Permeable membrane microchannel heat sinks and methods of making

Abstract

Permeable membrane microchannel heat sinks and methods of producing such a heat sink, wherein such a heat sink includes a base and at least first and second microchannels defined by at least one porous and permeable membrane that is on the base and defines primary heat exchange surfaces of the heat sink. The membrane has opposing faces exposed to the first and second microchannels, and a fluid flowing through the heat sink flows from the first microchannel to the second microchannel through pores in the membrane.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 62 / 676,494, filed May 25, 2018, the contents of which are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention generally relates to heat transfer devices and methods. The invention particularly relates to permeable membrane microchannel (PMM) heat sinks having complex and thin porous internal structures capable of exhibiting relatively low pressure drops, and methods of producing such heat sinks.[0003]The pursuit for higher power and more compact electronics in aerospace, automotive, and other applications requires complimentary thermal management technologies that can effectively remove large amounts of heat within a small envelope. Microchannel heat sinks are known in the art as capable of high-heat-flux cooling with low thermal resistance, and therefore suitable for removing dense heat loads from high-power electronic devices. Mic...

AI Technical Summary

Benefits of technology

The present invention provides permeable membrane microchannel heat sinks (PMMHS) with complex and thin porous internal structures that have low pressure drops and can improve heat transfer and reduce temperature rise of heat-generating surfaces. These heat sinks can be produced using direct metal laser sintering (DMLS) and incorporate non-linear structures with internal porosity. These heat sinks have a higher surface area available for heat transfer and do not require an increase in volume, which makes them advantageous for various applications requiring compact removal of large heat loads such as power electronics, radars, high-performance computing electronics, portable electronics, avionics, and automotive systems.

Problems solved by technology

Indeed, the high pressure drop associated with flow through the small channels in microchannel heat sinks is a primary drawback, and numerous design concepts have been proposed to address this issue.

However, while these numerical modeling efforts indicated the potential improvement that these increasingly complex designs may offer, fabrication of such heat sinks via conventional subtractive manufacturing techniques (e.g., micromachining, anisotropic chemical etching) is difficult if not impossible.

The complexity of structures with internal porosity have been limited to features that can be produced by sintering particles in a mold.

However, there has been little focus to date on leveraging these fabrication capabilities to enhance the performance of microchannel heat sinks for electronics cooling.

Work that has studied microscale heat exchangers made by additive manufacturing, specifically powder bed fusion processes, frequently highlights issues associated with material properties and high surface roughness.

The thermal performance was over-predicted, attributed to uncertainty in the thermal conductivity of the material.

Others have experimentally tested additively manufactured wavy microchannels having numerically optimized designs, with results indicating that wall roughness introduced by AM processes assisted in augmenting the heat transfer, while also contributing to an increase in pressure drop.

Designs optimized for minimum pressure drop were hampered by this roughness and did not meet the performance expectations, but designs that strived for both pressure drop reduction and heat transfer augmentation via the optimization scheme yielded improved performance compared to the baseline wavy channels having rectangular cross-sections.

Accurate production of sharp-edged solid features below 0.5 mm has been difficult or impossible.

Literature regarding the intentional introduction of stochastic porosity within parts fabricated with powder bed fusion processes is relatively rare, as this is generally an undesired result and significant efforts are commonly made to eliminate porosity in nominally solid parts.

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