Patent ID: 7373785

Claim:
A geo-thermal heat exchanging system facilitating the transfer of heat energy using coaxial-flow heat exchanging structures installed in the Earth, said geo-thermal heat exchanging system comprising: a heat exchanging subsystem installed above the surface of Earth, supporting the flow of a heat conducting stream, and exchanging heat energy between said heat conducting stream and an aqueous-based heat transfer flow flowing into and out of said heat exchanging subsystem; and one or more coaxial-flow heat exchanging structures installed in the Earth, for facilitating the transfer of heat energy in said aqueous-based heat transfer fluid, between said aqueous-based heat transfer fluid and material beneath the surface of the Earth; wherein each said coaxial-flow heat exchanging structure includes: a proximal end and a distal end; an input port, provided at the proximal end, for receiving said aqueous-based heat transfer fluid at a first temperature from said heat exchanging subsystem, and an output port, provided at the proximal end, for outputting said aqueous-based heat transfer fluid at a second temperature to said heat exchanging subsystem; an inner tube section having an outer wall surface extending between the proximal and distal ends, the inner tube section supporting an inner flow channel having a substantially uniform inner diameter along its length and along which the aqueous-based heat transfer fluid can flow in a substantially laminar manner; a thermally conductive outer tube section, disposed coaxially around the inner tube section, and having an inner wall surface extending between said proximal and distal ends, and a cap portion at said distal end sealing off said thermally conductive outer tube section from fluid leaks at said distal end; wherein an outer flow channel is formed between the outer wall surface of the inner tube section and the inner wall surface of the outer tube section, and is capable of conducting said aqueous-based heat transfer fluid flowing from the distal end of said inner flow channel, and past said cap portion, and along said thermally conductive outer flow channel towards said proximal end, so that said aqueous-based heat transfer fluid can exit from said output port and enter into said heat exchanging system; wherein a turbulence generating structure is disposed along a portion of the length of the outer flow channel so as to introduce turbulence into the flow of said aqueous-based heat transfer fluid flowing along the outer flow channel, thereby improving the transfer of heat energy between the aqueous-based heat transfer fluid and said Earth along the length of the outer flow channel; and wherein the heat transfer process occurring between said aqueous-based heat transfer fluid and said Earth is carried out without a change in state of said aqueous-based heat transfer fluid flowing within and along said inner and outer flow channels of each said coaxial-flow heat transfer structure.