Advanced Cooling Technologies, Inc. (ACT) is a leader in Heat Pipe (HP) products and technologies. ACT manufactures a large variety of heat pipes, HP heat sinks and HP assemblies for a wide range of applications. In fact, ACT is the only US manufacturer that routinely delivers HPs for terrestrial electronics cooling (copper-water), on-orbit satellite thermal management (aluminum-ammonia) and high temperature calibration equipment (liquid metal). In addition, ACT is a leader in developing new functionality and increased performance with emerging heat pipe technology.
This Heat Pipe Resource page contains the most extensive information on heat pipes and related technology available anywhere on the web, including Fundamentals, Limits, Wicks, Working Fluids and Envelopes, Different Kinds of Heat Pipes, and Advanced Developments.
An Overview of the Technology
A heat pipe is a two phase heat transfer device with a very high effective thermal conductivity. It is a vacuum tight device consisting of an envelope, a working fluid, and a wick structure. As shown in Figure 1, the heat input vaporizes the liquid working fluid inside the wick in the evaporator section. The saturated vapor, carrying the latent heat of vaporization, flows towards the colder condenser section. In the condenser, the vapor condenses and gives up its latent heat. The condensed liquid returns to the evaporator through the wick structure by capillary action. The phase change processes and two- phase flow circulation continue as long as the temperature gradient between the evaporator and condenser are maintained.
Benefits of these devices include:
- High Thermal Conductivity (10,000 to 100,000 W/m K)
- Low Cost
- Shock/Vibration tolerant
- Freeze/thaw tolerant
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If you are designing a thermal system and simply want to learn more about heat pipes for cooling, use the links in the Operation Section. If you still have questions, contact us and an engineer will be in contact with you.
Using liquid metal as the working fluid allows operation at temperatures up to 1,100 degrees C.
Wrap around heat exchangers create efficient operation to lower operating costs by pre-cooling incoming air.
ACT’s HiK™ (High Conductivity) plates are heat spreaders with embedded HP to increase the effective thermal conductivity for conduction cooled cards and electronics enclosures
Vapor Chambers are very high effective conductivity heat spreaders, as well as a flux transformer, lowering the effective heat transfer rate at the heat sink.
Background physics including a video that demonstrates the two-phase heat transport.
Learn about the various limits that determine the maximum power (W) a heat pipe can move.
Learn the basics on sizing and modeling with our heat pipe design guide. You'll be able to integrate these devices into your project in no time!
Learn about the advantages, limitations, and trade-offs of various wick structures.
Working fluids are determined primarily by the ambient conditions, the thermodynamic properties of the fluid, and compatibility with the wick/envelope.
A short history showing how applications have expanded since the heat pipe was invented back in 1963.
Advanced Heat Pipes and Loop Heat Pipes including new working fluids, passive thermal control with variable conditions, and freeze/thaw tolerance.
Learn how ACT has extended the operating temperature range for water working fluid from 150 to 300°C.
ACT is developing new working fluids for the intermediate temperature range, between water and alkali metal working fluids.
Alkali metal working fluids with superalloy envelopes allow operation at temperatures up to 1100°C.
ACT has developed vapor chamber heat spreaders that can accept heat fluxes up to 500 W/cm2 over a 4 cm2 area and transform the heat flux so that it can be removed with conventional cooling methods.
PCHPs vary the amount of Non Condensable Gas (NCG) in their reservoir, allowing very tight temperature control (± 5 mK) over hours of operation.
LHPs are passive, two-phase heat transport devices that can transfer higher amounts of heat over longer distances than conventional heat pipes.
High temperature titanium-water heat pipes with radiators have been developed for use in spacecraft fission power systems.
HPLs provide higher heat transport than heat pipes, with lower cost than LHPs.
Life tests are conducted to verify that the envelope, wick, and working fluid in a two-phase heat transfer device are compatible, allowing for long term operation.