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To evaluate the potential of a dedicated LPG direct injection (LPDI) vehicle, we investigated several engine control parameters that are closely related to the characteristics of mixture preparation and nano-particle emissions. Many researches have pointed out that any amount of particle emissions from GDI vehicles were made during the cold start and cold transient phase. Therefore, in the study, four types of engine control strategies for the LPDI vehicle were applied to evaluate particle number (PN) concentration and regulated emissions in the cold start phase and the hot start phase under the FTP-75 cycle. The reduction rate of the PN concentration with LPG application reached approximately over 99% less than that of the GDI vehicle.

PN emissions were measured using a 2012 1.6L gasoline direct injection (GDI) engine vehicle. The measurements were performed over NEDC using domestic fuel from South Korea and Euro 5 certification fuel, also FTP-75 cycle using domestic fuel and Indolene (official emission test fuel in the US). Domestic fuel is the most volatile and has the least aromatics, Euro 5 certification fuel is the least volatile and has the most aromatics. Lower volatile gasoline generates more particle emissions due to diffusion combustion of fuel attached on the piston and fuel residues which are burned in its liquid form. Gasoline with more aromatic contents generates more particle emissions, too. Because aromatics have higher boiling point, lower vapor pressure and ring structures. Fuel specification difference resulted in PN emission difference. In NEDC tests, result using Euro 5 certification fuel was 77.0% higher than the result using domestic fuel.

In this study, present level of 2.0L GDI vehicle is measured and it is figured out how to reduce particle emissions against European emission limit(EURO 6) and US emissions standards(LEV 3) through engine test and vehicle test. A cause of PM and PN formation is divided into several reasons. This paper describes the optimization of engine control parameter and hardware change like injector type and injection target position like spray pattern optimization with minimizing side effect. If particle emission limit is getting more strengthen GPF(Gasoline Particle Filter) is a simple solution to meet particle emission limit. But engine performance decreases according to exhaust pressure increase and there is cost problem. This paper have shown that 60% level of euro6c PN limit is accomplished without a GPF at demonstrated vehicle.

Mixing characteristics of a Direct-Injection engine with liquefied petroleum gas were numerically investigated using a 3D unsteady Eularian-Lagrangian two-phase model. Numerical results were validated to the experimental data of heat release rate, pressure and mass flow rate of air. The numerical results and experimental data were in a good agreement. Simulations were conducted with various engine operation conditions to investigate the effects of supercharging on the mixing characteristics of the DI engine with LPG. The results showed that the fuel uniformities and evaporation rates of LPG are higher than them of gasoline. Fuel consumption rates and maximum cylinder temperatures of LPG were also higher than them of gasoline.

As the current and future emission regulations become stringent, the research on exhaust manifold with CCC (Close Coupled Catalyst) has been the interesting and remarkable subject. To design of exhaust manifold with CCC is a difficult task due to the complexity of the flow distribution caused by the pulsating flows that are emitted at the exhaust ports. This study is concerned with the theoretical and experimental approach to improve catalyst flow uniformity through the basic understanding of exhaust flow characteristics. Computational and experimental approach to the flow for exhaust manifold of conventional cast type, stainless steel bending type with 900 cell CCC system in a 4-cylinder gasoline engine was performed to investigate the flow distribution of exhaust gases.

This study has mainly focused on the development of turbine type LPLi pump. The flow rate of turbine pump was examined with various fuel blends of LPG. The experimental results of flow rate and fuel injection quantity of turbine type fuel pump have equivalent or better performance using summer season LPG fuel compared to BLDC one. However, the flow rate of turbine type pump decreased as the proportion of propane content in LPG fuel increased. The cause of flow drop was thought as the cavitations phenomena at high speed impeller component. Finally, the noisy characteristics and durability performance of turbine pump were tested. The hot start delay of LPLi engine was assessed with various composition ratio of LPG. The engine starting and pressure settling time of turbine pump showed equivalent performance to those of BLDC one.

The air fuel ratio of current gasoline engine is mostly controlled by various air flow meters. When CVVT (Continuous Variable Valve Timing) device is applied to gasoline engine for higher engine performance, MAP (Manifold Absolute Pressure) sensor can not be applied anymore due to intake valve motion. Therefore HFM (Hot film airflow meter) is used for measuring the intake air flow instead of MAP sensor. Usually HFM has a little sensitivity in flow direction, therefore reverse flow from engine to air cleaner can not be measured. Also, HFM maker request enough straight duct length nearly 10 times of a duct diameter making a fully developed flow. But, most vehicles have no enough space to install such an intake system in engine room. Thus the inserted duct was applied to confirm the stable fully developed flow in air duct. The various duct configurations in front of HFM effect on the sensitivity of HFM.

One of the methods to reduce the engine exhaust emission is to use CCC. To obtain the maximum conversion efficiency in CCC, the exhaust gas should be uniformly distributed across the frontal area of catalytic substrate and the engine should be operated close to the stoichiometric air/fuel ratio through the use of an oxygen sensor in the exhaust system. A theoretical and computational study of three-dimensional unsteady compressible non-reacting flow in three kinds of exhaust manifold and CCC system was performed to understand the flow characteristics and to estimate the effects of the geometry change. Also, in each case, proper oxygen sensor location where the exhaust gas can be efficiently measured is proposed.

The shape of unit cell of catalytic converter has great influence on the conversion efficiency and pressure drop characteristics. Therefore, the properties of design parameters of catalyst monolith were analyzed and the parameters of various cell shapes of catalyst were compared. Also, the numerical study of a three dimensional compressible flow in a Close-coupled Catalyst Converter (CCC) system was performed to investigate the flow characteristics and the flow distribution of exhaust gases. Unsteady flow analysis shows that severe interferences of each pulsating exhaust gas flow as well as geometric factors (junction, mixing pipe, cell shape etc.) influence greatly on the flow uniformity and flow characteristic in substrate. The results can be applied for the catalytic converter design.

Natural gas is considered to be an alternative fuel for passenger cars, truck transportation and stationary engines that can provide both good environmental effect and energy security. However, as the composition of fuel natural gas varies with the location, climate and other factors, such changes in fuel properties affect emission characteristics and performance of CNG (Compressed Natural Gas) engines. The purpose of the present study is to investigate effects of difference in gas composition on engine performance and hydrocarbon emission characteristics. The results show that THC decreases with an increasing WI (Wobber Index) and MCP (Maximum Combustion Potential) of natural gas. The power is shown to be proportional to the total heat value of the actual amount of gas entering the cylinder. There is 20% power variation depending on the composition of gas when the A/F ratio and spark timing are adjusted and fixed for a specific gas.