Systems and methods for control of engine NOx emissions using liquid and dry reductant sources

摘要

Reductant delivery systems are disclosed that include a dry reductant source and a liquid reductant source which are operable to selectively provide gaseous reductant and liquid reductant to an exhaust aftertreatment system for treatment and reduction of NOx emissions. The gaseous reductant is provided to the exhaust aftertreatment system for treatment of NOx emissions under a first temperature condition associated with the exhaust system and the liquid reductant for treatment of NOx emissions under a second temperature condition associated with the exhaust system.

主权项

1. A method, comprising:
producing an exhaust gas in an exhaust flow path including a selective catalytic reduction (SCR) catalyst, wherein producing the exhaust gas includes operating an internal combustion engine; determining a temperature condition of the exhaust gas; determining an engine shut-down condition, wherein the engine shutdown condition includes a pre-shutdown condition and a post-shutdown condition; and selectively providing one of a gaseous reductant released from a dry reductant source and a liquid reductant from a liquid reductant source to the exhaust flow path upstream of the SCR catalyst in response to the engine shutdown condition, wherein the gaseous reductant is provided from the dry reductant source in response to the post-shutdown condition and the liquid reductant is provided from the liquid reductant source in response to the pre-shutdown condition.