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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.

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.