Real-Time and Robust Estimation of Biodiesel Blends Using NOx Sensor

Biodiesel as a renewable alternative fuel produces lower exhaust emissions with the exception of nitrogen oxides (NO_x) when compared to the conventional diesel fuel. Reducing nitrogen oxides produced from engines running on biodiesel is a challenging task to be able to meet the emission requirements. Knowledge of fuel blend could be very helpful for control and adaptation purposes to tune the engine control system parameters leading to lower NO_x emission and improved engine performance. Proposed in this paper is a NO_x sensor-based biodiesel blend estimation strategy. This strategy is fitted in a robust adaptive estimation structure for achieving a robust estimation. Sensitivity analysis has been done to check the robustness of the estimators against measurement errors.