Modeling the effects of the variability of temperature-related dynamic viscosity on the thermal-affected zone of groundwater heat-pump systems; [Modélisation des effets de la variabilité de la viscosité dynamique en fonction de la température sur la zone d’influence thermique de systèmes de pompe à chaleur sur nappe]; [Modelando os efeitos da variabilidade da viscosidade dinâmica relacionada à temperatura na zona afetada por efeitos térmicos em sistemas de bombeamento de água subterrânea por calor]; [Modelado de los efectos de la variabilidad de la viscosidad dinámica relacionada con la temperatura en la zona afectada por los sistemas de bomba de calor de agua subterránea]

Thermal perturbation in the subsurface produced in an open-loop groundwater heat pump (GWHP) plant is a complex transport phenomenon affected by several factors, including the exploited aquifer’s hydrogeological and thermal characteristics, well construction features, and the temporal dynamics of the plant’s groundwater abstraction and reinjection system. Hydraulic conductivity has a major influence on heat transport because plume propagation, which occurs primarily through advection, tends to degrade following conductive heat transport and convection within moving water. Hydraulic conductivity is, in turn, influenced by water reinjection because the dynamic viscosity of groundwater varies with temperature. This paper reports on a computational analysis conducted using FEFLOW software to quantify how the thermal-affected zone (TAZ) is influenced by the variation in dynamic viscosity due to reinjected groundwater in a well-doublet scheme. The modeling results demonstrate non-negligible groundwater dynamic-viscosity variation that affects thermal plume propagation in the aquifer. This influence on TAZ calculation was enhanced for aquifers with high intrinsic permeability and/or substantial temperature differences between abstracted and post-heat-pump-reinjected groundwater. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.