Catalyst Design and Analysis by CFD - 2

he extension of heat sinks to cylindrical shapes, especially the ones with holes inside, presented us with some challenges. To restrict the sinks to a thin layer at the catalyst particle surface, to reflect the "egg-shell" behavior of the catalyst, we had to develop an algorithm to locate each particle and then to test any location inside a particle to see if it was close enough to the surface. Then we tested our algorithms to make sure we were putting the heat sinks in the right place.

Preliminary results are shown in the two figures here. This work lets us compare different particle designs. The examples shown here contrast the temperature fields in full cylinder packings and 1-hole cylinder packings. A description of some of our research in this area was recently published in Nijemeisland, M., Dixon, A.G., and Stitt, E.H., 2004.

In our future work, we want to couple the flow information to reaction engineering models of diffusion, heat transfer and reaction inside catalyst pellets. This combined approach will allow us to assess, for a given chemistry, the importance of tube wall effects on catalyst design and performance and the effects of changes in catalyst design on reactor performance.