Abstract: An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway that receives exhaust gas from the engine, a temperature sensor configured to generate a temperature signal associated with a temperature of the exhaust gas at a position along the exhaust gas pathway, and a reductant source. The system also includes first and second injectors in fluid communication with the reductant source. The first and second injectors are configured to inject reductant into the exhaust gas pathway at first and second rates. The system also includes a first treatment element positioned downstream of the first injector and within the exhaust gas pathway, and a controller in communication with the temperature sensor. The controller is configured to receive the temperature signal from the temperature sensor and adjust at least one of the first rate or the second rate based at least in part on the temperature signal.

Abstract: An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, a first ammonia injector configured to inject ammonia into the exhaust gas pathway at a first rate, and a first treatment element positioned downstream of the first ammonia injector. A second ammonia injector is positioned downstream of the first treatment element. The second ammonia injector is configured to inject ammonia into the exhaust gas pathway at a second rate. A controller is configured to estimate an amount of particulate present in the exhaust gas and adjust at least one of the first rate or the second rate based on the estimate.

Abstract: An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, an ammonia source, and a first ammonia injector in fluid communication with the ammonia source. The first ammonia injector is configured to inject ammonia into the exhaust gas pathway at a first rate. The exhaust gas treatment system also includes a first treatment element positioned downstream of the first ammonia injector and a second ammonia injector in fluid communication with the ammonia source and positioned downstream of the first treatment element. The second ammonia injector is configured to inject ammonia into the exhaust gas pathway at a second rate different from the first rate. The exhaust gas treatment system further includes a second treatment element positioned downstream of the second ammonia injector.

Abstract: An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, an ammonia source, and a first ammonia injector in fluid communication with the ammonia source. The first ammonia injector is configured to inject ammonia into the exhaust gas pathway at a first rate. The exhaust gas treatment system also includes a first treatment element positioned downstream of the first ammonia injector and a second ammonia injector in fluid communication with the ammonia source and positioned downstream of the first treatment element. The second ammonia injector is configured to inject ammonia into the exhaust gas pathway at a second rate different from the first rate. The exhaust gas treatment system further includes a second treatment element positioned downstream of the second ammonia injector.