Heat Transfer Refrigerant Transport Tubing Coatings and Insulation for a Direct Exchange Geothermal Heating/Cooling System and Tubing Spool Core Size

Abstract

A method and/or apparatus for at least one of: protecting the sub-surface metal refrigerant transport tubing of a DX heat pump system from corrosive sub-surface environments via a specially designed protective coating; efficiently insulating the sub-surface liquid refrigerant transport line in a DX heat pump system; and enhancing at least one of the convective heat transfer rate and the efficiency of at least a DX heat pump system; and where the outside diameter (“OD”) of a central containment core upon which to roll a spool of sub-surface refrigerant transport tubing is specially sized so as not to damage any tubing insulation and so as to avoid any “S” bends during ground loop installation.

1 . Transport tubing for refrigerant used in a direct exchange heat pump system, the tubing being disposed in a sub-surface corrosive environment, the tubing comprising:
 metal tubing having an interior surface defining a conduit for the refrigerant and an exterior surface; and   a protective coating disposed on the exterior surface and having a thickness of between approximately 0.01 inches (0.025 cm) and 0.03 inches (0.08 cm), the protective coating being formed of a protective coating material comprising at least one of paint and plastic.   
     
     
         2 . The transport tubing of  claim 1 , in which the protective coating material is capable of withstanding a temperature of at least approximately 200 degrees F. (93 degrees C.). 
     
     
         3 . The transport tubing of  claim 1 , in which the refrigerant comprises an R-410A refrigerant. 
     
     
         4 . A direct exchange heat pump system for use with a well extending into a sub-surface environment, the direct exchange heat pump system comprising:
 an exterior heat exchanger including a liquid transport line disposed in the well and extending substantially vertically;   a refrigerant disposed in the liquid transport line; and   a first layer of insulation surrounding an upper portion of the liquid transport line, the upper portion including approximately ⅓ of an overall length of the liquid transport line, plus or minus approximately 20%.   
     
     
         5 . The direct exchange heat pump system of  claim 4 , in which the first layer of insulation has a thickness of at least approximately 0.10 inches (0.25 cm), plus or minus 20%, and is formed of an insulation material comprising at least one of a solid-state insulation and a polyethylene coating. 
     
     
         6 . The direct exchange heat pump system of  claim 4 , in which the first layer of insulation comprises a polyethylene raised temperature plastic. 
     
     
         7 . The direct exchange heat pump system of  claim 4 , in which the first layer of insulation is formed of a material capable of withstanding a temperature of at least approximately 200 degrees F. (93 degrees C.). 
     
     
         8 . The direct exchange heat pump system of  claim 4 , further including a second layer of insulation disposed around the first layer of insulation, the second layer of insulation extending along a top portion of the liquid transport line defined as either approximately 15% of the overall length of the liquid transport line, plus or minus about 20% of that approximately 15% of the overall length of the liquid transport line, or the upper approximately 45 feet of the liquid transport line. 
     
     
         9 . The direct exchange heat pump system of  claim 8 , in which the second layer of insulation comprises a solid-state insulation material having a thickness of approximately 0.1 inches (0.25 cm). 
     
     
         10 . The direct exchange heat pump system of  claim 8 , in which the second layer of insulation comprises an expanded foam material having a thickness of approximately 0.5 inches (1.27 cm). 
     
     
         11 . The direct exchange heat pump system of  claim 4 , in which the refrigerant comprises an R-410A refrigerant. 
     
     
         12 . Transport tubing for refrigerant used in a direct exchange heat pump system, the tubing being disposed above surface for convective heat transfer with surrounding air, the tubing comprising:
 metal tubing having an interior surface defining a conduit for the refrigerant and an exterior surface; and   a protective coating disposed on the exterior surface and formed of a protective coating material comprising at least one of paint and plastic.   
     
     
         13 . The transport tubing of  claim 12 , in which the protective coating is a plastic material having a thickness equal to or less than approximately 0.017 inches (0.043 cm). 
     
     
         14 . The transport tubing of  claim 12 , in which the protective coating is a plastic material having a thickness equal to or less than approximately 0.009 inches (0.023 cm). 
     
     
         15 . The transport tubing of  claim 12 , in which the protective coating material is capable of withstanding a temperature of at least approximately 200 degrees F. (93 degrees C.). 
     
