Multi-Phase Thermal Control Apparatus, Evaporators and Methods of Manufacture Thereof

Abstract

Multi-phase thermal control systems, evaporators, variable porous wick elements, heat transfer structures, and methods for their production are provided. Two-phase evaporators for use in such multi-phase thermal control systems are also provided. Two-phase evaporators incorporate a vapor plate body having there three major layers: a vapor channel network, a wick, and a liquid channel. The vapor channel network comprises a plurality of extrusions (e.g., vapor pillars) and associated channels (e.g., vapor channels) configured to allow a vapor to flow therethrough. The wick comprises a porous body configured to be disposed between the vapor channel network of and the liquid flow reservoir.

What is claimed is: 
     
         1 . A multi-phase evaporator comprising:
 an evaporator body having at least one outer heating surface and defining an internal volume;   a vapor channel network comprising a plurality of elongated heat transfer elements separated by a plurality of channels, wherein the elongated heat transfer elements have first ends interconnected with an inner wall of the internal volume opposite at least one outer heating surface such that the elongated heat transfer elements and the outer heating surface are in thermal contact, and having second ends distal from inner wall;   a wick element comprising a liquid porous body disposed in contact with the second ends of the plurality of elongated heat transfer elements;   a fluid reservoir disposed within the internal volume such that the wick element is interposed between the fluid reservoir and the vapor channel network;   at least one fluid inlet disposed in a wall of the evaporator body such that fluid flows into the fluid reservoir; and   at least one outlet disposed in a wall of the evaporator body distal from the at least one fluid inlet, the at least one outlet configured to transport both heated vapor and heated liquid from the evaporator body.   
     
     
         2 . The multi-phase evaporator of  claim 1 , further comprising:
 at least two outlets, wherein at least a first outlet is configured to transport heated liquid from the fluid reservoir, and wherein at least a second outlet is configured to transport heated vapor from the vapor channel network; and   wherein the wick element is disposed within the evaporator body and configured as a phase separator between the vapor channel network and the fluid reservoir.   
     
     
         3 . The multi-phase evaporator of  claim 2 , wherein the wick element spans the entire opening between the fluid reservoir and the vapor channel network. 
     
     
         4 . The multi-phase evaporator of  claim 1 , comprising at least one mixed-phase outlet configured to transport both heated vapor and heated liquid from the evaporator, and wherein the wick element only partially spans the opening between the fluid reservoir and the vapor channel network such that a mixing region is formed adjacent the at least one mixed-phase outlet where heated vapor from the vapor channel network and heated liquid from the fluid reservoir interact prior to flowing into the at least one mixed-phase outlet. 
     
     
         5 . The multi-phase evaporator of  claim 1 , further comprising an evaporator cap configured to seal the internal volume adjacent the fluid reservoir. 
     
     
         6 . The multi-phase evaporator of  claim 5 , wherein the evaporator cap further comprises a plurality of depressions formed into the inner surface thereof, the plurality of depressions being configured to engage a plurality of resilient members configured to engage and apply a preload force onto the wick element such that thermal contact is maintained between the wick element and the second surfaces of the plurality of elongated heat transfer elements. 
     
     
         7 . The multi-phase evaporator of  claim 1 , wherein the wick element is formed of a porous material having variable porosity. 
     
     
         8 . The multi-phase evaporator of  claim 7 , wherein the porosity of the wick element varies continuously through the cross-section of the wick element. 
     
     
         9 . The multi-phase evaporator of  claim 1 , wherein the wick element is integrally formed into the body of the evaporator. 
     
     
         10 . The multi-phase evaporator of  claim 1 , wherein the wick element serves as a structural member of the body of the evaporator. 
     
     
         11 . The multi-phase evaporator of  claim 1 , wherein the at least one heating surface is configured to conform with the body of an external heat generating element. 
     
     
         12 . The multi-phase evaporator of  claim 1 , further comprising a plurality of resilient members configured to engage and apply a preload force onto the wick element such that thermal contact is maintained between the wick element and the second surfaces of the plurality of elongated heat transfer elements. 
     
     
         13 . The multi-phase evaporator of  claim 1 , wherein the plurality of elongated heat transfer elements comprise pillars having a uniform geometric cross-section, the pillars being one of either solid or porous. 
     
     
         14 . The multi-phase evaporator of  claim 1 , wherein the ratio of the width of a length determined by the width of an elongated heat transfer element and adjacent vapor channel to the width of the elongated heat transfer element is from 0.5 to 0.8. 
     
     
         15 . The multi-phase evaporator of  claim 1 , wherein the width of the elongated heat transfer element is from 0.25 to 0.4 inches. 
     
     
         16 . The multi-phase evaporator of  claim 1 , wherein the walls of the evaporator are formed from low thermally conducting materials. 
     
     
         17 . A thermal control system comprising:
 a fluid handling system comprising a plurality of interconnected fluid conduits;   a pump in fluid communication with the fluid handling system;   an evaporator in fluid communication with the fluid handling system and configured to pick up a heat load comprising:
 an evaporator body having at least one outer heating surface an defining an internal volume, 
 a vapor channel network comprising a plurality of elongated heat transfer elements separated by a plurality of channels, wherein the elongated heat transfer elements have first ends interconnected with an inner wall of the internal volume opposite the at least one outer heating surface such that the elongated heat transfer elements and the outer heating surface are in thermal contact, and having second ends distal from inner wall, 
 a wick element comprising a liquid porous body disposed in contact with the second ends of the plurality of elongated heat transfer elements, 
 a fluid reservoir disposed within the internal volume such that the wick element is interposed between the fluid reservoir and the vapor channel network, 
 at least one fluid inlet disposed in a wall of the evaporator body such that fluid flows into the fluid reservoir, and 
 at least one outlet disposed in a wall of the evaporator body distal from the at least one fluid inlet, the at least one outlet configured to transport both heated vapor and heated liquid from the evaporator body; 
   a condenser in fluid communication with the fluid handling system downstream of the evaporator and configured to reject the heat load; and   an accumulator in fluid communication with the fluid handling system disposed at an inlet of the pump and configured to regulate the system pressure.   
     
     
         18 . The thermal control system of  claim 17 , further comprising:
 at least two outlets, wherein at least a first outlet is configured to transport heated liquid from the fluid reservoir, and wherein at least a second outlet is configured to transport heated vapor from the vapor channel network; and   wherein the wick element is disposed within the evaporator body and configured as a phase separator between the vapor channel network and the fluid reservoir.   
     
     
         19 . The thermal control system of  claim 17 , comprising at least one mixed-phase outlet configured to transport both heated vapor and heated liquid from the evaporator, and wherein the wick element only partially spans the opening between the fluid reservoir and the vapor channel network such that a mixing region is formed adjacent the at least one mixed-phase outlet where heated vapor from the vapor channel network and heated liquid from the fluid reservoir interact prior to flowing into the at least one mixed-phase outlet. 
     
     
         20 . The thermal control system of  claim 19 , further comprising a pre-heater in fluid communication with the fluid handling system upstream of the evaporator.