• Journal of Advanced Marine Engineering and Technology
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• v.19 no.3
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• pp.33-41
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• 1995

본 연구는 터보 과급기 부착 디젤 기관의 급가속 운전시 기관과 과급기의 과도 응답 성능을 규명하고 이를 개선하기 위한 실험을 수행하였다. 과도 응답 성능 구명은 일정한 회전 속도로 정상 운전중인 기관의 연료 펌프 랙을 10%에서 40%까지 일정 시간동안 급가속하였을 경우에 대하여 수행하였으며, 이때의 과급기 응답 지연 현상을 개선하기 위한 실험은 급가속과 동시에 압축기 출구의 흡기메니폴드 내에 일정한 압력의 공기를 추가 분사하는 방법을 이용하였다. 그리고 공기 분사 압력, 공기분사 기간, 가속률, 가속 시간 등이 압축기 출구의 압력과 온도, 터빈 입구의 압력과 온도, 실린더 압력, 기관과 과급기 회전 속도 등의 응답 성능에 미치는 영향을 가속전 정상 상태의 기관 회전 속도와 적용부하의 변화에 따라 시간의 함수로 나타내었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.153-153
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• 2014

건식 진공펌프(dry vacuum pump)는 기계적 저진공펌프 중 펌프 내부의 기체 배기통로에 오일을 전혀 사용하지 않는 펌프의 통칭으로써, 대개 비접촉형으로 여러 형태의 회전자가 고속으로 회전하면서 흡기구로부터 들어온 기체를 압축해 배기를 한다. 비접촉형에는 루츠(roots)형, 클로(claw)형, 스크류(screw)형, 스크롤(scroll)형 등이 있다. 그 중 스크류형 펌프는 큰 배기속도를 갖는 펌프의 설계에 유리하고 높은 운용온도가 가능하여 다수공정에 쉽게 적용할 수 있는 장점이 있다. 그러나 1단 펌프 구성을 갖게 됨에 따라 루츠형 대비 높은 소비전력 특성을 보이는 약점을 가지고 있다. 본 논문에서는 건식 진공펌프 중의 하나인 스크류형 진공펌프에 대하여, 기본적인 1단 펌프 구성에 스크류 리드(lead)의 변화를 주어 기존의 똑같은 리드의 스크류 진공펌프에 대한 소비전력 및 배기구 온도 등 스크류 형상에 대한 성능평가 연구를 진행 하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.84-86
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• 2001

본 논문에서는 고성능 활성탄의 악취 및 유해가스 흡착효율과 멜트브로운(M/B)부직포의 여과성능에 의한 복합적인 고기능 방진특성을 갖는 활성탄 부착 M/B 국산화 여과재를 제조개발하였다. 고성능 활성탄은 고순도의 일반활성탄에 금속염, 유기물 등을 담지시켜 활성화시킨 활성탄이고, M/B여과재의 웹(web)제조조건은 M/B 방사기에서 방사온도 250℃, 방사속도 150m/sec, 고온공기온도 250℃ 그리고 DCD(die to collector distance) 20cm가 적합함을 알 수 있었다. 또한 M/B 여과재에 활성탄 부착은 열롤러시스템에 의한 열적결합방법을 이용하여 균일한 분포의 점접착결합구조를 갖도록 하였고, 개발된 복합기능 여과재가 방진마스크용 여과재로의 이용이 가능하다는 것을 분진포집효율, 투과율, 흡기저항 등 여과재 성능기준실험 결과를 통해 확인하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.4
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• pp.248-254
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• 2009

The HCCI engine is a next generation engine, with high efficiency and low emissions. The engine may be an alternative to SI and DI engines; however, a pressure rise rate is a major limitation for high load range and power reduction. Recently, we were able to reduce the pressure rise rate using thermal stratification. Nevertheless, this was insufficient to produce high power. In this study, the reduction of the pressure rise rate using thermal stratification was confirmed and the HCCI engine power was increased using the boost pressure. The rate and engine power were produced by CHEMKIN and modified SENKIN. As a result of increasing the boost pressure, a higher IMEP was attained while the pressure rise rate increased only slightly in the HCCI with thermal stratification.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.1
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• pp.77-86
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• 1992

