• 한국수소및신에너지학회논문집
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• 제33권3호
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• pp.255-260
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• 2022

Hydrogen gas fuel was applied to a small-sized two stroke engine for a mobile power source instead of gasoline fuel. Port fuel supply showed a limitation in terms of power due to the back fire at the engine intake manifold. So in this study, hydrogen direct injection system was applied to overcome this drawback by using a low pressure direct gas injector. The result from this strategy showed that hydrogen direct injection improved fuel efficiency as well as torque and power comparing to the port fuel supply system.

• 한국소음진동공학회논문집
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• 제22권10호
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• pp.985-993
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• 2012

In this paper, a new method is proposed to estimate the sound pressure generated from gasoline direct injection (GDI) engine. There are many noise sources as much as components in GDI engine. Among these components, fuel pump, fuel injector, fuel rail, pressure pump and intake/exhaust manifolds are major components generated from top of the engine. In order to estimate the contribution of these components to engine noise, the total sound pressure at the front of the engine is estimated by using airborne source quantification (ASQ) method. Airborne source quantification method requires the acoustic source volume velocity of each component. The volume velocity has been calculated by using the inverse method. The inverse method requires many tests and has ill-condition problem. This paper suggested a method to obtain volume velocity directly based on the direct measurement of sound intensity and particle velocity. The method is validated by using two known monopole sources installed at the anechoic chamber. Finally the proposed method is applied to the identification and contribution of noise sources caused by the GDI components of the test engine.

• 한국가스학회지
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• 제19권4호
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• pp.22-28
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• 2015

LPG가 수송용 연료로서 경쟁력을 유지하기 위해서는 지속적인 기술개발을 통해 휘발유와의 연비격차를 감소시키고 후처리시스템 등에 의한 가격 부담을 낮추어야 한다. 이에 본 연구에서는 안정적인 희박연소 구현을 통한 연비개선을 얻기 위해 실린더 중앙에 점화플러그와 연료분사기가 인접해 있고, 연료가 분사된 후 바로 점화가 이루어지도록 하는 분무유도방식의 LPG 직접분사엔진을 개발의 일환으로 연소제어인자의 변화에 따른 연소 특성을 분석하였다. 안정적인 연소를 위해 국부적으로 농후한 혼합기를 형성하는 성층희박연소의 특성상 일정 수준이상의 질소산화물이 배출되는 문제점을 갖고 있다. 질소산화물 저감을 위해 EGR을 적용한 결과 연료소비율과 THC의 배출은 약간 증가하지만 $NO_x$배출은 약 15% 저감되었다. EGR 적용에 의한 연소속도의 감소는 초기 화염발달 시기에 집중되어 나타났으며 흡입공기의 희석효과에 의해 EGR율이 증가할수록 최대 열방출율 및 열방출율 증가 기울기가 감소하였다.