Experimental Study of Two Air Management Strategies for Emissions Control in Heavy Duty Engines at Medium to High Loads

摘要

Different air management strategies, Miller timing and internal EGR (iEGR), have been studied on internal combustion engines with the objective of decreasing NOx emissions. This paper explores heavy duty diesel engine performance by the application of both strategies separately through two different camshaft configurations, mounted and tested in the same engine. On one side, in the case of Miller timing, the early intake valve closing is explored, and on other side, for iEGR, the study is carried out opening the exhaust valve during the intake process. The engine emission and performance study is achieved through the application of a methodology which begins with the selection of the operating points focusing on medium to high loads. It continues with the exploration of different camshaft profiles by mean of a 1D model. Through the 1D model, two camshaft profiles are selected and tested in the test cell, determining the intake valve closing conditions followed by the identification of the thermodynamic behavior during the compression stroke before the injection. Later on, the combustion and emissions formation analysis is performed to conclude with the fuel consumption study for each implemented strategy taking into consideration the important influence of each camshaft profile in the pumping loop. A short discussion on the transient performance effect of each air management strategy completes the scope of the study.