Supercritical CO2 has been proposed as working fluid in various typology power plants, thanks to its potential higher efficiency and cost reduction with respect to well-known technology of steam cycles.However, the high operating temperature and pressure conditions pose significant concerns in terms of compatibility of the supercritical CO2 with the high temperature sections of the power block. Typically, to address this problem, samples of different materials are kept in contact with the supercritical CO2 in a pressure vessel in order to test experimentally the material compatibility. This research deals with sizing this innovative openable pressure vessel which must be able to withstand the high temperatures (700°C) and the pressures (100bar) typical of those power plants. Results obtained by analytical calculation and the finite element method are consistent. The results obtained with both methods are generalizable and applicable to each removable pressure vessel that must withstand 100 bar of pressure and a temperature of 700°C. Application field that is outside the ASME VIII div.1, standard usually used for the design of pressure vessels. It is important to underline that the use of a removable container allows to reduce the costs of compatibility tests since otherwise, after each test, the pressure vessel should be disposed of. In addition, this allows a reduction of the environmental impact due to the fact that the new container will not be disposed of after each use.

CO2 has been proposed in the past decades as a suitable working fluid in power plants. One way to reduce costs is to use carbon dioxide blends instead. There is a lack of knowledge about the behavior of sCO2 blending in the interaction with commercial alloys at high temperatures, so this aspect must be strictly considered. A preliminary study has been performed considering the oxidation behavior of some Ni-based and Fe-based alloy (i.e., alloy 625, AISI 304, and AISI 316) in different conditions. In each case, the oxidation layer developed on the alloy surface was investigated by scanning electron microscope (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). The analysis was also performed on the cross-section of the sample to evaluate the penetration depth of damage. The results show that the interaction with fluorine-containing compounds is more corrosive than pure CO2. This confirms that although the mixture improves the thermodynamic efficiency of the cycle, their compatibility with materials must be carefully investigated. However, in all the cases studied, in the test conditions, the preliminary analysis doesn’t recommend the use of the tested materials.