Effect of reactor size in a laterally-heated cylindrical reactor

Abstract

The current paper presents a numerical study of flow and thermal maps in cylindrical enclosures heated laterally of two different diameters while keeping the enclosure height constant at H = 821.7 mm. The current study aims to understand the impact of different reactor sizes on the flow and thermal maps inside the crystal growth reactor as they are the key parameters that affect the mass flow rate inside an ammonthermal crystal growth reactor. Three-dimensional (3D) Large Eddy Simulation (LES) simulations are conducted by implementing a commercial computational fluid dynamics (CFD) software, ANSYS FLUENT. The two Rayleigh (Ra) numbers are 2×107 and 8.2×104 based on properties at the mean fluid temperature (315 K) and the characteristic length of R/2 (volume/lateral area). As the main achievement of this study, it can be determined that the diameter (D) of the cylindrical reactor plays a major role in the flow causality and thermal map. In the small diameter reactor (D = 25.4 mm; H/D = 32.35), the temperature distribution roots the buoyant forces to be active both in the boundary layers in the vicinity of the walls and the core region of the reactor. However, in the large diameter reactor (D = 158.8 mm; H/D = 5.17), the temperature distribution in the core is practically constant, causing the shear forces exerted by the boundary layers to play the main role in moving the fluid core, while buoyancy is dominant only in creating the boundary layers adjacent to the walls. The new understanding from this research study would eventually help the next researches to better design a crystal growth reactor given the fact that flow and thermal maps would alter the mass transfer study which would further affect the deposition rate on the seeds.