| abstract |
The invention is directed to a procedure for fitting relevant parameters in SCR catalyst models and to an apparatus for carrying out such procedures. nFollowing the procedure of the present invention, it is possible to make a first estimate of the SCR model parameters by fitting the parameters individually. This is possible because of special measurements that simplify and isolate reactions in the SCR model. The set of parameters determined via this method are used as a starting point for a global optimization of the model parameters. The measurements made are the determination of the NOx conversion by the SCR catalyst using ammonia, and the determination of the NOx conversion by the SCR catalyst using urea. nThe apparatus comprises an engine (3), an engine brake (2), a SCR catalyst (10), an ammonia injection point (8), a urea injection point (9), a pre-SCR measurement point (7), a post-SCR measurement point (11) and an ambient measurement point (12). |