小型直接噴射式ディーゼル機関の排出未燃分および微粒子の特性 : 第2報, DME予混合気を供給した場合

概要

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Early stage fuel injection and its combustion system with lean and homogeneous mixture under compression ignition have been investigated to decrease the pollutant emission of DI diesel engines. This method enables drastic reductions in both NO_x and smoke emissions, but the operating load range is restricted due to the unusual combustion phenomena such as unsteady combustion or knocking. This research investigated the possibility of broadening the operating load range and reducing unburnt HC using Dimethyl Ether (DME) premixed gas charged through the intake pipe. However, the broadening in load range was found to be less than BMEP 0.1 MPa even when compression ratios were reduced and high octane gaseous fuel was mixed. Therefore, a DME premixed charge could be used only at light loads. At heavier loads, a hybrid fuel system with the DME premixed charge and diesel fuel injection is necessary. It was found that DME operation yielded significant reductions in both NO_x and smoke, and hybrid fuel operation could reduce smoke emission when DME was charged up to the knocking limit. Component analysis of unburnt emissions was made by gas-chrmomatography, and it was found that the high molecular weight fraction is reduced by the charging with DME mixture.
社団法人日本機械学会の論文
1999-09-25