• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.323-329
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• 2012

A thermal management system of a proton exchange membrane fuel cell is taken charge of controlling the temperature of fuel cell stack by rejection of electrochemically reacted heat. Two major components of thermal management system are heat exchanger and pump which determines required amount of heat. Since the performance and durability of PEMFC system is sensitive to the operating temperature and temperature distribution inside the stack, it is necessary to control the thermal management system properly under guidance of operating strategy. The control study of the thermal management system is able to be boosted up with hardware in the loop simulation which directly connects the plant simulation with real hardware components. In this study, the plant simulation of fuel cell stack has been developed and the simulation model is connected with virtual data acquisition system. And HIL simulator has been developed to control the coolant supply system for the study of PEMFC thermal management system. The virtual data acquisition system and the HIL simulator are developed under LabVIEWTM Platform and the Simulation interface toolkit integrates the fuel cell plant simulator with the virtual DAQ display and HIL simulator.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.242-245
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• 2007

Stack effects occurred in the stairwell, an important evacuation means of the high-rise building, give a big impact on stairwell pressure difference distribution and it could obstruct evacuation from the building, so should be controlled within proper range. Computer simulation was conducted with CONTAMW2.4 to find the solution of stack effects of the high-rise building. It was able to solve the imbalance pressure difference with a pressurization and a depressurization supplied by fans on higher and lower parts of the stairwell.

• Journal of the Korean Institute of Gas
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• v.4 no.1 s.9
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• pp.40-48
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• 2000

A fuel cell is an electrochemical device continuously converting the chemical energy in a fuel and an oxidant to electrical energy by going through an essentially invariant electrode-electrolyte system. Phosphoric acid fuel cell employs concentrated phosphoric acid as an electrolyte. The cell stack in the fuel cell, which is the most important part of the fuel cell system, is made up of anode where oxidation of the fuel occurs cathode where reduction of the oxidant occurs; and electrolyte, to separate the anode and cathode and to conduct the ions between them. Fuel cell performance is associated with many parameters such as operating and design parameters associated with the system configuration. In order to understand the design concepts of the phosphoric fuel cell and predict it's performance, we have here introduced the simulation of the fuel-cell stack which is core component and modeled in a 3-dimensional grid space. The concentration of reactants and products, and the temperature distributions according to the flow rates of an oxidant are computed by the help of a computational fluid dynamic code, i.e., FLUENT.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.2
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• pp.329-340
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• 1995

Basic refrigeration effect and efficiency of a thermoacoustic refrigerator is studied. The refrigerator model for numerical simulation is composed of half wavelength resonator and appropriate stack of plate. Theoretical model for thermoacoustic refrigeration suggested by Swift et. al is adapted for numerical calculation. The model contains arbitrary viscosity effect of the gas filled in the resonator. The wave equation is integrated by using 4-th order Runge-Kutta algorithm to give pressure distribution along the stack of plate. Heat flux and COP are also calculated based on the energy flux equation. By analyzing the numerical simulation results, optimum values of design parameters for thermoacoustic refrigerator are obtained.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1179-1180
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• 2006

This paper is aimed at presenting a computational model of a proton exchange membrane (PEM) fuel cell stack. The proposed simulation model is simple and at the same time includes all the important characteristics of a fuel cell stack. Close agreement between the simulation, manufacturer and experimental results confirm the validity and usefulness of the proposed FC model. Also, we propose the variable PI control method which has the best of follow efficiency than the PI control method. we confirm a reduced ripple and improved follow efficiencies when the system is applied the DC-DC converter, by simulation using PSIM.

