CHARACTERIZATION OF EXHAUST POLLUTANT EMISSIONS FOR DESIGN, IMPLEMENTATION & VALIDATION OF AFTER-TREATMENT SYSTEM EFFECTIVENESS
This paper reports on the development of a quasi-dimensional model for quantifying the formation of carbon monoxide (CO) and total unburned hydrocarbons (HC) within the cylinder of a reciprocating internal combustion engine. The proposed methodology is presented in two parts: 1) equilibrium combustion formation and in-cylinder storage, and 2) kinetic formation and oxidation during exhaust removal. On March 5, 2009, the EPA proposed modifications to the current National Emission Standards for Hazardous Air Pollutants (NESHAP) for existing stationary reciprocating internal combustion engines (RICE). The proposed 2009 NESHAP implements new carbon monoxide (CO) limits for all RICE as a surrogate for HAP, with the exception of a formaldehyde (CH2O) limit for 4SRB engines. This rule not only requires a significant reduction in HAP but moves completely away from the previous rule which included limits for NOx, CO and VOCs. This future promulgation has created the need for a comprehensive algorithm to characterize pollutant emission formation regardless of engine design and regulatory focus. The purpose of this work is to evaluate in-cylinder kinetic CO and THC formation in order to evaluate the effectiveness of current and future after-treatment technologies. The simplified CO and THC scheme has been tuned and validated with exhaust concentration data collected on a variety of two- and fourstroke cycle engines and directly relates to the impact of operating conditions and in-cylinder geometry.