Search Results

The automotive clean-air catalyst system from Engelhard Corporation (PremAir™) consists of a catalyst-coated vehicle radiator and air-conditioning condenser designed to catalytically remove ground-level ozone and carbon monoxide (CO) from ambient air. Although initial on-road testing of the PremAir™ system showed reasonably high ozone conversion activity and satisfactory catalyst durability during the course of relatively low mileage accumulation, the long-term durability of the catalyst coating, its potential negative impact on cooling efficiency and corrosion characteristics, and incompatibility with the existing radiator manufacturing process remain among the issues of some concern. This paper describes an alternative approach to the problem of on-road pollutant destruction, which involves placing a thin catalytic monolith brick immediately behind the uncoated vehicle radiator.

A transient three-dimensional model has been developed to simulate the thermal and conversion characteristics of nonadiabatic monolithic converters operating under flow maldistribution conditions. The model accounts for convective heat and mass transport, gas-solid heat and mass transfer, axial and radial heat conduction, chemical reactions and the attendant heat release, and heat loss to the surroundings. The model was used to analyze the transient response of an axisymmetric ceramic monolith system (catalyzed monolith, mat, and steel shell) during converter warm-up, sustained heavy load, and engine misfiring. The simulation indicates that high solid temperatures are encountered during sustained heavy load or engine misfiring, while steep temperature gradients are developed during the converter warm-up period. Flow maldistribution and radial heat loss are major sources for the thermal gradients.