• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.585-591
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• 2011

This study has focused on the development of high performance membrane-electrode assemblies (MEAs) fabricated by decal method for proton exchange membrane fuel cell (PEMFC). To study the effect of ionomer contents on performance, we fabricated MEAs with several electrodes which were prepared by varying the quantity of ionomer from 20 wt.% to 45 wt.% in catalyst layer. The MEA performance was obtained through single cell test. The MEA prepared from electrode with 25wt.% of ionomer showed the best performance. We evaluated the surface area and pore volume of electrode with BET. We found that the surface area and pore volume in electrode decreased rapidly at the electrode with 40wt.% of ionomer in catalyst layer. MEA was fabricated by roll laminator machine and the roll laminating conditions for the preparation of MEA, such as laminating press, temperature and speed, were optimized. The MEA performance is not affected by laminating temperature and speed, but roll laminating press have a great effect on MEA performance.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.660-669
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• 2016

A fluorinated-sulfonated, hydrophobic-hydrophilic copolymer was planed subsequently synthesized using typical nucleophilic substitution polycondensation reaction. A novel AB and ABA (or BAB) block copolymers were synthesized using sBCPSBP (sulfonated 4,4'-bis[4-chlorophenyl)sulfonyl]-1,1'-biphenyl), DHN (1,5-dihydroxynaphthalene), DFBP (decafluorobiphenyl) and HFIP (4,4'-hexafluoroisopropylidenediphenol). All block copolymers were easily cast and made into clear films. The structure and synthesized copolymers and corresponding membranes were analyzed using GPC (gel permeation chromatography), $^1H$-NMR ($^1H$ nuclear magnetic resonance) and FT-IR (Fourier transform infrared). TGA (Thermogravimetric analysis) and DSC (differential scanning calorimetry) analysis showed that the prepared membranes were thermally stable, so that elevated temperature fuel cell operation would be possible. Hydrophobic/hydrophilic phase separation and clear ionic aggregate block morpology was confirmed in both triblock and diblock copolymer in AFM (atomic force microscopy), which may be highly related to their proton transport ability. A sulfonated BAB triblock copolymer membrane with an ion-exchange capacity (IEC) of 0.6 meq/g has a maximum ion conductivity of 40.3 mS/cm at $90^{\circ}C$ and 100% relative humidity.

• Membrane and Water Treatment
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• 제6권1호
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• pp.53-75
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• 2015

This paper provides an overview of the role of membranes in bioelectrochemical systems (BESs). Bioelectrochemical systems harvest clean energy from waste organic sources by employing indigenous exoelectrogenic bacteria. This energy is extracted in the form of bioelectricity or valuable biofuels such as ethanol, methane, hydrogen, and hydrogen peroxide. Various types of membranes were applied in these systems, the most common membrane being the cation exchange membrane. In this paper, we discuss three major bioelectrochemical technology research areas namely microbial fuel cells (MFCs), microbial electrolysis cells (MECs) and microbial desalination cells (MDCs). The operation principles of these BESs, role of membranes in these systems and various factors that affect their performance and economics are discussed in detail. Among the three technologies, the MFCs may be functional with or without membranes as separators while the MECs and MDCs require membrane separators. The preliminary economic analysis shows that the capital and operational costs for BESs will significantly decrease in the future due mainly to differences in membrane costs. Currently, MECs appear to be cost-competitive and energy-yielding technology followed by MFCs. Future research endeavors should focus on maximizing the process benefits while simultaneously minimizing the membrane costs related to fouling, maintenance and replacement.

• 한국수소및신에너지학회논문집
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• 제27권2호
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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.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.42-48
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• 2016

This study presents an experiment investigation on natural convection heat transfer of air-cooling Proton exchange membrane fuel cells (PEMFCs) in a enclosure system for unmanned aerial vehicles (UAVs). Considered are replacing fuel cell stack with Aluminum block for heat generating inside a enclosure chamber. The volume ratio of fuel cell stack and chamber for simulation to the actual size of aerial vehicle is 1 to 15. The parameters considered for experimental study are the environmental temperature range from $25^{\circ}C$ to $-60^{\circ}C$ and the block heat input of 10 W, 20 W and 30 W. Effect of the thermal conductivity of the block and power level on heat transfer in the chamber are investigated. Experimental results illustrate the temperature rise at various locations inside the chamber as dependent upon heat input of fuel cell stack and environmental temperature. From the results, dimensionless correlation in natural convection was proposed with Nusselt number and Rayleigh number for designing air-cooling PEMFC powered high altitude long endurance (HALE) UAV.

