Design and Simulation of Two Stroke Engines

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Chapter 7 - Reduction of Fuel Consumption and Exhaust Emissions
QUB 500 RESEARCH ENGINE
AIR-ASSISTED FUEL INJECTION
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TRAPPED AIR-TO-FUEL RATIO
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Fig. 7.55 Effect of fueling on bsNOx at full load, 3000 rpm.
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QUB 500 RESEARCH ENGINE
AIR-ASSISTED
FUEL INJECTION
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TRAPPED AIR-TO-FUEL RATIO
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Fig. 7.56 Effect of fueling on bmep at part load, 1600 rpm.
The bsNOx characteristics, presented in Fig. 7.55, show that air-assisted injection gives
no significant change during operation at rich or lean air-fuel ratios. Note that it peaks at the
stoichiometric value. However, a reduction in NOx is noted during stratified charge operation,
close to the stoichiometric air-fuel ratio. This feature may be due to the stratification of
the charge and the reduced NOx formation in local combustion zones which are variably rich
or lean.
The part load (throttle) results, presented in Figs. 7.56-7.59, show similar highly significant
improvements in fuel economy and hydrocarbon emissions. The minimum bsfc is reduced
from 374 g/kWh to 303 g/kWh, and the minimum bsHC is reduced from 61 g/kWh to
525