Comparative Heat Transfer Efficiency Study of Coaxial and U-loop Boreholes

Abstract

Abstract—This paper presents the results of comparative heat
transfer efficiency study based on in situ full scale tests conducted
on conventional U-loop borehole heat exchangers (BHE) and a
coaxial BHE. The results show that the coaxial BHE has
considerably higher heat transfer efficiency, while consuming less
pumping power than the U-loop’s. The implication of a high
efficiency BHE on reducing borehole loop length and initial
investment cost is also discussed. It is concluded that the higher
efficiency coaxial BHE has the potential to reduce borehole
length 30% to 50%.