Experimental spray ignition and soot forming characteristics of high reactivity gasoline and diesel fuel in a heavy-duty single-hole injector

Recent trends in the transportation energy sector indicate that demand for middle distillate fuels, such as diesel, will increase due to growing commercial traffic in emerging economies. In contrast, demand for light distillate fuels, such as gasoline, is projected to decrease due to fuel economy regulations imposed on passenger vehicles. Therefore, market forces suggest that fuels within the gasoline property range may become an attractive alternative for the heavy-duty commercial transport sector if they can be utilized as efficiently and robustly as diesel. Prior experimental work on a production heavy-duty engine demonstrated that high reactivity gasoline (RON 60, CN 34) can burn in a conventional mixing-controlled combustion mode with similar efficiency and lower soot emissions than diesel at a given engine-out NOx level. The observed emissions benefit was attributed to the high volatility and low aromatic content of the gasoline-like fuel. The current study is aimed at investigating the single-plume reacting spray characteristics of this gasoline-like fuel compared to diesel in order to further elucidate the dominant physical and chemical processes behind previously observed engine performance differences. Spray ignition and soot forming characteristics are measured in an optically accessible, constant-volume combustion chamber under heavy-duty engine relevant conditions. A parametric investigation of charge gas temperature from 800 to 1200 K at fixed injection and charge gas pressure is conducted. Ignition characteristics are determined using both optical and pressure based diagnostics. Soot forming characteristics for both fuels are compared using high-speed natural luminosity images.