• Clean Technology
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• v.7 no.4
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• pp.243-250
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• 2001

The fuel cell has been continuously studied as environment-compatible alternative energy technology. Lately the basic techniques about stacking and widening are considered to be important for practical use. Although phosphoric acid fuel cell (PAFC) is the most progressed one in the fuel cell technologies, few studies about temperature profile of the stack which can be the basic data for the fuel cell design have been reported yet. In this study, the temperature profile of PAFC stack was simulated. The temperature profiles of stack were obtained at various operating conditions, and when stack is operated the proper position to measure the temperature could be predicted. Also we can propose more effective cooling design. The standard deviation of the temperature profile of the proposed design was is about 50% smaller.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.99-102
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• 2006

Optimal flow-field design of bipolar-plates for a commercial class PEM(polymer electrolyte membrane) fuel cell stack was carried out on the basis of three-dimensional computational fluid dynamics(CFD) simulation. A three-dimensional CFD model originally developed by Shimpalee et al., has been utilized for performing large-scale simulation of a single fuel cell consisting of bipolar-plates gas diffusion layers, and a membrane-electrode-assembly(MEA). The CFD model is able to predict the current density, pressure drops, gas velocities, vapor and liquid water contents, temperature distributions, etc. inside a single fuel cell. Depending on simulation results from the CFD modeling of a PEM fuel cell, several flow-fields of bipolar-plates were designed and verified. The final design of the bipolar-plate has been chosen from the simulations and experimental tests and showed the best performance as expected from the simulation results under a normal operating condition. Thus, the CFD simulation approach to design the optimal flow-field of the bipolar-plates was successful. The final design was adopted as the best flow-field to build a commercial scale PEM fuel cell stack, the performance of which shows about 42% higher than that of the older bipolar-plate design.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.155-161
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• 2005

In this paper, commercial CFD program FLUENT v5.3 is used for simulation of MCFC stack. Besides using conservation equations included in FLUENT by default, mass change, mole fraction change and heat added or removed due to electrochemical reactions and water gas shift reaction are considered by adding several equations using user defined function. The stacks calculated are 6 and 25 kW class coflow stack which are composed of 20 and 40 unit cells respectively. Simulation results showed that pressure drop took place in the direction of gas flow, and the pressure drop of cathode side is more larger than that of anode side. And the velocity of cathode gas decreased along with the gas flow direction, but the velocity of anode gas increased because of the mass and volume changes by the chemical reactions in each electrodes. Simulated temperature profile of the stack tended to increase along with the gas flow direction and it showed similar results with the experimental data. Water gas shift reaction was endothermic at the gas inlet side but it was exothermic at the outlet side of electrode respectively. Therefore water gas shift reaction played a role in increasing temperature difference between inlet and outlet side of stack. This results suggests that the simulation of large scale commercial stacks need to consider water gas shift reaction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.4
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• pp.145-152
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• 2016

For a general office building having a center core, the distinction between the outer wall and the compartment should be clear, and it should be set at a stack effect pressure distribution acting on the respective compartment by a relative area ratio of the respective leak compartment. In the case of office buildings with an independent core for core there, some blocks of shares and exterior pressure distribution in buildings and office buildings typically have different characteristics. Therefore, if the stack effect reduction measures, designed on the basis of a general office building are applied to a stand-alone building, the core of the building should reflect the unique pressure distribution characteristics. This study, performed as part of the object corresponding to the flat plan of the building in the diversification trend, analyzed the stack effect that actually occurs in an office building having the properties intended for stand-core construction, and thus on the basis of and tested by the method of using a conventional stack effect reduction measures. Reviewed in the study, an independent cored office building that does not have the air flow path through the specific space with respect to the center core type office building has a feature, and the variation in characteristics of the pressure distribution inside the building according to this air flow path stack effect was reduced by a variety of measures that should be applied to determine the application.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2007.11a
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• pp.193-198
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• 2007

KIER has been developing the anode supported flat tubular SOFC stack for the intermediate temperature $(700{\sim}800^{\circ}C)$ operation. for this purpose, we have first fabricated anode supported flat tubular cells by the optimization between the current collecting method and the induction brazing process. After that we designed the compact fuel & air manifold by adopting the simulation technique to uniformly supply fuel & air gas and the unique seal & insulation method to make the more compact stack. For making stack, the prepared anode-supported flat tubular cells with effective electrode area of $90cm^2$ of connected in series with 12 modules, in which one module consists of two cells connected in parallel. The performance of stack in 3 % humidified $H_2$ and air at $800^{\circ}C$ shows maximum power of 507 W. Through these experiments, we obtained basic & advanced technology of the anode-supported flat tubular cell and established the proprietary concept of the anode-supported flat tubular SOFC stack in KIER.