Humidification Control Device

Abstract

A humidification control device and an apparatus implementing the humidification control device is provided. The device includes a membrane electrode assembly (MEA) for the control of humidity in an enclosed space via electrolysis. The MEA includes an anode, a cathode and a proton exchange membrane (PEM) disposed between the anode and the cathode. The PEM is selected to increase the efficiency of the humidification control device by decreasing the back diffusion of water across the PEM. The PEM may include a functional tetrafluoroethylene (TFE) copolymer having a polymer chain of TFE and at least one comonomer having a proton conducting functional group pendant to said polymer chain. The comonomer may be present in an amount from about 0.01 mol. % to about 7 mol. % of the TFE copolymer. In one embodiment, the comonomer is a fluorovinyl ether such as perfluorosulfonyl vinyl ether (PSVE).

What is claimed is: 
     
         1 . A humidification control device configured for controlling the humidity of an enclosure, said humidification control device comprising:
 a membrane electrode assembly, said membrane electrode assembly comprising:
 an anode and a cathode; 
 at least a first proton exchange membrane disposed between said anode and said cathode, said proton exchange membrane comprising a polymeric material comprising a resin that includes a functional TFE copolymer having a polymer chain of TFE and at least one comonomer having a proton conducting functional group pendant to said polymer chain, wherein said at least one comonomer having a proton conducting functional group pendant to said polymer chain is present in an amount of at least about 0.01 mol. % and not greater than about 7 mol. % of said functional TFE copolymer; and 
   first and second electrically conductive terminals interconnected to said anode and cathode, respectively, and configured to apply an electric potential across said membrane electrode assembly.   
     
     
         2 . The humidification control device of  claim 1 , wherein said at least one comonomer having a proton conducting functional group pendant to said polymer chain is PSVE. 
     
     
         3 . The humidification control device of  claim 1 , wherein said polymeric material has an equivalent weight of at least about 1500. 
     
     
         4 . The humidification control device of  claim 1 , wherein said polymeric material has an equivalent weight of at least about 2400. 
     
     
         5 . The humidification control device of  claim 1 , wherein said polymeric material is fabricated by extruding a fine powder resin into a tape, calendering said tape, and subjecting said calendered tape to heat-treatment to a temperature greater than the crystalline melting temperature of PTFE to form a non-porous tape. 
     
     
         6 . The humidification control device of  claim 1 , wherein said polymeric material is fabricated by expanding said resin into a porous functional TFE copolymer material having a micro structure characterized by nodes interconnected by fibrils, and further densifying said porous material to form a non-porous structure. 
     
     
         7 . The humidification control device of  claim 1 , wherein said membrane electrode assembly is configured to be positioned across an aperture of an enclosure to dehumidify a gaseous enclosed volume within an enclosed space defined by said enclosure. 
     
     
         8 . The humidification control device of  claim 1 , further comprising a DC voltage source operatively connected to said first and second electrically conductive terminals. 
     
     
         9 . The humidification control device of  claim 1 , wherein said proton exchange membrane has a thickness of not greater than about 200 μm. 
     
     
         10 . The humidification control device of  claim 1 , wherein said at least one comonomer having a proton conducting functional group pendant to said polymer chain is present in an amount of not greater than about 5 mol. % of said functional TFE copolymer. 
     
     
         11 . The humidification control device of  claim 1 , wherein said proton exchange membrane has a Gurley number of at least about 1000 seconds. 
     
     
         12 . An apparatus, comprising:
 an enclosure defining an enclosed space; and   a humidification control device operatively affixed to said enclosure, said humidification control device comprising
 an anode and a cathode; 
 at least a first proton exchange membrane disposed between said anode and said cathode, said proton exchange membrane comprising a polymeric material comprising a resin that includes a functional TFE copolymer having a polymer chain of TFE and at least one comonomer having a proton conducting functional group pendant to said polymer chain, wherein said at least one comonomer having a proton conducting functional group pendant to said polymer chain is present in an amount of at least about 0.01 mol. % and not greater than about 7 mol. % of said functional TFE copolymer; and 
   first and second electrically conductive terminals interconnected to said anode and cathode; and   a DC voltage source operatively connected to said first and second electrically conductive terminals.   
     
     
         13 . The apparatus of  claim 12 , wherein said humidification control device is affixed to said enclosure such that said anode is in fluid communication with said enclosed space. 
     
     
         14 . The apparatus of  claim 12 , wherein said at least one comonomer having a proton conducting functional group pendant to said polymer chain is PSVE. 
     
     
         15 . The apparatus of  claim 12 , wherein said polymeric material has an equivalent weight of at least about 1500. 
     
     
         16 . The apparatus of  claim 12 , wherein said polymeric material has an equivalent weight of at least about 2400. 
     
     
         17 . The apparatus of  claim 12 , wherein said proton exchange membrane has a thickness of not greater than about 200 μm. 
     
     
         18 . The apparatus of  claim 12 , wherein said at least one comonomer having a proton conducting functional group pendant to said polymer chain is present in an amount of not greater than about 5 mol. % of said functional TFE copolymer. 
     
     
         19 . The apparatus of  claim 12 , wherein said proton exchange membrane has a Gurley number of at least about 1000 seconds.