Effects of Multi-Stage Split Injection on Efficiency and Emissions of Light-Duty Diesel Engine

Abstract

The efficiency of light-duty diesel engines should be improved for further emissions regulation. Multi-stage split injection with five injection events was investigated for improvement in efficiency at low-load conditions. The injection timing and quantity were adjusted to achieve a smooth in-cylinder pressure rise and continuous heat release. The multi-stage split injection was compared to injection strategies involving two-pilot and single-main injections. A 0.5 L single-cylinder diesel engine experiment was conducted under low-load conditions. Two multi-stage split injection processes with different combustion phases were developed. The multi-stage split injections yielded a smooth in-cylinder pressure trace and a lower peak heat release rate than the two-pilot injection process. The combustion duration was shorter for multi-stage split injection with an advanced combustion phase, and the fuel consumption was reduced by 1.78% with lower heat transfer, exhaust heat, and combustion loss. The multi-stage split injection flame penetration was shorter than the two-pilot injections. The shorter flame penetration and lower tip velocity reduced the heat transfer to the combustion chamber. The PM emissions were also reduced by 30% under the same NOx emissions, because increased PM oxidation and divided fuel injection prevented flame diffusion and improved air utilization.

Experimental Studies of the Effect of Air Filter Pressure Drop on the Composition and Emission Changes of a Compression Ignition Internal Combustion Engine

“…The parameters of the injection system and the injection characteristics have a very large influence on the combustion, emissions and performance of a compression ignition engine. The primary technique used in modern common rail injection diesel engines is the multiple injection method, which is used depending on the purpose to be served [21][22][23][24]. Depending on the engine speed and load, modern diesel engines have pilot injection, primary injection and secondary injection.…”