Evaluation of Burned Gas Ratio (BGR) as a Predominant Factor to NOx

To elucidate the effects of EGR, the gas compositions in the cylinder at the end of the compression stroke, have been analyzed. The relationship of the burned gas fraction in the cylinder (defined as BGR) to NOx emission and misfire limit have been investigated and imply the following:

1. 1)
   NOx and misfire limit are strongly affected by the BGR at specified air fuel ratio and spark timing.
2. 2)
   Gas-fuel ratio which is the ratio of the total gas to the fuel in the cylinder is the predominant factor used extensively to evaluate the effects of EGR and/or lean mixture on NOx and misfire limit of an engine.