Statistical Analysis of Diesel Vehicle Exhaust Emission: Development of Empirical Equations to Calculate Particulate Emission

Many studies have been completed over the past thirty years in search of a correlation between particulate emissions and exhaust smoke opacity for diesel fuel vehicles. A simple, direct correlation between opacity and particulate emissions does not exist due to the wide variety of factors that affect the production of diesel particulates. In an attempt to address this deficiency, data from the Australian National Environmental Protection Council for 72 vehicles deemed representative in terms of vehicle make, age and mass were analysed. The data included opacity and particulate measurements as well as a breakdown of emissions in terms of O₂, CO, CO₂, NO_x, and HC readings for each vehicle as it was tested according to a comprehensive drive cycle. These drive cycles were developed to be representative of driving in a range of urban traffic conditions on Australian roads. The best model for predicting particulate matter was identified to have a linear relationship with the average opacity, vehicle mass, fuel consumption and O₂, CO and NO_x readings. As diesel vehicles are classified into six categories by the Australian Design Rules (ADR), correlations for particulate matter were also developed for each vehicle category. The best model for predicting particulate matter across all six ADR categories (with different numerical coefficients for each category) was found to linearly depend on the average opacity, vehicle mass, cumulative power and O₂, CO, CO₂ and NO_x readings. Excellent results were found in four of the six ADR categories examined.