Byeong Soo Oh

An experimental study of controlling strategies and drive forces for hydrogen fuel cell hybrid vehicles

With shrinking energy reserves and rising concerns for the environment, efficient and clean-burning fuel is needed. At this point, fuel cell vehicles promise to be far more efficient, clean and truly zero emission with the only by-product being pure water (Texas Tech University develops fuel cell powdered hybrid electric vehicle for future car challenge. Electrical engineering and mechanical engineering departments, Texas Tech University, 1998). Fuel cell hybrid vehicles (FCHVs) offer additional flexibility to enhance the fuel economy in comparison with direct hydrogen fuel cell vehicles which cost a lot (Build your own electric vehicle. p. 162). FCHV mainly consists of fuel cell and battery power system which can assist and compensate for the total system power for the instance of low fuel cell power. To operate this system effectively, the controlling and optimizing the power proportion of the each power from fuel cell system and battery system must be primarily solved. In order to seek future vehicle power systems, the feature of hydrogen FCHV and its control are discussed in this paper.

A Study to Improve PEMFC Performance by Using Electro Polishing and CrN Coating on Metal Bipolar Plate

Abstract : As an important component of a fuel cell, the bipolar plate comprises a large proportion in the fuel cell’s volume, weight and price. The bipolar plate is the most widely used; however, graphite bipolar plate is large in volume, brittle and therefore easily broken during assembling. In addition, due to its poor machinability, production costs a lot, unless mass production. Compared with the graphite bipolar plate, the metal bipolar plate has good machinability, high electric conductivity and strong mechanical strength; however, it corrodes easily and has a high contact resistance, so in order to prevent corrosion and reduce the contact resistance, the basic metal needs to be processed by use of electro polishing and coating. The water which is produced by electrochemical reactions in the fuel cell must be discharged smoothly. In this study, in order to prevent corrosion the processes of electro polishing and CrN coating were used. According to the presence or absence of these processes, the contact angles can be measured and different metal bipolar plates can be made, these plates can be used for comparing and analyzing the performance of the fuel cell.

Study on Power Characteristics in the PEMFC Parallel Channel with Baffles through Numerical Analysis

고분자 분리막 연료전지의 성능향상을 위해 분리판 유로설계연구는 필요하다. PEMFC의 성능향상에 대한, 강제대류를 이용한 interdigitated 유로가 최근에 많이 연구되고 있다. 이 논문에서는interdigitated 유로를 배플들이 있는 평행류 채널에 비슷하게 적용하였다. 상용 multiphysicsprogram인 COMSOL을 이용하여 완전차단배플인 FBB가 있는 평행류 채널에 관해 전산해석을수행하였고 3가지 변인들(배플 위치, 유체 방향, 유체 속도)이 사용 되었다. 각각 변인들의 출력은 최대출력의 80%를 고려한 0.5V에서의 결과이다. 최종적으로, 실험설계법 중 완전요인실험법을 바탕으로 여러 수준을 갖는 각 실험인자로부터 결론을 도출하였다. 실험인자들의 주효과와 상호작용 분석은 출력을 향상시키는데 가장 영향을 주는 인자를 찾는데 유용하였다.Abstract: Research on flow channel designs of the separate plates is necessary to improve thePEMFC performance. On concerning the performance improvement of PEMFC, many recentstudies have been made on the interdigitated flow channel using forced convection. In thispaper, the interdigitated flow channel is similarly applied on the parallel flow channel with abaffle or baffles. Numerical analysis is performed by using a commercial multiphysics program,which is called COMSOL, on the parallel channel with the fully blocked baffle(FBB) and thereare three variables, the position of baffle, flow direction and flow velocity. Each power of thevariables is resulted from the fixed 0.5V, the voltage from 80 percents of the maximum power.Finally, based on the full factorial designs(FFD), one of the design of experiments(DOE), each

A Design of the Cooling Channel in the Bipolar Plate of PEMFC Using Experimental Design Method

Abstract : The heat generation in PEMFC is proportional to the electrical power output. Therefore, when the fuel cell produced the maximum output, the maximum heat was generated. In order to maintain the performance of the fuel cell, thermal management is as important as pressure and humidity conditions of the reactive gas. In this study, considering the thermal management for the maximum output operation, the optimal cooling channel design specifications of bipolar plate are found for the highest cooling performance. In the current bipolar plate research, many studies focused on analyzing various factors individually but there is no more study on the interaction between design factors. In this study, the heat transfer was simulated by COMSOL Multiphysics with the main design factors which are designated shape, width and rib length. One of the experimental design methods, general full factorial design method, was used to analyze the main factor and interaction on average temperature and maximum temperature for the design specification of fuel cell bipolar plate. When analysis result shows that all of these three factors are highly important, it can confirm that the interaction occurs between the factors.