• Transactions of the Korean hydrogen and new energy society
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• v.31 no.1
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• pp.49-56
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• 2020

Epoxy/carbon composite was used to prepare a bipolar plate for polymer electrolyte membrane fuel cell (PEMFC). Phenol novolac-type epoxy and diglycidyl ether of bisphenol A (DGEBA)-type epoxy mixture was used as a matrix and graphite powder, carbon fiber (CF) and graphite fiber (GF) were used as carbon materials. In order to improve the mechanical properties of the bipolar plate, surface-modified CF was incorporated into the epoxy/carbon composite. To determine the cure temperature of the epoxy mixture, differential scanning calorimetry (DSC) analysis was performed and the data were introduced to Kissinger equation in order to get reaction activation energy and pre-exponential factor. Tensile and flexural strength was obtained by using universal testing machine (UTM). The surface morphology of the fractured specimen and the interfacial morphology between epoxy matrix and CF or GF were observed by a scanning electron microscopy (SEM).

• Journal of Energy Engineering
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• v.23 no.3
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• pp.132-145
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• 2014

There is a general agreement that performance of hydrogen fuel cell vehicle(FCV) with respect to cold start, packaging, acceleration, refueling time and range has progressed to the point where vehicles that could be brought to market in 2015_2020 will satisfy customer expectations. However cost, durability and the lack of refueling infrastructure remain significant barriers. Cost have been dramatically reduced and durability has been enhanced over the past decade, yet are still about twice what appears to be needed sustainable market success. Advanced Technologies for the commercialization of hydrogen FCV were reviewed.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.3
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• pp.222-230
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• 2004

In this paper, a 3㎾ fuel cell generation system with an active fuel cell simulator has been proposed. The developed fuel cell simulator generates the actual voltage and current output characteristics of the Polymer Electrolyte Membrane Fuel Cell (PEMFC), so that the overall performance and the dynamics of the proposed system could be effectively examined and tested. In This paper, at first, the system configuration and operational principle of the developed fuel cell simulator has been investigated and the design process of the fuel cell generation system is explained in detail. In addition, the validity of the proposed system has been verified lly the informative simulation and experimental result

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.295-300
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• 2010

Metal bipolar plate applied to Polymer Electrolyte Membrane Fuel Cell is getting most attractive due to their good feasibility of mass production and low cost. But it is one of the immediate causes of performance decline because it is difficult to reduce channel pitch of metal bipolar plate. In this study, mesh was inserted in between bipolar plate and GDL to obtain uniform contact pressure without reducing channel pitch. The section measuring and performance test were carried out to confirm the mesh structure distributes contact pressure equally in reacting area. The performance of 3 type mesh structures developed in this study were higher than the normal cell at all over the current range. Especially, it showed that the mesh cell performance was increased and pressure drop was decreased with diminishing mesh gap size. The Mesh structure was more sensitive to humidification and contact pressure change than the normal cell.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.307-312
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• 2010

Poly (ether sulfone)s with Bisphenol-TP and Bisphenol-AF were prepared with Bisphenol-TP <4,4-dihydroxy tetraphenyl methane>, 4-Fluorophenyl sulfone, and Bisphenol-AF <4,4-(hexafluoroisopropylidene) diphenol> using Potassium carbonate in Sulfolane at $210^{\circ}C$. Sulfonated PBTP-AF were obtained by reaction of Chlorosulfuric acid with copolymers. A series of copolymers were studied by $^1H$-NMR spectroscopy, Differential Scanning Calorimeter (DSC), and Thermo Gravimetric Analysis (TGA). Sorption experiments were conducted to observe the interaction of polymers with water and methanol.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.10
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• pp.1031-1037
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• 2010

This paper proposed lightweight aluminum bipolar plates as an alternative for conventional graphite bipolar plates in fuel cell systems used as a power source for small reconnaissance UAVs. Since bipolar plates occupy more than 80% of the total weight of the fuel cell system, lightweight aluminum bipolar plates can improve the overall payload and flight time of the fuel cell UAV. The aluminum and graphite bipolar plates were fabricated to compare the performance of each of them. A 15% higher performance per weight was obtained from aluminum bipolar plates than the graphite bipolar plates. Also, the performance of a single cell using aluminum bipolar plates was evaluated under various operating conditions.

