Flow Simulation Of Ammonia Reactant Gases Via Micromixer

• Main Author: MOHD RADZANI, AHMAD SHAHIR
• Format: Final Year Project
• Language: English
• Published: IRC 2014
• Subjects: TP Chemical technology
• Online Access: http://utpedia.utp.edu.my/14513/1/DISSERTATION_FINAL.pdf; http://utpedia.utp.edu.my/14513/
• Institution: Universiti Teknologi Petronas

The conventional method to produce ammonia employs the Haber–Bosch process at extremely high temperature and pressure. These working conditions not only consumes tremendous amount of energy, it has higher safety risk and yields very low conversion. Prior to study on microreactor, it is essential to understand the hydrodynamics of flow in microchannel. The results will serve as a stepping point to design a microreactor for the ammonia synthesis in a very economical, energy saving, safer and achieving higher conversion and yield than the conventional Haber–Bosch process. At low gas flowrates, mixing of nitrogen and hydrogen gases are less effective as the flow regime within a microchannel is largely laminar. This work aims to enhance mixing of flow as well as shortening the residence time for reaction to occur by investigating the hydrodynamics of the mixing of nitrogen and hydrogen gases in different geometry configurations of a microchannel in order. Three geometry configurations were developed and tested via Computational Fluid Dynamics simulation. Velocity and Pressure distribution of the microsystem was analysed extensively contributed to approximating the mixing efficiency for ammonia reactant gases. The study had found that in all models, the pressure in micromixers ranged from approximately minimum 100 kPa abs. to 102.5 kPa abs. maximum and mostly working pressure is established at 101.3 kPa which conformed to desired atmospheric pressure. The flow of Nitrogen gas was found to be uniform across the micromixer gaining maximum speed at most intersections as it had less volume fraction. Velocity distribution for Hydrogen has wider spectrum which reflected good mixing strategies in many sections of the micromixer as well as center of mixing chambers