Heat transfer element with nucleate boiling surface and bimetallic fin formed from element

摘要

A metal foil for use as a heat transfer element has through holes formed as a narrow entrance opening to one surface and a wider diameter cavity opening to the other surface. Two foils are laminated with the narrow entrances opening to the outside and with the wider cavities closed by the inside surface of the other foil. In the completed structure the cavities and their entrances form nucleate boiling sites. In a manufacturing step of forming the through holes, the junction between the narrow entrance and the wider diameter cavity is shaped to prevent a heat transfer liquid from flooding the cavities. The structure is particularly useful for fins for cooling circuit devices that are immersed in a dielectric liquid. In one heat transfer structure, the fins are formed by laminating two metal foils that have differing coefficients of thermal expansion. The fins spread apart as their temperature increases, and components are cooled in proportion to the heat they produce.