Visualization of heat transfer to characterize energy foundations

Limited information exists about the thermo-dynamic interactions of geothermal structures and soil owing to practical constraints of placing measurement sensors in proximity to foundations. An alternative experimental method is explored using transparent soil to enable internal visualisation of heat flow in soil. Advocating the loss of optical clarity as a beneficial attribute of transparent soil, this paper explores the hypothesis that temperature change will alter its refractive index and therefore progressively reduce its transparency becoming more opaque. The development of the experimental methodology is discussed and a relationship between pixel intensity and soil temperature is defined and verified. This relationship is applied to an energy pile example to demonstrate heat flow in soil. The heating zone of influence is observed to extend to a radial distance of 1.5 pile diameters and is differentiated by a visual thermal gradient propagating from the pile.