• 한국유체기계학회 논문집
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• 제9권6호
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• pp.45-53
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• 2006

Turbo-blower as an air supply system is one of the most important BOP (Balance of Plant) systems for FCV(Fuel Cell Vehicle). For generating and blowing compressed air, the motor of air blower consumes maximum 25% of net power, and fuel cell demands a clean air. In this study, turbo-blower supported by air foil bearings is introduced as the air supply system used by 80kW proton exchange membrane fuel systems. The turbo-blower is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. Analysis for confirming the stability and endurance is conducted. The rotordynamic stability was predicted using the numerical analysis of air foil bearings and it is verified through experimental works. In spite of various transient dynamic situation, the turbo-blower had stable performances. After the performance test, results are presented. The normal power of driving motor has about 1.6 kW with the 30,000 rpm operating range and the flow rate of air has maximum 160 SCFM. The test results show that the aerodymic performance and stability of turbo-blower are satisfied to the primary goals.

• 한국식품영양과학회지
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• 제25권6호
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• pp.958-962
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• 1996

해조류인 참도박으로 부터 고지혈증 개선효과를 관찰하기 위하여 고지혈증을 유발시킨 흰쥐에 메탄올 추출물을 투여하고 혈액 및 간조직에서의 지방 함량을 측정하였다. 그 결과 참도박의 메탄올 추출물의 투여는 지방조직의 무게는 정상군에는 미치지 않으나 대조군에 비해 다소 감소하는 경향을 보였다. 고지방식이로 인위적으로 고지혈증을 유발시켰을때 정상군보다 total cholesterol, LDL-cholestero의 함량이 증가되던 것이 추출물의 투여로 total cholesterol의 함량이 현저히 감소되었으나 LDL-cholesterolt의 함량은 별다른 영향이 없었다. 또한 이들의 고지방식이군 보다 total lipid, triglyceride의 함량도 감소시켰다.

• 한국수소및신에너지학회논문집
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• 제19권3호
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• pp.232-238
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• 2008

Research has been proceeded on fuel cell which is fueled by hydrogen. Polymer electrolyte membrane fuel cell (PEMFC) is promising power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, temperature dependent performance. These problems could be solved by experiment which is useful for analysis and optimization of fuel cell performance and heat management. In this paper, when hydrogen flows constantly at the stoichiometry of ${\xi}=1.6$, the performance of the fuel cell stack was increased and the voltage difference between each cells was decreased according to the increase of air stoichiometry by 2.0, 2.5, 3.0. Therefore, the control of air flow rate in the same gas channel is important to get higher performance. Purpose of this research is to expect operation temperature, flow rate, performance and mass transportation through experiment and to help actual manufacture of PEM fuel cell stack.

• 한국수소및신에너지학회논문집
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• 제29권1호
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• pp.19-24
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• 2018

Fuel cells are used to generate electricity with a reformer. In particular, methanol has various advantages among the fuels for reformer. Methanol steam reformer devices can efficiently supply hydrogen to PEM fuel cell. This study investigated the optimal operation conditions of a methanol steam reforming process. For this purpose, aspen HYSYS was used for the optimization of reforming process. The optimal operating condition could be designed by setting independent variables such as temperature, pressure and steam to carbon ratio (SCR). The optimal temperature and steam to carbon ratio were $250-270^{\circ}C$ and 1.3-1.5, respectively. It is advantageous to operate at a pressure of 15-20 barg, considering the performance of the hydrogen purifier. In addition, a heat exchange network was designed to supply heat constantly to reformer through the latent heat of steam.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.35-38
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• 2007

The comparisons between measured performance of lab-scale PEMFC and calculation were conducted to understand the detail phenomena of PEMFC for the various inlet oxygen humidity of cathode side. Experiments were performed at $65^{\circ}C$ operation temperature and different inlet humidity conditions such as 40%, 60% and 80%. We used the MEA manufactured by oneself which include $Nafion^{(R)}$ 112 membrane, Nafion solution 20%, and carbon paper(E-TEK). As a result of this experiment, cell performance was getting higher by increasing inlet humidity condition at cathode side because ion conductivity of electrolyte membrane is increased. A 3D CFD simulation model of PEMFC was developed using commercially available CFD code that is one of the STAR-CD module, es-pemfc under same operating conditions. Model calculations results were compared with experimental ones on the polarization curves and calculation results are in good agreement with the experimental ones. Local water distribution and current density inside PEMFC are discussed in detail.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.147-151
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• 2007

A serpentine channel geometry often used in a polymer electrolyte membrane fuel cell has a strong pressure gradient between adjacent channels in specific regions. The pressure gradient helps some amount of reactant gas penetrate through a gas diffusion layer(GDL). As a result, the overall serpentine flow structure is slightly different from intention of a designer. The purpose of this paper is to examine the effect of serpentine flow structure on current density distribution. By using a commercial code, STAR-CD, a numerical simulation is performed to analyze the fuel cell with relatively high aspect ratio active area. To increase the accuracy of the numerical simulation, GDL permeabilities are measured with various compression conditions. Three-dimensional flow field and current density distribution are calculated. For the verification of the numerical simulation results, water condensation process in the cathode channel is observed through a transparent bipolar plate. The result of this study shows that the region of relatively low current density corresponds to that of dropwise condensation in cathode channels.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.161-164
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• 2007

