• 대한기계학회논문집B
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• 제22권9호
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• pp.1317-1324
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• 1998

In general, DI gasoline engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance and lower emissions due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. In order to apply the concept of stratified charge into direct injection gasoline engine, some kinds of methodologies have been adapted in various papers. In this study, a reflector was adapted around the injector nozzle to apply the concept of stratified charge combustion which leads the air-fuel mixture to be rich near spark plug. Therefore, the mixture near the spark plug is locally rich to ignite while the lean mixture is wholly introduced into the combustion chamber. The characteristics of combustion is analyzed with the variations of fuel injection pressure and load in a stratified -charge direct injection single cylinder gasoline engine. The obtained results are summarized as follows ; 1. The MBT spark timing approached to TDC with the increase of load on account of the increase of evaporation energy, but has little relation with fuel injection pressure. 2. The stratification effects are apparent with the increase of injection pressure. It is considered by the development of secondary diffusive combustion and the increase of heat release of same region, but proceed rapidly than diesel engine. Especially, in the case of high pressure injection (l70bar) and high load (3.0kgf m), the diffusive combustion parts are developed excessively and results in the decrease of peak pressure than in the case of middle load. 3. The index of engine stability, COVimep value, is drastically decreased with the increase of load. 4. To get better performance of DI gasoline engine development, staged optimizaion must be needed such as injection pressure, reflector, intake swirl, injection timing, chamber shape, ignition system and so on. In this study, the I50bar injection pressure is appeared as the optimum.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.121-126
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• 2006

A gasoline-fueled stratified charge compression ignition (SCCI) engine with both direct fuel injection and intake temperature and compression ratio was examined. The fuel was injected directly by using the high temperature resulting from heating intake port. With this injection strategy, the SCCI combustion region was expanded dramatically without any increase in NOx emissions which were seen in the case of compression stroke injection. Injection timing during the intake temperature was found to be an important parameter that affects the SCCI region width. The effect of mixture stratification and the effect of fuel reformation can be utilized to reduce the required intake temperature for suitable SCCI combustion under each set of engine speed and compression ratio conditions.

• 한국산업융합학회 논문집
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• 제10권1호
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• pp.21-26
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• 2007

As DDI or GDI engine discharges very low heat due to its high thermal efficiency, the heat source is not enough for heating the passenger compartment in cold climate condition. To remedy the heating problem, the conventional HFC-134a automotive air-conditioning system has been attempted to run as a heat pump mode. Futhermore, an auxiliary electric heater of new type was equipped to the heat pump air-conditioning loop as a new approach. Hence, a proto-type heat pump air conditioner has been made and tested to investigate the feasibility of the HFC-134a automobile air-conditioning system that could be worked as a heat pump. The experiment results showed that the sufficient heating capacity could be obtained by adding a heat pump with an new electric type auxiliary heater into the conventional heat core in low temperature condition.

• 한국분무공학회지
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• 제14권4호
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• pp.184-189
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• 2009

Recently, ultrafine particles emitted from internal combustion engine is main concern because of its well known adverse health effects. So Europe decided to start the regulation about diesel engine particle number emissions. The nanoparticles smaller than 50nm in diameter have the ability to penetrate deep into interstitial tissue of luge, where they may cause severe respiratory inflammation and acute pulmonary toxicity. Recent studies have showed that spark ignition engines emit particles number concentration comparable to those from diesel engines with DPF under high load and rich mixture conditions, including cold starts and acceleration. So this study investigated emission characteristics of ultrafine particles according to fuel injection type in gasoline vehicles and LPG vehicles. The test vehicles were tested on CVS-75 and NEDC vehicle test mode using the chassis dynamometer, CPC system applied as a particle measuring instrument at the end of dilution tunnel. As a result, the correlation between fuel injection type and particulate emission was determined. GDI vehicle emitted 10 times higher particles than PFI vehicles, and compared to Mixer and LPGI type LPG vehicle, LPLI vehicle emitted particles high.

• 대한기계학회논문집B
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• 제39권7호
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• pp.609-615
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• 2015

본 연구는 직접분사식 가솔린엔진에서 공기 과잉률 및 바이오에탄올-가솔린 혼합연료의 혼합비에 따른 연소특성과 배기배출물 특성을 실험적으로 규명한 것이다. 다양한 공기 과잉률 및 혼합비 조건에서 실험을 수행하였으며, 연소실 압력, 열발생률, 연료소비율 등을 통해 연소특성을 분석하였으며, 배기배출물 특성은 미연탄화수소(HC), 일산화탄소(CO), 질소산화물($NO_x$) 분석을 통해 확인하였다. 혼합연료의 실험결과는 100% 가솔린 및 바이오에탄올 실험결과와 비교하였다. 실험결과 최고연소압력과 열발생률, 제동연료소비율은 혼합비의 증가에 따라 증가하였으며, CO, HC, $NO_x$와 같은 배기배출물은 바이오 에탄올 혼합비율이 증가함에 따라 감소하였다. 혼합연료의 배기배출물 수준은 가솔린 보다 낮게 나타났다.

