• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.11
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• pp.1065-1072
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• 2012

Due to its oxygen (O) content, biodiesel (BD) is advantageous in that it lowers PM emissions in CI engines. Therefore, BD is considered one of the best candidates for low temperature combustion (LTC) operation because its use can extend the regime for simultaneous reduction of PM and $NO_x$. Thus, in this study, LTC operation was realized using BD and diesel with a 5~7% $O_2$ fraction. Engine test results show that the use of BD increased the efficiency and reduced emissions such as PM, THC, and CO; furthermore, IMEP reduced by 10~12% owing to the lower LHV of the fuel. In particular, smoke was suppressed by up to 90% because O atoms in the BD enhanced the soot oxidation reaction. To compensate the IMEP loss, turbocharging (TC) was then tested, and the results showed that the power output increased and PM was reduced further. Moreover, TC in BD engine operation allowed a similar level of reduction in both $NO_x$ and PM at 11~12% $O_2$ fraction, suggesting that there is a potential to widen the operating range by the combination of TC and BD.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.283-283
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• 2015

• Journal of the KSME
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• v.23 no.6
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• pp.427-433
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• 1983

내연기관의 성능은 실린더에서 연료의 화학에너지가 열에너지로 얼마만큼 빠르고 완전하게 변화하느냐에 좌우된다. 이를 위해서는 실린더 내에서 뜨거운 압축공기와 연료의 혼합 및 증기화가 요구된다. 엔진의 출력은 매 사이클당 흡입.압축할 수 있는 공기량에 좌우되므로 연소의 해석을 위해서는 실린더 내의 공기유동, 연료의 분무 및 연소과정을 이해 해야한다. 배기와 엔진효율의 요구성때문에 희박 혼합기 또는 EGR (exhaust gas recirculation)이 필요하게 된다. 그러나 희석이 크면 낮은 연소온도, 낮은 층류흐름속도와 화염전면의 낮은 난류강도 때문에 연소기간이 증대하게 된다. 실제로 희박의 증가는 실화 또는 긴 연소 지연기간, 사이클 마다의 연소맥동현상, HC배기의 증가등을 초래하게 된다. 이러한 저온연소의 단점들은 연소상태를 안정시키고 연소량을 증대시키는 공기의 유동을 이용해서 해결 될 수 있다. 최근에는 선회류와 난류의 강도를 증가시켜서 빠른연소(fast burning)를 이루고 있다. 선회류와 난류의 강도를 증대시키는 가장 중요한 2가지 방법은 흡입포트(port), 매니홀드(manifold)설계이다.

• Journal of the KSME
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• v.30 no.6
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• pp.521-534
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• 1990

유동층 연소방식을 이용한 열병합설비는 상당수가 전세계적으로 성공리에 운전되고 있으며, 연료의 폭넓은 수용성, 저온연소에 기인한 저공해 특성으로 인해 기존연소 방식보다 월등한 강 점이 인정되고 있다. 따라서 에너지 활용의 극대화와 환경오염의 최소화라는 두가지 명제를 만족시키는 금세기 최대의 매력적인 석탄 연소 방법으로서 유동층 연소 기술은 지속적인 확산이 예상된다. 그러나 그 동안의 문제가 제작자와 사용자의 노력에 의해 거의 해결되었다고는 하나, 아직도 대형화 및 기본설계상의 문제가 부분적으로 해결되어야할 숙제로 남아 있다. 최근의 추세는 다양한 형태의 설계개념이 차츰 서로 비슷해지는 추세로서, 이는 구체적인 설계과정에서 최적 시스템으로 취합되는 경향을 나타내고 있다. 각공정에 맞는 최적 시스템/최적 설계를 도 입하기 위해서는 각 제작자의 독특한 시스템에 대한 검토 분석이 있어야 하며, 사용코자하는 연료와 석회석의 물리화학적 특성을 사전에 분석하여 선택코자 하는 유동층 시스템과의 적합성 여부에 대한 사전 검토가 요망된다.

