High Temperature Heat Pipes

High-temperature heat pipes (also known as alkali metal heat pipes) are typically defined as heat pipes that operate between 400 and 1100°C. They are often used to provide precise temperature uniformity or provide high-temperature heat transfer. In these temperature ranges, many traditional heat transport methods and materials are not suitable for practical operations; whereas alkali-metal heat pipes provide robust, high power transport.

Fluid Options for High-Temperature Heat Pipes

  • High temperature heat pipes can use the following fluids: Cesium 300 to 600°C (572 to 1,112°F) Potassium 400 to 1000°C (752 to 1,832°F) NaK 500 to 800°C (932 to 1472°F) Sodium 500 to 1100°C (932 to 2,012°F)Cesium 300 to 600°C (572 to 1,112°F)
  • Potassium 400 to 1000°C (752 to 1,832°F)
  • NaK 500 to 800°C (932 to 1472°F)
  • Sodium 500 to 1100°C (932 to 2,012°F)


Envelope Material Options for Alkali Heat Pipes

ACT has experience with a variety of traditional and superalloys to withstand the high internal pressure associated with multi-phase metals. Some common envelope materials include Stainless Steel, Inconel Alloy 600, and Haynes. ACT will select the appropriate envelope for the working fluid and operating conditions in partnership with the customer.

Alkali Metal Heat Pipes Examples


Applications for Alkali Metal Heat Pipes


High-temperature heat pipes can be used to build custom heat transfer devices for both high power throughput and precise temperature uniformity. Power throughput in the 1 to 100 kW range is typical. Precision heat treating and materials processing furnaces are capable of extraordinarily precise temperature set points and isothermality. Setpoint accuracy, stability, and isothermality of ± 0.1°C is common with a single heated zone, using an off-the-shelf temperature controller.

Because of the inherent temperature uniformity and stability of high temp heat pipes, they are an integral component in nearly all of the most precise temperature calibration instruments in the primary calibration laboratories around the world (See ACT’s Temperature Calibration and Control Products). This technology can also be applied to research, commercial, and industrial applications for processes such as annealing, sintering, crystal growing, brazing, and controlled diffusion.

Everything You Need To Know About Heat Pipes


ACT designs and manufactures cesium, potassium, and sodium heat pipe products for a wide range of high-temperature applications. As a leading provider of thermal management solutions since 2003 with a solid foundation built on research and development. ACT custom engineers high-temperature heat pipe products to meet unique requirements and temperature ranges. As an AS9100:2009-certified manufacturer, you can be sure your high-temperature heat pipe system will meet the highest quality standards in the industry.

Which industries use high-temperature heat pipes?

  • Material processing
  • Solar Energy
  • Temperature calibration and control

Different Types of Heat Pipes

Why choose ACT for your high-temperature heat pipes?

The alkali metals used in high-temperature heat pipes are extremely reactive to water or air, so achieving purity and containment is of the utmost importance. The ACT facility is one of the few commercial facilities set up to safely handle the construction of these unique heat pipes. ACT has a dedicated lab space, trusted safety measures, and experienced personnel to make and deliver properly sealed vessels that will safely operate and have a long life.

ACT engineers and technicians are able to draw on the experience gained from the company’s work with NASA on the Kilopower project starting in 2015, to deliver both alkali metal and titanium-water heat pipes to support NASA’s investigation into using small fission reactors for future space transportation and surface power applications.

Contact ACT today!

We look forward to learning about your high-temperature application, contact ACT today!

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