• 대한기계학회논문집B
• /
• 제33권1호
• /
• pp.60-68
• /
• 2009

The steam reformer for hydrogen production from methane is studied by a numerical method. Langmuir- Hinshelwood model is incorporated for catalytic surface reactions, and the pseudo-homogeneous model is used to take into account local equilibrium phenomena between a catalyst and bulk gas. Dominant chemical reactions are Steam Reforming (SR) reaction, Water-Gas Shift (WGS) reaction, and Direct Steam Reforming (DSR) reaction. The numerical results are validated with experimental results at the same operating conditions. Using the validated code, parametric study has been numerically performed in view of the steam reformer performance. As increasing a wall temperature, the fuel conversion increases due to the high heat transfer rate. When Steam to Carbon Ratio (SCR) increases, the concentration of carbon monoxide decreases since WGS reaction becomes more active. When increasing Gas Hourly Space Velocity (GHSV), the fuel conversion decreases due to the heat transfer limitation and the low residence time. The reactor shape effects are also investigated. The length and radius of cylindrical reactors are changed at the same catalyst volume. The longer steam reformer is, the better steam reformer performs. However, system energy efficiency decreases due to the large pressure drop.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
• /
• pp.1000-1001
• /
• 2006

In this paper, an DC/DC converter system has been proposed, which is suitable for fuel cell based power generation systems. The proposed converter system has outstanding advantages over the conventional dc-dc converters with respect to high efficiency and high power density. The developed converter system has been experimentally tested with using DSP PWM controller so that the performance of the proposed converter could be effectively examined and the validity of the converter could be verified.

• International Journal of Automotive Technology
• /
• 제6권5호
• /
• pp.529-536
• /
• 2005

This paper presents a novel design of a fuzzy control strategy (FCS) based on torque distribution for parallel hybrid electric vehicles (HEVs). An empirical load-regulating vehicle operation strategy is developed on the basis of analysis of the components efficiency map data and the overall energy conversion efficiency. The aim of the strategy is to optimize the fuel economy and balance the battery state-of-charge (SOC), while satisfying the vehicle performance and drivability requirements. In order to accomplish this strategy, a fuzzy inference engine with a rule-base extracted from the empirical strategy is designed, which works as the kernel of a fuzzy torque distribution controller to determine the optimal distribution of the driver torque request between the engine and the motor. Simulation results reveal that compared with the conventional strategy which uses precise threshold parameters the proposed FCS improves fuel economy as well as maintains better battery SOC within its operation range.

• 조명전기설비학회논문지
• /
• 제26권9호
• /
• pp.18-25
• /
• 2012

Recently, the depletion of fossil fuel carbon dioxide emissions due to limitations in the internal combustion engine vehicles is rising concern about electric vehicle. Neighborhood Electric Vehicle(NEV) is maximum speed 60km/h and one day driving distances less than 80km. In this paper, Power Conversion Controller is proposed for Neighborhood Electric Vehicle. To verify the developed Power conversion Controller, Test performed integration test, max load, power density, efficiency. Confirmed that the vehicle can be applied.

• 한국자동차공학회논문집
• /
• 제24권3호
• /
• pp.345-351
• /
• 2016

This study was carried out to determine an optimal lean $NO_x$ trap (LNT) regeneration condition based on a $NO_x$ storage fraction. The LNT regeneration was performed by an in-cylinder post fuel injection method. A $NO_x$ storage fraction is defined by the ratio of current cumulated $NO_x$ amount in the LNT to the $NO_x$ storage capacity: 0 means empty and 1 fully loaded. In this study five engine operating conditions were chosen to represent the New European Driving Cycle. With various $NO_x$ storage fractions each engine operating condition, the LNT regeneration was executed and then $NO_x$ conversion efficiency, additional fuel consumption, CO and THC slip, peak catalyst temperature were measured. The results showed that there exist an optimal condition to regenerate the LNT, eg. 1500 rpm 6 bar BMEP with below 0.7 $NO_x$ storage fraction in this experimental constraint.

