Canopy Wick For Extreme Heat Transfer And Small Resistance

Abstract

A flow-boiling canopy wick (FBCW) employing film (meniscus) evaporation and perforated distribution layer separating the liquid stream from the underlying vapor space is provided. The vapor vents continuously through periodic perforations, in contrast to plain surface which becomes completely covered by vapor at high heat flux. The FBCW allows streamwise liquid tracks on the distribution layer between perforations providing capillary liquid flow toward heated surface and evaporation on high-effective-conductivity monolayer wick. Under extreme heat flux, various hydrodynamic limits prevent liquid supply and vapor removal, i.e., the capillary-viscous, wick superheat, perforation pressure drop and chocking and liquid-vapor stability limits. The liquid and vapor inertia control the streamwise continuous liquid track (with isolated and/or merged vapor track) and, for saturated water at 1 atm CFD and wick pressure drop, predict heat flux up to 0.1qmax=20 MW/m 2 , an order-of-magnitude larger than the nucleate flow-boiling limit.

What is claimed is: 
     
         1 . A flow-boiling canopy wick comprising:
 a monolayer configured to be disposed on a copper layer;   a distribution layer being parallel to the monolayer, the distribution layer being spaced apart from the monolayer to define a vapor space, the distribution layer having a plurality of perforations fluidly open to the vapor space and configured to permit vapor within the vapor space to continuously vent, the distribution layer being configured to separate a liquid stream from the vapor space;   a plurality of permeable posts extending between the monolayer and the distribution layer; and   streamwise liquid tracks on the distribution layer between the plurality of perforations, the streamwise liquid tracks configured to provide capillary liquid flow toward a heated surface and evaporation, the liquid and vapor inertia control the streamwise liquid track.   
     
     
         2 . The flow-boiling canopy wick according to  claim 1 , further comprising:
 a channel formed on the distribution layer between the plurality of perforations, the channel configured to separate the vapor from the streamwise liquid tracks.   
     
     
         3 . The flow-boiling canopy wick according to  claim 2  wherein the channel comprises at least a pair of upward levees extending between the liquid tracks and the plurality of perforations. 
     
     
         4 . The flow-boiling canopy wick according to  claim 2  wherein the channel comprises at least a pair of sidewalls and a top wall extending between the pair of sidewalls to define an enclosed channel. 
     
     
         5 . The flow-boiling canopy wick according to  claim 4  wherein the vapor is substantially outside the enclosed channel. 
     
     
         6 . The flow-boiling canopy wick according to  claim 1  wherein the plurality of perforations are disposed in a periodic arrangement. 
     
     
         7 . The flow-boiling canopy wick according to  claim 1  wherein the plurality of permeable posts are each configured to permit the liquid stream to travel from the distribution layer down to the monolayer there through. 
     
     
         8 . A flow-boiling canopy wick comprising:
 a first layer configured to be disposed on a heated layer;   a second layer being parallel to the first layer, the second layer being spaced apart from the first layer to define a vapor space, the second layer having a plurality of perforations fluidly open to the vapor space and configured to permit vapor within the vapor space to continuously vent, the second layer being configured to separate a liquid stream from the vapor space;   a plurality of permeable posts extending between the first layer and the second layer; and   wherein the second layer is configured to permit streamwise liquid tracks to flow along the second layer between the plurality of perforations, the streamwise liquid tracks configured to provide at least capillary liquid flow toward the heated layer within the first layer and result in evaporation,   
     
     
         9 . The flow-boiling canopy wick according to  claim 8 , further comprising:
 a channel formed on a side of the second layer opposite the vapor space between the plurality of perforations, the channel configured to separate the vapor from the streamwise liquid tracks.   
     
     
         10 . The flow-boiling canopy wick according to  claim 9  wherein the channel comprises at least a pair of upward levees extending between the liquid tracks and the plurality of perforations. 
     
     
         11 . The flow-boiling canopy wick according to  claim 9  wherein the channel comprises at least a pair of sidewalls and a top wall extending between the pair of sidewalls to define an enclosed channel. 
     
     
         12 . The flow-boiling canopy wick according to  claim 11  wherein the vapor is substantially outside the enclosed channel. 
     
     
         13 . The flow-boiling canopy wick according to  claim 8  wherein the plurality of perforations are disposed in a periodic arrangement. 
     
     
         14 . The flow-boiling canopy wick according to  claim 8  wherein the plurality of permeable posts are each configured to permit the liquid stream to travel from the second layer down to the first layer there through.