If you are exploring cooling tower solutions for your industrial facility or HVAC system, you have likely encountered the term "open type" or "open circuit" cooling tower. This is the most common and historically proven method of heat rejection in the world.
But what exactly defines an open type water cooling tower? How does it differ from other systems, and why do so many engineers prefer it?
At CTP Mühendislik, we specialize in manufacturing high-durability CTP (composite) open circuit cooling towers. Here is everything you need to know.
What Is an Open Type Water Cooling Tower?
An open type cooling tower (also called an open circuit cooling tower) is a heat rejection device where the process water comes into direct contact with the air.
Unlike closed-loop systems where the process fluid stays inside sealed coils, an open tower sprays the actual hot water from your system directly over a heat transfer surface (called "fill" or "infill"). Air is blown or drawn through this falling water, causing a small portion of it to evaporate. This evaporation removes heat from the remaining water, which is then collected and returned to your process.
Key distinction: There is no physical barrier between the water you are cooling and the atmosphere. The water itself is the cooling medium.
How Does an Open Type Cooling Tower Work?
The operating principle of an open cooling tower is elegantly simple yet highly efficient. Here is the step-by-step process:
1. Hot Water Enters the Tower
Warm water from your industrial process or condenser (typically 35°C to 45°C / 95°F to 113°F) is pumped to the top of the cooling tower through piping.
2. Water Is Distributed Evenly
At the top, the water passes through a network of low-pressure nozzles that spray it evenly over the fill media. This ensures the water spreads out into a thin film or tiny droplets, maximizing the surface area exposed to air.
3. Air-Water Contact (The Evaporative Event)
Simultaneously, a fan (either forced draft at the bottom or induced draft at the top) draws fresh air through the tower. As the air rises and the water falls:
A small portion of the water (typically 3–4%) evaporates.
This evaporation requires latent heat of vaporization.
The heat is drawn from the remaining water mass, instantly lowering its temperature.
This evaporative cooling process allows open towers to achieve water temperatures lower than the ambient dry-bulb temperature—something air-cooled systems cannot do.
4. Cooled Water Is Collected
The now-cooled water falls into a basin at the bottom of the tower. It is then pumped back to your system to absorb more heat, completing the cycle.
5. Drift Elimination
Special drift eliminators at the air outlet capture water droplets that might otherwise escape with the exhaust air, minimizing water loss.
Two Main Airflow Configurations
Open type cooling towers come in two primary designs:
| Configuration | Airflow Direction | Key Advantage |
|---|---|---|
| Counterflow | Air moves vertically up while water falls down (opposite directions) | Higher heat exchange efficiency (up to 20% more than crossflow); compact footprint |
| Crossflow | Air moves horizontally across the falling water | Easier maintenance access; lower pumping head |
At CTP Mühendislik, we offer both configurations to match your specific site requirements.
Advantages of Open Type Cooling Towers
Why do most industrial plants and large commercial buildings choose open circuit towers? The benefits are substantial:
1. Superior Cooling Performance
Because the water and air are in direct contact, open towers achieve the lowest possible water temperatures—often within 2–3°C of the ambient wet-bulb temperature. This is impossible with dry coolers or closed-loop systems.
2. High Energy Efficiency
Open cooling towers are significantly more energy-efficient than closed-circuit alternatives. For the same cooling duty, an open tower requires less fan power and no spray pump (unlike closed towers which need both).
3. Lower Installed Cost
With fewer components (no heat exchanger coils, no secondary pumping loop), open towers have a lower upfront cost compared to closed-loop systems. Studies show open towers can be up to 3.7 times less expensive than closed-circuit towers for the same application.
4. Compact Footprint
Open cooling towers offer an excellent kW-to-footprint ratio. They require less floor space than closed-loop fluid coolers of equivalent capacity.
5. Lower Operating Weight
With less water volume and no heavy coil bundles, open towers are significantly lighter—sometimes one-third the operating weight of a closed-loop system.
6. Simpler Maintenance
Open towers are designed for straightforward access to internal components like fill, nozzles, and drift eliminators. Many models feature large access panels and sloped basins for easy cleaning.
7. Proven Reliability
Open circuit cooling towers are the industry standard for large-scale heat rejection—from power plants and petrochemical refineries to data centers and commercial HVAC. The technology is mature, well-understood, and supported globally.
Considerations for Open Type Towers
While open towers offer many advantages, they do require:
Water treatment to manage mineral concentration (blowdown) and biological growth.
Make-up water to replace water lost through evaporation and drift.
These are manageable operational costs that are far outweighed by the energy savings and performance benefits.
Why CTP Mühendislik for Your Open Cooling Tower?
At CTP Mühendislik, we manufacture open type cooling towers using CTP (Glass Reinforced Polyester) —a material that outperforms steel and concrete in corrosive industrial environments.
Our CTP composite towers offer:
100% corrosion resistance – no rust, no rot.
Smooth, non-porous surfaces that resist algae and biofilm, reducing chemical usage.
Long service life (25+ years) with minimal maintenance.
Lightweight construction for easier installation and lower structural support costs.
We engineer both counterflow and crossflow open towers, customized to your flow rate, thermal duty, and site constraints.
Open Type Cooling Tower - CTP Engineering
An open type water cooling tower is a direct-contact, evaporative heat exchanger that delivers the lowest possible water temperatures with high energy efficiency and a compact footprint. Its advantages—lower cost, lighter weight, and proven performance—make it the go-to choice for most industrial and HVAC cooling applications.
While closed-loop systems have their place, nothing beats the raw thermodynamic efficiency of an open circuit cooling tower when you need to reject large amounts of heat reliably and cost-effectively.
Ready to specify an open cooling tower for your facility? Contact CTP Mühendislik for a personalized engineering study and a competitive quote.
