Reductant decomposition system

A method for decomposing urea into ammonia, comprising:

• passing exhaust gas through a first tubular exhaust distribution component and into a decomposition chamber, the decomposition chamber having a non-cylindrical shape with a curved edge transitioning from a side wall to a top wall of the decomposition chamber, the top wall of the decomposition chamber having a first height proximate the first tubular exhaust gas distribution component, the first tubular exhaust distribution component extending into the decomposition chamber from an inlet and having a perforation pattern on a sidewall surface, the perforation pattern causing the exhaust gas to swirl within the decomposition chamber;
• injecting urea into the exhaust gas within the decomposition chamber to form an exhaust gas and urea mixture, the injected urea downstream of the first tubular exhaust distribution component;
• and
• passing the exhaust gas and urea mixture within the decomposition chamber through a second tubular exhaust distribution component, the top wall of the decomposition chamber having a second height proximate the second tubular exhaust gas distribution component, the second height being smaller than the first height, the second tubular exhaust gas distribution component defined by a first end, a second end, and a curved tubular sidewall surface extending between the first end and the second end, the second tubular exhaust gas distribution component extending into the decomposition chamber from an outlet and having a plurality of circumferential blades formed in the curved tubular sidewall surface of the second tubular exhaust distribution component to swirl the exhaust gas and urea mixture within an interior volume of the second tubular exhaust distribution component, the second tubular exhaust distribution component downstream of the injected urea, the plurality of circumferential blades directing the exhaust gas and urea mixture to enter through slots at an angle relative to a radial direction of the second tubular exhaust gas distribution component to direct flow of the exhaust gas and urea mixture in a circular swirling pattern about a central axis of the second tubular exhaust distribution component effectively increasing a distance the exhaust gas and urea mixture travels relative to linear flow along an axial length of the second tubular exhaust gas distribution component.