• Journal of the korean Society of Automotive Engineers
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• v.2 no.1
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• pp.9-20
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• 1980

디이젤기관의 냉시동성이 가솔린기관에 비하여 떨어지는 것은 이미 우리가 알고 있는 사실이다. 근년에는 소형트럭, 승용차, 소형건설기계 등의 분야에 있어서도 고속디이젤기관을 널리 사용하게 되었고 앞으로 디이젤연료의 중질화 및 세탄가 저하의 영향 등을 고려할 경우 시동성의 확보는 더욱 중요한 문제로 된다. 시동성에 영향을 미치는 인자 혹은 시동성개선의 방책으로서는 분 무의 착화에 직접 관련되는 것 외에 축전지의 저온특성 혹은 기관의 마찰토오크 등 여러가지에 걸쳐 있으나 이들 중에서 특히 분무의 착화에 직접 관련되는 방책에 관해서는 그것이 시동성에 미치는 영향에만 그치는 것이 아니고 시동개시직후에 있어서 배출가스, 혹은 출력성능 등에 미 치는 영향에 대해서도 함께 고려를 하여야 할 경우가 있다. 본고에 있어서는 냉시동시의 분무의 착화에 대하여 직접 관련하거나 그것을 촉진시킨다고 생각되는 몇개의 인자와 구체적인 방책을 취급하므로써 그것들이 시동성 및 시동직후의 청백연 혹은 출력성능 등에 대하여 미치는 영향에 대해서 기술하며 아래에서 취급되는 시동시의 착화를 촉진하기 위한 실제적인 인자 및 방책은 어느 것이나 기본적으로는 하나의 개념에 집약된다. 즉 그것은 연표와 효소로부터 이루어지는 연소계에 있어서 착화조건을 갖추어야함을 말할 것도 없다.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.122-129
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• 2005

연료전지 차량이 기존의 내연기관 차량과 동등한 성능을 확보하기 위해서는 80kW 이상의 용량을 가진 스택이 탑재되어야 하며, 별도로 차량 구조를 변경시키지 않고 탑재하기 위해서는 높은 출력밀도를 가진 연료전지 스택의 개발이 필요하다. 현대 자동차가 독자 기술로 개발하고 있는 연료전지 스택은 출력 80kW, 출력밀도 1.0kW/l를 목표로 하고 있으며 지난 1년간의 과제 수행을 통해 어느 정도 성능을 만족하는 스택을 개발하였다. 앞으로는 연료전지 스택의 내구성 및 냉시동성을 개선하기 위해 많은 연구가 수행될 예정이다.

• New & Renewable Energy
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• v.1 no.4 s.4
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• pp.25-29
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• 2005

연료전지 차량이 기존의 내연기관 차량과 동등한 성능을 확보하기 위해서는 80kW 이상의 용량을 가진 스택이 탑재되어야 하며, 별도로 차량 구조를 변경시키지 않고 탑재하기 위해서는 높은 출력밀도를 가진 연료전지 스택의 개발이 필요하다. 현대 자동차가 독자 기술로 개발하고 있는 연료전지 스택은 출력 80kW, 출력밀도 1.0kW/l를 목표로 하고 있으며 지난 1년간의 과제 수행을 통해 어느 정도 성능을 만족하는 스택을 개발하였다. 앞으로는 연료전지 스택의 내구성 및 냉시동성을 개선하기 위해 많은 연구가 수행될 예정이다.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.7-14
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• 2002

In order to reduce exhaust omissions of spark ignition engine, it is important not only to improve catalyst conversion efficiency but also to directly reduce engine out exhaust emissions, during cold starting and warm up process. Therefore many researchers have been attracted to develop an early fuel evaporator(EFE) by Introducing a ceramic heater fur a solution of engine out exhaust 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 not been clarified yet. The purpose of this study is to evaluate the feasibility of a glow plug far EFE. Impinging spray using heated and unheated glow plug helps the vaporization of the fuel and heat up the three way catalyst sufficiently. The amount of CO, and UHC is reduced overall. The amount of NOx is higher at the initial stage, but become lower as time goes on than without glow plug.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.71-79
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• 1992

Recently, air pollution and energy security problems have necessitated the development of alternative fuel vehicles. As an alternative fuel vehicle FFV(Flexible Fuel Vehicle) which can be operated by and mixture between gasoline and M85(methanol 85% and gasoline 15% by vol. percent) has been drawing great attention. But poor cold startability of high methanol- content fuel which is characteristic of lower fuel volatility and higher latent heat of vaporization than gasoline is one of the major problems to be solved for the development of FFV. In this paper, important factors influencing cold startability of general S.I. engines are described. And, so-me cost-effective and practical methods were investigated in view of the optimization of fuel-ing parameters and ignition system for M85 fuel. The test results showed good startability up to (-22)-(-23).deg.C.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.1-10
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• 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.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.6
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• pp.585-592
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• 2011

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 $80^{\circ}C$ 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.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.73.1-73.1
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• 2010

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 $-20^{\circ}C$ to $80^{\circ}C$ using the four-point probe method. The experimental results revealed that the thin films was mainly composed of Karelianite $V_2O_3$ 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 $-20^{\circ}C$. 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. $T{\geq}40^{\circ}C$. 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.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.6
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• pp.859-867
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• 2011

The cold start problem is one of major obstacles to overcome for the commercialization of fuel cell vehicles. However, the cold start characteristics of fuel cell systems are very complicated since various phenomena, i.e. ice-blocking, electro-chemical reactions, heat transfer, and defrosting of BOP components, are involved in them. This paper presents a framework to approach the problem at a full stack scale using Axiomatic Design (AD). It was characterized in terms of Functional Requirements (FRs) and Design Parameters (DPs) while their relations were established in a design matrix. Considering the design matrix, the endplates should have low thermal conductivity and capacity without increase in weight or decrease in structural stiffness. Consequently, composite sandwich endplates were proposed and examined both through finite element analyses and experiments simulating cold start conditions. From the examinations, it was found that the composite sandwich endplates significantly contributed to improving the cold start characteristics of PEMFC.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.711-717
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• 2017

Startability and harmful emissions are the main issues in diesel engine development under cold conditions. The characteristics of combustion with multiple injection were investigated under cold start conditions. For quantitative analysis, the in-chamber pressure profile was measured and combustion visualization using direct imaging was accomplished. With multiple injection, the peak in-chamber pressure and heat release rate were increased compared to single injection. In addition, the period of flame luminosity detection was shortened using multiple injection. Combustion by main injection was improved with an increase in heat released by pilot combustion when the pilot injection quantity was increased. Finally, an increase in injection pressure also showed the possibility of combustion improvement. On the other hand, an increase of in the pilot injection quantity and injection pressure can cause an increase in harmful emissions, such as HC and CO due to wall wetting. Therefore, more sensitive calibration will be needed when applying a multiple injection strategy under cold start conditions.