Modeling of Flooding in the Channel of Contact Devices

Abstract

Background. Contact economizers for recuperation of waste gases use hydraulic and aerodynamic flows and require a deeper understanding of their physical phenomena. So, the problem of hydrodynamics of common air flow and water film in channels of regular packing of contact economizers is important.

Objective. Finding dependencies between water film and air flow at critical modes of coolant flow in the contact heat mass transfer devices with a regular packing containing a system of vertical channels.

Methods. The goal is achieved by formulating and solving analytical model of stationary flowing of incompressible viscous liquids: water film and air. The model is described by the Navier–Stokes equation, reduced to a system of ordinary differential equations for viscous flow in a cylindrical coordinate system.

Results. It is shown that at the interface (for countercurrent movement of air and water film) there is air flow near water film that is moving down along with a water film. The thickness of the air-flow moving down near the interface (for countercurrent movement of air and water film), depends on the pressure gradient which prevents the gravitational running-off of the film. At a certain value of the pressure gradient the film stops at the interface of phases and the two-phase flow enters the mode of the film hanging. A further increasing of the pressure gradient at the film hanging mode causes the movement of the water film and air near the film layer vertically upwards. In this case, at the interface (for countercurrent movement) there is a film flow near the film layer moving in the direction of air flow.

Conclusions. Dimensionless values of the air velocity at movement flipping, film hanging, and flooding depending on the channel radius and Reynolds number values are established.