• 에너지공학
• /
• 제11권2호
• /
• pp.178-185
• /
• 2002

본 연구의 목적은 조기 연료 기화장치가 승용차의 냉간 주행성능에 미치는 영향을 조사하여 평가하는 것이다. 이를 위해 실험은 냉 시동성과 냉간 주행성능으로 나누어 실시하여 연료소비율과 유해 배출 가스량을 측정하고, 실린더내의 연소압력을 근거로 열 발생율, 적산 열 발생량, 질량연소율을 구하였다. 결과는 다음과 같다. 조기연료 기화장치의 장착은 냉 시동 초기부터 난기 완료까지의 연료소비량을 17.7%향상, 냉 시동 초기의 일산화탄소의 배출량은 23%, 탄화수소 배출량은 45% 저감 되고, 또한 냉간 주행시의 엔진의 연소 최고압력, 도시 평균 유효압력의 변동을 4∼6% 개선시키고, 단위 출력당 연료 소비율이 0.2∼2.3% 절감된다. 이것은 조기연료기화장치에 의한 연소실내 최대 열 발생 지연기간 및 주 연소기간이 짧아지기 때문이다.

• 한국자동차공학회논문집
• /
• 제10권4호
• /
• pp.43-50
• /
• 2002

In the present study, reduction of harmful exhaust gas in a diesel engine using stratified injection system of dual fuel (diesel fuel and methanol) was tried. The nozzle and fuel injection pump of conventional injection system were remodeled to inject dual fuel in order from the same injector. The quantity of each fuel was controlled by micrometers, which were mounted at rack of injection pumps. The injection ratio of dual fuel was certificated by volumetric ratio in injection quantity test. Cylinder pressure and exhaust gas were measured and analyzed under various supply condition of duel fuel. We confirmed that combustion of dual fuel was performed successful1y by using modified injection system in a D.I. diesel. Soot and NOx are simultaneously reduced by stratified injection without large deterioration of thermal efficiency, but THC and CO are relatively increased.

• 한국자동차공학회논문집
• /
• 제18권3호
• /
• pp.88-94
• /
• 2010

In this paper, the effect of the ultrasonic energy on the diesel engine's smoke reduction has been investigated for indirect injection diesel engine. The smoke concentration of the ultrasonically reformed diesel fuel was reduced remarkably in comparison with conventional diesel fuel. And in-cylinder pressure, heat release rate and mass fraction burned was improved but combustion duration was decreased. However, The combustion durations and the smoke concentrations of both diesel fuels were proportional to the increases of engine loads. Also, When the combustion duration has been increasing, the smoke emission has been augmenting in the shape of the exponential functions.

• Journal of Mechanical Science and Technology
• /
• 제16권4호
• /
• pp.564-571
• /
• 2002

Three-dimensional numerical analysis of the turbulent premixed flame propagation in a constant volume combustion chamber is performed using the KIVA-3V code (Amsden et. al. 1997) by the flame surface density (FSD) model. A simple near-wall boundary condition is eaployed to describe the interaction between turbulent premixed flame and the wall. A mean stretch factor is introduced to include the stretch and curvature effects of turbulence. The results from the FSD model are compared with the experimental results of schlieren photos and pressure measurements. It is found that the burned mass rate and flame propagation by the FSD model are in reasonable agreement with the experimental results. The FSD combustion model proved to be effective for description of turbulent premixed flames.

• 한국산업융합학회 논문집
• /
• 제18권4호
• /
• pp.197-206
• /
• 2015

Recently the automobile engine has been developed in achieving the high performance, fuel economy, and emission reduction. In a conventional spark ignition engine the fuel and air are mixed together in the intake system, inducted through the intake valve into the cylinder, and then compressed. Under normal operating conditions, the combustion is initiated towards the end of the compression stroke at the spark plug by an electric discharge. Following inflammation, a flame develops and propagates through this premixed fuel-air mixture. Therefore the state of mixture is very important in the combustion and emission characteristics. In this study the combustion and emission characteristics were tested and analyzed with changing the mixture composition and engine operating parameters in order to improve the combustion and performance in engine.

