• Journal of the Korean Electrochemical Society
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• v.3 no.4
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• pp.191-195
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• 2000

Electrochemical properties of the oxygen electrode in phosphoric acid fuel cell have been studied using AC impedance method as a function of applied potential, operating temperature and teflon content in the electrode. The oxygen electrode reaction in the $105wt.\%$ phosphoric acid is characterized by a parallel resistive component, $R_p$ and a capacitive component, $C_p$ with serial electrolyte resistance, $R_s$. The conductivity of the phosphoric acid is found to be 0.31-0.47 S/cm in the range of $130\;to\;190^{\circ}C$ from the measured impedance. The increase of applied potential and temperature produced the decreased RP and the increased $C_p$, which means the increase of the oxygen electrode reaction rate. The single cells with the cathode of various teflon contents were tested, and the cathode with $40wt.\%$ teflon showed good performance, which is considered to be related to an optimized impedance behavior.

• Plant Journal
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• v.18 no.1
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• pp.43-49
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• 2022

In this study, the operational characteristics of the 7.48 MW fuel cell power plant consisting of 17 units of 440 kW Phosphoric Acid Fuel Cell (PAFC) in operation since its commercial operation in December 2017 were explained and the heat recovery process of the plat using Organic Rankine Cycle (ORC)was simulated. The fuel cell system performance improvement and economic assessment were analyzed by calculating the amount of heat recovery and electric power available when connecting a 125 kW XLT Model ORC for hot water heat sources with 105℃, 40.8 t/h. The result of the study shows that integrating the 125 kW ORC to PAFC power plant would improve generating efficiency by about 0.6% through annually 851,472 kWh of electricity produced by ORC, and fuel cell and ORC integrated systems were calculated to have a 0.35% higher Internal Return Ratio and more Net Present Value of 1,249 million KRW than not installing ORC despite installation costs.

• Journal of the Korean Ceramic Society
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• v.34 no.12
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• pp.1205-1212
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• 1997

The matrices which consisted of SiC whisker, PES(polyesterasulfone) as a binder, span 80(sorbitan monooleate) as a surfactant, TPP(triphenyl phosphate) as a plasticizer and dichloromethane as a solvent, have been prepared by the various methods such as tape casting, rolling, tape cast-coating and roll-coating method. The fuel cells of single stack type using these matrices are characterized by ac impedance spectroscopy and cyclic voltammetry technique. A fuel cell using a matrix prepared by the tape cast-coating method shows the best performance of 466.34 mA/$\textrm{cm}^2$ at 0.6V because it has the lowest polarization resistance at the interface between electrodes and a matrix due to the largest three phase contact region of gases, catalyst and electrolyte.

• 한국전기화학회:학술대회논문집
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• 1999.10a
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• pp.69-69
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• 1999

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.73-77
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• 1991

200hrs operational characteristics of the single cell in phosphoric acid fuel cell was studied. The initial performance of single cells was examined as a function of PTFE content of electrode in the range of 30 to 60 wt.%. The cell with the electrode of 40wt.% PTFE was chosen for the 200hrs operation. The cell voltage decay was found to be about 0.5mV/hr for 200hrs operation. These results of cell performance were discussed as related to the internal resistance and the exchange current density of the cell.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.184-184
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• 2006

We have succeeded in the preparation of high molecular weight polybenzimidazoles by solution polycondensation of 3,3'-diaminobenzidine tetrahydrochloride with isophthalic acid, terephthalic acid, or with their derivatives using polyphosphoric acid both as solvent and as condensing agent. Also, we modified phosphoric acid into fluoroalkyl-phosphonic acids[F-PA]. The main reasons are as follows, first of all F-PAs are stronger acids than PA and alkylphosphonic acids which should promote proton hopping and transport. In addition, F-PA has weaker adsorption onto Pt which help to prevent electrocatalyst poisoning and promote higher oxygen reduction activity. The ionic conductivity of 85%-H3PO4 doped membranes show $10^{-2}\;Scm^{-1}\;to\;3{\times}10^{-2}\;Scm^{-1}\;at\;150^{\circ}C$ MEA with 2 %-added electrolyte shows slightly higher cell voltage than the others.

• 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.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.09a
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• pp.396-396
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• 1995

• Journal of Hydrogen and New Energy
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• v.27 no.2
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• pp.144-154
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• 2016

HT-PEMFC (high temperature polymer electrolyte membrane fuel cell) using PA (phosphoric acid) doped PBI (polybenzimidazole) membrane has been researched for extending the lifetime. However, the existing work on durability of HT-PEMFC focuses on identifying degradation causes of lab scale. The short life time of HT-PEMFC is still the problem for its commercialization. In this paper, an operating method to maximize life time of 5kW HT-PEMFC stack are proposed. The proposed method includes major steps such as minimization of OCV (Open Circuit Voltage) exposure, control of the proper stack temperature, and N2 purging for the stack. This long life operating method was based on the fragmentary results of degradation from previous research works. Experimentally, the 5 kW homemade HT-PEMFC stack was operated for a long time based on the proposed method and the stack successfully can operate within the desired degradation rate for the target life time.

• Journal of Energy Engineering
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• v.2 no.1
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• pp.75-82
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• 1993

A 50 ㎾ phosphoric acid fuel cell(PAFC) system using natural gas was simulated for steady state with the commercial software, ASPEN PLUS. The USER block and the FORTRAN block were prepared to simulate the cell. The changes of hydrogen yield according to the variation of several operating conditions were examined and the operating conditions to maximize hydrogen yield were obtained. The simulation results agree with the real data, which can be used to prepare the basic process data and the optimal conditions for the domestic commercial fuel cell system. H$_2$utilization rate over 50% should be maintained to achieve the efficiency of the conventional electricity generation. Energy consumption can be reduced by utilizing the heat released from the reformer and the cell which are operated at high temperatures.