연료전지의 상용화 시점에 이르러 내구성에 대한 기술 확보가 점점 더 부각되고 있다. 현재 연료전지의 내구성을 감소시키는 1차적인 요인은 핵심부품인 촉매, 전해질막, MEA(Membrane & Electrode Assembly) 등에 의한 것이며 2차적인 요인은 운전 시스템 및 환경 등에 의해 결정되어진다. 특히, 연료전지자동차는 이동용, 가정용, 발전용에 비하여 부하변동이 극심한 조건에서 운전되기 때문에 연료전지 시스템의 내구성 확보에 많은 제어기술이 요구된다. 본 연구에서는 연료전지자동차 운전조건(Driving mode)을 부하변동 기준에 의한 고전류, 중전류, 저전류의 3가지 모드로 분류하였다. 각각의 운전조건에서 일정 cycle마다 성능곡선을 측정하여 10만 cycle 이상의 반복운전을 수행하였으며 측정된 성능곡선을 empirical equation에 적용하여 시간에 따른 overvoltage 인자에 대한 분석을 하였다. 운전시간이 증가함에 따라 고전류 모드의 경우 activation overvoltage 인자 중 current density loss가 증가하여 OCV가 급격히 감소하였으나 내구성은 저전류 모드에 비하여 높게 나타났다. 저전류 모드의 경우 고전류 모드와 상반된 결과를 보였으며 성능감소요인은 activation 및 ohmic overvoltage의 점차적인 증가에 의한 것으로 분석되었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 추계학술대회 논문집
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• pp.209-212
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• 2007

고분자전해질형 연료전지의 구조 및 구성품의 물성에 따른 성능 및 물이동 현상에 관해서 많은 연구가 진행되고 있다, 이들 연구는 대체적으로 연료 전지의 BOP(Balance of plant)를 포함하는 연료전지 시스템에 관한 연구 보다는 단위 전지 및 스택에 관한 연구에 국한되어 왔다. 연료전지의 시스템에 관한 연구들 또한 세부적인 연료전지 내부의 거동에 대해서는 고려하지 않고 있었다. 이는 연료전지의 상세 모델을 이용해 연료전지 시스템에 대해 접근하기 보다는 시스템의 성능 및 동특성에 대한 연구가 주를 이루었기 때문으로 생각된다. 본 연구에서는 연료전지 음극의 수소 배출가스를 재순환할 경우 연료전지 내부에서의 거동에 미치는 영향에 대해 2차원 정상상태 모델을 이용하여 분석해 보았다. 또한 재순환된 수소에 의한 연료전지 내부 거동의 변화 및 수소 이용율 상승 효과를 연료 전지 성능과 함께 비교해 보았다 이를 위해 2차원 정상상태 모델을 개발하였고 이를 실험을 통해 검증하는 작업을 수행하였다. 여기에 사용된 연료전지 모델은 Gore社 의 $PRIMea^{(R)}$을 사용한 연료전지의 성능을 잘 예측하고 내부의 유동 및 물이동 현상에 관한 정보를 제공한다. 이는 여러 하이브리드 자동차용 연료전지 시스템이 연료전지 배출가스의 재순환을 고려하고 있는 상황에서 연료전지 작동 조건의 최적화에 유용한 정보를 제공 할 수 있다는 의의를 가진다.

• 한국수소및신에너지학회논문집
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• 제27권4호
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• pp.341-348
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• 2016

The experiments related on structure and water electrolysis performance of HALE UAV stack were conducted in this study. Anode catalyst $IrRuO_2$ was prepared by Adam's fusion methods as 2~3 nm nano sized particles, and the cathode catalyst was used as commercial product of Premetek. The MEA (membrane electrode assembly) was manufactured by decal methods, anode and anode catalytic layers were prepared by electro-spray. HALE stack was composed of 5 multi-cells as $0.2Nm^3/hr$ hydrogen production rate with hydrogen pressure as 10 bar. The water electrolysis performance was investigated at atmospheric pressure and temperature of $55^{\circ}C$. Best performance of HALE UAV stack was recorded as cell voltage efficiency as 86%.

• 한국수소및신에너지학회논문집
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• 제24권5호
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• pp.393-400
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• 2013

The air supply system has a significant effect on the efficiency of polymer electrolyte membrane fuel cell (PEMFC) systems. The performance and efficiency of automotive PEMFC systems are greatly influenced by their air supply system configurations. This study deals with the system simulation of automotive PEMFC systems using MATLAB/Simulink framework. In this study, a low-pressure operating PEMFC system adopting blower sub-module (turbo-blower) is modeled to investigate the effects of stack operating temperature and air stoichiometry on the parasitic power and efficiency of automotive PEMFC systems. In addition, the PEMFC net system efficiency and parasitic power of air supply system are mainly compared for the two types (low-pressure operating and high-pressure operating) of automotive PEMFC systems under the same net power conditions. It is suggested that the obtained results from this system approach can be applied for establishing the novel operating strategies for FC vehicles.