• Journal of ILASS-Korea
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• v.18 no.1
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• pp.21-26
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• 2013

Diesel low temperature combustion (LTC) is the concept where fuel is burned at a low temperature oxidation regime so that $NO_x$ and particulate matters (PM) can simultaneously be reduced. There are two ways to realize low temperature combustion in compression ignition engines. One is to supply a large amount of EGR gas combined with advanced fuel injection timing. The other is to use a moderate level of EGR with fuel injection at near TDC which is generally called Modulated kinetics (MK) method. In this study, the effects of fuel injection pressure on performance and emissions of a single cylinder engine were evaluated using the latter approach. The engine test results show that MK operations were successfully achieved over a range of with 950 to 1050 bar in injection pressure with 16% $O_2$ concentration, and $NO_x$ and PM were significantly suppressed at the same time. In addition, with an increase in fuel injection pressure, the levels of smoke, THC and CO were decreased while $NO_x$ emissions were increased. Moreover, as fuel injection timing retarded to TDC, more THC and CO emissions were generated, but smoke and $NO_x$ were decreased.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.3
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• pp.61-68
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• 2010

A small high altitude test facility has been developed to investigate ignition performance of a small gas-turbine combustor under high altitude conditions. Supersonic diffusers and a heat exchanger were used to perform a low pressure and a low temperature condition, respectively. Experimental results showed that the low pressure environment could be controlled by upstream pressure of primary nozzle flow and low temperature environment by mixture ratio of cooled air and ambient air. Ignition performance tests were performed to verify the performance of the facility under simulated high altitude conditions. Conclusively, it was proven that the test facility could be used for ignition performance test of a small gas-turbine combustor under high altitude condition of approximately 6,100m.

• Journal of the KSME
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• v.55 no.6
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• pp.45-48
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• 2015

이 글에서는 저온 플라즈마를 이용한 연소로 배출 가스상 오염 물질을 제거하는 방법에 대해 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1121-1126
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• 2010

This study is to investigate the effects of aromatics and T90 for low cetane number (CN) fuels on combustion and exhaust emissions in low-temperature diesel combustion. We use a 1.9-L common rail direct injection diesel engine at 1500 rpm and 2.6 bar BMEP. Low temperature diesel combustion was achieved via a high external EGR rate and strategic injection control. The tested fuels four sets: the aromatic content was 20% (A20) or 45% (A45) and the T90 temperature was $270^{\circ}C$ (T270) or $340^{\circ}C$ (T340) with CN 30. Given the engine operating conditions, the T90 was the stronger factor on the ignition delay time, resulting in a longer ignition delay time for higher T90 fuels. All the fuels produced nearly zero PM because of the extension of the ignition delay time induced by the low cetane number. The aromatic content was the main factor that affected the NOx and the NOx increased with the aromatic content.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.10
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• pp.941-946
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• 2010

This study aims to investigate the effects of soybean biodiesel fuel on exhaust emissions with regards to two combustion modes: conventional combustion(existence of PM-NOx trade-off behavior) and low temperature combustion(LTC) in a 1.7 L common rail direct injection diesel engine. As compared to conventional combustion, LTC was achieved by adopting a heavier exhaust gas recirculation and strategic injection parameter optimization. Two sets of fuels, i.e. ultra low sulfur diesel(ULSD) and 20% volumetric blends of soybean biodiesel with ULSD(B20) were used. Regardless of the fuel type, in LTC the simultaneous reduction of PM and NOx was observed and both levels were significantly lower than in case of conventional combustion. Under the given engine operating condition in the case of conventional combustion, B20 produced less PM and more NOx than ULSD. In the case of LTC combustion, B20 produced more PM and NOx than ULSD.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.149-152
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• 2009

A pyrostarter is a sort of gas generator, which supplies the energy to drive turbines by the combustion gas of a solid propellant charged internally. The igniter of the pyrostarter should guarantee the ignition reliability expecially for the solid propellant with a low fame temperature. For the development of the igniter, several closed bomb testes have been performed to decide several design parameters to get a sufficient chamber pressure build-up for the ignition. Moreover, as a result of the firing testes with pyrostarters, the ignition reliability have been verified and the amount of igniter propellants has been reviewed.