Prediction of soot emission from a diesel engine by using phenomenological soot formation model modified by the concept of threshold sooting index

Abstract

The existing phenomenological soot model, which unburned fuel is considered soot precursor, cannot predict the soot emission of alcohol blend fuel with high accuracy. Therefore, we proposed to introduce the coefficient Keff including the concept of Threshold Sooting Index (TSI) which quantitatively expresses the fuel sooting tendency of blend fuel. In this research, for more accurate prediction of soot emission we conducted the elementary reaction analysis of blend fuel using reduced mechanism for n-heptane, n-butanol and Polycyclic Aromatic Hydrocarbon (PAH) with 76 species and 349 reactions. Based on the clarified relationship between pyrene (A4) and TSI, we derived the equation through which Keff is calculated. By using the equation, the accuracy of the soot emission prediction was improved particularly in the low alcohol blend rate.

Keywords

• diesel engine
• alcohol blend
• numerical simulation
• phenomenological model
• threshold sooting index