Ammonia storage capacity of scr catalyst unit
AssigneePACCAR Inc
InventorsCharles Wayne Reinhardt SWART, Cynthia Chaffin WEBB, Maarten MEIJER, Varun RAMESH
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Abstract
The present disclosure describes methods for evaluating ammonia storage capacity of a close-coupled SCR unit while remaining compliant with prescribed emissions limits, methods of controlling an emission aftertreatment system including multiple SCR units and emission management systems for a vehicle including an internal combustion engine and an emission aftertreatment system that includes two or more SCR units.
Claims20
A method of evaluating ammonia storage capacity of a selective catalytic reduction (SCR) unit in an emission aftertreatment system (EAS), the method comprising:
- operating the EAS at steady state conditions;
- dosing diesel exhaust fluid, into exhaust gas from the internal combustion engine, upstream of a close-coupled SCR unit;
- flowing the exhaust gas, into which the diesel exhaust fluid has been dosed, through the close-coupled SCR unit;
- flowing the exhaust gas from the close-coupled SCR unit through a downstream SCR unit;
- controlling NOx emissions from the EAS using the downstream SCR unit;
- terminating the dosing of diesel exhaust fluid into the flowing exhaust gas upstream of the close-coupled SCR unit;
- depleting ammonia stored in the close-coupled SCR unit;
- restarting the dosing of diesel exhaust fluid into the flowing exhaust gas upstream of the close-coupled SCR unit;
- reloading the close-coupled SCR unit with ammonia;
- determining the close-coupled SCR unit has reached a maximum ammonia loading;
- and
- upon determining the close-coupled SCR unit has reached the threshold ammonia loading, determine (1) an amount of ammonia loaded in the close-coupled SCR unit after restarting dosing of diesel exhaust fluid into the flowing exhaust gas upstream of the close-coupled SCR unit, (2) an amount of ammonia used for NOx conversion in the close-coupled SCR unit after restarting dosing of diesel exhaust fluid into the flowing exhaust gas close-coupled of the close-coupled SCR unit and (3) an amount of ammonia oxidized in the SCR unit after restarting dosing of diesel exhaust fluid into the flowing exhaust gas upstream of the close-coupled SCR unit;
- and
- evaluating an amount of ammonia stored in the close-coupled SCR unit by subtracting (2) and (3) from (1).
A method of operating an emission aftertreatment system (EAS) that includes two or more selective catalytic reduction (SCR) catalyst units and is connected to an internal combustion engine, the method comprising:
- evaluating ammonia storage capacity of a close-coupled SCR unit while operating the EAS at steady state conditions;
- during the evaluating ammonia storage capacity of an close-coupled SCR unit, controlling NOx emissions from the EAS using a downstream SCR unit;
- and
- adjusting one or more operation parameters of the EAS based on the result of the evaluating ammonia storage capacity of an close-coupled SCR unit.
An emission management system for a vehicle including an internal combustion engine and an emission aftertreatment system (EAS) that includes a close-coupled SCR unit and a downstream SCR unit, the emission management system comprising:
- at least one nontransitory processor-readable storage medium that stores one of processor-executable instructions or data;
- at least one processor communicatively coupled to the at least one nontransitory processor-readable storage medium, in operation, the at least one processor:
- receives an indication of an ammonia storage capacity of a close-coupled SCR unit determined while operating the EAS at steady state conditions;
- stores the received indication of an ammonia storage capacity of a close-coupled SCR unit determined while the EAS operates at steady state conditions in the nontransitory processor-readable storage medium;
- and
- controls the operation of the internal combustion engine and/or the EAS, using the received indication of ammonia storage capacity, to control emissions from the EAS to within prescribed limits.
Dependencies are inferred from the claim text.