Thermal devices for controlling heat transfer

Abstract

In one embodiment, a thermal device includes a sealed housing that defines an interior space, a liquid-attracting element provided on one side of the interior space, a liquid-repelling element provided on another side of the interior space opposite to the liquid-attracting element, and a liquid provided within the interior space.

1 . A thermal device comprising:
 a sealed housing that defines an interior space maintained in a vacuum;   a sheet-like porous element that substantially fills the interior space;   a hydrophobic portion of the sheet-like porous element that extends from a first side of the sheet-like porous element to a first depth across a thickness of the sheet-like porous element;   a hydrophilic portion of the sheet-like porous element that extends from a second side of the sheet-like porous element to the hydrophobic portion of the sheet-like porous element; and   a fluid within a void space of the sheet-like porous element.   
     
     
         2 . The thermal device of  claim 1 , wherein a first portion of the fluid is contained in a vapor phase within the first portion of the sheet-like porous element, and a second portion of the fluid is contained in a liquid phase within the second portion of the sheet-like porous element. 
     
     
         3 . The thermal device of  claim 1 , wherein the hydrophobic portion and the hydrophilic portion of the sheet-like porous element enable thermal diodicity of the thermal device by causing vapor diffusion to be opposite capillary liquid flow across the thickness of the sheet-like porous element. 
     
     
         4 . The thermal device of  claim 1 , wherein the hydrophobic portion of the sheet-like porous element comprises a hydrophobic coating. 
     
     
         5 . The thermal device of  claim 4 , wherein the hydrophobic coating comprises one or more of an alkane, oil, fat, grease, or polytetrafluoroethylene (PTFE). 
     
     
         6 . The thermal device of  claim 1 , wherein the hydrophilic portion of the sheet-like porous element comprises a hydrophilic coating. 
     
     
         7 . The thermal device of  claim 1 , wherein at least one portion of the sheet-like porous element comprises a self-assembled monolayer (SAM) coating. 
     
     
         8 . The thermal device of  claim 1 , wherein a wettability of at least one of the hydrophilic portion and the hydrophobic portion is achieved using nano-structures grown on a surface of the sheet-like porous element. 
     
     
         9 . The thermal device of  claim 1 , wherein a thermal resistance of the device changes with ambient temperature change. 
     
     
         10 . The thermal device of  claim 9 , wherein a liquid-phase volume of the fluid is less than a total void space of the hydrophilic portion of the sheet-like porous element. 
     
     
         11 . The thermal device of  claim 1 , wherein the sheet-like porous element comprises a length, a width, and the thickness, wherein each of the length and the width are greater than the thickness. 
     
     
         12 . An object comprising:
 a thermal device comprising a sealed housing that defines an interior space;   a porous element that substantially fills the interior space, the porous element comprising a hydrophobic portion and a hydrophilic portion, wherein the hydrophobic portion extends a distance from a first side of the porous element towards a second side of the porous element, and the hydrophilic portion extends from the second side to the hydrophobic portion; and   a fluid within the interior space.   
     
     
         13 . The object of  claim 12 , wherein the object is a wearable object. 
     
     
         14 . The object of  claim 12 , wherein the object is a house or building. 
     
     
         15 . The object of  claim 12 , wherein the object is a heat-producing electrical device. 
     
     
         16 . The object of  claim 12 , wherein the object is a thermal storage unit. 
     
     
         17 . A system comprising:
 a sealed housing;   a porous element that substantially fills an interior space of the sealed housing, the porous element comprising:
 a hydrophobic portion that extends a distance from a first side of the porous element towards a second side of the porous element; and 
 a hydrophilic portion that extends from the second side of the porous element to the hydrophobic portion of the porous element; and 
 a fluid within a void space of the porous element. 
   
     
     
         18 . The system of  claim 17 , wherein a first portion of the fluid is contained in a vapor phase within the first portion of the porous element, and a second portion of the fluid is contained in a liquid phase within the second portion of the porous element. 
     
     
         19 . The system of  claim 17 , wherein the hydrophobic portion and the hydrophilic portion of the porous element enable thermal diodicity by causing vapor diffusion to be opposite capillary liquid flow across the porous element. 
     
     
         20 . The system of  claim 17 , wherein the hydrophobic portion of the porous element comprises a hydrophobic coating.