Believed to have a potential in reducing the NOx emission level, hydrogen peroxide was fumigated into the inlet duct of the AVL single cylinder research engine via a standard gasoline injector, normally used in the Volvo 850-car engine. A small metallic sphere installed 3 cm downstream the injector tip, improved the spray formation and the uniform distribution of the fumigated peroxide fluid upstream the intake valve. The hydrogen peroxide flow was varied according to the desired value via an electronic pulse frequency generator.
The engine, equipped with an electronic unit injector, was initially run without any fumigation fluid until the specifications of the engine test point were reached and remained very stable. Further, the hydrogen peroxide injection was activated with three different injection flows, and the engine performance, including emission levels, was compared to reference performance. To avoid secondary effects on combustion processes and emission levels, the engine was run with the same fuel/air ratio.
The most expected effect of the hydrogen peroxide fumigation would be on the NOx emission reduction. However, it was observed that other emissions such as CO and HC were remarkably affected as well. Experimental results have shown that the hydrogen peroxide fumigation affects the engine thermochemistry, but not necessarily the fuel consumption and other energetic parameters of the engine. However, the increase of the fumigation flow above a certain limit could deteriorate the combustion quality, thereby increase HC, CO and soot formation levels.
Nevertheless, heat release and ignition delay, (evaluated according to the “Dragon” software program and acquisition from “Burst to File” PC based sampling system)[1], [3] show that the optimal fumigated flow of the hydrogen peroxide might reduce the ignition delay, and thereby significantly improve the engine thermochemistry output.
Verified effective possibilities for using hydrogen peroxide fumigation, would lead to a proper version of the intake manifold design, which would bring to another solution for low emission level diesel engines