Simulation of VGT control based on charge oxygen concentration

A turbocharged diesel engine model was built with the GT-Power software, and experimentally verified. Then two different control variables for the control of the variable geometry turbocharger (VGT) were described, and their distinct effects on engine performance, i.e. NO_x and soot emissions and fuel consumption, were simulated and compared on the basis of this model. The results showed that NO_x emissions decreased obviously with the increase of exhaust gas recirculation (EGR) rate at constant boost pressure condition, but soot emissions and fuel consumption considerably increased. It was a good way to reduce NO_x emissions without increasing fuel consumption and soot emissions when VGT was controlled to maintain the excess oxygen ratio unchanged as EGR rate increases.