Two-phase-flow, panel-cooled, battery apparatus and method

Abstract

Two-phase, boiling heat transfer in confined channels close to a source of heat, such as an electrical component or device, carries the latent heat of vapors away to remote locations where “real estate” demands of air convection are tolerable operationally, economically, and technologically. Liquid-to-vapor, phase-change, heat transfer in a narrow channel (e.g., typically less than 0.200 inches total thickness, and often less than 0.150 in the channel itself) improves by several hundred percent the heat extraction from modest temperature (e.g., about 120 degree F.) devices, when compared to heat fluxes in pool boiling. Saturated working fluids provide nearly isothermal conditions in the working fluid. Minimal conduction paths provide minimal temperature gradients, and capillary action may maintain nearly constant temperature conditions about a surface of a heat source, while carrying heat of vaporization away to a condensation location.

1 . A method of heat removal comprising:
 providing a source of heat;   providing a first panel comprising a wall containing a single working fluid operating in two phases;   passing heat from the electrical component into the wall;   passing heat from the wall into the working fluid;   forming discrete bubbles of vapor by boiling the working fluid at the wall;   rising by some of the discrete bubbles;   sweeping others of the discrete bubbles of the vapor from the wall by the some of the discrete bubbles;   condensing the vapor to a liquid; and   returning the liquid to proximate the source of heat.   
     
     
         2 . The method of  claim 1 , wherein the source of heat is an electrical component generating heat losses. 
     
     
         3 . The method of  claim 2 , wherein the working fluid is dielectric. 
     
     
         4 . The method of  claim 1 , wherein the wall is vertical, the method further comprising connecting a second panel to the first panel in mutually orthogonal relation. 
     
     
         5 . The method of  claim 4 , further comprising sharing by the first and second panels a common working fluid. 
     
     
         6 . The method of  claim 5 , wherein:
 the wall is planar;   the second panel extends parallel to a plane orthogonal to the wall.   
     
     
         7 . The method of  claim 6 , wherein the second panel is oriented horizontally and carrying heat horizontally from the heat source to the first panel. 
     
     
         8 . The method of  claim 7 , further comprising carrying, by a line connected to the first panel, a vapor phase of the working fluid from the first panel to a condenser. 
     
     
         9 . The method of  claim 8 , further comprising returning a liquid phase of the working fluid to the first panel from the condenser. 
     
     
         10 . The apparatus of  claim 1 , wherein the panel is sealed to contain exclusively the working fluid, the method further comprising:
 providing a heat exchanger removing heat from the first panel by conduction;   the first panel boiling the liquid phase of the working fluid to vapor and condensing the vapor phase of the working fluid to liquid.   
     
     
         11 . An apparatus comprising:
 a source of heat;   a working fluid operating at saturation temperature and pressure;   a first panel comprising a first wall exposed to the working fluid in two phases;   the first panel, further comprising a second wall spaced from the first wall and parallel thereto;   the working fluid contained to be free to convect in a space between the first and second walls, the space between the first and second walls being about an order of magnitude less than the planar dimensions thereof;   at least one first source in intimate contact with the first wall and exposed to conduct heat into the working fluid;   at least one second source in intimate contact with the first wall and exposed to conduct heat directly into the working fluid;   the first wall spaced from the second wall a distance selected to form first discrete bubbles of vapor by boiling the working fluid at the wall;   the first and second walls forming second discrete bubbles above the first discrete bubbles, and the first discrete bubbles sweeping the second discrete bubbles away from the first and second walls by rising along and expanding against the first and second walls; and   a condenser receiving a flow of vapor comprising the content formed of the coalescing of the first discrete bubbles and the second discrete bubbles, to condense the flow from the vapor phase back to the liquid phase.   
     
     
         12 . The apparatus of  claim 11 , further comprising a first line returning the liquid to proximate the source of heat. 
     
     
         13 . The method of  claim 12 , wherein the source of heat is an electrical component generating heat losses and the wall is a mounting surface supporting the electrical component. 
     
     
         14 . The apparatus of  claim 13 , wherein the working fluid is dielectric. 
     
     
         15 . The apparatus of  claim 14 , wherein the first and second walls are vertical, the apparatus further comprising a second panel connected to the first panel in mutually orthogonal relation. 
     
     
         16 . The apparatus of  claim 15 , further comprising an open connection between the first and second panels, sharing between the first and second panels the working fluid as a common working fluid. 
     
     
         17 . The apparatus of  claim 11 , wherein:
 the wall is planar;   the second panel extends parallel to a plane orthogonal to the wall.   
     
     
         18 . The apparatus of  claim 17 , wherein the second panel is oriented horizontally and carrying heat horizontally from the heat source to the first panel. 
     
     
         19 . The apparatus of  claim 11 , wherein the apparatus is sealed to contain and maintain uncontaminated the working fluid, the apparatus further comprising:
 the first panel comprising a lower portion containing a boiling, liquid phase of the working fluid, evaporating to vapor;   the first panel comprising an upper portion condensing the vapor phase of the working fluid to liquid; and   a heat exchanger removing heat from the vapor phase of the working fluid.   
     
     
         20 . The apparatus of  claim 11 , wherein the first source is selected from an electrical component on the first wall operating as a circuit board, a battery, and another chemical heat generator.