• 한국수소및신에너지학회논문집
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• 제24권1호
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• pp.70-75
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• 2013

It has fabricated membrane electrode assemblies (MEA) for proton exchange membrane fuel cell by hot-pressing method. The hot-pressing was used for the fabrication of MEA which is composed of commercial platinum electrode on carbon paper. The performance of MEA was studied with different fabrication conditions of temperature, pressure and torque. As the temperature increased, the performance of MEA was increased. and started to decrease l after arrived at the maximum performance of MEA. This is related with good contact between electrode and polymer electrolyte membrane at high temperature and microstructural change at much higher temperature. Similarly, as the pressure increased, the performance of the MEA increased up to highest values and start to decrease. According to the our results, the maximal performance of the MEA was at the temperature of $140^{\circ}C$ and the pressure of $1.5{\times}10^3$ kPa. The optimal torque to assemble the single stack was 3.2 N m.

• Advances in Energy Research
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• 제8권4호
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• pp.203-211
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• 2022

The aim of this paper is to analyze the performance of commercial fuel cell (rated capacity 1000W) with the help of resistive load and output power variation with change in H₂ flow rate and calculate the maximum power point (MPP) of the proton exchange membrane (PEM) while changing AC and DC load respectively. The factors influencing the output power of a fuel cell are hydrogen flow rate, cell temperature, and membrane water content. The results show that when the H₂ flow rate is changed from 11, 13, and 15 Lpm, MPP is increased from lower to higher flow rate. The power of the fuel cell is increased at the rate of 29% by increasing the flow rate from 11 to 15 lpm. This study will allow small-scale industries and residential buildings (in remote or inaccessible areas) to characterize the performance of PEMFC. Furthermore, fuel cell helps in reducing emission in the environment compared to fossil fuels. Also, fuel cells are ecofriendly as well as cost effective and can be the best alternative way to convert energy.

• 한국표면공학회지
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• 제56권6호
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• pp.427-436
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• 2023

In the industry, it is recognized that human activities significantly lead to a large amount of wastewater, mainly due to the increased use of water and energy. As a result, the growing field of wastewater resource technology is getting more attention. The common technology for hydrogen production, water electrolysis, requires purified water, leading to the need for desalination and reprocessing. However, producing hydrogen directly from wastewater could be a more cost-effective option compared to traditional methods. To achieve this, a series of first-principle computational simulations were conducted to assess how waste nutrient ions affect standard electrolysis catalysts. This study focused on understanding the adsorption mechanisms of byproducts related to the oxygen evolution reaction (OER) in anion exchange membrane (AEM) electrolysis, using Co₃O₄ as a typical non-precious metal catalyst. At the same time, efforts were made to develop a comprehensive free energy prediction model for more accurate predictions of OER results.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.205-215
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• 2024

This study introduced a direct contact heat exchanger to enhance the efficiency of polymer electrolyte membrane fuel cells (PEMFCs) systems. According to previous research, 28% of the operating costs of fuel cell systems are attributed to heat exchanger devices, prompting the design of a direct contact heat exchanger to address this issue. Optimal configurations were determined through computational fluid dynamics analysis and experimental device fabrication, and the enhanced heat exchange performance of the heat exchanger was experimentally confirmed. Through this, the contribution of the direct contact heat exchanger to the heat management and efficiency enhancement of PEMFC systems was established.

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2657-2662
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• 2013

Multiwalled carbon nanotube (MWCNT)-g-poly (aniline-co-2,5-diaminobenzenesulfonic acid) (DABSA) reinforced Nafion$^{(R)}$ nanocomposite membranes were prepared and characterized for direct methanol fuel cells (DMFCs). The nanocomposite membranes with approximately $90{\mu}m$ thickness were prepared by the water assisted solution casting method. To evaluate the properties of nanocomposite membranes for DMFC applications, the nanocomposite membranes were characterized by methanol and water uptake, thermal stability, and ion exchange capacity (IEC). Furthermore, oxidative stability measurements in terms of the hydrogen peroxide decomposition rate that represent the oxidative stability of the membranes were examined. The methanol uptake values of the nanocomposite membranes were dramatically decreased compared to the cast Nafion$^{(R)}$ membranes. The IEC values of the nanocomposite membranes were increased about 30% compared to the cast Nafion$^{(R)}$ membrane.