Ground Loops and Insulation for Direct Exchange Geothermal Systems

Abstract

A direct exchange geothermal heating and cooling system has a vacuum insulation layer surrounding the liquid phase working fluid transport line in the system's ground loop, as well as optional multiple vapor phase working fluid transport lines.

What is claimed is: 
     
         1 . A direct exchange geothermal heat pump for use with a sub-surface formation, comprising:
 a closed loop for transporting a working fluid, the closed loop including:
 a liquid transport line including a liquid transport line sub-surface portion; and 
 a vapor transport line including a vapor transport line sub-surface portion fluidly communicating with the liquid transport line sub-surface portion and positioned in thermal conductive relation with the sub-surface formation to provide an exterior heat exchanger; 
 wherein the liquid transport line sub-surface portion and the vapor transport line sub-surface portion define a closed sub-surface ground loop; and 
   a vacuum insulation assembly surrounding at least an upper portion of the liquid transport line sub-surface portion to define a vacuum-insulated portion of the liquid transport line sub-surface portion.   
     
     
         2 . The direct exchange geothermal heat pump of  claim 1 , in which the vacuum insulation assembly comprises a housing surrounding the vacuum-insulated portion of the liquid transport line sub-surface portion to define a vacuum chamber between an interior surface of the housing and an exterior surface of the vacuum-insulated portion of the liquid transport line sub-surface portion, and a vacuum pressure formed in the vacuum chamber. 
     
     
         3 . The direct exchange geothermal heat pump of  claim 2 , in which the exterior surface of the vacuum-insulated portion of the liquid transport line sub-surface portion is spaced from the housing interior surface. 
     
     
         4 . The direct exchange geothermal heat pump of  claim 3 , further comprising a solid-state insulation material disposed between the exterior surface of the vacuum-insulated portion of the liquid transport line sub-surface portion and the housing interior surface. 
     
     
         5 . The direct exchange geothermal heat pump of  claim 3 , further comprising nubs or spacers disposed between the exterior surface of the vacuum-insulated portion of the liquid transport line sub-surface portion and the housing interior surface. 
     
     
         6 . The direct exchange geothermal heat pump of  claim 1 , in which the vacuum pressure comprises a vacuum pressure level of at least 1,000 microns. 
     
     
         7 . The direct exchange geothermal heat pump of  claim 2 , further comprising gas absorbing pellets disposed within the vacuum chamber. 
     
     
         8 . The direct exchange geothermal heat pump of  claim 1 , further comprising a radiant heat transfer insulation layer disposed around the vacuum-insulated portion of the liquid transport line sub-surface portion. 
     
     
         9 . The direct exchange geothermal heat pump of  claim 1 , in which the vapor transport line sub-surface portion comprises at least two distributed vapor transport lines. 
     
     
         10 . The direct exchange geothermal heat pump of  claim 2 , in which the housing is formed of a housing material having poor heat conductivity. 
     
     
         11 . The direct exchange geothermal heat pump of  claim 10 , in which the housing material comprises polyethylene. 
     
     
         12 . The direct exchange geothermal heat pump of  claim 1 , in which the vacuum-insulated portion of the liquid transport line sub-surface portion comprises at least 30% of an overall length of the liquid transport line sub-surface portion. 
     
     
         13 . The direct exchange geothermal heat pump of  claim 1 , in which The direct exchange geothermal heat pump is operable in a cooling mode or a reverse cycle mode, and in which the vacuum-insulated portion of the liquid transport line sub-surface portion comprises at least 90% of an overall length of the liquid transport line sub-surface portion. 
     
     
         14 . The direct exchange geothermal heat pump of  claim 1 , in which the liquid transport line and the vapor transport line define a transport line set positioned near or above a ground surface, and in which at least a portion of the transport line set is surrounded by a vacuum insulation.