Liquid Immersion Cooling for Modular Electronics

Foster-Miller proposes a conformal microchannel liquid flow-over (LFO) avionics card which allows up to 1,000 Watts heat rejection per card without the liquid inventory weight of clamshell enclosures or other similar direct immersion cooling methods. The proposed card exactly matches the external geometry of todays liquid flow-through cards so could directly replace them in an existing system. The conformal microchannel circuit covering will direct a flow of non-electrically conductive liquid coolant over an avionics card and all its components. Preliminary calculations show very acceptable pressure drops and temperature rises in the LFO microchannels. The conformal covering will be removable for card repair. The space needed for the conformal microchannel at the card surface will come from space saved at the card core. Namely, the central 125 mil aluminum heat sink (or flow through channels) of todays standard modules will be replaced by a thin, stiff composite core, possibly hollow. Such a hollow core, used to carry liquid coolant, could optionally increase the cooling capacity of the proposed LFO concept beyond 1,000 Watts. A successful Phase I will demonstrate feasibility of the proposed conformal microchannel LFO avionics card. In Phase II Foster-Miller plans to fabricate and test a working prototype with help from Lockheed.