Accurate Measurements of Heat Release, Oxidation Rates, and Soluble Organic Compounds of Diesel Particulates through Thermal Reactions

In an effort of providing better understanding of regeneration mechanisms of diesel particulate matter (PM), this experimental investigation focused on evaluating the amount of heat release generated during the thermal reaction of diesel PM and the concentrations of soluble organic compounds (SOCs) dissolved in PM emissions. Differences in oxidation behaviors were observed for two different diesel PM samples: a SOC-containing PM sample and a dry soot sample with no SOCs. Both samples were collected from a cordierite particulate filter membrane in a thermal reactor connected to the exhaust pipe of a light-duty diesel engine. A differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA) were used to measure the amount of heat release during oxidation, along with subsequent oxidation rates and the concentrations of SOCs dissolved in particulate samples, respectively. The DSC experiments revealed that the amounts of heat released from the oxidation of SOC-containing PM sample, dry soot, and SOC itself were approximately 14.6 kJ/g, 17.2 kJ/g, and 5.4 kJ/g, respectively, in which the largest heat release was obtained from the dry soot sample. The effects of ambient heating temperature on dry soot oxidation were also investigated under isothermal oxidation conditions. The results revealed that the oxidation rate depends on the heating temperature. Meanwhile, the amount of SOCs dissolved in PM samples was turned out to be approximately 20 % in average with respect to the initial sample mass.