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상온 작동 환경하에서의 고분자 전해질막 연료전지의 성능에 대한 실험적 연구
차도원(Dowon Cha),김보성(Bosung Kim),김용찬(Yongchan Kim) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.8
본 연구에서는 휴대용 기기에 고분자 전해질막 연료전지(PEMFC)를 적용하기 위하여 상온에서 작동 시의 성능특성을 정상상태와 동적상태에서 관찰하였다. 상대습도 및 공기 화학양론비에 따른 PEMFC성능 변화를 실험적으로 분석하였다. 또한, EIS(Electrochemical Impedance Spectroscopy)를 이용하여 내부 오믹 저항의 변화를 고찰하였다. 35℃ 조건에서 물질 전달률이 감소하여 45℃ 조건에 비해 전압 변동이 10배 정도 크게 관찰되었으며 안정적인 작동을 위해 공기의 화학양론비를 2.5 보다 크게 유지하여야 한다. 또한 낮은 상대습도는 오믹 저항을 크게 증가시키며, 이를 감소시키기 위해 상대습도 60% 이상으로 작동하여야 한다. In this study, the performance characteristics of a polymer electrolyte membrane fuel cell (PEMFC) were investigated at low operating temperatures under steady-state and dynamic conditions. The performance of the PEMFC was analyzed according to the external humidifying rate and air stoichiometry. The ohmic resistance was also investigated using EIS tests. At the operating temperature of 35 ℃, voltage fluctuation occurred to a greater degree compared to that at 45 ℃. Therefore, it was found that the air stoichiometry should be higher than 2.5 for the stable operation of the fuel cell. In addition, the relative humidity of the reactant gases should be higher than 60 to reduce the ohmic resistance.
마이크로채널이 적용된 고분자 전해질 연료전지 가스확산층의 물 이송에 대한 전산해석 연구
우아영,차도원,김보성,김용찬,Woo, Ahyoung,Cha, Dowon,Kim, Bosung,Kim, Yongchan 한국전기화학회 2013 한국전기화학회지 Vol.16 No.1
물 관리는 저온에서 작동하는 고분자전해질 연료전지의 성능에 큰 영향을 미친다. 가스확산층(gas diffusion layer, GDL)은 반응 가스를 촉매층의 반응영역으로 확산시키는 역할을 한다. 연료전지의 작동온도가 $60{\sim}80^{\circ}C$이기때문에, 고전류 밀도에서 생성된 물은 액적을 형성한다. 만약 생성된 물이 적절하게 제거되지 않는다면, GDL 내의 기공을 막게 되고 연료전지 성능이 저하된다. 본 연구에서는 플러딩 현상을 막기 위해 마이크로채널 GDL 을 제안하였다. 기존 GDL과 마이크로채널 GDL을 3차원으로 구현하여 공기 속도, 물속도, 접촉각의 변화에 따른 물의 이송을 연구하였다. 전산해석 결과를 통해 마이크로채널 GDL에서는 낮은 유동 저항으로 인해 물이 빠르게 제거되는 것으로 나타났다. 그러므로, 마이크로채널 GDL이 가스채널과 GDL 내부의 물 제거에 효율적임을 알 수 있다. The water management is one of the key issues in low operating temperature proton exchange membrane fuel cells (PEMFCs). The gas diffusion layer (GDL) allows the reactant gases flow to the reaction sites of the catalyst layer (CL). At high current density, generated water forms droplets because the normal operating temperature is $60{\sim}80^{\circ}C$. If liquid water is not evacuated properly, the pores in the GDL will be blocked and the performance will be reduced severely. In this study, the microchannel GDL was proposed to solve the flooding problem. The liquid water transport through 3-D constructed conventional GDL and microchannel GDL was analyzed varying air velocity, water velocity, and contact angle. The simulation results showed that the liquid water was evacuated rapidly through the microchannel GDL because of the lower flow resistance. Therefore, the microchannel GDL was efficient to remove liquid water in the GDL and gas channels.
Short-side-chain을 가지는 고분자 전해질막 연료전지의 수치해석적 연구
양원석(Wonseok Yang),차도원(Dowon Cha),윤성호(Sungho Yun),임준엽(Junyub Lim),김용찬(Yongchan Kim) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
Polymer electrolyte membrane (PEM) fuel cell with short-side-chain (SSC) membrane has been widely studied due to its higher proton conductivity, crystallinity, and glass transition temperature. However, most researches on SSC membrane are confined into experimental study, and more specific analysis should be conducted through numerical study. In this study, SSC membrane PEM fuel cell simulations were conducted with a steady-state three-dimensional model. The proton conductivity of the SSC membrane was expressed as a function of temperature and water uptake based on the existing measurements. To validate the SSC model, the simulation results were compared with the experimental data in the literature. The simulation results were consistent with the experimental data within ±7.1% deviation. The cell performance increased with increasing operating temperature and the optimal relative humidity of reactant gases was 75%.
저습도 조건에서 고분자 전해질막 종류에 따른 연료전지의 성능 동특성에 관한 해석적 연구
양원석(Wonseok Yang),차도원(Dowon Cha),조원희(Wonhee Cho),김용찬(Yongchan Kim) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.-
In automotive applications of polymer electrolyte membrane (PEM) fuel cells, operating without an external humidifier is beneficial to the overall efficiency, since an auxiliary humidifier can diminish volume and weight power density. Without the humidifier, the electrolyte membrane is self-humidified by internal water generated from electrochemical reaction, and the amount of water for membrane hydration is very small. Therefore, the performance of the PEM fuel cell depends largely on the proton conductivity of electrolyte membranes under low humidity condition. In this study, three-dimensional simulation is conducted to compare two types of electrolyte membrane of short-side-chain (SSC) and long-side-chain (LSC). The transient characteristics of voltage and proton conductivity are investigated to study on automotive application of PEM fuel cell where load change occurs frequently. The SSC membrane shows better performance than the LSC membrane during the load change in low humidity condition, since the proton conductivity in the SSC membrane has much higher than that in LSC membrane. In addition, the voltage in SSC membrane largely increases after undershoot, and the increase in the voltage in the LSC membrane is very small. This is because the increment of the proton conductivity in the SSC membrane is much larger than that in the LSC membrane.