• 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.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.112-117
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• 2007

With the Euro-4 regulation coming into effect, the domestic car industry is forced to look for newer options to reduce NOX in the exhaust. EGR(Exhaust Gas Recirculation) Cooler is an effective method for the reduction of NOX form a diesel engine. High efficiency, low pressure loss and compactness are desirable features of an EGR Cooler. The cooling performance of EGR depends on the shape of tubes and the location of the entrance and exit. This paper reports the computational work conducted to estimate the performance of EGR cooler with three different cross section tubes and a triangular spiral tube. Three dimensional computation results show that the triangular tube is more effective than circular and rectangular tube. The most effective geometry is a triangular spiral tube with offset inlet and outlet locations.

• 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.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.928-933
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• 2001

EGR(Exhaust Gas Recirculation) is an effective strategy to control nitrogen oxides emissions from diesel engine. The EGR reduces $NO_x$ through lowering the oxygen concentration in the combustion chamber as well as through heat absorption. However, application of EGR system is difficult because of the penalty in fuel consumption and the increase in particulate matter. The engine used for the experimental was a 3-cylinder 0.8-liter turbo-charged light duty diesel engine with an electronic EGR valve. In this study, experiments were performed at variable vehicle speeds and loads on the chassis dynamometer. To evaluate the exhaust emissions with the EGR system testing was performed using cvs-75 mode test procedure. Results of the cvs-75 mode test achieve sufficiently to meet EURO3 standards.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.3-15
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• 1993

A multi-cylinder four cycle spark ignition engine equipped with on exhaust gas recirculation(EGR) system to reduce nitric oxide emission and to improve fuel consumption rate has been comprehensively simulated In a computer program including intake and exhaust manifolds. To achieve these goals, this program was tested against experiments performed on a standard production four cylinder four cycle gasoline engine with EGR system. As EGR rate Increased, the maximum temperature of combustion chamber and NO omission concentration decreased under each driving condition. But the emission concentration of CO didn't change much through whole district in spite of the increase of EGR rate. Fuel consumption rate improved under each driving condition according to the increased of EGR rate until 10 percent EGR rate. Therefore the degree of EGR depend not only on the NO emission but also on the economy and the engine performance criteria of the engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.37-43
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• 2003

The exhaust gas recirculation (EGR) is needed for one of various strategies to reduce NOx emission. But to get the proper EGR rate, the intake and exhaust system become complicated, also application of EGR system is difficult because of the penalty in fuel consumption and the increase in particulate matter. This study is focused on the development of EGR valve using the electrical method. The effects of EGR on the characteristics of NOx, CO, CO2 emissions and particulate mater have been investigated using small-displacement size 0.8-liters engine of diesel passenger car operating at several loads and speeds. After the analysis and comparison between conventional E-EGR valve and developed E-EGR valve performance by test bench, the estimation of vehicle application was executed through the EGR map and CVS-75 test result measured on the chassis dynamometer.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.135-137
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• 2014

Excess enthalpy flame propagating an porous inert medium, which recirculate exhaust heat to the upstream cold mixture, is theoretically analyzed. Using the activation-energy asymptotics, the flame structure is divided into the thin reaction and the gas-phase preheat zone, as is traditionally done. Ahead and behind of the two, there exist an outer preheat zone, where heat is convectively transferred from solid to gas, and a downstream re-equilibrium zone, where thermal equilibrium between phases is established. Asymptotic solutions of species and energy equations in each zone are obtained and then matched to each other, and finally the mass burning rate is obtained as a function of the flame propagation velocity with respect to the solid phase and physical properties of gas and solid.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.329-334
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• 2009

An oxy-fuel boiler has been developed to capture $CO_2$ from the exhaust gas. FGR (flue gas recirculation) is adopted to be compliant with the retrofit scenario. Numerical simulations have been performed to study the detailed physics inside the combustion chamber of the boiler. The temperature field obtained from the simulation agrees with the flame image from the experiment. The FGR combustion yields similar heat transfer characteristics with the conventional air combustion while the flame is formed further downstream in case of the FGR combustion.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.151-158
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• 2007

The static and dynamic behaviour of VGT and EGR systems has a significant impact on overall engine performance, fuel economy and exhaust emissions. This is because they define the state and composition of the air charge entering the engine. This work focused on the effect of the aperture ratio of VGT and EGR on the emission and flow characteristics under partial loads conditions. The investigation carried out using 2 liter PCCI 4 cylinder diesel engine with VGT and EGR. The result of this study shows that smoke increases with increasing EGR rate and NOx decreases with increasing EGR rate. It was also found that the residual gas contents greatly impact on soot emission under partial load condition. Finally, it can be concluded that VGT and EGR aperture ratio can greatly impact not only on soot and NOx but also air charging.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.4
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• pp.493-501
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• 2013

Taking into account the increasingly stringent legislation on emissions from marine engines, this work aims to analyze several internal engine modifications to reduce $NO_x$ (nitrogen oxides) and other pollutants. To this end, a numerical model was employed to simulate the operation cycle and characterize the exhaust gas composition. After a preliminary validation process was carried out using experimental data from a four-stroke, medium-speed marine engine, the numerical model was employed to study the influence of several internal modifications, such as water addition from 0 to 100% water to fuel ratios, exhaust gas recirculation from 0 to 100% EGR rates, modification of the overlap timing from 60 to $120^{\circ}$, modification of the intake valve closing from 510 to $570^{\circ}$, and modification of the cooling water temperature from 70 to $90^{\circ}C$. $NO_x$ was reduced by nearly 100%. As expected, it was found that, by lowering the combustion temperature, there is a notable reduction in $NO_x$, but an increase in CO (carbon monoxide), HC (hydrocarbons) and consumption.