• 대한기계학회논문집B
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• 제25권10호
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• pp.1303-1310
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• 2001

In order to be applicable to the combustion modelling of stratified charged combustion like that of - lean burn and GDI engine, the correlations of laminar burring velocities fur several hydrocarbon fuels and methanol are needed over a wide range of equivalence ratio, pressure and temperature. In this study, these correlations are modeled in the 1311owing form based on the experimental and Muller\`s modeling results for several fuels, where $\alpha$, ξ, and ξ are functions of pressure and temperature, $S_{L}$ =$\alpha$ exp[-ξ($\Phi$-$\Phi$$_{m}$)$^{2}$ -exp {-ζ($\Phi$-$\Phi$$_{m}$)}-ζ($\Phi$-$\Phi$$_{m}$)]. By using the results calculated by PREMIX code with Sloane\`s detailed chemical reaction mechanism for propane, it is verified that the coefficients of the abode modeling can be determined by considering laminar burning velocity data only in a range of equivalence ratio less than $\Phi$$_{m}$. Therefore, Muller\`s modeling results can be adopted leer modeling of the pressure and temperature dependency. Compared with the results of the existing Keck'and Gulder's models, those of the present one showed the good agreement of the recent experimental data, especially in the range of lean and rich sides.s.des.s.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3467-3472
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• 2007

The effects of the wall geometry on the spray-wall impingement process of a hollow-cone fuel spray emerging from a high-pressure swirl injector of the Gasoline Direct Injection (GDI) engine were investigated by means of a numerical method. The ized Instability Sheet Atomization (LISA) & Aerodynamically Progressed Taylor Analogy Breakup (APTAB) model for spray atomization process and the Gosman model were applied to model the atomization and wall impingement process of the spray. The calculation results of spray characteristics, such as a spray development process and a radial distance after wall impingement, compared with the experimental ones by the Laser Induced Exciplex Fluorescence (LIEF) technique. It was found that the radial distance of the cavity angle of 90$^{circ]$ after wall impingement was the shortest and the ring shaped vortex was generated near the wall after spray-wall impingement process.

• 한국분무공학회지
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• 제6권4호
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• pp.39-48
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• 2001

The Gasoline Direct Injection(GDI) system has been highlighted due to the improvement of fuel consumption and the control of exhaust emission from gasoline engines. Main purpose of the present study is to measure spray characteristics of GDSI for real engine application. We have investigated experimentally spray tip penetration, spray angle, tip velocity and spatial spray distribution. Counter-rotating vortex grown on the spray surface plays an important role in the spray characteristics. Accordingly the spray tip penetration and tip velocity do not excess 50mm, 20m/s respectively, under 0.6MPa ambient pressure. the spray cone angle of GDSI have a same tendency to a simplex swirl atomizer.

• 한국자동차공학회논문집
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• 제22권2호
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• pp.37-43
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• 2014

Exhaust emissions were studied as a function of gasoline olefin composition in two vehicles-MPI and GDi engine equipped vehicles. Three different gasolines were tested which varied in olefin contents-12, 16 and 20 vol%. Exhaust emissions in two vehicles were affected by changes in gasoline olefin composition. Responses to changes in olefins were similar in both vehicles : reducing olefins lowered emissions of NOx and CO. Measured exhaust emissions included total hydrocarbons (THC), oxides of nitrogen (NOx), carbon monooxide(CO), carbon dioxide($CO_2$), formaldehyde, benzene, toluene, xylene, 1,3-butadiene and acetylene.

• 한국자동차공학회논문집
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• 제7권8호
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• pp.1-6
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• 1999

An experimental study was carried out to investigate the global spray behavior and spray characteristics of high-pressure fuel injector in the direct-injection goasoline enginet. The atomization characteristics of fuel spary such as mean droplet size, mean velocity , and velocity distribution were measured by the phase Doppler particle analyzer. The spray tip penetration and spray width were investigated by the result fo visualizaiton experiment. The quantitiative spary characteristics of injector spray were measured under various sparay conditions and ambient pressures. The results of experiment show that the increase in ambient pressure have influence on the spray tip penetration and spray development process. Also, the influence of injection pressure and measuring location on the mean velocity and droplet size distribution were discussed.