Modeling a Variable-Geometry Turbocharged Diesel Engine under Steady-State and Transient Conditions

In the present work, a detailed thermodynamic model of a variable-geometry turbocharged (VGT) truck diesel engine has been built in the GT-Power environment in order to study its operation in terms of turbocharger and engine performance and engine-out emissions. The studied pollutants are nitrogen oxides and smoke, the latter used here as a surrogate for regulated particulate matter. The important feature of the paper is that not only the steady-state but also the transient operation is under investigation. By doing this, the much more demanding dynamic engine operation is analyzed, and useful conclusions are derived in comparison to the fixed-geometry operation of the engine in hand. In particular, the advantages of VGT operation in terms of higher boost pressure and air supply to the engine cylinders, resulting in higher injected fuel, faster acceleration, and a smaller amount of engine-out soot compared to the base line engine, are among the most important results of the study. (C) 2018 American Society of Civil Engineers.