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두기수,육성민,최선규,이동현,이동욱,김현규,김희탁 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
With the demands for better performance of polymer electrolyte membrane fuel cells (PEMFCs), studies on controlling the distribution of ionomers have recently gained interest. Here, we present a tunable ionomer distribution in the catalyst layer (CL) with dipropylene glycol (DPG) and water mixtures as an ionomer dispersion medium. Dynamic light scattering and molecular dynamics simulation demonstrate that, by increasing the DPG content in the dispersion, the size of the ionomer aggregates in the dispersion is exponentially reduced due to the higher affinity of DPG for Nafion ionomers. The ionomer distribution of the resulting CLs dictates the dimensional feature of the ionomer dispersion. At an intermediate DPG content, an optimal ionomer distribution is obtained in terms of power performance as a result of balanced proton and mass transports.
내부에 원형 실린더가 존재하는 기울어진 정사각형 밀폐계 내부의 자연대류 현상에 Prandtl 수가 미치는 영향
문기수(Gisu Mun),두정훈(Jeonghoon Doo),하만영(Man Yeong Ha) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
Two-dimensional numerical analysis were conducted to investigate the effect of Prandtl number on the natural convection in a cold outer tilted square enclosure with an inner hot circular cylinder for different Prandtl numbers (10-2≤Pr≤102) and Rayleigh numbers (103≤Ra≤106). The numerical solutions are obtained using immersed boundary method to configurate an inner circular cylinder based on the finite volume method. The outer square enclosure is tilted from γ=0˚ to γ=45˚ by each 5 degrees. The effect of the Prandtl number on natural convection in an enclosure is analyzed by the distribution of the streamlines, isotherms and surface-averaged Nusselt numbers.
A magnetic field-induced through-plane alignment of proton highway in proton exchange membrane
현종현,두기수,김희탁,육성민,이동현,이동욱,최선규,권지윤 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Proton exchange membranes with high proton conductivity in the through-plane direction are enormously required for fuel cells. However, isotropically distributed proton conducting channels of current membranes imposes a limitation. Herein, we present aligned proton conducting channel in membrane thickness direction, achieved by magnetic field-induced alignment of proton conductive magnetic tungsten disulfides nanowires in Nafion membrane. In contrast to a tortuous proton pathway in conventional Nafion membranes, the nanowire/Nafion composite membrane provides unidirectional pathway in thickness direction. Due to the unidirectional water channels enriched at the interface of the nanowire and Nafion, the composite membrane exhibits enhanced proton conductivity at low humidifications. The proton exchange membrane fuel cell employing the composite membrane shows significantly improved power performance.
Ultrathin Nafion-filled porous membrane for zinc/bromine redox flow batteries
김리율,김현규,두기수,최찬용,김수현,이주혁,허지윤,정호영,김희탁 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
In this work, we present a 16 μm-thick Nafion-filled porous membrane for Zn/Br redox flow batteries (ZBBs). By using molecular dynamics simulation and dynamic light scattering analysis, we rationally design Nafion solution for Nafion impregnation into a porous polypropylene (PP) separator. A void-free Nafion/PP membrane is successfully fabricated by using NMP as a solvent for the Nafion solution. The resulting membrane shows a smaller area specific resistance in comparison with 600 μm-thick, commercial SF-600 porous membrane. Due to its dense morphology, Br<sub>2</sub> diffusivity of the Nafion/PP membrane is two orders of magnitude lower than that of SF-600, resulting in a comparable Br<sub>2</sub> crossover in spite of 37.5 times smaller membrane thickness. As a result, the ZBB based on the Nafion/PP membrane exhibits a higher energy efficiency, demonstrating that ion exchange membrane can outperform the conventional porous membrane by reducing the membrane thickness with inexpensive porous substrate.
1LL-4 Interfacial engineering for membrane electrode assembly of polymer electrolyte fuel cells
김희탁,육성민,최선규,이동현,두기수,이동욱 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
가정용, 건물용 및 자동차용 연료전지의 상용화를 위한 고성능 저가 막-전극 접합체 기술에 대한 니즈가 증대되고 있다. 기존 촉매 및 멤브레인의 소재적 한계를 극복하는 한가지 방법으로서, 막 전극 접합체 내 다양한 스케일의 계면에 대한 새로운 공학적 접근이 필요하다. 본 발표에서는 멤브레인과 촉매층내 여러 계면들을 마이크론에서 나노 스케일 수준으로 구조 설계 및 제어를 함으로서 소재 적용성의 확장 및 출력 성능의 향상을 이루어 낼 수 있음을 최신 연구결과를 중심으로 소개하고자 한다.
2P-481 In-plane channel-structured catalyst layer for polymer electrolyte membrane fuel cells
이동현,조원희,육성민,최재호,최선규,두기수,이동욱,김희탁 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
In this study, we present a novel catalyst layer (CL) with in-plane flow channels to enhance mass transports in polymer electrolyte membrane fuel cells (PEMFCs). The membrane electrode assembly (MEA) with the in-plane channel-patterned CL (IC-CL) shows superior power performances in high current densities compare with un-patterned, flat CL (FCL), demonstrating significant enhancement of mass transport property by the in-plane channels carved in the CL. The performance gain is more pronounced when the channel direction is perpendicular to the flow field direction, indicating that the in-plane channels increase the utilization of the CL under rib area. The direct CL patterning technique provides a platform for the fabrication of advanced CL structures with a high structural fidelity and a rational guideline for designing high performance CLs.