乘用車 輕量化에 대한 考察

박권하 한국자동차공학회 1990 한국자동차공학회 학술강연초록집 Vol.- No.-

박용디젤기관의 질소산화물 저감기술

박권하 한국마린엔지니어링학회 2001 한국마린엔지니어링학회지 Vol.25 No.5

취부득<SUB>取不得</SUB> 사부득<SUB>捨不得</SUB>

박권하 수필미학 2021 수필미학 Vol.31 No.-

벽면충돌분무 계산에서 확장충돌모델의 적용범위에 관한 고찰

박권하,정창화,Park, Gwon-Ha,Jeong, Chang-Hwa 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.8

This paper addresses to the area where the extended collision model is applied. In order to find the optimum shape of wall sprays, the extended model is applied to the nearest cells of just over the impaction wall, spray core or over all. The droplet distribution, wall spray radii, heights and gas flows are shown in all the cases. Those results show that the best spray shape represents in the case applying the extended model just on the impinging wall.

선박엔진에서 배기재순환이 연소과정에 미치는 영향

박권하,R. Prosser 한국동력기계공학회 2023 동력시스템공학회지 Vol.27 No.3

Regulations on carbon dioxide emitted from ships have been strengthened, and technologies for low-carbon or carbon-free fuel have been developed. However, marine engines currently operating on heavy fueled oil are expected to continue to be used. Therefore, it is necessary to continue research on the performance improvement of marine diesel engines using heavy fueled oil. This study analyzed the effects of exhaust gas recirculation (EGR) on combustion behaviors. The effect of EGR on the combustion process such as fuel, flame, temperature, and combustion products behavior in the combustion chamber was analyzed. The emission of nitrogen oxides is reduced exponentially with the increase of the EGR rate. However, when the EGR rate increases, the propagation distance of the fuel spray increases and a large amount of fuel is distributed on the lower surface of the chamber in a low temperature state with the increase of the EGR rate. Therefore, the amount of unburned fuel is greatly increased up to 13.3%. Considering both energy efficiency and other emissions, it is desirable to keep the EGR rate below 23%. 선박에서 배출되는 이산화탄소에 대한 규제가 강화되고 저탄소 또는 무탄소 연료에 대한 기술이 개발되고 있다. 그러나 현재 중유로 작동하는 선박용 디젤엔진은 계속 사용될 것으로 예상되며 중유를 이용한 선박용 디젤엔진의 성능향상에 대한 연구가 지속되어야 한다. 본 연구에서는 배기가스재순환기술(EGR)이 연소거동에 미치는 영향을 분석하였다. 연소실에서 연료, 화염, 온도 및 연소 생성물 거동과 같은 연소과정에 대한 EGR의 영향을 분석하였다. 질소산화물 배출은 EGR 비율이 증가함에 따라 기하급수적으로 감소된다. 그러나 EGR율이 증가하면 연료분무의 전파거리가 증가하고 저온상태에서 다량의 연료가 연소실 하부면에 분포하게 되면서 미연소 연료량은 13.3%까지 크게 증가한다. 에너지 효율과 기타 배출가스를 종합적으로 고려할 때 EGR율은 23% 이하로 유지하는 것이 바람직하다.

물혼합 연료 및 EGR의 조합에 의한 디젤기관의 질소산화물과 매연미립자 동시저감 기술에 관한 연구

박권하,박태인,김기형 한국마린엔지니어링학회 1997 한국마린엔지니어링학회지 Vol.21 No.4

Many research works have been carried out to investigate the factors governing the performance of diesel engine. The area of the study has been focused on reducing both of NOx and smoke because of many difficulties to reduce them simultaneously in diesel engines. One of the efforts is an application of EGR technology to reduce NOx emission, which is very effective, but increases other emissions and makes fuel economy worse. In order to solve the problem, EGR is employed with water emulsified fuel and tested in this paper. Emulsified fuel is produced by centrifugal mixer and the amount of water is controlled by water injector and pulse generator, and EGR rate is controlled with 6-step control valve. The chamber pressure, fuel consumption and emissions are measured with various values of both EGR and water mixing rate, The results show that NOx emission is reduced much rather and smoke is also reduced simultaneously.

Effect of cylinder wall temperature on marine engine combustion

박권하 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.6

With the strengthening of fuel-efficiency regulations for marine engines, many studies are underway to enhance their effi-ciency. To achieve greater fuel efficiency, ship operating speeds are reduced. However, a reduction in the ship speed significantly lowers the temperature of the cylinder liner wall, leading to increased heat loss owing to the enhanced heat transfer to the cooling water. This study presents a detailed analysis of the effect of the surface temperature of the cylinder liner in long-stroke marine engines on fuel spray and combustion. A detailed analysis is conducted on the effect of the surface temperature of the cylinder liner in a slow-speed marine engine on fuel spray and combustion. This study analyzes parameters such as the penetration and distribution of the fuel spray, variations in the combustion speed, distribution of OH radicals representing the combustion boundary layer, and the generation processes of combustion products such as NO and CO. The analysis indicates that, for a comprehensive consideration of combustion efficiency and exhaust emissions, maintaining the cylinder liner wall temperature within the range of 150 to 180 °C is desirable.

분무충돌을 이용하는 디젤연소실 설계를 위한 충돌면 분석

박권하 한국액체미립화학회 1996 한국액체미립화학회지 Vol.1 No.2

Most of the research of small engines to date focused on developing spark ignition engines occupied much parts. Recently the number of a small direct injection diesel engine applied in small cars has been increased and considered as a next generation power source for passenger cars because of its high efficiency. Therefore the combustion chamber becomes smaller and the fuel injected pressure goes higher, which makes fuel sprays impinged easily on the combustion chamber walls. When strong swirls are not induced, the fuel may not mix with air because of fuel deposition an the wall. As a positive way, the combustion chamber systems which is using spray wall impaction has been intraduced and assessed by an experimental or a simulate manner. In these systems the raised lands are positioned in the chamber for spray impaction in order to break up the fuel drops into much smaller and direct them into desirable direction. This study addresses to the effects of the position and size of the raised land or glow plug to help the chamber design using spray wall impaction. The characteristics of the spray impinged on various lands are investigated and compared with each other. Then the chamber shapes are discussed with the characteristics and their proper position and size is proposed in any chamber volume.

디젤분무의 벽면충돌모델

박권하 한국액체미립화학회 2000 한국액체미립화학회지 Vol.5 No.4

BEHAVIOR OF LIQUID LPG SPRAY INJECTING FROM A SINGLE HOLE NOZZLE

박권하 한국자동차공학회 2005 International journal of automotive technology Vol.6 No.3

Liquefied petroleum gas (LPG) has been used as motor fuel due to its low emissions and low cost. A liquid direct injection system into a cylinder was suggested as a next generation system to maximize a fuel economy as well as a power. This study addresses the analysis of the LPG spray injecting from single hole injector. Two different test conditions are given, which are a fully developed spray case with various injection pressures and a developing spray case with ambient pressure variation. The LPG spray photographs are compared with the sprays of gasoline and diesel fuel at the same conditions, and the spray angles and penetration lengths are also compared, and then the spray behavior is analyzed. The LPG spray photos show that the dispersion characteristic depends very sensitively on the ambient pressure soon after injection. The spray angle is very wide in a low ambient pressure condition until the saturated pressure, but the angle is quickly reduced at the condition over the pressure. However, the down stream of the LPG spray shows much wider dispersion and less penetration than those of gasoline and diesel sprays regardless ambient pressure condition.