Since 1970 Aavid, Thermal Division of Boyd has been on the forefront of heat pipe technology and it continues to push the boundaries of the technology today. As electronics have become smaller and more powerful, heat pipe technology has become much more prevalent across all industries. Aavid is uniquely equipped to meet all industry needs from the high volume production Consumer Electronics to the intense research and development for Aerospace & Defense.
Aavid manufactures its own heat pipes and maintains strict quality standards to ensure longevity and reliability. Heat pipes capabilities also include loop heat pipes and high temperature heat pipes. Aavid has been performing heat pipe and loop heat pipe life testing on a variety of material systems and heat rejection conditions for over 40 years. Material systems and heat rejection conditions include copper-water, copper-water sintered powder, copper-methanol, aluminum-ammonia, inconel-sodium, natural convection, forced convection, and liquid cooling.
With over 300,000 hours of life of continuous, ongoing life testing on copper-water-sintered power heat pipe systems, Aavid has developed proven manufacturing processes that ensure product lifetime and reliability.
Heat Pipe Sizes
The most popular heat pipe diameters for Aavid embedded heat pipes and heat pipe assemblies are 3mm, 4mm, 6mm, 8mm, and 9.5mm. However, Aavid manufactures commercial heat pipes up to 15.88mm and offers custom sizes. Typical lengths range from 76mm to 457mm (3in – 18in).
For applications that require heat transport over longer distances, loop heat pipes are able to transfer heat from 50mm to greater than 1000mm. By separating the vapor and liquid paths, Aavid can design and produce loop heat pipe assemblies (LHPs) that can provide reliable operation to transfer heat up to 75 feet even in high gravity environments. Aavid has developed and manufactured different designs of LHPs ranging from powerful, large size LHPs that can transfer over 2000W to miniature LHPs that move less than 100W which have been successfully employed in a wide range of aerospace and ground based applications.
Materials and Working Fluids
Although Copper and Water are the most common material and working fluid combination, Aavid has experience working with a wide range of materials and fluids to meet more stringent temperature and application requirements. Currently, Aavid has designed, developed, and manufactured heat pipes utilizing more than 27 working fluids.
Proper fluid selection is dependent on environmental conditions as the heat pipe only functions when the working fluid temperature is above its freezing point. When the temperature is above the vapor condensation point of the working fluid, the vapor will not condense back to liquid phase. If the working fluid freezes and cannot circulate, the assembly cannot transfer heat or cool sensitive equipment.
Working Fluid selection is based on the operating temperature range of the application. Aavid has designed and developed heat pipes and loop heat pipes for operating temperature ranges for cryogenic applications operating below -250°C to high temperature applications above 2000°C. Water is the most common working fluid due to its favorable thermal properties and operating temperature range of 5°C to 250°C.
Aavid works with all wick structures but specializes in four commercial heat pipe wick structures. These heat pipe wick structures include: internal grooved heat pipe walls, wire or screen mesh, sintered powder metal, and fiber or spring. Standard Aavid heat pipes contain a sintered copper wick, however Aavid is experienced in applying alternative wick structures for application optimization.
Different wicks have varying capillary limits, which determines the capillary pumping rate at which the working fluid travels from condenser to evaporator. Wick selection in conjunction with gravity orientation can have a large impact on heat pipe performance. For example, the groove wick has the lowest capillary limit but works best under gravity-assisted conditions, where the evaporator is located below the condenser. Loop heat pipes are less sensitive to orientation and rely on a high capillary pumping wick in the evaporator to drive performance.
With specialized bending methods, Aavid can achieve extremely tight bend radii for complex shaping. More complex heat pipe shapes will reduce the maximum amount of heat the heat pipe can carry, but Aavid Engineers can accommodate this tradeoff in the design phase. For specific industries and applications such as Crystal Growing and Vapor Deposition, Aavid also offers specialized annular heat pipes.
Heat Pipe Kits
For experimentation and learning with heat pipes, Aavid has developed Heat Pipe Demonstration Kits. These kits are designed to enable engineers to design and build their own heat pipe solutions that they can test in their labs for prototyping purposes or just to see how they work. The smaller Discovery Kit is best for small groups and students while the larger Exploration Kit is best for use in the lab or for multiple prototypes.