|Authors: || G. McCullough, R. Douglas, G. Cunningham, L. Foley |
|Title: ||The Validation of a Two-Dimensional Transient Catalyst Model for DI Two-Stroke Applications|
|Date: || 2001 |
|Published:|| Proceedings of the Institution of Mechanical Engineers, Volume 215, Part D, pp. 935 - 955 |
This paper describes the detailed validation of a computer model designed to simulate the transient
light-off in a two-stroke oxidation catalyst. A plug flow reactor is employed to provide measurements of
temperature and gas concentration at various radial and axial locations inside the catalyst. These
measurements are recorded at discrete intervals during a transient light-off in which the inlet temperature
is increased from ambient to 300oC at rates of up to 6oC/sec. The catalyst formulation used in the flow
reactor and its associated test procedure are then simulated by the computer and a comparison made between
experimental readings and model predictions. The design of the computer model is too detailed for
publication here and is the subject of a separate technical paper.
The first section of the paper investigates the warm-up characteristics of the substrate and examines the
validity of the heat transfer predictions between the wall and the gas in the absence of chemical reactions.
The predictions from a typical single-component CO transient light-off test are discussed in the second
section and are compared with experimental data. In particular the effect of the temperature ramp on the
light-off curve and reaction zone development is examined. An analysis of the C3H6 conversion is given in
the third section while the final section examines the accuracy of the light-off curves which are produced
when both CO and C3H6 are present in the feed gas.
The analysis shows that the heat and mass transfer calculations provided reliable predictions of the warm-up
behavior and post light-off gas concentration profiles. The self-inhibition and cross-inhibition terms in
the global rate expressions were also found to be reasonably reliable although the surface reaction rates
required calibration with experimental data.