Geothermal system utilizing supplemental ground heat from drainage fields

Abstract

Geothermal ground coils are installed and embedded in fill at the bottom of excavations, made for drainage fields associated with septic and other effluent systems, prior to the addition of the drainage field sanitary fill. This configuration eliminates the need for expensive bore holes and provides a ground heat source that is at a higher temperature than natural ground formations due to the supplemental heat imparted to the ground by the drain field effluent Fouling of the outside heat transfer surfaces of the ground coils is also avoided because of the clarifying and filtering action of the drain field fill. This provides an improved ground source heat pump system wherein the installation costs are reduced arid the capacity and efficiency of the system are improved.

1 . A system whereby the ground loops used in domestic, commercial and industrial geothermal systems are installed in such a manner as to take advantage of the natural geothermal properties of the ground as well as take advantage of the supplemental heat the ground receives from fluids discharged into the drainage fields which are associated with septic systems, dry wells, catch basins, or any other effluent or fluid which eventually is distributed into the ground and affects the temperature of the ground in the vicinity of geothermal loops.  
     
     
         2 . A system as described in  claim 1  whereby horizontal ground loops are installed below and before the installation of new or replacement drainage fields which are integral to domestic, commercial or industrial waste treatment systems thereby eliminating the cost of drilling expensive bore holes or separate excavations for installation of the geothermal coils.  
     
     
         3 . A system as described in  claim 1  whereby the effluent flow to the drainage fields originates from hospitals, schools, prisons, airports or any military, government or institutional site or any other type of installation.  
     
     
         4 . A system as described in  claim 1  whereby the geothermal ground coils are installed and are connected preferably in series with either horizontal or vertical geothermal ground coils installed in ground outside the influence of the higher temperature drainage fields. During the period when cooling is required, fluid in the geothermal ground loops would flow from the outlet of the air conditioning portion of the heat pump then to the ground loops installed in the drainage fields according to  claim 1  and then to the ground loops outside the influence of the drainage fields so that the temperature of the circulating fluid in the ground loop would be further lowered before flowing to the inlet of the air conditioning portion of the heat pump.  
     
     
         5 . A system according to  claim 1  and  claim 4  whereby when heating is required the flow of the circulating fluid is reversed so that the flow from the outlet of the heating portion of the heat pump goes to the regular ground coil first and then to the coils installed according to  claim 1  where the temperature is further increased before it flows to the inlet of the heating portion of the heat pump.  
     
     
         6 . A system as described in  claim 1  whereby because of the low installation costs extra geothermal ground coils are added in parallel with ground coils installed according to  claim 1  so that during periods when cooling is required the higher temperature of the circulating fluid due to the higher temperature of the drainage fields would be offset by the higher volumetric flow from the extra parallel coils. The extra volume of circulating fluid would remove the required heat load at a lower temperature differential.  
     
     
         7 . A system as described in  claim 1  whereby fouling of the heat exchange outside surface of the geothermal coils is minimized by allowing the fill of the drainage field to further digest, filter and clarify fluids before they come into contact with the heat transfer surfaces of the geothermal ground coils.  
     
     
         8 . A system as described in  claim 1  whereby geothermal ground coils are installed horizontally, diagonally or vertically in any combination in new or existing drainage fields so as to take advantage of the supplemental heat imparted into the ground as a result of fluid flows from septic systems, drywells, catch basins and other drainage systems.