PACCAR Inc
Thermally integrated compact aftertreatment system

Abstract:

A thermally integrated catalyst aftertreatment exhaust system includes a flow channel that directs diesel exhaust through a diesel oxidation catalyst unit that includes a diesel oxidation catalyst, by a doser that introduces DEF into the diesel exhaust, through a mixing chamber that includes a static metallic mixer coated with a DEF hydrolysis catalyst, and through an SCR unit that includes an SCR catalyst. The diesel oxidation catalyst converts a portion of diesel exhaust into water, carbon dioxide, or nitrogen dioxide. The DEF hydrolysis catalyst facilitates hydrolysis of the mixed DEF and diesel exhaust. The SCR catalyst facilitates reduction of NOx in the diesel exhaust. A first portion of the flow channel is in direct thermal contact with a second portion of the flow channel that houses the SCR unit such that heat from the diesel exhaust before the diesel exhaust reaches the doser is passed to the SCR unit.