Science – Society – Technology
Table 1 Proposed assessment criteria for suitability categorization of shallow geothermal development by vertical closed-loop GSHP in fracture developed regions (depth < 200 m)
Categorization | Thermophysical properties of energy storage rock mass | Aquifer properties | Energy flow in fracture water | Note | |||
|---|---|---|---|---|---|---|---|
Overall heat capacity, Cr, kJ/(kg ℃) | Overall heat conductivity, λr, W/m K | Thickness, H, m | Volumetric water flow rate, qmax, 10L/s | Water flow velocity, um/s | Departure from rock temperature, ΔT | ||
Optimum |  > 1 (DZ/T 225-2009 2009) | > 1.5 (DZ/T 225-2009 2009) |  > 10 (very abundant) |  > 1000 (Jiang et al. 2018) |  > 10(Cheng et al. 2018) | Meeting all 6 requirements | |
Suitable | 0.5–1 (DZ/T 225-2009 2009) | 0.9–1.5 (DZ/T 225-2009 2009) | 1–10 (abundant) | 400–1000 (Jiang et al. 2018) | 5–10 (Cheng et al. 2018) | Except optimum and unsuitable indexes | |
Unsuitable |  < 0.5 kJ (DZ/T 225-2009 2009) |  < 0.9 (DZ/T 225-2009 2009) | 0.1–1 (unabundant) |  < 400 (Jiang et al. 2018) |  < 5 (Cheng et al. 2018) | Meeting at least 4 requirements | |