Modeling of nonlinear fuel utilization phenomena during engine start and crank-to-run transition

In addition to profound nonlinear effects of fuel dynamics, a phenomenon related to unbalanced mass conservation, characterized by inefficient fuel utilization, has a significant impact for control purposes in engine cold start conditions. In particular, the incomplete fuel utilization effect has been found to be nonlinear throughout the first few fueling cycles in a robust engine start. In order to understand the impact of this phenomenon on cold start emission control, this paper addresses these issues and approximates the diminishing return effect by means of a nonlinear model, based on experimental data. The resulting model, by properly capturing the utilized fuel effect, is promising for fuel dynamics compensation