Numerical simulation on flow behavior of twin‐liquid films over a vertical plate with an open window

Abstract

A novel element for gas–liquid contact, a plate with rectangular windows was designed to enhance absorption process. Coexistence and interaction of wall‐bounded films and confined free films named as “twin‐liquid films” were observed on the plate. Volume of fluid (VOF) method was used to simulate its flow behavior. Flow phenomena such as flow around a step‐in, jet impingement, varicose waves, and sinuous waves were observed. Different from thin films flow on an unperforated plate, larger mean velocity, thinner film thickness, more intensive capillary waves, and stronger vorticity on the free surfaces were detected inside the window, and the disturbances could propagate over the whole plate. Three‐dimensional simulation results generally agreed with our experimental observations and further demonstrated complex wavy structures both inside and outside the window. The results would broaden traditional knowledge of liquid films flow and clarify the mechanism of mass transfer intensification for the plate with windows. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1458–1468, 2018

Experimental study of a liquid film flowing over a perforation

“…Similar phenomena have already been reported by Ruschak 41 for liquid films or jets entering a relatively large pool and more recently by Hancock and Bush for a laminar liquid jet impinging on a deep liquid reservoir 42 . According to Xie et al, 17 the varicose waves induce strong generation of vorticity, which is expected to enhance mass transfer.…”

“…This feature, called inertial ridge, is also observed right downstream of a step‐out or trench 22 . The present experimental results exhibit the same features (ridges upstream and downstream of the perforation, standing varicose waves on the curtain) as the simulation results reported by Xie et al 17 for liquid films flowing over a rectangular open window with two‐face supply ().…”

“…As the Reynolds number of the film increases, a so‐called inertial ridge appears after a step‐out 22 . The same features were observed by Xie et al 14,17 at the entrance and at the exit of a rectangular open window.…”

“…They note a hysteresis: The Reynolds number of the film for liquid curtain rupture is several times lower. In a second paper, Xie et al 17 further investigated the curtain regime using computational fluid dynamics. This regime is referred to as twin‐liquid films by these authors because of the coexistence of a supported film on the solid plate and a suspended liquid film in the open window.…”

A comprehensive study of the liquid transfer from the front to the back of a vertical perforated sheet

“…Studies focusing on a single geometrical feature (perforation or channel, for example) provide helpful insight into the elementary mechanisms involved in packed column. Xie et al 14,15 and Iyer et al 16 considered the liquid flow down a vertical plate with a single perforation, round, 16 or rectangular. 14,15 The plate was supplied with liquid either on one or two sides.…”