Design and development of three test facilities to evaluate heat transfer performances of advanced and low cost materials and coatings for geothermal application

Geothermal energy is accredited as a flexible, controllable and green source of energy. Heat exchangers (HXs) are one of the most critical components of a geothermal power plant due to corrosion and scaling phenomena. Hence, improvements in the antiscaling and anticorrosion properties as well as heat transfer performance of the HX materials will lead to smaller, more efficient and less costly systems. EU H2020 GeoHex project relies on the use lowcost carbon steel-based material for HXs. Through modifying the surface with nano porous coating and controlling the surface chemistry, the heat transfer performance of single phase and phase change process will be improved. This paper presents the design and development of three lab scale test rigs to test the effectiveness of innovative materials and superficial treatments on heat exchange with geothermal brine in single, condensing and evaporating phases. The rigs have been equipped with all the necessary instrumentation for control and for data acquisition. In particular, the advanced coatings are applied on a small stainless-steel plate and R134a fluid has been used for heat transfer coefficient characterization in different phase conditions. GeoHex project has received funding from the European Union's Horizon 2020 research and innovation programme. Grant agreement n.851917.