In short: A cooling tower removes heat from process or HVAC water by evaporating a small part of it into a moving air stream. FRP is widely used for tower casings, basins, fan stacks, structures and fan blades because it resists corrosion from warm, aerated and chemically treated water. Towers are classified by airflow (counterflow or crossflow), draft (induced or forced) and shape (round or square/rectangular). They are sized from four numbers: water flow rate, hot water temperature, cold water temperature and design wet-bulb temperature.
How an evaporative cooling tower works
Warm water is distributed over a heat-transfer surface called the fill. A fan draws or pushes air through the fill. A small fraction of the water evaporates, and the latent heat of evaporation cools the remaining water, which collects in the basin and returns to the process. Because cooling is driven by evaporation, the water can be cooled below the dry-bulb air temperature. The theoretical limit is the ambient wet-bulb temperature.
Key terms:
- Range: hot water temperature minus cold water temperature
- Approach: cold water temperature minus design wet-bulb temperature
- Drift: water droplets carried out with the exhaust air, limited by drift eliminators
- Blowdown: water bled off to control dissolved solids, which concentrate as water evaporates
- Make-up: water added to replace evaporation, drift and blowdown
Main tower types
Counterflow vs crossflow
- Counterflow: air moves vertically upward through the fill while water falls downward. These towers are compact in plan and widely used.
- Crossflow: air moves horizontally through the fill while water falls vertically. Gravity distribution basins on top are easy to inspect, and the towers are usually larger in plan.
Induced vs forced draft
- Induced draft: the fan sits on top and pulls air through the tower. This is the most common arrangement and reduces the chance of hot exhaust air recirculating into the inlet.
- Forced draft: the fan sits at the air inlet and pushes air in. It is more common in smaller packaged units.
Round vs square towers
- Round (bottle-type) towers are factory-made FRP units, usually counterflow, used for small to medium loads such as injection molding, HVAC and small process loads.
- Square or rectangular towers are modular and can be combined into multi-cell installations for larger loads.
See our FRP cooling towers and the cooling towers and components collection.
Components
| Component | Function | Notes |
|---|---|---|
| Casing and basin | Contain the water and air | FRP resists corrosion and is light |
| Fill | Spreads water to maximize air contact | Film or splash type; see below |
| Water distribution | Nozzles, sprinkler heads or gravity basins | Even distribution is critical for performance |
| Drift eliminators | Remove droplets from exhaust air | Reduce water loss and drift emissions |
| Fan and motor | Move air | FRP or aluminum blades |
| Fan stack (cylinder) | Improves fan efficiency, discharges air upward | Often FRP |
| Air inlet louvers | Keep water in and sunlight and debris out | Reduce algae growth in the basin |
Fill: film or splash
Film fill spreads water into thin films over closely spaced sheets and usually gives higher thermal performance in less volume. It is more sensitive to fouling from suspended solids, biological growth and scale. Splash fill breaks water into droplets as it falls through bars or grids. It tolerates dirtier water and poorer distribution but gives lower performance per unit volume. We compare them in Cooling Tower Fill: Film vs Splash. See our cooling tower fill media.
Why FRP?
- Corrosion resistance: cooling water is warm, oxygen-rich and often chemically treated, which accelerates corrosion of steel
- Light weight: good for rooftop installation
- Factory-made shells with consistent quality
- Electrically non-conductive structural members
- Low maintenance: no galvanizing or repainting cycle for corrosion
Sizing data
To size a tower, provide:
- Water flow rate (m³/h or GPM)
- Hot water inlet temperature
- Required cold water outlet temperature
- Design wet-bulb temperature for the site, usually from local climatic design data
- Heat load (if known), water quality and make-up source
- Space, noise limits, power supply and installation height
A smaller approach requires a much larger tower for the same heat load. Designing to an unrealistic approach is a common cause of underperforming towers. Field thermal acceptance tests are commonly carried out to the Cooling Technology Institute code CTI ATC-105, and CTI also runs a thermal certification program (CTI STD-201) for listed product lines. Ask your supplier exactly which performance documents apply to the model offered. We will not claim CTI certification for a product unless it is listed.
Water treatment and maintenance
- Control scale, corrosion and biological growth with a water treatment program.
- Manage Legionella risk according to local regulations and guidance, such as ASHRAE Standard 188 in the USA. Keep drift eliminators in good condition.
- Clean basins and strainers, inspect nozzles, and check fill for fouling.
- Check fan balance, gearbox oil and belt tension.
Customization
FIBROVX supplies FRP cooling towers and components to order: round or square towers in a range of flows, replacement fill and drift eliminators, FRP fan stacks, basins, structural profiles and grating walkways. Colors, layouts and OEM branding are available. For replacement parts, send photos and dimensions of the existing component.
Need a quote or a drawing check?
FIBROVX manufactures FRP products in our own factory in China and builds every item to order: sizes, resin system, color, molds and OEM branding. Send your application, dimensions or drawing, quantity and destination port.
Request a QuoteKey terms
- Range: Hot water temperature minus cold water temperature.
- Approach: Cold water temperature minus wet-bulb temperature.
Watch: FRP Cooling Towers in 27 Seconds
FAQ
What is the difference between range and approach?
Range is the temperature drop across the tower (hot minus cold water). Approach is how close the cold water gets to the ambient wet-bulb temperature. Approach strongly affects tower size.
Can a cooling tower cool water below air temperature?
Yes. Evaporative cooling can cool water below the dry-bulb air temperature. The limit is the wet-bulb temperature, and practical designs keep an approach of several degrees.
Why are cooling towers made of FRP?
FRP resists corrosion from warm, aerated, chemically treated water, is light for rooftop use, and needs no repainting for rust protection.
How often should fill be replaced?
It depends on water quality, fouling and temperature. Inspect fill regularly. Fouled, collapsed or scaled fill reduces performance and should be cleaned or replaced.
Do you supply spare parts for other brands?
We can make many FRP components, fill and drift eliminators to the dimensions of existing towers. Send drawings or photos and measurements.
Can FRP towers be used in coastal areas?
Yes. FRP does not rust, which is an advantage in salty air. Fixings and mechanical parts must also suit the environment.
Related guides
- Cooling Tower Fill: Film vs Splash
- What Is FRP?
- FRP Grating: Complete Guide
- Cooling Tower Sizing Basics: Range, Approach and Wet-Bulb
- Cooling Tower Fill Fouling: Causes, Cleaning and Replacement
- FRP for Power Plants and Substations: A Site Map
- Industries we serve
- Data Center Cooling: FRP Towers, Pipes and Rooftop Grating
Sources
- ASHRAE Handbook, HVAC Systems and Equipment, Chapter 40 "Cooling Towers" (principles, range, approach, film vs splash fill): https://www.ashrae.org/technical-resources/ashrae-handbook
- Cooling Technology Institute, "CTI Certification" (STD-201 thermal certification): https://www.cti.org/cti-certification
- ASHRAE, Standard 188 "Legionellosis: Risk Management for Building Water Systems": https://www.ashrae.org/technical-resources/bookstore/ansi-ashrae-standard-188-2021-legionellosis-risk-management-for-building-water-systems
- A cooling tower fill manufacturer, cooling tower fill overview (film vs splash)