• 한국가스학회지
• /
• 제19권5호
• /
• pp.7-12
• /
• 2015

현재까지 수소는 주로 천연가스의 연료 개질에 의해 발생된 합성가스를 이용해 생산된다. 합성가스 내의 수소 수율을 높이기 위해선 추가적인 공정이 필요하다. 하지만, 수소의 수율 향상을 위한 공정에는 별도의 에너지원과 경제적 비용이 수반된다. 그러므로 보다 효율적으로 합성가스를 활용하기 위해 그 자체로 혼합물로 이용하는 방법에 관한 관련 연구들이 이루어지고 있다. 본 연구에서는 30kW급 발전용 스파크 점화 가스엔진에서 메탄/합성가스 혼합물이 엔진의 주요 성능에 미치는 영향을 조사하였다. 그 결과 메탄/합성가스 혼합물에 의해서 최대 실린더 내부 압력과 그 때의 크랭크 각도와 같은 엔진 내 연소 현상은 개선되는 것으로 나타났다. 이를 통해 메탄-합성가스 혼합물의 연료 전환 효율은 메탄-수소 혼합물의 약 98% 수준으로 향상시킬 수 있고 질소산화물 배출량은 메탄-수소 혼합물의 약 12%만큼 감소시킬 수 있다.

• Korean Chemical Engineering Research
• /
• 제52권6호
• /
• pp.720-726
• /
• 2014

PEMFC(Proton Exchange Membrane Fuel Cell) 차량은 미래 청정수송기관으로 각광받고 있지만 수소스테이션의 인프라부족으로 현재는 수소를 공급해주는 연료개질기를 함께 장착하여 구동하여야 한다. 탄화수소연료로부터 수소를 생산하는 연료개질기를 대상으로 다양한 연구가 진행되어왔는데 기존연구에서는 열적중립 조건의 ATR(Auto-Thermal Reformer) 반응기에 대해 집중적으로 분석하거나 공정최적화부문에서 최대수소생산을 목표로 주로 열효율을 목적함수로 설정하여 평가해 왔다. 본 연구에서는 100 kW PEMFC용 연료개질기를 대상으로 간단한 소형시스템을 얻기 위해 외부 유틸리티가 필요없는 단열열교환망으로 구성된 조건에서 기존 열효율이 아닌 수소효율을 새로이 정의하여 가솔린, LPG, 디젤 각 연료에 대해 최적운전조건을 도출하였다. 가솔린의 경우 기존 비교문헌보다 9.43% 연료절감효과를 얻음으로써 제안한 목적함수의 타당성을 입증하였고, 추가적으로 수소효율 및 열교환량, 열교환면적에 대한 민감도 분석을 실시하였다. 마지막으로 제안한 시스템을 한국시장에 적용할 경우 LPG 연료를 사용하는 연료개질기가 가장 경제적임을 알 수 있었다.

• 한국대기환경학회지
• /
• 제14권4호
• /
• pp.387-392
• /
• 1998

Recently, among after-treatment devices which have high possibility of utility, diesel oxidation catalyst (DOC) is concerned over the world. DOC oxidizes pollutants by means of activate-reaction during by -passing in the catalyst, in doing so, conversion efficiency of PM, CO and HC is high, and this device does not have an effect on engine performance because back pressure is not nearly increased. But, as a small amount of sulfur content in fuel is oxidized, it makes sulfate, which is absorbed on the surface of catalyst. So, in this study, the experiment is carried out by means of using ordinary fuel (0.1wt%) and low sulfur fuel (0.05wt%) with DOC, and the emission gas of diesel engine is measured.

• 한국자동차공학회논문집
• /
• 제8권6호
• /
• pp.60-69
• /
• 2000

In order to obtain underwater or underground power sources, the closed cycle diesel engine is operated in the non air-breathing circuit system where the major species of the working fluid include oxygen, argon, and recycled exhaust gas. In the present study, the closed cycle diesel engine is designed to operate at the intake pressure between 2 and 3 bar. For operating in the open-cycle and closed-cycle situations, experimental apparatus using this diesel engine is made with ACAP as data acquisition system. In open, semi-open, and closed cycle modes, the predicted p-$\theta$ and P-V are compared with load bank power. Computation have been performed for wide range of major experimental parameters such as the specific fuel and oxygen concentrations, fuel conversion efficiency and polytropic exponent, IMEP and maximum cylinder pressure.

• 한국자동차공학회논문집
• /
• 제9권2호
• /
• pp.1-10
• /
• 2001

In order to reduce hydrocarbon emissions of spark ignition engine, it is important not only to improve catalyst conversion efficiency but also to reduce direct engine out hydrocarbon emissions, during cold starting and warm up process. Tjerefore many researchers have been attracted to develop an early fuel evaporator (EFE) by introducing a ceramic heater for a solution of engine out hydrocarbon emissions in SI engine. But, the performance of the EFE in MPI engine to reduce the exhaust emissions and to improve the cold startability has nat been clarified yet. The purpose of this study is to evaluate the feasibility of a glow plug for EFE.