METHOD FOR DETERMINING UREA FEEDING IN AN EXHAUST GAS AFTERTREATMENT SYSTEM, AN EXHAUST GAS AFTERTREATMENT SYSTEM AND A VEHICLE COMPRISING AN INTERNAL COMBUSTION ENGINE AND AN EXHAUST GAS AFTERTREATMENT SYSTEM

The present disclosure relates to a method for determining urea feeding in an exhaust gas aftertreatment system (100,200), the exhaust gas aftertreatment system (100,200) being connectable to an internal combustion engine (101,201) operating under an engine operating condition, the system (100,200) comprising a first Selective Catalytic Reduction (SCR1) system comprising a first selective reduction catalyst (SCR1c) and a first doser (103,203) configured for feeding urea upstream the SCR1 system, at least one Particulate Filter (PF) downstream the SCR1 system or as a substrate for the SCR1c and a second Selective Catalytic Reduction (SCR2) system downstream the PF, the SCR2 system comprising a second selective reduction catalyst (SCR2c) and a second doser (104,204) configured for feeding urea upstream the SCR2c, the method comprising the steps of estimating the amount of particles in the PF; and determining the amount of urea to be fed by the respective first and second doser (4,5) based on the engine operating condition and such that: a) the amount of particles in the PF is within a predefined particle amount range, and, b) the NOx level of the exhaust gas exiting the SCR2 system is within a predetermined NOx level range. The present disclosure also relates to an exhaust gas aftertreatment system (100,200) and a vehicle comprising the exhaust gas aftertreatment system (100,200), a computer program comprising program code means for performing the steps of the method, a computer readable medium carrying a computer program comprising program code means for performing the steps of the method and a control unit for controlling urea feeding in the exhaust gas aftertreatment system (100,200).