Thermal analysis and cold start performance of automotive emission systems

Abstract

Automotive exhaust emission regulations are becoming stricter due to increasing awareness of the hazardous effects of exhaust emissions. The main challenge to comply with the EPA regulations is to reduce the emissions during cold start, because catalytic converters are ineffective until they reach a 'light-off' temperature - the temperature at which the converter starts reducing 50 % of emissions. A thermal model of a catalytic converter is presented which reduces the light-off time and significantly reduces the concentration of exhaust gas emissions. This thesis describes a numerical model of the catalytic converter, which is used to predict catalytic converter performance during cold-starts. Simulations were carried out using a finite element software - Abaqus, to study the catalytic converter performance at various temperatures. After analyzing thermal models for both - uniform heat distribution and cost effectiveness, a heat source of 90 W was chosen for a three-heater configuration (30 W each) to pre-heat the converter. A reduction in the concentration of emissions by a factor of 4 to 6 were recorded as a result of vehicle simulation with this thermally designed catalytic converter. ADVISOR (Advanced Vehicle Simulator), a vehicle simulator, was used to calculate 'engine-out emissions.'