커먼레일 엔진의 인젝터 종류 및 EGR 장착에 따른 바이오 디젤유의 배출가스 특성에 대한 연구

Abstract

Modern society has made progress in many areas after the industrial revolution, including the development of mechanical engineering. The Industrial Revolution from the mid-18th century to the early 19th century due to technical innovation which started in British society is based on the great economic transformation. This development has been achieved many changes and developments throughout the human life. 1892 by the German engineer Rudolf Diesel diesel engine was invented, and it was to play a pivotal role in modern industry and it has modified by using new fuel, which corresponds to the environmental pollution and improve the performance of the car in order to reduce the use of fossil fuels. In this paper, the injector type and biodiesel mixed rate was changed to investigate the performance and the composition variation of the exhaust gas with respect to the exhaust of an odd component in the current diesel vehicle by using a simulation engine. Besides, those were analyzed with/without the EGR system in the diesel engine. Component of the exhaust gas like HC, NOx, CO2, and CO, was measured under various operating conditions. The experimental was carried out by using a simulation engine which was the D-2.0 (D4EA) diesel engine with a displacement of 1,997 cc. Each experiment was carried out 10 times which were analyzed obtaining the average of the experimental data. The set speed of the engine was changed by 780, 1000, 1500, 2000, 2500 rpm, and classified as to analyze the exhaust gas components according to operating condition change. Experiment performed with a variation of the injection holes which was varied by 5-, 6-, and 7-hole injector. In addition, diesel and biodiesel fuel blend ratio was changed by 100:0, 90:10, 80:20, and 70:30 of diesel:biodiesel in order to determine the effect of gas fuel blend ratio with biodiesel into diesel. Hydrocarbon (HC), nitrogen oxide (NOx), carbon monoxide (CO), and carbon dioxide (CO2) were analyzed with the concentration ratio of bio-diesel and engine speed. Finally, the effect of injector cleaning in the fuel injector was also investigated by using experimental test on the point of smoke generation. As a result, the spray shape and pressure increased after injector cleaning. The average particulate concentration after injector cleaning is significantly reduced. Before the injector cleaning, the maximum soot generation rate was about 80% and the average soot generation rate was also 72% for long period. But after injector cleaning, the maximum soot generation rate was reduced by 32% and the average soot generation rate was also 28%. Besides, for ten cars, the amount of soot can be reduced over the 20% by the injector cleaning, which was changed from 46.7% to 22.5%. In case of the performance comparison with injector nozzle holes, the 6- and 7-hole injector was effective to the reduction of HC, NOx, CO2, CO compared to the 5-hole injector. Among 6- and 7-hole injector, the 7-hole injector had better performance to the reduction of exhaust gas. Therefore, the 7-hole injector was the best to the reduction of HC, NOx, CO2, and CO, so it can be applied to the other test. The exhaust gas composition analysis with biodiesel blend ratio(0%, 10%, 20%, 30%) for 7-hole injector, the reduction effect of exhaust gas like HC and NOx, becomes strong by using biodiesel compared to that of non-use biodiesel. By injection the biodiesel to the diesel, the exhaust concentration of HC decreased by 5%~6% for any engine speed. In addition, that of NOx could be reduced by 4.4 ppm. Especially, the bio-diesel blend ratio of 20% showed the best performance to the decrease of harmful gases. However, the exhaust concentration of CO and CO2 did not affected by the biodiesel blend ratio. When the EGR system was operated with bio-diesel blend ratio of 20% and the 7-hole injector to the diesel engine, the exhaust rate of NOx decreased by 52.8% and 53.8% for engine speed of 1000 and 1500 rpm. However, that did not affected over the 2000 rpm. Besides, the exhaust concentration of CO was decreased by 0.004%~0.012%. In case of exhaust rate of CO2, it increased over 50% by using EGR system. Therefore, the EGR system has good effect to the reduction of CO and NOx, but it play a role of increase the CO2 and HC. Overall, it was confirmed that the emission can be reduced by the injector cleaning and the 7-hole injector has the best performance and low emission. Besides, the biodiesel blend ratio of 20% is the most effective to reduction of exhaust gas. EGR system is also effective to the decrease of NOx. Required study for next plan, the performance test is need under the high-speed state with/without EGR system. Further studies should be made also for the mathematical modeling of the combustion process in the exhaust gas with the variation of biodisel mixing ratio.