A coaxial-flow heat transfer system for installation in a geological environment and facilitating the transfer of heat energy between an external heat energy producing system and the geological environment. In the coaxial-flow heat transfer system, aqueous-based heat transfer fluid is pumped through...http://www.google.ca/patents/US7347059?utm_source=gb-gplus-sharePatent US7347059 - Coaxial-flow heat transfer system employing a coaxial-flow heat transfer structure having a helically-arranged fin structure disposed along an outer flow channel for constantly rotating an aqueous-based heat transfer fluid flowing therewithin so as to improve heat transfer with geological environments
