Gas heating apparatus

Abstract

A thermally sprayed gas heater comprises a gas flow apparatus that propels a gas through a housing; and a thermally sprayed heater bonded to a surface of the apparatus, the heater positioned to heat the gas flow in the housing. In other aspects, a heater system for a turbulent flow gas duct comprises a duct having a gas flow channel, the channel having a shaped surface providing turbulent gas flow in the channel, and a thermally sprayed heater positioned to heat the gas flow in the channel.

1 . A thermally sprayed gas heater comprising:
 a gas flow apparatus that propels a gas through a housing; and   a thermally sprayed heater bonded to a surface of the apparatus, the heater positioned to heat the gas flow in the housing, the thermally sprayed heater including a resistive heating layer having s substantially lamellar structure, the resistive heating layer including a first material and a second material, the first material being an electrically conducting material including a metallic material and the second material being an electrically insulating material including a reaction product of the metallic material, the reaction product comprising at least one of an oxide, a nitride, a carbide and a boride.   
     
     
         2 - 26 . (canceled) 
     
     
         27 . The thermally sprayed gas heater of  claim 1 , wherein the circulation system comprises a blower apparatus. 
     
     
         28 . The thermally sprayed gas heater of  claim 27 , wherein the heater is bonded on a surface of the blower apparatus. 
     
     
         29 . The thermally sprayed gas heater of  claim 28 , wherein the blower apparatus comprises a fan and a housing that surrounds at least a portion of a circumference of the fan, the thermally sprayed heater being bonded to the fan housing. 
     
     
         30 . The thermally sprayed gas heater of  claim 29 , wherein the fan housing surrounds substantially an entire circumference of the fan, the thermally sprayed heater being bonded to the fan housing and extending over substantially the entire circumference of the fan. 
     
     
         31 . The thermally sprayed gas heater of  claim 27 , wherein the blower apparatus comprises a fan having one or more blades, the thermally sprayed heater being bonded to a blade of the fan. 
     
     
         32 . The thermally sprayed gas heater of  claim 1 , wherein the thermally sprayed heater is bonded to a surface of the housing. 
     
     
         33 . The thermally sprayed gas heater of  claim 1 , wherein the housing comprises internal vanes, the heater positioned to heat the vanes. 
     
     
         34 . The thermally sprayed gas heater of  claim 33 , wherein the vanes promote turbulent flow of the gas. 
     
     
         35 . The thermally sprayed gas heater of  claim 33 , wherein a thermally sprayed heater is bonded to a vane. 
     
     
         36 . The thermally sprayed gas heater of  claim 35 , wherein the vane comprises a helical vane. 
     
     
         37 . The thermally sprayed gas heater of  claim 35 , further comprising a perforated substrate positioned inside the housing, the gas being propelled through the perforated substrate, the heater being bonded to the perforated substrate. 
     
     
         38 . The thermally sprayed gas heater of  claim 37 , wherein the perforated substrate comprises a thermally-sprayed screen material. 
     
     
         39 . The thermally sprayed gas heater of  claim 1 , wherein the gas flow apparatus promotes turbulent gas flow over at least a portion of the apparatus, the heater positioned to heat the turbulent gas flow within the housing. 
     
     
         40 . The thermally sprayed gas heater of  claim 39 , wherein the gas flow apparatus is characterized by a Reynolds number that is greater than about 2000. 
     
     
         41 . The thermally sprayed gas heater of  claim 39 , wherein the gas flow apparatus is characterized by a Reynolds number that is greater than about 3000. 
     
     
         42 . The thermally sprayed gas heater of  claim 1 , wherein the gas flow apparatus is configured to transfer heat predominantly by forced convection. 
     
     
         43 . The thermally sprayed gas heater of  claim 42 , wherein the gas flow apparatus is configured to minimize radiative heat loss. 
     
     
         44 . The thermally sprayed heater of  claim 1 , wherein the thickness of the thermally sprayed heater is less than about 0.030 inches. 
     
     
         45 . The thermally sprayed heater of  claim 1 , wherein the thermally sprayed heater is characterized by a material resistivity of greater than about 10 −4  Ω-cm.