• Journal of the Korean Electrochemical Society
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• v.27 no.1
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• pp.32-39
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• 2024

The key components of a Phosphoric acid fuel cell (PAFC) are an electrode catalyst, an electrolyte matrix and a gas diffusion layer (GDL). In this study, we introduced a microporous layer on the GDL of PAFC to enhance liquid electrolyte management and overall electrochemical performance of PAFC. MPL is primarily used in polymer electrolyte membrane fuel cells to serve as an intermediate buffer layer, effectively managing water within the electrode and reducing contact resistance. In this study, electrodes were fabricated using GDLs with and without MPL to examine the influence of MPL on the performance of PAFC. Internal resistance and polarization curves of the unit cell were measured and compared to each other to assess the impact of MPL on PAFC electrode performance. As the results, the application of MPL improved power density from 170.2 to 192.1 mW/cm². MPL effectively managed electrolyte and water within the matrix and electrode, enhancing stability. Furthermore, the application of MPL reduced internal resistance in the electrode, resulting in sustained and stable performance even during long-term operation.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.522-532
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• 2020

Conductive polymer composites with high electrical and mechanical properties are in demand for bipolar plates of phosphoric acid fuel cells (PAFC). In this study, composites based on natural graphite/fluorinated ethylene propylene (FEP) and different ratios of carbon black are mixed and hot formed into bars. The overall content of natural graphite is replaced by carbon black (0.2 wt% to 3.0 wt%). It is found that the addition of carbon black reduces electrical resistivity and density. The density of composite materials added with carbon black 3.0 wt% is 2.168 g/㎤, which is 0.017 g/㎤ less than that of non-additive composites. In-plane electrical resistivity is 7.68 μΩm and through-plane electrical resistivity is 27.66 μΩm. Compared with non-additive composites, in-plane electrical resistivity decreases by 95.7 % and through-plane decreases by 95.9 %. Also, the bending strength is about 30 % improved when carbon black is added at 2.0 wt% compared to non-additive cases. The decrease of electrical resistivity of composites is estimated to stem from the carbon black, which is a conductive material located between melted FEP and acts a path for electrons; the increasing mechanical properties are estimated to result from carbon black filling up pores in the composites.

• Journal of Hydrogen and New Energy
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• v.29 no.5
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• pp.442-449
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• 2018

Research on High temperature polymer electrolyte fuel cell (HT-PEMFC) has actively been conducted all over the world. Since the HT-PEMFC can be operated at a high temperature of $120-180^{\circ}C$ using phosphoric acid-doped polybenzimidazole (PBI) electrolyte membrane, it has considerable advantages over conventional PEMFC in terms of operating conditions and system efficiency. However, If the thermal distribution is not uniform in the stack unit, degradation due to local reaction and deterioration of lifetime are difficult to prevent. The thin plate separator reduces the volume of the fuel cell stack and improves heat transfer, consequently, enhancing the cooling effect. In this paper, a large area flow field of thin plate separator for HT-PEMFC is designed and sub-stack is fabricated. We have studied stack performance evaluation under various operating conditions and it has been verified that the proposed design can achieve acceptable stack performance at a wide operating range.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.7
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• pp.558-565
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• 2008

Solid oxide fuel cell(SOFC) has a higher fuel flexibility than low temperature fuel cells, such as polymer electrolyte fuel cell(PEMFC) and phosphoric acid fuel cell(PAFC). SOFCs also use CO and $CH_4$ as a fuel, because SOFCs are hot enough to allow the CH4 steam reformation(SR) reaction and water-gas shift(WGS) reaction occur within the SOFC stack itself. Diesel is a good candidate for SOFC system fuel because diesel reformate gas include a higher degree of CO and $CH_4$ concentration than other hydrocarbon(methane, butane, etc.) reformate gas. Selection of catalyst for autothermalr reforming of diesel was performed in this paper, and characteristics of reforming performance between packed-bed and microchannel catalyst are compared for SOFC system. The mesh-typed microchannel catalyst also investigated for diesel ATR operation for 1kW-class SOFC system. 1kW-class diesel microchannel ATR was continuously operated about 30 hours and its reforming efficiency was achieved nearly 55%.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.4
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• pp.569-579
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• 1994

