte Carlo) method. Because the organic materials are evaporated under vacuum, molecules flow at a high Knudsen number of the free molecular regime, where the continuum mechanics is not valid. A guide block is designed as a part of the linear cell source to transport the evaporated materials to a deposition chamber, When solving the flows, the inlet boundary condition is proved to affect significantly the whole flow pattern. Thus, it is proposed that the pressure should be specified at the inlet. From the analysis of the density distributions at the nozzle exit of the guide block, it is shown that the longer nozzle can emit molecules more straightly. Finally, a nondimensionalized mass flow profile is obtained by numerical experiments, where various nozzle widths and inlet pressures are tested.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.4
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• pp.233-239
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• 2000

There are many difficult problems in analyzing the gas flow in puffer type circuit breaker such as complex geometry, moving boundary, shock wave and so on. To predict the interruption performance accurately, these should be considered in the simulation. In this paper, the analysis procedure of the cold gas flow in the circuit breaker is presented. Euler equation is solved by FVFLIC method which is an explicit time difference scheme for an unsteady flow computation. Moving boundaries are treated with a cell elimination-addition technique. The pressure and density in front of piston are calculated from the rate of the cell volume change. The presented method is applied to the real circuit breaker model and the pressure in front of the piston is good agreement with the experimental one.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3191-3196
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• 2007

The present study addresses a method to operate a fuel-cell system effectively using a recirculation ejector which recycles wasted hydrogen gas. Configuration of a recirculation ejector is changed to investigate the flow behavior through it under varying operating conditions, and how such conditions affect the fuel-cell hydrogen cycle. The numerical simulations are based on a fully implicit finite volume scheme of the axisymmetric, compressible, Reynolds-Averaged, Navier-Stokes equations for hydrogen gas, and are compared with available experimental data for validation. The results show that a hydrogen recirculation ratio is effectively controlled by a configurational alteration within the operational region in which the recirculation passage doesn't plugged by a sonic line.

• 한국전산유체공학회:학술대회논문집
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• 2009.11a
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• pp.93-96
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• 2009

In the cathode channel of a PEM fuel cell, the local concentration of oxygen near the gas diffusion layer (GDL) decreases in streamwise direction due to chemical reactions, which degrades the efficiency of the oxygen consumption and overall fuel cell efficiency. We numerically studied the influence of the swirling flow generated by a slanted groove mixer (SGM) on the concentration distribution of oxygen. We found that the swirling flow can increase the concentration of oxygen near the GDL, and subsequently improves the oxygen consumption rate.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.91-91
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• 2011

This paper describes development procedure of the four types of fuel cell's blowers: pressurized fuel blower, selective oxidation air blower, cathode air blower, and burner air blower. Diaphragm blowers having two heads are selected to maintain force balance when the rotating arms are moving by the driving motor. Dimensions of a diaphragm cavity is designed according to the optimal design procedure using numerical simulation and experimental measurement. Experimental apparatus is designed by considering the bower characteristics having low flow rate and high pressure. Test blower is operated by a diaphragm, which has suction and discharge port on the top of the blower. For analyzing the internal flow of the blower, three-dimensional Navier-Stokes analysis is introduced in the present study. Throughout the optimal design of the blowers, blower performance is enhanced by reducing the unbalance motion of the rotating arm and loss region in the diaphragm cavity.