Thermal management for solid state high-power electronics

Abstract

The invention is for an apparatus and method for removal of waste heat from heat-generating components including high-power solid-state analog electronics such as being developed for hybrid-electric vehicles, solid-state digital electronics, light-emitting diodes for solid-state lighting, semiconductor laser diodes, photo-voltaic cells, anodes for x-ray tubes, and solids-state laser crystals. Liquid coolant is flowed in one or more closed channels having a substantially constant radius of curvature. Suitable coolants include liquid metals and liquids with low vapor pressure. The former may be flowed by magneto-hydrodynamic effect or by electromagnetic induction. The latter may be flowed by magnetic forces. Alternatively, an arbitrary liquid coolant may be used and flowed by an impeller operated by electromagnetic induction or by magnetic forces. The coolant may be flowed at very high velocity to produce very high heat transfer rates and allow for heat removal at very high flux.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. provisional patent applications U.S. Ser. No. 61 / 463,040, filed on Feb. 12, 2011 and entitled “Thermal Management for Solid State High-Power Electronics,” and U.S. Ser. No. 61 / 463,210, filed on Feb. 14, 2011 and entitled “Thermal Management for Solid State High-Power Electronics,” the entire contents of all of which are hereby expressly incorporated by reference This patent application is a continuation-in-part patent application of: U.S. Ser. No. 12 / 290,195 filed on Oct. 28, 2008 and entitled HEAT TRANSFER DEVICE; U.S. Ser. No. 12 / 584,490 filed on Sep. 5, 2009 and entitled HEAT TRANSFER DEVICE; and U.S. Ser. No. 12 / 932,585 filed on Feb. 28, 2011 and entitled THERMAL INTERFACE DEVICE; the entire contents of all of which are hereby expressly incorporated by reference.FIELD OF THE INVENTION[0002]This invention relates generally to a removal of heat from heat-generating component and more specifical...

AI Technical Summary

Benefits of technology

[0024]Accordingly, it is an object of the present invention to provide a heat transfer device (HTD) for removing waste heat from HGC. The HTD of the present invention is simple, compact, lightweight, self-contained, can be made of materials with a coefficient of thermal expansion (CTE) matched to that of the HGC, requires relatively little power to operate, and it is suitable for large volume production.

Problems solved by technology

Cooling requirements for the new generation of heat-generating components (HGC) are very challenging for thermal management technologies of prior art.

Traditional heat sinks and heat spreaders have large thermal resistance contributing to elevated junction temperatures and thus reducing device reliability.

As a result, removal of heat often becomes the limiting factor and a barrier to further performance enhancements.

Waste heat must be effectively removed from the LED chip to reduce junction temperature, thereby prolonging LED life and making LED cost effective over traditional lighting sources.

Anodes in x-ray tubes are subjected to very high thermal loading.

Such rotating anodes inside a vacuum enclosure are impractical for use in a new generation of x-ray tubes for use in compact and portable devices in medical and security applications.

However, even with heat spreading materials having extremely high thermal conductivity such as diamond films and certain graphite fibers, a significant thermal gradient is required to conduct large amount of heat even over short distances.

In addition, passive heat spreaders are not conducive to temperature control of the HGC.

This results in a very high coolant consumption and requires a large pumping system.

Known forced convection systems have many components, are bulky, heavy, and have geometries that require the coolant to make complex directional changes while traversing the coolant loop.

Such directional changes are a potential source of increased flow turbulence causing higher pressure drop in the loop and, therefore, necessitate higher pumping power.

Such configurations may not self-contained and may be impractical for many applications because they may have a large size, may not sealed, may use incompatible materials, and may have large electromagnetic interference (EMI).

In addition, above disclosures do not address the challenges of handling and pumping liquid metal, namely:1) Galinstan has a specific gravity of about 6.4, which means that galinstan flow loop may require nearly 7-times more pumping power to operate than a comparable water flow loop having the same flow velocity.2) Gallium alloys have a tendency to form amalgams with other metals, which may result in severe corrosion in commonly used engineering metals.

In addition, the solid inter-metallic compounds produced by the corrosive action may form deposits inside the liquid metal flow channel, impeding the heat transfer, and possibly block the flow channels.3) Pumping of liquid metal with an electromagnetic pump may be very simple in theory, but it may be challenging in practice due to possible complex magneto-hydro-dynamic (MHD) boundary layers and MHD instabilities.4) Volumetric specific heat of liquid metal may be only about half of that of water.

This means that, a liquid metal cooling loop operating at low velocity may not be much more effective (and may be actually less effective) than a comparable water loop.

In summary, prior art does not teach a heat transfer device capable of removing heat at very loads and high fluxes that is also compact, lightweight, self contained, capable of accurate temperature control, has a low thermal resistance, and requires very little power to operate.

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