Double-Walled Round and Oval HVAC Ductwork Systems Using Phenolic Insulation

Abstract

The present invention involves the preparation and manufacture of phenolic insulation boards for use in double-walled ductwork systems. The preparation of the phenolic insulation board, having a first and second surface each having a foil coating, includes the cutting or grooving of V-grooves into the first surface of the phenolic insulation and first foil coating. This grooving process creates a continuous piece of phenolic insulation having trapezoidal shapes along the second surface and second foil coating. The prepared phenolic insulation board can then be wrapped around an inner sheet metal duct and then covered with an outer shell. Alternatively, the prepared phenolic insulation board can be inserted between an inner duct and outer shell. Both result in a double-walled phenolic insulation ductwork systems.

1 . A double-walled ductwork segment comprising:
 a first cylindrical sleeve comprising an interior diameter;   a second cylindrical sleeve comprising an outer diameter smaller than the interior diameter of the first cylindrical sleeve; and   an insulation layer situated between the first cylindrical sleeve and the second cylindrical sleeve, the insulation layer comprising a first surface, a second surface, and a closed-cell membrane, wherein the insulation layer further comprises a plurality of trapezoidal segments comprising channels formed on the first surface and in the closed-cell membrane, wherein each trapezoidal segment comprises a first surface and a second surface, wherein when the insulation layer is situated between the first cylindrical sleeve and second cylindrical sleeve the first surface of a first trapezoidal segment abuts the second surface of an adjoining trapezoidal segment.   
     
     
         2 . The double-walled ductwork segment of  claim 1 , wherein the first cylindrical sleeve is circular. 
     
     
         3 . The double-walled ductwork segment of  claim 2 , wherein the second cylindrical sleeve is circular. 
     
     
         4 . The double-walled ductwork segment of  claim 1 , wherein the first cylindrical sleeve is oval. 
     
     
         5 . The double-walled ductwork segment of  claim 4 , wherein the second cylindrical sleeve is oval. 
     
     
         6 . The double-walled ductwork segment of  claim 1 , wherein the insulation layer comprises phenolic insulation board. 
     
     
         7 . The double-walled ductwork segment of  claim 6 , wherein the first surface of the insulation layer comprises a first foil coating. 
     
     
         8 . The double-walled ductwork segment of  claim 7 , wherein the first surface of the insulation layer comprises a second foil coating. 
     
     
         9 . The double-walled ductwork segment of  claim 8 , wherein the trapezoidal segments are shaped and angled to minimize voids between the first and second surfaces of the plurality of trapezoidal segments in the insulation layer when the insulation layer is wrapped around an exterior surface of the second cylindrical sleeve. 
     
     
         10 . An apparatus comprising:
 a first circular tube comprising an interior diameter;   a second circular tube comprising an outer diameter smaller than the interior diameter of the first circular tube;   an insulation layer situated between the first circular tube and second circular tube, wherein the insulation layer comprises a first surface, a second surface, and a phenolic insulation board.   
     
     
         11 . The apparatus of  claim 10 , wherein the insulation layer further comprises a plurality of v-shaped grooves formed on the first surface and in the phenolic insulation board, wherein each v-shaped groove comprises a first surface and a second surface. 
     
     
         12 . The apparatus of  claim 11 , wherein when the insulation layer is situated between the first circular tube and the second circular tube the first surface of a first v-shaped groove of the plurality of v-shaped grooves abuts a second surface of an adjacent second v-shaped groove. 
     
     
         13 . The apparatus of  claim 12 , wherein the first surface of the insulation layer is a first foil coating. 
     
     
         14 . The apparatus of  claim 13 , wherein the second surface of the insulation layer is a second foil coating. 
     
     
         15 . The apparatus of  claim 12 , wherein the first circular tube and second circular tube comprise sheet metal. 
     
     
         16 . The apparatus of  claim 14 , wherein the first circular tube and second circular tube comprise sheet metal. 
     
     
         17 . The apparatus of  claim 16  wherein the v-shaped grooves are shaped and angled to minimize voids between the first and second surfaces of the plurality of v-shaped grooves in the insulation material when the insulation material is wrapped around the exterior surface of the second circular tube. 
     
     
         18 . A method of preparing a double-walled ductwork segment comprising:
 routing a plurality of v-shaped grooves into an insulation material, wherein each v-shaped groove has a first surface and a second surface; wherein the plurality of v-shaped grooves are spaced and angled to allow the first surface of a first v-shaped groove to abut the second surface of an adjacent v-shaped groove when the insulation material is wrapped around an exterior surface of an interior duct; and   insertion of the insulation material wrapped interior duct into an annular space of an exterior duct.   
     
     
         19 . The method of  claim 18  wherein the insulation material comprises phenolic insulation board further comprising a first surface, a second surface, and a close-cell membrane situated between the first and second surfaces. 
     
     
         20 . The method of  claim 19  wherein the v-shaped grooves are shaped and angled to minimize voids between the first and second surfaces of the plurality of v-shaped grooves in the insulation material.