Renewable Energy: Heller Dry Cooling Tower

This project simulates the airflow and heat transfer inside a Heller-type dry cooling tower — the indirect cooling system used in thermal power plants to reject heat from the working fluid (water) to ambient air without evaporative water loss. After leaving the condensers, the hot water is pumped through a ring of air-cooled heat exchangers; the tower draws cooling air through them by natural draft, created by the density difference between the warm air inside the tower and the cooler air outside.

The study captures the core physics that governs tower performance: the temperature driving force. The larger the gap between the working fluid and ambient air, the stronger the natural draft and the better the cooling. This is also why these towers lose efficiency in summer — as ambient temperature rises, the driving force shrinks, forcing the plant to cut power output and increase water consumption to maintain cooling. The simulation lets you see and quantify that buoyancy-driven flow directly.

Geometry & mesh: the model includes the cooling tower, the heat-exchanger (radiator) ring, the flow domain, and the air inlet, built and meshed in GAMBIT with an unstructured mesh of 1,343,988 cells.

Setup: the case is solved steady with a pressure-based solver, with gravity enabled at −9.81 m/s² in the Y direction — essential, since the natural draft is entirely buoyancy-driven. Turbulence uses the standard k-ε model with standard wall functions, and the energy equation is on.

Boundary conditions reproduce the natural-draft setup:

• Inlet: pressure inlet, 0 Pa gauge total pressure, normal to boundary

• Outlet: pressure outlet, 0 Pa gauge, backflow temperature 303 K

• Radiator (heat exchanger): modeled as a heated surface at 318 K with a heat generation rate of 14,861.52 W/m³, and its shadow face at 313 K

• Walls: stationary, zero heat flux

Solution uses SIMPLE pressure–velocity coupling with first-order upwind discretization for momentum, energy, and turbulence (standard scheme for pressure and density), and standard initialization at 303 K.

What the results show: contours of velocity, pressure, and temperature, along with flow streamlines through the tower. Together they reveal how air is drawn in through the heat exchangers, heats up, and rises through the tower — and how the temperature field across the radiator ring sets the cooling capacity available to the plant.

You'll learn to: set up a buoyancy-driven natural-draft flow, represent a heat-exchanger ring with a heated radiator surface and heat generation rate, configure a steady pressure-based solver with the energy equation, and interpret cooling-tower performance from temperature and streamline fields.