JP Journal of Heat and Mass Transfer
Volume 17, Issue 1, Pages 165 - 182
(June 2019) http://dx.doi.org/10.17654/HM017010165 |
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NUMERICAL STUDY ON THE HEAT TRANSFER CHARACTERISTICS ACCORDING TO VARIOUS HEAT TUBE SHAPES OF VERTICAL CLOSED-LOOP GEOTHERMAL HEAT EXCHANGER
Jangyoul You and Changhee Lee
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Abstract: We conduct work on the branch tube type, concentric tube type, and spline type underground heat exchanger in addition to the single U-tube type, which is the heat pipe type mainly used in the vertical closed type earth heat exchanger. Difference due to the geometrical effect was shown according to each heat pipe shape. In the case of a branch tube type, geothermal heat exchanger disperses the flow path and enlarges the heat transfer surface area, the outflow region is widely distributed in the radial direction of the borehole, and the heat transfer is strong. On the contrary, in the case of the concentric tube type and spline type, subsea heat exchanger made up of one tube and easy to install, the distance from the wall surface of the borehole where the heat transfer takes place is too far, and the heat transfer rate is relatively small. Especially, in the case of the spline type geothermal heat exchanger, the pressure drop is largely caused by the geometric characteristics of the flow field in the outflow region, and it is judged that the efficiency is low as compared with the same pump head. |
Keywords and phrases: thermal conductivity, effective thermal conductivity, borehole geothermal heat exchanger, heat pump.
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