     
         16 . The transport tubing of  claim 12 , in which the protective coating material comprises at least one material selected from the group of protective coating materials consisting of a polyethylene, a polycarbonate, a tetrafluoroethylene resin, a fluoropolymer dip coating, a plasma-polymerized fluoroethylene monomer, a triazine-dithiol derivative, and a nylon. 
     
     
         17 . A transport device for refrigerant transport tubing used in a DX system having a vertically oriented well, comprising:
 a spool configured to receive a length of coiled refrigerant transport tubing;   a containment core of the spool having a diameter of at least 33 inches (84 cm).   
     
     
         18 . A direct exchange geothermal heating/cooling system for use with a well extending into a sub-surface environment, comprising:
 an exterior heat exchanger including a liquid transport line disposed in the well and extending substantially vertically;   a refrigerant disposed in the liquid transport line; and   a first layer of insulation surrounding an upper portion of the liquid transport line, the upper portion including approximately ⅓ of an overall length of the liquid transport line, plus or minus approximately 20%, the first layer of insulation having a thickness of at least approximately 0.10 inches (0.25 cm), plus or minus 20%, being formed of a first insulation material comprising a solid-state material; and   a second layer of insulation disposed around the first layer of insulation, the second layer of insulation extending along a top portion of the liquid transport line defined as either approximately 15% of the overall length of the liquid transport line, plus or minus about 20% of that approximately 15% of the overall length of the liquid transport line, or the upper approximately 45 feet of the liquid transport line.   
     
     
         19 . The direct exchange geothermal heating/cooling system of  claim 18 , in which the second layer of insulation comprises a solid-state insulation material having a thickness of approximately 0.1 inches (0.25 cm). 
     
     
         20 . The direct exchange geothermal heating/cooling system of  claim 18 , in which the second layer of insulation comprises an expanded foam material having a thickness of approximately 0.5 inches (1.27 cm). 
     
     
         21 . The direct exchange geothermal heating/cooling system of  claim 18 , further comprising an above-surface section of heat transfer tubing for convective heat transfer with surrounding air, the above-surface section of heat transfer tubing comprising metal tubing having an interior surface defining a conduit for the refrigerant and an exterior surface, and a protective coating disposed on the exterior surface and formed of a protective coating material comprising at least one of paint and plastic 
     
     
         22 . The direct exchange geothermal heating/cooling system of  claim 21 , in which the protective coating is a plastic material that has a thickness equal to or less than approximately 0.017 inches (0.043 cm). 
     
     
         23 . The direct exchange geothermal heating/cooling system of  claim 21 , in which the protective coating is a plastic material having a thickness equal to or less than approximately 0.009 inches (0.023 cm). 
     
     
         24 . The direct exchange geothermal heating/cooling system of  claim 18 , in an exposed portion of the exterior heat exchanger is exposed to a corrosive environment, and in which a protective layer is disposed around the exposed portion, the protective layer comprising at least one of a grout material and a solid-state coating having a thickness of approximately 0.03 inches (0.08 cm), plus or minus approximately 20%. 
     
     
         25 . The direct exchange geothermal heating/cooling system of  claim 24 , in which the protective layer comprises Grout 111. 
     
     
         26 . A direct exchange geothermal heating/cooling system for use with a well extending into a sub-surface environment, comprising:
 an exterior heat exchanger including a liquid transport line disposed in the well and extending substantially vertically;   a protective coating disposed on the exterior surface and having a thickness of between approximately 0.01 inches (0.025 cm) and 0.03 inches (0.08 cm), plus or minus approximately 20%, the protective coating being formed of a solid state material; and   a layer of grout material surrounding the protective coating.   
     
     
         27 . The direct exchange geothermal heating/cooling system of  claim 26 , in which the protective coating has a thickness between approximately 0.01 inches (0.025 cm) and 0.02 inches (0.05 cm), plus or minus approximately 20%. 
     
     
         28 . The direct exchange geothermal heating/cooling system of  claim 26 , in which the protective coating comprises at least one material selected from a group of coating materials consisting of a polyethylene, a polycarbonate, a tetrafluoroethylene resin, a fluoropolymer dip coating, a plasma-polymerized fluoroethylene monomer, a triazine-dithiol derivative, and a nylon.