Biodiesel Imposed System Responses in a Medium-Duty Diesel Engine
The often-observed differences in nitrogen oxides, or NOx, emissions between biodiesel and petroleum diesel fuels in diesel engines remain intense topics of research. In several instances, biodiesel-fuelled engines have higher NOx emissions than petroleum-fuelled engines; a situation often referred to as the "biodiesel NOx penalty." The literature is rich with investigations that reveal many fundamental mechanisms which contribute to (in varying and often inverse ways) the manifestation of differences in NOx emissions; these mechanisms include, for example, differences in ignition delay, changes to in-cylinder radiation heat transfer, and unequal heating values between the fuels. In addition to fundamental mechanisms, however, are the effects of "system-response" issues.