Robust fuel consumption estimation for on-line optimization of diesel engines

Accurate estimation of Brake Specific Fuel Consumption (BSFC) is required to enable on-line optimization of real-world fuel efficiency of diesel engines. This work aims to develop a BSFC estimation method which is accurate enough for an adaptive controller for on-line engine optimization, e.g., using Extremum Seeking. In this paper two different BSFC estimation methods are evaluated: A heat-release based method using in-cylinder pressure sensors and an approach based on injector opening time. Analysis of the two approaches shows that the injector opening time approach yields the highest accuracy. This method together with an adaptive controller is validated experimentally on a Euro-VI diesel engine. Experimental results show that the BSFC estimation is robust against variations in combustion phasing and scavenging losses. The estimated location, in terms of combustion phasing and scavenging losses, of the BSFC minimum remains within 0.1% relative error with respect to the measured BSFC minimum.