Modeling and Parameter Identification of Spark Plug Deposit Formation Mechanism for Different Fuel/Lubricant Combination

Abstract

The identification of model parameters is complex and requires many approximations and laboratory investigations. Here, a novel approach to identifying these parameters is proposed, which uses experimental data, and a parameter estimation method to minimize a cost function made up of errors between the predicted and experimental deposit thickness. Parameters are determined for various ethanol–gasoline mixtures and lubricants. Simultaneously, the thermal and electrical properties of deposits are studied, and this information, coupled with the identified parameters, is utilized to infer potential deposit formation sources, mechanisms, and other elements that will influence the characteristics of the spark plug. It is found that the deposit formation model along with the identified parameters has the potential to reliably estimate the deposit growth with time as good correlations have been observed between measured and predicted spark plug deposit mass for all fuels and lubricants. The thermal and electrical conductivity of the spark plug deposit increases with a high ethanol fraction and high viscous oil, which results in increased chances of side sparking.