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Table 6 Thermal Results as total borehole resistance \({R_b^*}\) [mm K/W] for several scenarios

From: Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates

\({c}\)[-] \({\lambda }\)[W/ mK] \({L}\)[m] \({\text{SDR}}\)[-] \({r_o}\)[m] \({Re}_{{c}}\)[-]
  Stand. Switch Plastic Steel 100 5 6 41 min max \(4\cdot 10^3\) \(10^5\)
  Laminar  
0.010 56.94 104.03 104.03 56.94 92.67 35.06 56.94 56.94 70.38 37.79  
0.108 49.55 96.66 96.64 49.56 71.56 31.88 49.54 49.56 58.82 34.19  
0.206 44.81 91.94 91.90 44.85 63.43 29.32 44.78 44.83 52.58 31.36  
0.304 40.30 87.47 87.40 40.38 56.34 26.77 40.26 40.35 46.88 28.56  
0.402 35.74 82.95 82.84 35.85 49.35 24.12 35.70 35.80 41.20 25.66  
0.500 31.01 78.25 78.11 31.16 42.23 21.34 30.97 31.09 35.38 22.62  
0.598 26.04 73.30 73.14 26.20 34.93 18.35 25.99 26.11 29.36 19.36  
0.696 20.72 68.00 67.82 20.90 27.41 15.09 20.68 20.79 23.04 15.81  
0.794 14.96 62.24 62.05 15.14 19.66 11.42 14.91 15.01 16.37 11.82  
0.892 8.56 55.84 55.66 8.74 11.69 7.05 8.52 8.62 9.25 7.12  
0.990 1.25 48.53 48.35 1.43 3.47 1.13 1.22 1.32 1.57 0.92  
  Turbulent
0.010 1.99 49.09 49.09 1.99 2.08 1.90 1.99 1.99 2.07 1.70 12.25 0.56
0.108 2.42 49.54 49.52 2.44 2.58 2.32 2.42 2.43 2.51 2.12 13.92 0.62
0.206 2.50 49.62 49.60 2.53 2.65 2.40 2.50 2.51 2.58 2.20 13.84 0.63
0.304 2.48 49.61 49.58 2.51 2.61 2.38 2.48 2.49 2.56 2.18 13.30 0.63
0.402 2.38 49.52 49.48 2.42 2.50 2.30 2.38 2.39 2.46 2.10 12.44 0.62
0.500 2.22 49.36 49.32 2.26 2.32 2.15 2.22 2.23 2.29 1.94 11.29 0.59
0.598 1.99 49.13 49.09 2.03 2.07 1.94 1.99 2.00 2.06 1.73 9.86 0.56
0.696 1.69 48.83 48.79 1.74 1.76 1.66 1.69 1.70 1.76 1.44 8.15 0.52
0.794 1.33 48.47 48.43 1.37 1.39 1.31 1.33 1.33 1.39 1.09 6.12 0.47
0.892 0.90 48.04 47.99 0.94 0.94 0.89 0.89 0.90 0.95 0.66 3.70 0.41
0.990 0.39 47.54 47.49 0.44 0.43 0.39 0.39 0.39 0.44 0.16 0.70 0.34