Mixing tube for exhaust system and operating strategy for same

An exhaust system comprising:

• a housing;
• a catalyst bank located in the housing;
• and
• a mixing tube located in the housing and coupled to the catalyst bank, the mixing tube including an exhaust inlet located in a first tube end, an exhaust outlet located in a second tube end, and an inner tube surface circumferentially extending around a center axis and forming an exhaust passage;
• the mixing tube body further including a diesel exhaust fluid (DEF) injection port positioned proximate to the first tube end;
• the mixing tube defining a mixing tube inner diameter dimension of about 400 millimeters or greater, and a mixing tube axial length dimension ranging from about 2595 millimeters to about 2615 millimeters;
• and
• the mixing tube defines an exhaust flow path advancing in a first axial direction between the first tube end and the second tube end, and the housing defines an exhaust flow path advancing in a second axial direction opposed to the first axial direction through the catalyst bank.

A method of operating an aftertreatment system comprising:

• injecting diesel exhaust fluid (DEF) into exhaust passing through an aftertreatment mixing tube defining a center axis, an axial length dimension defined parallel to the center axis, an inner diameter dimension defined normal to the axial length dimension, and a ratio of the mixing tube axial length dimension to the mixing tube inner diameter dimension ranging from 5.9 to 6.7;
• feeding a flow of the exhaust and injected DEF toward an exhaust outlet of the aftertreatment mixing tube fluidly connected to a first catalyst bank and a second catalyst bank;
• and
• increasing mixing of the exhaust and injected DEF at least in part by impinging a flow of the exhaust and injected DEF upon a plurality of exhaust impingement surfaces serially arranged between an exhaust inlet and the exhaust outlet of the aftertreatment mixing tube.