System And Method For Injection Control Of Urea In Selective Catalyst Reduction

Abstract: A system includes an exhaust aftertreatment system (10) configured to treat emissions from a combustion engine (12). The exhaust aftertreatment system (10) includes a selective catalytic reduction (SCR) catalyst assembly (34) and at least one radio frequency (RF) probe (36) disposed within the SCR catalyst assembly (34). A controller (28) is coupled to the exhaust aftertreatment system (10) and utilizes an NH3 storage estimate (68) measured by the at least one RF probe (36) and an NH3 storage estimate (68) determined by an NH3 storage estimate model (56) to output a control action (54) for a reductant injection system (38). The NH3 storage estimate model (56) utilizes measured concentrations of nitrogen oxides (NOx) (58) in the fluid upstream (40) or downstream of the SCR catalyst and/or measured concentrations of NH3 (60) in the fluid upstream (40) or downstream of the SCR catalyst, and the NH3 storage measurement (70) from the at least one RF probe (36) to determine the NH3 storage estimate (68).

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