nanofluid, fumed Al2O3, secondary fluid, geothermal application, efficiency
The European Project Cheap-GSHPs, recently approved, aims at reducing the total cost of shallow geothermal systems by 20-30%, also improving actual drilling/installation technologies and designs of Ground Source Heat Exchangers (GSHEs), in combination with a holistic engineering approach to optimize the entire systems for building and district heating and cooling applications, across the different underground and climate conditions existing within the EU. In this frame, the efficiency of the system heat pump/GSHE will be an important task and a part of this project will be on the analyses of possible alternative secondary fluids to be used in the geothermal probe. Here, suspensions of fumed Al2O3 in water will be considered as possible efficient secondary fluids. Three different concentrations will be studied, i.e. 10%, 30% and 40%, and the stability, thermal conductivity and dynamic viscosity of these fluids will be characterized, in order to analyse their possible employment as thermal fluids.