Thermal Management centers around the movement and removal of heat from a system, often in electronics. This includes heat spreading, heat transfer, and heat dissipation. Aavid, Thermal Division of Boyd Corporation has been a world leader in the optimization of thermal solutions and the development of innovative thermal technologies for over 50 years.
Heat spreaders offer cost-effective, reliable high thermal conductivity and efficacy with almost no moving parts.
Moving heat by remote heat dissipation with passive devices like heat pipes or loop heat pipes provides an efficient thermal solution with high performance, low weight, low cost and high reliability – there are no moving parts to fail, wear out, replace or lubricate.
The type of working fluid also influences heat pipe performance. A heat pipe or loop 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, and no fluid circulation – and no cooling – occurs. 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 from Cryogenic (<-250°C) to High Temperature (>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 has designed, developed and manufactured heat pipes using over 27 different working fluids.
The orientation of a heat pipe relative to gravity, combined with its wick structure, also plays an important role in its 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.
Heat pipes can be formed (flattened or bent) for integration into an assembly. If a heat pipe is flattened or bent, it will reduce the maximum amount of heat that can be transported. Avoiding this limitation is a design consideration.
For moving heat in industrial, electronic, aerospace and other applications, heat pipes and loop heat pipes are generally integrated into a thermal subsystem to transport heat from the heat source to remote areas. Heat pipes are effective in carrying heat away from heat sources and heat-sensitive components to a finned array or a heat sink in another location.
A high-capacity power electronics cooler is an example of a thermal solution where space is often insufficient for mounting a finned heat sink directly adjacent to the heat source. Instead, high-capacity heat pipes move the heat to the finned array, which dissipates heat energy using forced convection. Hundreds of watts can be dissipated this way.
The integration of heat pipes and loop heat pipes into a thermal solution delivers many benefits, including.
• High effective thermal conductivity (>5000 W/m•K)
• Long distance heat transport
• High reliability
• No moving parts
• Passive — do not require moving parts and other similar potential maintenance challenges
In addition, heat pipes and loop heat pipes can be designed for a variety of external environmental factors such as mechanical shock, vibration, force impact, thermal shock/cycling, and corrosive environment that can affect heat pipe life.
Using thermal solution technologies from Aavid such as heat sinks, heat pipes, vapor chambers, loop heat pipes, k-Core®, liquid cold plates, and heat exchangers, designers can choose to dissipate waste heat to air (natural or forced convection), to liquid (water, water/glycol, PAO), or radiate to space.
Dissipating Heat to Air
In many applications, the preferred method of thermal management is convection cooling to air, especially in electronics cooling applications. With Aavid’s heat sink, heat pipe assemblies, and heat spreader technologies, waste heat is typically absorbed from a heat generating device (e.g., an electrical component within an electronics system — i.e. computers and data centers) and then moved or spread for dissipation into the ambient air through either natural or forced (using a fan air mover). Thermal technologies from Aavid such as remote heat pipe assemblies and vapor chambers allow the designer to move heat from high heat flux components to a location with a larger surface area (typically plate fins or folded fins) and lower heat flux for dissipation into the ambient air.
Dissipating Heat to Liquid
Applications with large heat loads such as military radars or power electronics often require waste heat to be dissipated into the liquid coolants (water, water/glycol, PAO) of a secondary system for ultimate heat dissipation. Aavid’s heat pipe cold plates and liquid cold plates allow designers to move heat from a heat generating device into a coolant being circulated from a secondary system.
Dissipating Heat through Radiation
As satellites are packaged with more electronics, the challenge of rejecting heat through the limited surface area becomes greater. Aavid’s low temperature, axially grooved heat pipes (ammonia/aluminum, ethane/aluminum) and loop heat pipe technology make it possible to reject heat through radiator panels that are stored for launch, then deployed from the satellite when the satellite achieves orbit. Our low temperature axially grooved heat pipes spread heat out from the satellite electronics to the radiator panels, dissipating waste heat to space. And our loop heat pipe technology is capable of transporting and rejecting heat loads from hundreds of W to greater than 2,000 W.