• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.286-293
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• 2004

The air fuel ratios of current gasoline engines are almost controlled by several air flow meters. When CVVT (Continuous Variable Valve Timing) is applied to a gasoline engine for higher engine performance, the MAP (Manifold Absolute Pressure) sensor is difficult to follow the instantaneous air fuel ratio due to the valve timing effect. Therefore, a HFM (Hot Film Flow Meter) is widely used for measuring intake air flow in this case. However, the HFMs are incapable of indicating to reverse flow, the oscillation of intake air flow has an negative effect on the precision of the HFM. Consequently, the various duct configurations in front of the air flow sensor affect the precision of HFM sensitivity. This paper mainly focused on the analysis of the reverse flow, flow fluctuation in throttle upstream and the geometry of intake system which influence the HFM measurement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.6
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• pp.1921-1930
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• 1996

To design an optimum engine intake system, a flow model for the intake manifold was developed by the finite difference method. The flow in the intake manifold was one-dimensional, and the finite difference equations were derived from governing equations of flow, continuity, momentum and energy. The thermodynamic properties of the cylinder were found by the first law of thermodynamics, and the boundary conditions were formulated using steady flow model. By comparing the calculated results with experimental data, the appropriate boundary conditions and convergence limits for the flow model were established. From this model, the optimum manifold lengths at different engine operating conditions were investigated. The optimum manifold length became shorter when the engine speeds were increased. The effect of intake valve timings on inlet air mass was also studied by this model. Advancing intake valve opening decreased inlet air mass slightly, and the optimum intake valve closing was found. The difference in inlet air mass between cylinders was very small in this engine.

• Journal of Advanced Engineering and Technology
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• v.11 no.4
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• pp.253-257
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• 2018

Exhaust gas from the combustion of automobiles adversely affects the human body and even pollutes the atmosphere. This study investigated the influence of exhaust gas change on intake manifold using the nozzle. First, the flow analysis was performed using the 3D flow analysis program. When the nozzle inlet air velocity increased, the average air velocity in the nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$ increased 37.3% and 31.9% respectively at the intake manifold outlet. As the nozzle inlet air velocity increased, the maximum flow rate of air increased to 42.2% and 32.6%, respectively at nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$. In order to verify the analysis results, experiments on the exhaust gas were performed in the engine simulation system. As the nozzle inlet velocity increased, HC values decreased by 42.4% and 31.4% at nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$, respectively. And CO values decreased by 40.7% and 31.1% at nozzle diameters of ${\Phi}2.5$ and ${\Phi}5$.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.3
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• pp.394-403
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• 2008

The effects of water injection (WI) and urea injection for NOx on a 4-cylinder Direct Injection (DI) diesel engine were investigated experimentally. For water injection, it was installed at the intake pipe and the water quantity was controlled at the intake manifold and Manifold Air Flow (MAF) temperatures while the urea injection was located at the exhaust pipe and the urea quantity was controlled by NOx quantity and MAF. The effects of WI system, urea-SCR system and the combined system were investigated with and without exhaust gas recirculation (EGR). Several experiments were performed to characterize the urea-SCR system, using engine operating points of varying raw NOx emissions. The results of the Stoichiometric Urea Flow (SUF) and NOx map were obtained. In addition, NOx results were illustrated according to the engine speed and load. It is concluded that the NOx reduction effects of the combined system without the EGR were better than those with the EGR-based engine.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.6
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• pp.645-653
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• 2005

The effects of a WI(Water Injection) at the intake Pipe and an urea injection at the exhaust pipe for a 4-cylinder DI(Direct Injection) diesel engine were investigated experimentally The water quantity was controlled by temperature of intake manifold and MAF(Manifold Air Flow). In addition, the urea quantify was controlled by NOx quantify and MAF. Effects of WI system, urea-SCR system and tandem system were investigated for with and without EGR(Exhaust Gas Recirculation). As the results. the SUF(Stoichiometric Urea Flow) and NOx map were obtained. In addition, NOx results can be visualized with engine speed and engine load. It was concluded. therefore, that the NOx reduction effects of the tandem system without the EGR were more than those with the EGR base engine.

• Journal of Korean Society for Quality Management
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• v.9 no.2
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• pp.15-25
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• 1981

This paper deals with the experimental study on the behavior of fuel flow in intake manifold of gasoline engine. The main purpose of this study is an analysis of air stream velocity, behavior of liquid film flow, generation of atomization and atomization rate by using the basic apparatus which is manufactured the visible, straight tube type model of intake manifold. As the result, we have found factors which influenced on the behavior of liquid film flow in intake manifold.

• Journal of Power System Engineering
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• v.7 no.1
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• pp.14-19
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• 2003

A diesel engine has been widely used for ship and industry power because it has many merits of high thermal efficiency, reliability and durability. However its exhaust gas is harmful to human and air environment. Reducing the hurtful exhaust gas emissions, the study of the gas flow in the inlet and exhaust manifold is in progress in the world. In this paper we modeled the gas flow as one dimensional isentropic flow to predict the gas flow in the exhaust manifold. The method of characteristics was used for the model calculation, and the calculated results were compared with the experimental ones.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.3
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• pp.176-185
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• 2009

A general flow distribution model and a simple process of numerical analysis, which can be applied to multi-pass systems with manifolds, are presented. A numerical procedure, namely a modified equal pressure method based on the discrete model, was developed to predict flow rates at branch tubes. The predicted pressure distribution agreed well with the previous research with the average error less than 11%. A parametric study was performed to demonstrate the effect on the flow distribution.

• Journal of the korean Society of Automotive Engineers
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• v.5 no.3
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• pp.33-44
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• 1983

This paper deals with the experimental study on the behavior of fuel (methanol) in intake manifold by using the basic apparatus which is manufactured the visible straight tube type model. In this study, the new device for liquid film thickness measurement and vaporization rate measurement are introduced to investigate the variation of liquid film thickness along the intake manifold and to observe the effect of vaporization of injected fuel. the results are summarized as follows: 1) The vaporization rate increases in proportion to decreasing of throttle valve angle and growing air fuel ratio. 2) The liquid film thickness along the intake manifold is mostly independent for the throttle valve angle in low air velocity and then affected in high air velocity, but the distribution of the liquid film thickness on circumferential position almost constant in the region of 300mm down stream from carburetor. 3) The mean liquid film thickness is 0.04 - 0.18mm in case of methanol in the region of air velocity Va = 12m/s - 55m/s and decreases with decreasing the throttle valve angle.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1184-1189
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• 1990

In order to investigate liquid fuel filming over the intake manifold wall, an electrode-type probe has been developed by lines of authors and this probe was employed in a single cylinder two and four-stroke cycle engine and in a four cylinder four-stroke engine operated by neat methanol fuel. The performance of the probe was dependent upon several parameters including the liquid fuel layer thickness, temperature, additive in the fuel, and electric power source (i.e., AC and voltage level) and was independent of other variables such as direction of liquid flow with respect to the probe arrangement. Several new findings from this study may be in order. The flow velocity of the fuel layer in the intake manifold of engine was about (if the air velocity in the steady state operation, the layer thickness of liquid fuel varied in both the circumferential and longitydinal directions. In the transient operation of the engine, the temporal variation of fuel thickness was determined, which clearly suggests that there was difference between fuel/air ratio in the intake manifold and that in the cylinder. The variation was greatly affected by the engine speed, fuel/air ratio and throttle opening. And the variation was also very significant from cylinder to cylinder and it was particularly strong different engine speeds and throttle opening.