• 한국연소학회지
• /
• 제18권1호
• /
• pp.7-12
• /
• 2013

A quasidimensional program is developed for a four stroke cycle homogeneous GDI (Gasoline Direct Injection) engine. It includes models for spray, burning rate and chemistry to predict knock and emissions. With early injection a homogeneous GDI engine goes through spark ignited, turbulent premixed combustion as in PFI (Port Fuel Injection) engines. The cylinder charge is divided into unburned and burned zone with the latter divided into multiple zones of equal mass to resolve temperature stratification. Validation is performed against measured pressure traces, NOx and CO emissions at different load and RPM conditions. Comparison is made between an empirical knock model and predictions by the chemistry model in this work.

• 한국연초학회:학술대회논문집
• /
• 한국연초학회 2000년도 24회 정기총회 및 43회 학술발표회
• /
• pp.12-21
• /
• 2000

The smoke from a burning cigarette is classified as mainstream, which is the smoke inhaled by the smoker during a puff, and sidestream, which is defined by ISO 10185 as all smoke which leaves a cigarette during the smoking process other than from the butt end. Most of the sidestream smoke is generated during static burn, that is, in between puffs. The amount of sidestream smoke generated by a cigarette depends on the cigarette construction, tobacco blend, and properties of the cigarette paper, The main paper properties affecting sidestream smoke generation are: porosity, basis weight, type and amount of filler, type and amount of burn additive.Sidestream smoke is composed of a visible phase (small liquid droplets) and an invisible phase (gaseous molecules). This paper focuses on the visible portion of the sidestream smoke. Optical methods, which are based on the relationship between light scattering and density of the rising plume of smoke, have been used successfully by the industry. However, the present trend is to use gravimetric methods where the particulate matter is captured on a Cambridge(R) filter pad and weighed. The gaseous portion of the sidestream smoke, which does not contribute to the visible sidestream smoke, passes through the Cambridge filter pad.Sidestream smoke reduction is achieved by modifying certain mass transport processes occurring in a smoldering cigarette. There are four main pathways for reducing sidestream smoke: A) less tobacco burned, B) slower rate of tobacco combustion, C) more efficient trapping of smoke by the cigarette paper, and D) more complete combustion of tobacco. This paper discusses how the physical properties of paper and cigarette construction affect sidestream smoke reduction via the above four mechanisms.

• 대한기계학회논문집
• /
• 제16권9호
• /
• pp.1736-1743
• /
• 1992

본 연구에서는 기화기부착 4행정 4기통 전기점화기관을 사용하여 흡기관내 액 막흐름에 의한 연료의 불균일화가 기관의 연소특성과 배기특성에 미치는 영향을 규명 하는데 궁극적인 목적을 두고 우선, 연소특성을 해석하기 위하여 비교적 고가인 연소 해석 시스템을 개발하는데 1차적인 목적으로 하였으며, 시험제작한 연소해석 시스템으 로 액막흐름의 가시화 및 배기가스 농도측정과 지압선도 해석을 행하여 구조적으로 대 칭인 1번과 4번 실린더의 연소특성과 배기특성을 비교 검토하였다.

• 한국산업융합학회 논문집
• /
• 제18권2호
• /
• pp.110-118
• /
• 2015

In this study, it is designed and used the test engine bed which is installed with turbocharger, and in addition to equipped using by oxygen adder. It has been controlled the oxygen volumetric fraction of intake air chrge, and supercharged flow rate into the cylinder of SI 4-stroke engine, and then, has been analyzed engine performance, combustion characteristics, and exhaust emission as analysis parameters. The tested parameters were the oxygen fraction and the variation of engine speed and air-fuel ratio.

• 대한기계학회논문집B
• /
• 제27권7호
• /
• pp.1007-1014
• /
• 2003

This work deals with a controlled auto-ignition (CAI) single cylinder gasoline engine, focusing on the extension of operating conditions. The fuel is injected indirectly into electrically heated inlet air flow. In order to keep a homogeneous air-fuel mixing, the fuel injector is water-cooled by a specially designed coolant passage. Investigated are the engine performance and emission characteristics under the wide range of operating conditions such as 32 to 63 in the air-fuel ratio, 1000 to 1800 rpm in the engine speed, and 150 to 18$0^{\circ}C$ in the inlet air temperature. The compression ignition gasoline engine can be achieved that the ultra lean-burn with self-ignition of gasoline fuel by heating inlet air. For example. the allowable lean limit of air-fuel ratio is extended until 63 at engine speed of 1000 rpm and inlet air temperature of 17$0^{\circ}C$. It can be achieved that the emission concentrations of carbon monoxide, hydrocarbons and nitrogen oxide had been significantly reduced by CAI combustion compared with conventional spark ignition engine.