Two Stage Box Mixer

A mix box comprising:

• a housing including a first inlet, a second inlet, a third inlet and an outlet;
• first, second, and third chambers positioned within the housing;
• a decomposition tube positioned within the housing and defining the first chamber, the decomposition tube including a first end in fluid communication with the first inlet and a second end spaced apart from the housing, wherein a first flow path extends a first direction from the first inlet through the decomposition tube, wherein a gap is provided between the second end of the decomposition tube and the housing to define a second flow path extending in a second direction opposite the first direction in the second chamber outside of the decomposition tube,
• the second inlet being in fluid communication with the second chamber defining a third flow path bypassing the decomposition tube and extending in the first direction;
• the third inlet being in fluid communication with the first chamber and configured to receive reductant injected along an injection axis, wherein the injection axis extends substantially perpendicular to the first direction;
• and
• a mixer positioned within the housing and including an opening in communication with the second chamber, the mixer defining a third chamber therein, the third chamber being in fluid communication with the outlet,
• wherein the second flow path and the third flow path intersect one another in opposite directions within the second chamber upstream of the mixer.