Optimizing brake specific fuel consumption of low-NOx, emission standard compliant CI engines, by tuning engine parameters

Abstract

Reducing NOx from about 10.7 g/bhp-hr to about 4.5 g/bhp-hr caused a 6% loss in fuel economy in engine designs of the late 1980s and early 1990s [1]. Reasons for this loss in fuel economy are attributed to the loss in peak combustion pressure due to the delayed fuel injection among other technologies used in NOx control that leads to reduced cycle work. To compensate for the loss of work output, more fuel is provided to produce the desired work and leading to increased Brake Specific Fuel Consumption (BSFC). To optimize BSFC in Automobile Diesel Engines using Low-NOx technologies like fuel injection retard and fuel injection rate shaping, to stay within emission norms, a transient model was developed in Matlab/Simulink to control and optimize the various engine parameters contributing to the production of NOx and to realistically determine an ideal operating point for the functioning of an engine of a given configuration keeping in mind NOx production as well as BSFC. � 2009 Combustion Institute. All rights reserved.