Systems and methods for controlling reductant delivery to an exhaust stream

A system, comprising:

• an internal combustion engine providing an exhaust stream including an amount of NOx into an exhaust flow path;
• a reductant introduction device connected to a reductant supply and to the exhaust flow path, wherein the reductant introduction device is structured to introduce a pressurized reductant gas directly into the exhaust stream;
• a NOx conversion catalyst receiving the exhaust stream downstream from the introduction of the reductant gas into the exhaust stream;
• a controller structured to:
• determine a NOx reduction amount to achieve a NOx emissions level target for the exhaust stream;
• determine a reductant feed rate amount from the NOx reduction amount to achieve the NOx emissions target;
• and
• control the reductant introduction device to directly introduce the reductant gas into the exhaust stream at the reductant feed rate.