Abstract: A coaxial borehole heat exchanger includes an innermost pipe and an intermediate pipe arranged coaxially outside the innermost pipe. The intermediate pipe has an inner surface provided with a plurality of axial grooves, and the inner diameter of the intermediate pipe corresponds to the outer diameter of the innermost pipe. The coaxial borehole heat exchanger further includes an outermost pipe arranged coaxially outside the intermediate pipe, wherein the outermost pipe has an inner surface provided with a plurality of axial grooves, and wherein the inner diameter of the outermost pipe corresponds to the outer diameter of the intermediate pipe, wherein the innermost pipe and the plurality of axial grooves of the outermost pipe define liquid flow channels, and wherein the axial grooves of the intermediate pipe define a thermal insulation layer between the axial grooves of the outermost pipe and the innermost pipe. A method of producing a coaxial borehole heat exchanger is also presented herein.

Abstract: A coaxial borehole heat exchanger includes an innermost pipe and an intermediate pipe arranged coaxially outside the innermost pipe. The intermediate pipe has an inner surface provided with a plurality of axial grooves, and the inner diameter of the intermediate pipe corresponds to the outer diameter of the innermost pipe. The coaxial borehole heat exchanger further includes an outermost pipe arranged coaxially outside the intermediate pipe, wherein the outermost pipe has an inner surface provided with a plurality of axial grooves, and wherein the inner diameter of the outermost pipe corresponds to the outer diameter of the intermediate pipe, wherein the innermost pipe and the plurality of axial grooves of the outermost pipe define liquid flow channels, and wherein the axial grooves of the intermediate pipe define a thermal insulation layer between the axial grooves of the outermost pipe and the innermost pipe. A method of producing a coaxial borehole heat exchanger is also presented herein.