The development of a two-dimensional transient catalyst model for direct injection two-stroke applications

This paper describes the development of a two-dimensional transient catalys t model. Although designed primarily for two-stroke direct injection engine s, the model is also applicable to four-stroke lean burn and diesel applica tions. The first section describes the geometries, properties and chemical processes simulated by the model and discusses the limitations and assumpti ons applied. A review of the modelling techniques adopted by other research ers is also included. The mathematical relationships which are used to repr esent the system are then described, together with the finite volume method used in the computer program. The need for a two-dimensional approach is e xplained and the methods used to model effects such as flow and temperature distribution are presented. The problems associated with developing surfac e reaction rates are discussed in detail and compared with published resear ch. Validation and calibration of the model are achieved by comparing predi ctions with measurements from a flow reactor. While an extensive validation process, involving detailed measurements of gas composition and thermal gr adients, has been completed, the analysis is too detailed for publication h ere and is the subject of a separate technical paper.