超高EGRによる低酸素濃度雰囲気ディーゼル燃焼の諸特性と燃料噴射量依存性(熱工学,内燃機関,動力など)

概要

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Ultra-low NO_x, smokeless, and quiet operation without significant deterioration of engine performance and emissions is possible at up to half of rated torque (0.45MPa IMEP) with a large ratio of cold EGR to create an oxygen concentration of less than 9-10%. However, at higher loads, with the oxygen concentration kept below 9-10%, the air/fuel ratio has to be set over-rich in order to attain or exceed half of rated torque, and thermal efficiency, CO, and THC deteriorate significantly. As EGR rate increases, exhaust gas emissions and thermal efficiency vary according to intake oxygen content rather than with excess air ratio. While decreasing the oxygen content to 12% actually increases smoke emission, a further reduction of oxygen can decrease smoke. With low oxygen combustion, ISF of particulate matter is significantly reduced, but SOF cannot be eliminated. Although the combustion efficiency suffers remarkably from the reduced oxygen content, the indicated thermal efficiency does not significantly deteriorate because the low combustion temperature results in reduced cooling loss.
2005-10-25