Thermal management for solid state high-power electronics

Abstract

The invention is for an apparatus and method for removal of waste heat from heat-generating components including high-power solid-state analog electronics such as being developed for hybrid-electric vehicles, solid-state digital electronics, light-emitting diodes for solid-state lighting, semiconductor laser diodes, photo-voltaic cells, anodes for x-ray tubes, and solids-state laser crystals. Liquid coolant is flowed in one or more closed channels having a substantially constant radius of curvature. Suitable coolants include liquid metals and liquids with low vapor pressure. The former may be flowed by magneto-hydrodynamic effect or by electromagnetic induction. The latter may be flowed by magnetic forces. Alternatively, an arbitrary liquid coolant may be used and flowed by an impeller operated by electromagnetic induction or by magnetic forces. The coolant may be flowed at very high velocity to produce very high heat transfer rates and allow for heat removal at very high flux.

1 . A heat transfer device comprising:
 a) a body having a first surface, a second surface, and a chamber;
 said chamber being formed as a hollow cylinder comprising an inner cylindrical surface and an outer cylindrical surface; 
 said outer cylindrical surface comprising a central axis of symmetry, a first constant radius of curvature, and an azimuthal direction; 
 said inner cylindrical surface comprising a second constant radius of curvature; 
 said inner cylindrical surface being substantially concentric with said outer cylindrical surface; 
 said first surface is arranged to be in a good thermal communication with a heat generating component; 
 said first surface being generally tangential to said outer cylindrical surface with only a small separation between the two; 
 said second surface is arranged to be to be in a good thermal communication with a heat sink; 
   b) a liquid coolant substantially filling said chamber; and   c) a means for flowing said liquid coolant in said azimuthal direction.   
     
     
         2 . The heat transfer device of  claim 1 , wherein two times the height of said hollow cylinder multiplied by the difference between said first constant radius of curvature and said second constant radius of curvature, divided by the sum of said height and said difference is in the range of 10 to 2000 micrometers. 
     
     
         3 . The heat transfer device of  claim 1 , wherein said first constant radius of curvature is between 5 and 25 millimeters. 
     
     
         4 . The heat transfer device of  claim 1 , wherein the difference between said first constant radius of curvature and said second constant radius of curvature is in the range of 10 to 2000 micrometers. 
     
     
         5 . The heat transfer device of  claim 1 , wherein said liquid coolant is a liquid metal and wherein said means for flowing said liquid coolant in said azimuthal direction comprise an MHD drive comprising:
 a) a permanent magnet generating a magnetic field within at least a portion of said liquid coolant; said magnetic field having a substantial component in a radial direction of said hollow cylinder; and   b) a plurality of electrodes for drawing electric current through at least a portion of said liquid coolant in a direction substantially parallel to said central axis of symmetry.   
     
     
         6 . The heat transfer device of  claim 1 , wherein said liquid coolant is a liquid metal and wherein said means for flowing said liquid coolant in said azimuthal direction comprise a plurality of electromagnets; said electromagnets adapted for generating a magnetic field rotating in said azimuthal direction in response to excitation by poly-phase alternating current. 
     
     
         7 . The heat transfer device of  claim 1 , wherein said means for flowing said liquid coolant in said azimuthal direction comprise on impeller; said impeller arranged to form at least a portion of said inner cylindrical surface; and said impeller arranged to rotate with respect to said body; and said impeller arranged to substantially rotate about said central axis of symmetry. 
     
     
         8 . A heat transfer device comprising: a body, an impeller, and liquid coolant;
 a) said body having a first surface, a second surface;
 (i) said first surface being arranged to be in a good thermal communication with a heat generating component; 
 (ii) said second surface being arranged to be to be in a good thermal communication with a heat sink; 
   b) said impeller being rotatably suspended inside said body;   c) said impeller and said body being arranged to form a chamber;
 (i) said chamber being formed as a hollow cylinder comprising an outer cylindrical surface and an inner cylindrical surface; 
 (ii) said outer cylindrical surface comprising a first constant radius of curvature; 
 (iii) said inner cylindrical surface comprising a second constant radius of curvature 
 (iv) said outer cylindrical surface of said chamber being substantially formed by said body; 
 (v) said inner cylindrical surface of said chamber being substantially formed by said impeller; 
 (vi) said inner cylindrical surface comprising an axis of rotational symmetry; 
 (vii) said chamber being substantially filled by said liquid coolant; and 
   d) said impeller arranged to rotate substantially about said axis of rotational symmetry.   
     
     
         9 . The heat transfer device of  claim 8 , wherein said first surface being generally tangential to said outer cylindrical surface with only a small separation between the two. 
     
     
         10 . The heat transfer device of  claim 8 , wherein the difference between said first constant radius of curvature and said second constant radius of curvature is less than about 2,000 micrometers. 
     
     
         11 . The heat transfer device of  claim 8 , further comprising a means to rotate said impeller about said axis of rotational symmetry. 
     
     
         12 . The heat transfer device of  claim 8 , further comprising a plurality of electromagnets fed with poly-phase alternating current; said electromagnets being arranged to generate an electromagnetic field rotating substantially about said axis of rotational symmetry; said electromagnetic field being arranged to operatively couple to said impeller; said electromagnetic field arranged to rotate said impeller substantially about said axis of rotational symmetry. 
     
     
         13 . The heat transfer device of  claim 12 , further comprising a permanent magnet; said permanent magnet being mechanically coupled to said impeller; and said permanent magnet being arranged to operatively couple to said electromagnetic field. 
     
     
         14 . The heat transfer device of  claim 12 , further comprising an electromagnetic coil; said coil being mechanically coupled to said impeller; and said coil being arranged to operatively couple to said electromagnetic field. 
     
     
         15 . A method for transferring heat from a heat generating component to a heat sink comprising the steps of:
 a) providing a body, an impeller, and liquid coolant; said body comprising a first surface and a second surface; said impeller rotatably installed in said body; said impeller and said body arranged to form together a chamber; said chamber shaped generally as a hollow cylinder; said chamber being substantially filled with said liquid coolant;   b) rotating said impeller;   c) causing said liquid coolant to flow substantially azimuthally inside said cylindrical chamber;   d) transferring heat from a heat generating component into said liquid coolant;   e) transporting heat in said liquid coolant; and   f) transferring heat from said liquid coolant to a heat sink.   
     
     
         16 . The method for transferring heat of  claim 15 , wherein said impeller substantially forms an inner cylindrical surface of said hollow cylinder. 
     
     
         17 . The method for transferring heat of  claim 15 , further comprising the steps of:
 a) providing a heat generating component arranged to be in a good thermal communications with said body; and   b) providing a heat sink arranged to be in a good thermal communications with said body.   
     
     
         18 . The method for transferring heat of  claim 15 , further comprising the step of providing a means for rotating said impeller. 
     
     
         19 . The method for transferring heat of  claim 18 , wherein said a means for rotating said impeller comprise a plurality a plurality of electromagnets adapted for operation with poly-phase alternating current. 
     
     
         20 . The method for transferring heat of  claim 18 , wherein said a means for rotating said impeller are selected from the group of electric motor, rotating magnetic field, hydraulic motor, and a turbine.