An Evaluation of Three-Way Control Single and Dual Bed Catalysts as Applied to Heavy-Duty Gasoline Engines

摘要

A test program to evaluate the applicability of three-way control (TWC) and dual-bed catalysts (TWC and Oxidation Catalysts) in combination with a closed-loop control stoichiometric (feedback) carburetor on a production 1978 IHC 404 CID heavy duty gasoline engine was conducted at EPA's Office of Mobile Source Air Pollution Control Laboratory. Testing was conducted according to the Federal test procedure for the heavy-duty transient cycle. The test program consisted of forty-six cold-start tests, fifty-eight confirmatory hot-start tests run to insure accuracy and precision of the cold-start tests, and fourteen hot-start tests run to identify the effects of air/fuel ratio control points on NOx emissions. The effects of various combinations of catalysts, EGR, air/fuel ratio control points, carburetor response times and air pump capacity on emissions, fuel economy and engine power were examined.