Figure 2
Panel A presents three soil layers with thermal conductivities lambda soil 1, lambda soil 2 and lambda soil 3. The upper two layers have depths L 1 and L 2. A vertical dimension marks the pile length plus 20 metres. Panel B places a concrete pile within the layered soil. Its width is labelled pile diameter. A central U-shaped channel represents power output, with outlet temperature directed upwards and inlet temperature directed downwards. The concrete thermal conductivity is labelled lambda concrete. Panel C uses the same pile and soil arrangement for thermal response. A heat-flux input, q flux, enters at the top, and the central U-shaped channel represents the thermal response.Schematic of (a) soil deposit and pile geometry, (b) power output pile and (c) thermal response pile