FLUENT models of furnace tubes and their use to guide geometric changes

A modified straight-through single-ended furnace tube is modeled in FLUENT. The modification was created in order to save on fuel and prolong the life of the tubes. The research described in this thesis is based on an ongoing research project with Gas Technology Institute and North American Manufacturing Company. The objective of this research is to determine if simple modifications to an existing furnace tube setup can be made to decrease tube temperatures and emissions. Another important objective is to make the temperature of the outermost tube, radiant tube, more uniform in the axial direction, since the heat radiating off of it will dictate the quality of the manufacturing process of the pieces placed in the furnace. This thesis will describe the process in which creating this model was done, and solutions to problems that occur. It will explain the setup of the programs used, and the ways to check for quality meshes. The concerns of the existing setup will be discussed based on the model. To address these concerns, a few modified models are also presented in order to show how ideas of geometric changes were either supported or disproved. These results show that depending on the location at which increased mixing is caused by varying the geometry, the combustion will either lengthen or shorten the flame length. Optimal results were found to be difficult to predict, but by controlling the mixing at the initial stages, and causing mixing downstream of the initial combustion, certain objectives were satisfied.