Micropost waste heat removal system

Abstract

A cooling device formed in a thermally conductive substrate having a microstructure, such as a plurality of thermally conductive posts spaced apart by dimensions that induce capillary action in a liquid coolant. The posts extend away from the heated region and a space between the posts is supplied with liquid coolant which is contained by a meniscus near the tips of the posts. The coolant vaporizes at the meniscus and absorbs heat but, due to increased pressure in the coolant contained by the meniscus, does not boil within the space between the posts, allowing more liquid coolant contact with the thermally conductive substrate and posts. The vaporized coolant may be discharged into the air or into a chamber adjoining the tips having a lower pressure for removal of additional heat by gaseous expansion. The discharge of gaseous coolant allows the capillary flow of the liquid coolant in the space to be unimpeded, and the flow of liquid coolant may be augmented by a fluid pump. The gaseous coolant may be in thermal contact with a condenser that liquefies the coolant for supply to the space, by an array of capillaries, in a self contained cooling device. An array of such devices is provided with holes and stacked to connect adjacent liquid and gaseous coolant flows to cool an array of heated objects, such as laser diode bars.