A physical model for the interdigitated fuel drivability index sensor

Abstract An on-board drivability index (DI) sensor has been invented at Delphi Corporation. It is anticipated that the sensor could be used to reduce exhaust emission and improve engine performance during cold starts. During a DI measurement, the initial amount of fuel captured in the sensor declines as the sensor temperature is raised by built-in heating elements. A volatilization curve, a plot of the fuel level versus the sensor temperature, is thus obtained and the DI of the test fuel can be estimated. In this work, a model is proposed that simulates the curves obtained from the DI sensor measurement. This model assumes that the saturated vapor pressure curve for the test fuel determines the shape of its volatilization curve. The model suggests that mass transfer of fuel constituents to the liquid–air interface could be a rate-determining factor for the volatilization process.