Preliminary Thermal Analyses on Diesel Converter Overheating

The use of oxidation catalytic converters (OCC) in Diesel engines has proved to be an effective method to reduce emissions of total hydrocarbons (THC), carbon monoxide (CO), and the soluble organic fractions (SOF) of particulate matter (PM). However, the exothermal reaction effected by the oxidation of THC, CO, and especially the soot accumulated in the converters impose a risk of catalytic flow bed overheating that subsequently results in catalyst failure and may cause safety concerns. This paper presents a one-dimensional transient model that uses an energy balance method to analyze the overheating scenario when considering combustible gas reaction, clogged soot burning, and active flow control for a number of Diesel aftertreatment devices. The monolith temperature profiles were simulated by varying the exhaust gas temperature, oxygen concentration, and flow rate. Simulation results indicated that the potential of overheating elevates with increases in combustible gas concentration, soot loading, oxygen concentration, and engine exhaust temperature. The impacts of active control, such as flow reversal control, on converter overheating have also been investigated therein.