Application of Flame Temperature Correlations to Emissions from a Direct-Injection Diesel Engine

The influence of flame temperature on NOx, particulate and hydrocarbon emissions from a single-cylinder light-duty direct-injection diesel engine was examined by varying the composition of the intake air with the engine operating at different speeds and loads. At a fixed engine speed, load, and start-of-combustion timing, the effects of intake-gas composition on emissions were found to correlate with variations in the characteristic diffusion flame temperature. Furthermore, this flame temperature dependence was not significantly affected by the engine operating conditions. These results indicate that the flame temperature correlations originally developed for divided-chamber diesel engines can be applied to direct-injection diesel engines.