A 5.9kW phosphoric acid fuel cell(PAFC) power generation system that consists of a reformer, a stack, heat exchangers, an automatic data acquisition and control system was designed, fabricated and analyzed. This system which was firstly fabricated in Korea has been operated for 140 hours with an electricity generation of 684kWh. The PAFC generate electricity in the range of 38-52V and 50-160A and has a typical I-V characteristics of a fuel cell. Using the reformed fuel, the system performance is decreased in some degree due to CO content, compared to using the simulated fuel. At steady state operation condition, the total efficency of this system was 45.2%.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.200-207
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• 1993

A methanol reformer was designed and fabricated using a CuO-ZnO low temperature shift catalyst, and its operation characteristics have been studied for the phosphoric acid fuel cell (PAFC) power generation system. The type of reactor was annular Methanol was consumed both for heating and for reforming fuel. Contents of carbon monoxide produced from the reformer increased as the reaction temperatures increased, but decreased as the mole ratios of water to methanol(H$_2$O/CH$_3$OH) increased. At steady state operating conditional, temperature profile of the catalytic reactor of the reformer was well coincide with the model equation, and it took 50 minutes from start to the rated condition of the reformer. When the system was operated at 4/4 and 1/4 of load, thermal efficiencies of the system were 72.3% and 77%, respectively. When the PAFC system was operated with reformed gas in the range of 62 V-37.6 V and 0-147 A, the trend of I-V curve showed a typical fuel tell characteristic. At steady state condition, the flow rates of reforming and combustion methanol were 88.1 mol/h and 50.1 mol/h, respectively.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.187-193
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• 1993

Porous matrices to contain and support phosphoric acid were prepared with PTFE as binder and SiC whisker or SiC powders of various particle size for phosphoric acid fuel cell(PAFC). Among the matrix characteristics the most important factors in stack performances were thought to be the bubble pressure and electrolyte wettability And then matrix was constructed to have pore size smaller than that of electrode. The bubble pressures and wettabilities of matrices manufactured with various size of SiC and different PTFE contents were investigated and related with the porosities measured by porosimeter, and then the optimum manufacturing condition of matrix for PAFC was determined.

• Journal of Hydrogen and New Energy
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• v.24 no.1
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• pp.50-60
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• 2013

High temperature proton exchange membrane fuel cells (PEMFCs) using phosphoric acid (PA) doped polybenzimidazole (PBI) membranes have been concentrated as one of solutions to the limits with traditional low temperature PEMFCs. However, the amount of reported experimental data is not enough to catch the operational characteristics correlated with cell performance and durability. In this study, design of experiments (DOE) based operational optimization method for high temperature PEMFCs has been proposed. Response surface method (RSM) is very useful to effectively analyze target system's characteristics and to optimize operating conditions for a short time. Thus RSM using central composite design (CCD) as one of methodologies for design of experiments (DOE) was adopted. For this work, the statistic models which predict the performance and degradation rate with respect to the operating conditions have been developed. The developed performance and degradation models exhibit a good agreement with experimental data. Compared to the existing arbitrary operation, the expected cell lifetime and average cell performance during whole operation could be improved by optimizing operating conditions. Furthermore, the proposed optimization method could find different new optimal solutions for operating conditions if the target lifetime of the fuel cell system is changed. It is expected that the proposed method is very useful to find optimal operating conditions and enhance performance and durability for many other types of fuel cell systems.

• 한국전기화학회:학술대회논문집
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• 1998.10a
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• pp.93-93
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• 1998

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.05a
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• pp.87-87
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• 1998