Method to estimate no2 concentration in an exhaust gas of an internal combustion engine

An internal combustion engine, comprising:

• an exhaust pipe having a first section and a second section;
• an aftertreatment device located in the exhaust pipe between the first section and the second section;
• and
• an ECU configured to
• determine a parameter related to a NO2 concentration of exhaust gas flowing in the first section;
• determine an oxidization index expressive of a rate of NO contained in an exhaust gas which oxidizes into NO2 inside the aftertreatment device;
• determine a reduction index expressive of a rate of NO2 contained in the exhaust gas which is reduced into NO inside the aftertreatment device;
• and
• calculate the parameter related to a NO2 concentration in the second section as a function of the parameter related to the NO2 concentration in the first section, of an oxidization index and of a reduction index of the aftertreatment device.

A computer readable medium embodying a computer program product, said computer program product comprising:

• a program to estimate a NO2 concentration in an exhaust gas flowing through an exhaust pipe of an internal combustion engine, the exhaust pipe has a first section and a second section and is equipped with an aftertreatment device located between the first section and the second section, the program configured to:
• determine a parameter related to a NO2 concentration of exhaust gas flowing in the first section;
• determine an oxidization index expressive of a rate of NO contained in the exhaust gas which oxidizes into NO2 inside the aftertreatment device;
• determine a reduction index expressive of a rate of NO2 contained in the exhaust gas which is reduced into NO inside the aftertreatment device;
• and
• calculate the parameter related to the NO2 concentration in the second section as a function of the parameter related to the NO2 concentration in the first section, of an oxidization index and of a reduction index of the aftertreatment device.