Heller Dry Cooling Tower

Heller Dry Cooling Tower — ANSYS Fluent CFD Simulation

Description

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 the ambient air, the stronger the natural draft and the better the cooling. This is also why these towers lose efficiency in summer, as a rising ambient temperature shrinks the driving force and forces the plant to cut power output and increase water consumption to maintain cooling. Within the Renewable Energy: Beginner CFD Training Package, this project covers heat rejection in a power-plant context, applying buoyancy-driven flow to a large-scale natural-draft system.

Methodology

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. 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. The boundary conditions reproduce the natural-draft setup: the inlet is a pressure inlet at 0 Pa gauge total pressure normal to the boundary; the outlet is a pressure outlet at 0 Pa gauge with a backflow temperature of 303 K; the radiator (heat exchanger) is 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; and the walls are stationary with zero heat flux. The 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.

Analysis

The results provide 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. By the end of this project, you'll be able 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 the temperature and streamline fields.