Clean Water: Distillation Column Tray

What You'll Build

This lesson walks you through a complete CFD simulation of a distillation column tray — one of the most important pieces of equipment in clean water treatment, chemical separation, and process engineering. Tray columns work by bringing rising vapor into direct contact with falling liquid on a perforated tray, allowing volatile components to evaporate and heavier components to condense and drain.

In this project, you'll model the hydrodynamic two-phase behavior of air and water at the tray location, focusing on how the two phases interact, mix, and separate — without yet introducing heat transfer or evaporation (which are covered in later courses).

What You'll Learn

• How to design a symmetrical 3-D tray column geometry in Design Modeler, modeling only half the chamber to save computation

• How to generate an unstructured mesh (~866,000 elements) appropriate for two-phase tray flow

• How to set up the VOF multiphase model with air as the primary phase and water as the secondary phase, using implicit formulation and sharp interface modeling

• How to apply mixed boundary conditions: velocity inlet for gas (23.35 m/s), mass flow inlet for liquid (4 kg/s), and pressure outlets for both phases

• How to configure the RNG k-ε turbulence model with standard wall functions for swirling, separating flows

• How to use PRESTO! pressure discretization and Modified HRIC for volume fraction — the recommended scheme for VOF simulations

• How to patch the initial water region so the simulation starts with realistic phase distribution

• How to post-process pressure contours, velocity contours, phase volume fractions, and velocity vectors in both 2-D cross-sections and 3-D views

Why It Matters

Distillation columns are everywhere — from desalination plants and wastewater treatment to petrochemical refineries. Mastering this case gives you a portable, industry-relevant skill set for multiphase separation problems.