This paper discusses the thermodynamic study on the suction cooling-steam injected gas turbine cycle. The aim of this study is to improve the thermal efficiency and the specific output by steam injection produced by the waste heat from the waste heat recovery boiler and by cooling compressor inlet air by an ammonia absorption-type suction cooling system. The operating region of this newly devised cycle depends upon the pinch point limit and the outlet temperature of refrigerator. The higher steam injection ratio and the lower the evaporating temperature of refrigerant allow the higher thermal efficiency and the specific output. The optimum pressure ratios and the steam injection ratios for the maximum thermal efficiency and the specific output can be found. It is evident that this cycle considered as one of the most effective methods which can obtain the higher thermal efficiency and the specific output comparing with the conventional simple cycle and steam injected gas turbine cycle.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.1
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• pp.26-31
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• 2011

In this study, it made to run conventional single direct injection(DI) diesel engine, which adapted bulk combustion system not following spark ignition system without any ignition apparatus. It was heated and controlled inlet-air into conventional single DI diesel engine. The maximum value of brake thermal efficiency was at 35 region of air-fuel ratio. On the contrary, when the region of air-fuel ratio leaner than 35, brake thermal efficiency was decreased suddenly. And brake thermal efficiency was increased as much as inlet-air heating temperature increased. So, when air-fuel ratio was decreased and inlet-air heating temperature was higher, the engine was in optimal operation condition.

• Journal of the Korean Institute of Gas
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• v.13 no.6
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• pp.21-28
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• 2009

The purpose of this study is to gain a better understanding of the effects of thermal stratification and partial fuel stratification on reducing the pressure-rise rate and emission in HCCI combustion. The engine is fueled with Di-Methyl Ether(DME) which has unique 2-stage heat release. Computational work is conducted with multi-zones model and detailed chemical reaction scheme. Calculation result shows that wider thermal stratification and partial fuel stratification prolong combustion duration and reduce pressure rise rate. But too wide partial fuel stratification increases CO and NOx concentration in exhaust gas, and decreases combustion efficiency.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.22-30
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• 2003

Engine-out HC emissions were investigated during cold and hot start. The tests were conducted according to engine cooling temperatures which were controlled by simulated coolant temperatures of cold and hot start, on a 1.5L, 4-cylinder, 16 valve, multipoint-port-fuel-injection gasoline engine. Real time engine-out HC emissions were measured at a exhaust port and cylinder head using Fast Response Flame Ionization Detector(FRFID). Unburned hydrocarbons emitted at the cold coolant temperature were much higher than those of the hot coolant temperatures. And the main source of the high HC emission was confirmed as misfire at cold coolant temperature. In addition, the effect of intake valve timing on engine-out HC emissions was investigated. The results obtained indicate that optimized intake phasing provides the potential for start-up engine-out HC emissions reduction.

• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.11-18
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• 2021

Since hydrogen has the lower minimum ignition energy than that of gasoline, hydrogen could be also appropriate for the IC engine systems. However, due to the low ignition energy, there might be a 'back-fire' and 'pre-ignition' problems with hydrogen SI(Spark-ignition) combustion. In this research, cooling effects of intake gas mixture on the improvement of the maximum power output were evaluated in a 2.4 L SI engine. There were two ways to cool intake gas mixtures. The first one was cooling intake fresh air by adjusting inter-cooler system after turbocharger. The other one was cooling hydrogen fuel before supplying by using heat ex-changer. Cooling hydrogen was performed under natural aspired condition. The result showed that cooling fresh air from 40 ℃ to 20~30 ℃ improved the maximum brake power up to 6.5~8.6 % and cooling hydrogen fuel as -6 ℃ enhanced the maximum brake power likewise.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.5
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• pp.735-741
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• 1986

An experimental study on the effects of exhaust pipe curvature on the performance of a diesel engine is presented. The experiments were carried out on a 4-cycle, 216 c.c diesel engine and two types of pipe curvature, circular arc and rectangle, were tested. The shaft output, shaft torque and specific fuel consumption were obtained by inserting bent pipes of different dimensions into the exhaust pipe at various engine operation conditions. It was found that the engine performance was decreased by the circular arc bent pipe and the effects were dominated by its arc angle. The decrease of engine performance was minimized by the arc angle of 180.deg.. By the rectangle pipes the performance was more decreased and the effects were little influenced by its dimensions.