Method, apparatus, conduit, and composition for low thermal resistance ground heat exchange

摘要

A method, apparatus, conduit, and composition for low thermal resistance ground heat exchange which preferably comprise, include, and/or use one or more of: a thin-walled, highly conductive filament wound conduit/casing formed using a thermosetting plastic composition containing a thermal conductivity enhancer; a grout backfill preferably including a sufficient amount of graphite, coke, or similar additive to provide a thermal conductivity of 3 Btu/hr-ft-° F. and higher; and a drop tube delivery conduit within the casing, the drop tube having radial exterior ribs which extend into the fluid return annulus formed between the interior wall of the casing and the exterior of the drop tube.

主权项

1. A method of subterranean ground heat exchange comprising the step of flowing a fluid medium through an underground casing such that thermal energy is conducted through a wall of said casing between said fluid medium and an underground environment surrounding said casing, said wall of said casing being a composite wall formed from a thermosetting plastic composition and a reinforcing fiber material, wherein:
said reinforcing fiber material is fiberglass, carbon fiber, aramid fiber, or a combination thereof; said thermosetting plastic composition from which said composite wall is formed including an amount of a thermal conductivity enhancing additive of at least 1.5% by weight based upon the total weight of said thermosetting plastic composition; said thermal conductivity enhancing additive is aluminum flake, aluminum powder, aluminum oxide, aluminum nitride, graphite, boron nitride, silicon carbide, Raney nickel, silver-coated nickel, silver-coated copper, or a combination thereof; said composite wall of said casing is a filament wound structure formed by applying said thermosetting plastic composition to said reinforcing fiber material and winding said fiber material around a mandrel; said composite wall has an interior surface, an exterior surface, a thickness from said interior surface to said exterior surface of not more than 0.1 inch, and a collapse pressure of at least 75 psig; and said thermal conductivity enhancing additive is included throughout said thickness of said composite wall from said interior surface to said exterior surface.