Effect of Compression Ratio and Injection Pressure on Emissions and Fuel Consumption of a Small Displacement Common Rail Diesel Engine
Date Published: 2005-04-11
Paper Number:2005-01-0379
DOI: 10.4271/2005-01-0379
Citation:
Mallamo, F., Badami, M., and Millo, F., "Effect of Compression Ratio and Injection Pressure on Emissions and Fuel Consumption of a Small Displacement Common Rail Diesel Engine," SAE Technical Paper 2005-01-0379, 2005, doi:10.4271/2005-01-0379.
The effect of variations of compression ratio (CR) and injection pressure (IP) on the emissions and performance of a small displacement common rail off-road diesel engine was evaluated.
The operating point corresponding to the 5th mode of the ISO 8178 - C1 test cycle (intermediate speed / full load) was considered, since it represents one of the most critical operating conditions as far as exhaust emissions are concerned.
The main effect of a reduction of the compression ratio, for a fixed injection timing, was found to be, as expected, an increase in NOx emissions along with a decrease of PM emissions, with a substantial redefinition of the PM-NOx trade-off curve; the choice of a proper value for the start of injection can therefore lead to a better compromise among pollutant emissions, although remarkable variations in BSFC and combustion noise must be taken into account.
Further improvements of the trade-off between PM and NOx emissions as well as of the combustion noise could also be achieved by means of a proper choice of the injection pressure.
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