Technical Paper

This paper describes the development of a two-dimensional transient catalyst model. Although designed primarily for two-stroke direct-injection applications, the model is also applicable to four-stroke lean burn and diesel applications. The first section describes the geometries, properties and chemical processes simulated by the model and discusses the limitations and assumptions applied. A review of the modelling techniques adopted by other researchers is also included. The mathematical relationships that are used to represent the system are then described, together with the finite volume method used in the computer program. The need for a two-dimensional approach is explained and the method used to model effects such as flow and temperature distribution are presented. The problems associated with developing surface reaction rates are discussed in detail and compared with published research. Validation and calibration of the model are achieved by comparing predictions with measurements from a flow rector. While an extensive validation process, involving detailed measurements of gas composition and thermal gradients has been completed, the analysis is too detailed for publication here and is the subject of a separate technical paper.