Heat extraction characteristics of a single U-tube downhole heat exchanger with square cross section

Abstract

The heat extraction rate from a stratum using a single U-tube downhole heat exchanger with square cross section was studied numerically. First, the present computer simulation program was made, and the computed results were checked with the field experimental data conducted by other researchers. After inspecting the effectiveness of the present computer simulation program, a numerical simulation was performed for a working 50-m full-scale model of in U-tube depth with this program. The effects of the flow rate of the heat extraction medium (water) and that of the tube material on the heat extraction rate were investigated for the case of a single U-tube. The computed results showed that increasing the flow rate of the working fluid of the heat extraction medium increases the heat extraction rate, and also suggests that the use of resin, such as polyethylene or polyvinyl chloride, for the tube is a possible alternative, even though a resin tube is inferior to a metal version with respect to heat transfer performance.