Study on the Effect of Catalyst Loading to the Flow Dynamics of Ammonia Reactant Gases in a Microchannel via Computational Fluid Dynamics (CFD) Approach

There are many advantages of using microreactor compared to the conventional mixing process in industry nowadays. In order to replace the conventional mixing process, researches need to be done to get the best design that gives good mixing and able to maximize the quality of the final product. This work investigates the effect of catalyst loading to the mixing dynamics of ammonia reactant gases in the microchannel using computational fluid dynamics (CFD) simulation. ANSYS CFX 14.5 is used to simulate the flow of gases in the microreactor. The geometry used for this study is a ZA channel. Mesh sensitivity study was conducted using three different mesh quality; coarse, medium and fine mesh. It is found that a finer mesh quality with higher number of nodes and elements will produce a better quality of contour and more accurate data but for this study, medium mesh is selected due to software limitation. Further analysis shows that the hydrogen and nitrogen gas that flow in a porous media are able to achieve its developed-flow state and increase its mixing rate between the gases at a shorter mixing length. As for radial view, it can be observed that both gas components flow uniformly across the diameter of the microchannel. In term of pressure drop, a lower porosity gives a higher pressure drop in the microchannel. Therefore, it is proposed that the catalyst with an optimum porosity (ε = 0.45) should be used throughout the microchannel.