Closed Circuit Air Coolers

Closed circuit air coolers to remove excess heat from your closed system

Closed circuit air coolers are coolers designed to remove excess heat from a closed system. The heat may be generated mechanically, electrically or by a chemical reaction but must be eliminated to ensure the continued safe and efficient operation of the process.

Sterling Thermal Technology supplies bespoke closed circuit solutions for your cooling requirements whatever the process is. We have developed customised solutions for a range of batch and continuous processes across the full spectrum of industrial, marine and naval sectors.


Key benefits

  • Compact - Using our optimised fin surface technologies, we can build closed circuit coolers to suit your equipment configuration. We are able to minimise our design envelope while matching your interface requirements.

  • Compliant - Our bespoke design allows us to address a full range of technical specifications. We offer design options where different areas of specifications may suggest alternative solutions.

  • Robust - We select the materials to suit the available cooling medium, which can be fresh, river or seawater. Correct material selection ensures the potential for erosion and corrosion is minimised and operating life is maximised.

How it works

Closed circuit coolers are used in a wide range of continuous, intermittent and batch applications. They eliminate excess heat from a system to ensure the process operates safely and efficiently. This heat is generated mechanically, electrically or by a chemical reaction.

Circulating air is the primary coolant; it takes away the heat from the components it passes over. Water is normally the secondary coolant. It removes heat from the airstream as it passes through the closed circuit cooler, returning the airstream to within 5 to 10oC of the circulating water temperature.

The quality of the cooling water determines the materials used in the closed circuit cooler. Tube materials vary from copper through stainless steel to titanium.

Example of marine applications

Recirculating marine breaking resistors are an example of a process which is intermittent and where a large amount of thermal energy must be taken out from a closed system, in a short period of time. A centrifugal fan circulates large volumes of air through the resistor stack as the braking is applied and the heat is generated. The air removes the heat from the resistor stack and in turn, the air is cooled by a closed circuit air to water heat exchanger.

The cooling water for the majority of marine applications is seawater. 90/10 cupronickel is a standard tube material for clean seawater. However, in some instances, the requirement to minimise weight may have an impact. Titanium, while marginally reducing the heat transfer, can contribute to weight reduction in addition to corrosion and erosion resistance.

Because of the large amount of heat input, the recirculating air temperature rises to more than 100o C. Over a specified period, the circulating air is reduced in temperature to within 5 to 10o C of the circulating water temperature. The resistors are returned to their normal standby temperature profile so that they are available for operation when next called upon.

If you feel you need another type of heat exchanger, visit our products and services page or contact us.


Customised heat exchangers

Over 100 years of design & manufacturing knowledge

Your partner for the entire lifecycle of your business

A high-performance compact system is essential for us, and we know the Sterling Thermal Technology closed circuit coolers can be configured to meet our specific project needs. Their capability to meet exacting standards set by ourselves and our clients is essential. Sterling has a proven record in meeting rigorous naval standards.



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We customise our heat exchange solution to meet your requirements, so contact us today to discover the right equipment for you.

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