Patent ID: 8635859

Claim:
An exhaust gas treatment system for an internal combustion engine, comprising: an exhaust gas conduit in fluid communication with, and configured to receive an exhaust gas from the internal combustion engine, the exhaust gas containing oxides of nitrogen (“NO x ”); a reductant source in fluid communication with the exhaust gas conduit and configured for injecting an amount of reductant that is released into the exhaust gas conduit; a temperature sensor situated in the exhaust stream, the temperature sensor being disposed and configured for determining a temperature of the exhaust gas at the reductant source; an intake mass air flow sensor for measuring an air mass flow entering the internal combustion engine; and a control module in communication with the reductant source, the temperature sensor, and the intake mass air flow sensor, the control module having a memory that stores a boiling point temperature of the reductant, comprising: a control logic for monitoring the reductant source and estimating the amount of the reductant that is released into the exhaust gas conduit; a control logic for monitoring the intake mass air flow sensor and calculating an exhaust flow rate based on the air mass flow; a control logic for determining an enthalpy of a reductant phase change value; a control logic for calculating a maximum dose rate of the reductant based on at least the exhaust flow rate, the temperature of the exhaust gas, the enthalpy of the reductant phase change value, and the boiling point temperature of the reductant; a control logic for comparing the amount of reductant that is released into the exhaust gas conduit with the maximum dose rate of the reductant; and a control logic for adjusting the amount of reductant that is released into the exhaust gas conduit if the amount of reductant that is released into the exhaust gas conduit is greater than the maximum dose rate of the reductant.