Simulation of Gas Vapor -Liquid Two-Phase Flow

Most mass transfer equipments consist of gas (vapor) and liquid two-phase flow, for instance, vapor-liquid two-phase cross-current flow is undertaken in tray distillation column gas-liquid two-phase countercurrent flow is taken place in packed absorption column. Some processes may also include solid phase, such as adsorption or catalytic reaction. Thus, the fluid system may contain gas and liquid two phases, or gas, liquid single phase besides solid phase. 

For the two-phase flow, the modeling equations should be written for the designated phase while such phase occupies only a fraction of the total volume therefore, the volume fraction of the designated phase should be involved in the equation for the reason that the fluid velocity of the designated phase is determined by the fractional flow area. Note that, the volume fraction is generally varying with position. 

Let Pe be the volume fraction of the designated phase 6 (for instance, 0 — L refers to liquid phase 9 = G refers to gas phase), pg be the density of the designated phase 0. Both Pg and pg need to insert into the CFD equation sets. 

The simulated two-phase flow model can be in one of the following three forms  

There are two kinds of two-fluid models based on different viewpoints  

---