A Physical Two-Zone NO _x Model Intended for Embedded Implementation 2009-01-1509

This paper offers a two-zone NO_x model suitable for vehicle on-board, on-line implementation. Similar NO_x modeling attempts have previously been undertaken. The hereby suggested method does however offer clear and important benefits over the previously methods, utilizing a significantly different method to handle temperature calculations within the (two) different zones avoiding iterative computation. The new method significantly improves calculation speed and, most important of all, reduces implementation complexity while still maintaining reasonable accuracy and the physical interpretation of earlier suggested methods. The equations commonly used to compute NO_x emissions is also rewritten in order to suit a two-zone NO_x model. An algorithm which can be used to compute NO_x emissions is presented and the intended contribution of the paper is a NO_x model, implementation feasible for an embedded system, e.g. embedded processor or embedded electronic hardware (FPGA). For that purpose parts of the algorithm can be pre-computed and stored in tables allowing significant acceleration of the computation.