CPC F01N 3/208 (2013.01) [F01N 3/106 (2013.01); F01N 3/2013 (2013.01); F01N 3/2033 (2013.01); F01N 3/0871 (2013.01); F01N 3/206 (2013.01); F01N 3/2066 (2013.01); F01N 9/005 (2013.01); F01N 11/005 (2013.01); F01N 2610/02 (2013.01); F01N 2610/10 (2013.01); F01N 2610/1453 (2013.01); F01N 2900/04 (2013.01); F01N 2900/1402 (2013.01); F01N 2900/1404 (2013.01); F01N 2900/1602 (2013.01); F01N 2900/18 (2013.01); F01N 2900/1811 (2013.01)] | 17 Claims |
1. A modular exhaust subsystem for purifying an exhaust gas feedstream of a compression-ignition internal combustion engine upstream of a base exhaust aftertreatment system, comprising:
a selective catalytic reduction (SCR) catalyst,
a first exhaust gas sensor and a first temperature sensor arranged to monitor the SCR catalyst;
a reductant delivery system arranged to inject a reductant into the exhaust gas feedstream upstream of the SCR catalyst;
a controller, operatively connected to the reductant delivery system and in communication with the first exhaust gas sensor and the first temperature sensor,
the controller further in communication with a second exhaust gas sensor and a second temperature sensor that are arranged to monitor the base exhaust aftertreatment system; and
an engine-out exhaust gas sensor arranged to monitor the exhaust gas feedstream upstream of the SCR catalyst,
wherein the controller includes an instruction set that is executable to control the reductant delivery system to inject the reductant into the exhaust gas feedstream upstream of the SCR catalyst based upon inputs from the engine-out exhaust gas sensor, the first and second exhaust gas sensors and the first and second temperature sensors,
wherein the instruction set is executable to control the reductant delivery system to inject the reductant into the exhaust gas feedstream upstream of the SCR catalyst to achieve a target reductant/NOx ratio upstream of the base exhaust aftertreatment system.
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