Advanced understanding of local wetting behaviour in gas-liquid-solid packed beds using CFD with a volume of fluid (VOF) method

Computational Investigation of Liquid Holdup and Wetting Efficiency Inside Trickle Bed Reactors with Different Catalyst Particle Shapes

“…The velocity field and bubble profile in a vertical gas-liquid slug flow inside the capillaries has been modeled with a VOF technique, and the result was found to be in good agreement with published experimental measurements [15]. In the past two decades, the VOF model has been predominately practiced in the field of CFD simulation of TBRs [6,13,[16][17][18][19][20].…”

“…In high liquid viscosity cases the liquid-solid shear plays a greater role than the gas-liquid interactions [1], making the liquid harder to leave the particle surface and the whole packing. Film flow was easier to be found under high viscosity while rivulet flow can be observed under low viscosity [16], which is responsible for the increase in wetting efficiency. Differences between the first and the second was greater than that between the second and the third.…”

“…Thus, the liquid attained a higher speed and was able to leave the packing and the particle surface faster, resulting in a lower liquid holdup and wetting efficiency. Besides, it was reported that a higher liquid density makes rivulet flow easier than film flow [16], which was another reason for the lower wetting efficiency.…”

“…viscosity [16], which is responsible for the increase in wetting efficiency. Differences between the first and the second was greater than that between the second and the third.…”

“…Lopes et al proposed a high-resolution CFD approach using discrete particles and designed a TBR with regular positioned catalyst particles for the Euler-Euler [21] and Eulerian VOF simulations [13], and studied the catalytic wet oxidation of phenolic wastewaters in their later studies [22,23]. Du et al performed CFD simulations on regular particles arrangement within a rectangular domain to investigate the local wetting behavior in a TBR [6,16]. Simulations performed by both groups modeled particles with regular configuration and fixed distance between each other, which is difficult to achieve in a real reactor where catalyst particles are packed randomly, and the particle's shape can be complex such as a cylinder or hollow cylinder.…”