• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.163-163
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• 2004

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1264-1276
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• 2000

Light-off catalyst has been used for minimization of cold-start emissions. Improved cold-start performance of light-off catalyst needs the optimal design in terms of flow distribution, geometric surface area, precious metal loading, cell density and space velocity. In this study, these influential factors are numerically investigated using integrated numerical technique by considering not only 3-D fluid flow but also heat and mass transfer with chemical reactions. The present results indicate that uneven catalyst loading of depositing high active catalyst at upstream of monolith is beneficial during warm-up period but its effect is severely deteriorated when the space velocity is above 100,000 $hr^{-1}$ To maximize light-off performance, this study suggests that 1) a light-off catalyst be designed double substrate type; 2) the substrate with high GSA and high PM loading at face be placed at the front monolith; and 3) the cell density of the rear monolith be lower to reduce the pressure drop.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2375-2380
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• 2013

In this paper, we have implemented the unified fuel heater and performance evaluation system for diesel cars. In order to strengthen an engine starting of diesel car, we need to assembly the fuel filter and heater. Especially, this assembly fuel heater is very important in winter, it is necessary for heating to operate the diesel engine. The heater for unifying the sensor and heater body can advance the performance of car and reduce the production cost. Finally, the performance test chamber is needed to evaluate the performance of heater.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.219-222
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• 2009

Pyrostarters play a role as a turbopump starter in liquid propellant propulsion systems by supplying pressurized gas to power turbines for engine start. A rupture disk in pyrostarters, which is usually installed behind a nozzle throat, not only isolates the charged solid propellants from the external environment but also improves the ignitability of the solid propellants by increasing a chamber pressure at the beginning of combustion. Experimental tests have been performed to study the effects of rupture disk thickness, depth and shape of scores, and pressure build-up rates on burst pressures and burst diameters. The experimental results show that the developed rupture disk fulfills the performance requirements expected in a real operational condition.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.1
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• pp.8-18
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• 2012

This paper presents a three-dimensional, transient cold-start polymer electrolyte fuel cell (PEFC) model to numerically evaluate the effects of membrane electrode assembly (MEA) design and cell location in a PEFC stack on PEFC cold start behaviors. The cold-start simulations show that the end cell experiences significant heat loss to the sub-freezing ambient and thus finally cold-start failure due to considerable ice filling in the cathode catalyst layer. On the other hand, the middle cells in the stack successfully start from $-30^{\circ}C$ sub-freezing temperature due to rapid cell temperature rise owing to the efficient use of waste heat generated during the cold-start. In addition, the simulation results clearly indicate that the cathode catalyst layer (CL) composition and thickness have an substantial influence on PEFC cold-start behaviors while membrane thickness has limited effect mainly due to inefficient water absorption and transport capability at subzero temperatures.

• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.11-17
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• 2007

The CCFLs, EEFLs and FFLs use mercury and the operating conditions are different at warm or cold temperature. At start of operation, there may exist a possibility of inhomogeneous operation of lamps or channels of FFL to the very low vapor pressure of mercury at low temperature. In this paper, an inverter with level control block (LCB) was developed to drive LCD backlight using FFL stably at low temperature range. The operation of FFL backlight at $-20^{\circ}C$ was successfully demonstrated by developing inverter with LCB under 130 Watt of power consumption.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.144-153
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• 2015

At low temperature, Wax build-up and settling can affect adversely the cold weather performance of the diesel vehicle. In this study, we test the cold properties of diesel by blending ratio of biodiesel, kerosene and WAFI. Also, we test the cold weather performance for diesel vehicle by fuel cold properties. Cold properties of diesel are improved by adding the WAFI, kerosene and get worse by adding the biodiesel. WAFI is effective to improve a cold filter plugging point(CFPP) and Kerosene is effective to improve a cloud point(CP). CFPP and pour point(PP) are related to cold weather performance of diesel vehicle but CP is unrelated. CFPP indicate a limit temperature of vehicle driving possibility.

• 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.

• Journal of ILASS-Korea
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• v.25 no.2
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• pp.74-80
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• 2020

The jet in crossflow is a spray method used in the various air-breathing engine. In order to understand the spray characteristics in various environments, many prior studies have been conducted. However, there is a lack of understanding of the low-temperature liquid spray characteristics below 273 K. With this in mind, we tried to enhance the knowledge of the low-temperature liquid spray characteristics by identifying the penetration height of low-temperature ethanol. The experiment was conducted under phase pressure, and 273 K of air and 293, 263, and 233 K of ethanol was used. Shadowgraphy was employed to measure the liquid penetration, and Otsu's method was used to analyze the penetration height. The heights tend to decrease as the temperature of the liquid jet decreases. A correlation for the penetration height in the experimental conditions was derived and presented.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.66-72
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• 2008

Fuel reforming technology for the fuel cell vehicles could be adopted to internal combustion engine for the reduction of engine out emissions. Since syngas which is reformed from fossil fuel has hydrogen as a major component, it has abilities to enhance the combustion characteristics with wide flammability and high speed flame propagation. In this paper, syngas was feed to 2.0 liter gasoline engine during the cold start and early state of idle condition. Not only cold start HC emission but also $NO_x$ emission could be dramatically reduced due to the fact that syngas has no HC and has nitrogen up to 50% as components. Exhaust gas temperature was lower than that of gasoline feeding condition. Delayed ignition timing, however, resulted in increased exhaust gas temperature approximated to gasoline condition. It is supposed that the usage of syngas in the gasoline internal combustion engine is an effective solution to meet the future strict emission regulations by the reduction of cold start THC and $NO_x$ emissions.