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- 주제어 : Cold Start(냉시동성) (검색결과 3 건)
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연료전지 차량의 냉시동성 개선을 위한 금속 분리판 표면의 바나듐 산화물 박막 제조 및 특성 분석에 관한 연구
정혜미(Hye-Mi Jung),노정훈(Jung-Hun Noh),임세준(Se-Joon Im),이종현(Jong Hyun Lee),안병기(Byung Ki Ahn),엄석기(Sukkee Um) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.6
냉시동 성능 개선은 연료전지 차량의 고분자 전해질 연료전지 발전 모듈 및 시스템의 내구성과 신뢰성 향상의 측면에서 매우 중요하다. 이에 본 연구에서는 영하의 기후에서 연료전지 차량의 초기 구동 시 금속 분리판 표면에 형성된 바나듐 산화물 박막의 자기 발열 특성을 이용하여 신속한 온도 상승 구현이 가능한 냉시동 향상 기술을 제안하고, 실험적 방법을 통해 그 적용 가능성을 검증하였다. 졸-겔 침지 법에 의해 제조된 바나듐 산화물 박막의 특성 평가를 위해 X 선 회절, 광전자 분광, 전자 주사 현미경을 이용한 화합물 조성 및 미세구조 분석, 4-탐침법을 이용한 -20 ~ 80℃의 온도 구간에서의 온도-저항 이력 특성 분석을 각각 수행하였다. 본 실험 결과, 냉시동 조건에서 박막의 자기 발열량은 연료전지 내부의 생성 수 결빙 방지에 필요한 열 에너지를 모두 충족시킬 수 있음을 확인하였다. The enhancement of the cold-start capability of polymer electrolyte fuel cells is of great importance in terms of the durability and reliability of fuel-cell vehicles. In this study, vanadium oxide films deposited onto the flat surface of metallic bipolar plates were synthesized to investigate the feasibility of their use as an efficient self-heating source to expedite the temperature rise during startup at subzero temperatures. Samples were prepared through the dip-coating technique using the hydrolytic sol-gel route, and the chemical compositions and microstructures of the films were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. In addition, the electrical resistance hysteresis loop of the films was measured over a temperature range from -20 to 80℃ using a four-terminal technique. Experimentally, it was found that the thermal energy (Joule heating) resulting from self-heating of the films was sufficient to provide the substantial amount of energy required for thawing at subzero temperatures.
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정혜미(Jung, Hye-Mi),노정훈(Noh, Jung-Hun),임세준(Im, Se-Joon),이종현(Lee, Jong Hyun),안병기(Ahn, Byung Ki),엄석기(Um, Sukkee) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
For the successful cold starting of a fuel cell engine, either internal of external heat supply must be made to overcome the formation of ice from water below the freezing point of water. In the present study, switchable vanadium oxide compounds as variable temperature-electrical resistance materials onto the surface of flat metallic bipolar plates have been prepared by a dip-coating technique via an aqueous sol-gel method. Subsequently, the chemical composition and micro-structure of the polycrystalline solid thin films were analyzed by X-ray diffraction, X-ray fluorescence spectroscopy, and field emission scanning electron microscopy. In addition, it was carefully measured electrical resistance hysteresis loop over a temperature range from -20?C to 80?C using the four-point probe method. The experimental results revealed that the thin films was mainly composed of Karelianite V₂O₃ which acts as negative temperature coefficient materials. Also, it was found that thermal dissipation rate of the vanadium oxide thin films partially satisfy about 50% saving of the substantial amount of energy required for ice melting at -20?C. Moreover, electrical resistances of the vanadium-based materials converge on an extremely small value similar to that of pure flat metallic bipolar plates at higher temperature, i.e. T{geq}40?C. As a consequence, experimental studies proved that it is possible to apply the variable temperature-electrical resistance material based on vanadium oxides for the cold starting enhancement of a fuel cell vehicle and minimize parasitic power loss and eliminate any necessity for external equipment for heat supply in freezing conditions.
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차량용 연료전지 엔진의 금속 분리판 표면에 형성된 바나듐 기반 박막 저항체의 온도 의존성 전기적 특성 연구
정혜미(Hye-Mi Jung),노정훈(Jung-Hun Noh),엄석기(Sukkee Um) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
In the present study, vanadium oxide thin film resistors have been coated on the flat surface of metallic separators for cold start improvement of automotive fuel cell engines. The resistors have been fabricated to examine applicabilities as a source of thaw heat in subfreezing environments. We have prepared samples by a vanadium-based sol-gel route in combination with a dip-coating process and then temperature-induced electrical properties of these films have been directly measured over the temperature range -20 ~ 80℃ using 4-point probes installed in a thermo-hygrostat. It was found that the maximum value of electrical resistance of the film resistor with 0.385㎛ average thickness was about 1.65Ω at -20℃ and the corresponding temperature rise was approximately 45℃. The results show that the vanadium-based thin film resistors on metallic separators can be applied to enhance cold star capability of fuel cell vehicles by minimizing the electrical energy consumed in thaw.
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