A simulation framework for cold-start evaluation of a gasoline engine equipped with an electrically heated three-way catalyst
Paper i proceeding, 2021
Cold start emissions of exhaust gas pollutants in current generation gasoline internal combustion engine (ICE) comprise the most significant quantity of regulated exhaust emissions in both standard test drive cycles and in real-world drive scenarios. Electrification of ICE provides the possibility of using an electrically heated catalyst (EHC), that offers the potential to fulfil future emission legislation such as Eu7. The EHC has the potential to reduce cold start exhaust emission by attaining early and quick catalyst light-off with lower impact on drivability and fuel consumption. A control-oriented simulation model of a gasoline ICE with a two-brick three-way catalyst (TWC) equipped with an EHC between the bricks is described and analysed for use in cold start evaluation of the complete system. The ICE is modelled using a mix of static lookup tables optimized using part load engine test bench measurements, to provide the exhaust emission species flow and gas temperature to the downstream TWC. An axial and radially resolved TWC model, including non-uniform axial lengths of the TWC slices that are relevant for cold start emission control is used. The EHC is modelled as a TWC component with the possibility to generate heat from electrical energy. Significant ICE control measures such as high engine idle, retarded ignition timing and strategic air-fuel ratio that are potentially used for cold start control are emulated. The entire simulation framework is set-up in a manner such that for a given engine speed and torque demand trace, the simulation framework emulates the power-train system. The internal states are modelled to provide fuel consumption and tailpipe exhaust emissions, which would form the significant costs of a cold start controller objective function. A set of proposed heating profiles of the EHC is simulated and available measurements are used for comparison. The resultant framework can estimate the use of engine control measures and the EHC impacts with desired accuracy for carrying out the development and analysis of cold start controller strategies.
Engine exhaust emissions