Generator coolers

Power generation is a crucial in many industrial sectors. Keeping electrical generators cool improves their performance and longevity.  

Sterling TT designs and manufactures generator cooling solutions for all demanding applications.

How to cool a generator

Generators are typically efficient machines, but their high output generates unwanted heat that requires dissipation outside the machine. Professionally designed, cooling systems effectively remove this heat, preventing overheating and permanently damaging the equipment.

Internal fans flush ambient air, sometimes filtered, through the internal mechanisms of open machines to the atmosphere to effectively remove the waste heat created by frictional and electrical losses. 

For those machines located in “sensitive areas” – enclosed spaces, hot, dusty or contaminated climates or hazardous environments – it is no longer possible to simply flush the machine with fresh air. In these cases, the generator is totally enclosed (TEFC), with the encapsulated air (the primary coolant) forced to recirculate around the machine. A cooler is added to the circuit to remove the waste heat using a secondary coolant.

The secondary coolant is typically air or water, which may contain additives such as glycol for cold locations or seawater, often used offshore.

The addition of generator coolers maintains the generator temperature, which keeps it performing optimally, maximising their performance and reducing operating costs. Continue reading for more information about each cooling stage and examples of relevant products.

Types of generator cooling systems

Water-cooled generators

Water has better thermal properties than air and is usually available at a lower temperature, making it the more popular solution. Water coolers pass the primary coolant over finned tubes, and water passes through the tubes.

Many TEFC generators utilise water as the secondary coolant when it is available.

CACW coolers – Air-to-Water Coolers

Short for “Closed Air Circuit, Water Cooled”, CACW coolers are ideal for cooling generators and large electrical motors, no matter the environment.

To improve machine availability and redundancy, Sterling TT can install additional cooling elements. A double tube arrangement is often used for offshore and marine applications, where twin-walled tubes eliminate the possibility of water leaks entering the machine. Material selection is determined by water quality and material thickness is based on the pressure of the water supply.

“WEG has a long-standing partnership with Sterling Thermal Technology, and their CACW/TEWAC have proven to be reliable for various of our applications. Even for the most hazardous environments, we could always count with Sterling TT for a solution that can attend our demand.”
Anderson Fernandes, Global Director of High Voltage Motors and Generators WEG Equipamentos Elétricos S/A

Explore our CACW water coolers, or contact Sterling TT for a quote

CACA/TEEAC coolers

Short for “Closed Air Circuit Air-cooled,” CACA coolers are air-to-air heat exchangers that effectively cool generators or motors. They are also known as TEAAC (Totally Enclosed Air-to-Air Cooled) coolers.

“We have used CACA coolers for a number of different generator installations. Sterling Thermal Technology has an understanding of our requirements which is second to none and their products have always met our expectations.”
Jonathan Southam, Global Commodity Leader, GE Power Conversion

Explore Sterling TT’s CACA/TEEAC coolers

Avantair

A unique high-performance cooling solution that uses heat pipes. Ideal for hazardous and challenging environments from offshore to desert locations. Avantair is an advanced CACA/TEEAC cooler.

“We use Avantair for air-to-air cooling as it allows us to provide higher power output compared to conventional coolers, while meeting the most stringent safety standards. This gives our clients the edge in efficient production of clean, safe and reliable energy.
Dirk Petzoldt, Manager Stator Design, Siemens Generator Plant Erfurt

Explore our Avantair coolers or contact us

Hydrogen-cooling in generators

Hydrogen, in this case, refers to the primary coolant. In very large machines such as nuclear-fuelled power plants, hydrogen is mixed with air to improve the thermal performance of the primary coolant. Hydrogen is also used in less efficient, older generators.

In a hydrogen cooling system, a blend of hydrogen and air circulates through the active parts of the generator, such as the rotor and stator. The heat is dissipated into water coolers, as explained above. This thermal exchange occurs within a finned tube.

Sterling TT hydrogen coolers

Heat exchangers for hydrogen-cooled generators use near conventional heat transfer surfaces housed within a precision-designed and built framework.

There are special design requirements for hydrogen coolers because of the size of the machines and the propensity of hydrogen to escape. Sterling TT designs the carcass that carries the cooler tubes and the tubeplates with high-tolerance dimensions and surface finishes, together with designs to avoid the natural frequency of the generator.

Explore our hydrogen coolers, or contact us

Generator cooling FAQs

What type of cooling is provided for generators in power plants?

Power plants vary in output, are situated in different locations and are subject to different regulations. Simpler plants tend to use open generators, but as soon as output rises or spaces are confined, designers switch to TEFC machines. Water cooling is the first consideration, which is why most plants are found on the coast or beside rivers. When water is not available, air is used.

Find out more in our blog: How Coolers Keep Nuclear Power Generators Safe.

How are large generators cooled?

Large generators use air as their primary coolant plus water as a secondary coolant. Very large generators may use a hydrogen mix as the primary coolant and water as the secondary coolant plus direct de-ionised water cooling within the stator.

Why is hydrogen used for generator cooling?

Hydrogen has the highest thermal conductivities among gases, making it exceptionally effective at transferring heat away from hot surfaces. Furthermore, unlike many other cooling fluids, hydrogen is non-corrosive, minimising the risk of damage to generator components over time. Hydrogen-cooled generators have additional design features to reduce the risk of coolant escape and potential explosion.

Generator cooling systems with Sterling TT

Whether you’re an EPC company, an OEM, or an end-user seeking guidance for your specific process, we can partner with you throughout the entire journey, from design and manufacturing to aftermarket and service support.

With proven expertise and experience in generator cooling, we have gained the confidence of large and small businesses. We supply across most industry sectors, particularly in the oil and gas, chemical and power generation industries, including nuclear, hydropower, waste to energy, and biomass.