High performance miniature heat pipe

High performance miniature heat pipes are developed for the cooling of high heat flux electronics using new capillary structures made of a folded copper sheet fin. Using the folded sheet fin, capillary flow channels with fully and partially opened grooves are made by electric-discharge-machining technique. It is easy to form the capillary grooves as dense as desired through the present fabrication techniques. Heat pipes with two different capillary structures and different fill amounts are tested in the horizontal orientation. Three heating modes of the evaporator are simulated by activating different numbers of chip resistors. The heat pipe with partially opened groove wick performs better than that with fully opened groove wick. The condenser heat transfer coefficient is higher by 120% or greater in the case of the former wick type compared to the latter at an operating temperature of 110 °C. Heat fluxes higher than 140 W/cm2 are achieved using concentrated heating modes.