: The purpose of this study is to investigate the performance characteristics of the counterflow exhaust heat recovery device for the applied gasoline engines. The EHRS device is installed behind the catalyst. This study investigates the engine warm-up characteristic, the exhaust noise characteristic, the back-pressure characteristic . The engine warm-up characteristics is (load 0%, load 10%, load 20%) in (idle, 1000rpm, 1500rpm, 2000rpm, 2500rpm) conditions by measuring the time it warmed up, coolant temperature (25°C~80°C) until the performance evaluation is performed. The wide open throttle and the coast down the exhaust noise and the back-pressure characteristic experiment repeated twice. The test conditions is 950rpm~6,050rpm proceed experiment repeated 3-5 times. Load 0% idle conditions except the results improved engine warm-up characteristics. The exhaust noise obtain similar results the BASE+EHRS W/O_FRT_MUFF with BASE and back-pressure to obtain similar results BASE+EHRS W/O_FRT_ MUFF with BASE+EHRS.

Performance optimization of a small engine intake port has been studied through computational and experimental approach. Port angle, flange area and port shape are very important design parameters affecting performance of an intake port. Especially, radius of curvature of intake port inner surface has major effect on the flow coefficient of an intake port. As increasing port angle and flange area, flow coefficient is increased because pressure distribution and pressure gradient in the intake port are improved. Even though computational results over-predict maximum 8% compared with experimental result, they describe the tendency of flow coefficient according to the design parameters. Optimized intake port shows about 4.5% improved flow performance.

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This study has the purpose to consider a new ignition source in order to increase the inflammable limit of a gasoline engine at its lean region. To analyze flame propagation characteristics, a CVCC (constant volume combustion chamber) was produced, and three types of devices – conventional type, arc type, and jet type – were manufactured to conduct combustion testing. Experimental variables were the air/fuel ratio from 1.0 to 1.8 and charging pressure from 2 bar to 4 bar. The result of flame propagation analysis showed that the spread for jet type was faster than that of conventional type by 10 ms, and that of arc type by 5 ms. Result of combustion pressure experiment showed that, at air/fuel ratio of 1.0, arc type showed the highest value, with 22 bar, while jet type showed 19.4 bar and convention type was 17 bar. At maximum inflammable limit experiment, combustion was possible at jet type and arc type in an area above an air/fuel ratio of 1.8, but the conventional type showed miss fire, where combustion did not occur in the area above 1.6. The Study on new ignition source concluded that the jet type shows superior results in terms of combustion speed while the arc type is excellent in terms of combustion pressure.

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