• Journal of the Korean Applied Science and Technology
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• v.28 no.1
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• pp.57-63
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• 2011

Polymer electrolyte membrane fuel cell (PEMFC) performance degrades when hydrogen sulfide ($H_2S$) is present in the fuel hydrogen gas; this is referred to as $H_2S$ poisoning. This paper reveals $H_2S$ poisoning on PEMFC by measuring electrical performance of single cell FC under various operating conditions. The severity of $H_2S$ poisoning depended on $H_2S$ concentration under best operating conditions($65^{\circ}C$ of cell temperature and 100% of anode humidification). $H_2S$ adsorption occured on the surface of catalyst layer on MEA, but not on the gas diffusion layer(GDL) by analyzing SEM/EDX data. In addition, MEA poisoning by $H_2S$ was cumulative but reversible. After poisoning for less than 150 min, performance of PEMFC was recovered up to 80% by just inert nitrogen gas purging.

• Journal of Power Electronics
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• v.11 no.2
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• pp.202-210
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• 2011

Polymer electrolyte membrane (PEM) fuel cell is one of the popular renewable energy sources and widely used in commercial medium power areas from portable electronic devices to electric vehicles. In addition, the increased integration of the PEM fuel cell with power electronics, dynamic loads, and control systems requires accurate electrical models and simulation methods to emulate their electrical behaviors. Advancement in parallel computation techniques, various real-time simulation tools, and smart power hardware have allowed the prototyping of novel apparatus to be investigated in a virtual system under a wide range of realistic conditions repeatedly, safely, and economically. This paper builds up advancements of optimized model constructions for a fuel cell stack system on a real-time simulator in the view points of improving dynamic model accuracy and boosting computation speed. In addition, several considerations for a power hardware-in-the-loop (PHIL) simulation are provided to electrically emulate the PEM fuel cell stack system with power facilities. The effectiveness of the proposed PHIL simulation method developed on Opal RT's RT-Lab Matlab/Simulink based real-time engineering simulator and a programmable power supply is verified using experimental results of the proposed PHIL simulation system with a Ballard Nexa fuel cell stack.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.10
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• pp.955-965
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• 2014

Transport phenomena of reactant and product are directly linked to intrinsic inhomogeneous random configurations of catalyst layer (CL) that consist of ionomer, carbon-supported catalyst (Pt/C), and pores. Hence, electrochemically active surface area (ECSA) of Pt/C is dominated by geometrical morphology of mass transport path. Undoubtedly these ECSAs are key factor of total fuel cell efficiency. In this study, non-deterministic micro-scale CLs were randomly generated by Monte Carlo method and implemented with the percolation process. To ensure valid inference about Pt/C catalyst utilization, 600 samples were chosen as the number of necessary samples with 95% confidence level. Statistic results of 600 samples generated under particular condition (20vol% Pt/C, 30vol% ionomer, 50vol% pore, and 20nm particle diameter) reveal only 18.2%~81.0% of Pt/C can construct ECSAs with mean value of 53.8%. This study indicates that the catalyst utilization in fuel cell CLs cannot be identical notwithstanding the same design condition.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.341-344
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• 2009

In this paper, protective function evaluation was conducted to determine the performance and safety of a power conditioning system(PCS) for 1kW residential fuel cell system. It is essential to have a power quality, grid-connection and safety of PCS. Even though it is under 500ms by KGS-A410 standard, it is shown a rapid response time of 25ms from input under-voltage test. In terms of output over/under-voltage test, it is shown 29.15 and 79.4ms. Especially using anti-islanding test, it is shown all times under 100ms for combination cases of real and reactive power. We confirmed a rapid response characteristics and safety of PCS. The results of this evaluation are being used to develop a new test protocols of PCS.