Experimental investigation of the CO2+SiCl4 mixture as innovative working fluid for power cycles: Bubble points and liquid density measurements

• Published in: Energy (Oxford) 2024-07, Vol.299, p.131197, Article 131197
• Main Authors: Doninelli, M., Morosini, E., Di Marcoberardino, G., Invernizzi, C.M., Iora, P., Riva, M., Stringari, P., Manzolini, G.
• Format: Article
• Language: English
• Subjects: Chemical and Process Engineering; CO2 mixtures; CSP; Engineering Sciences; Liquid density; sCO2; Vapour-liquid equilibrium; Working fluids
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2024.131197

Supercritical CO2 is recognized as a promising working fluid for next-generation of high temperature power cycles. Nevertheless, the use of CO2 mixtures with heavier dopants is emerging as a promising alternative to supercritical CO2 cycles in the recent years for air-cooled systems in hot environments. Accordingly, this work presents an experimental campaign to assess the thermodynamic behaviour of the CO2+SiCl4 mixture to be used as working fluid for high-temperature applications, conducted in the laboratories of CTP Mines Paris PSL. At first, bubble conditions of the mixture are measured in a variable volume cell (PVT technique), then liquid densities are measured with a vibrating tube densimeter, for molar composition in the range between 70 % and 90 % of CO2. The Peng Robinson EoS was fine-tuned on the bubble points obtained, resulting in a satisfactory accuracy level. Finally, a non-conventional methodology has been developed to measure bubble points with the vibrating tube densimeter, whose results are consistent with the VLE data obtained with the standard PVT technique. Thermodynamic analysis in next-generation concentrated solar power plant, at 700 °C turbine inlet, confirms the mixture overcomes 50 % thermal efficiency, providing +4.2 % net electrical output over pure supercritical CO2 at equal thermal power from the solar field. •Carbon dioxide/Silicon Tetrachloride mixture is proposed as innovative working fluid.•Bubble points and liquid densities of the mixture are experimentally obtained.•The experimental data are used for the fine-tuning of the equation of state.•The thermodynamic efficiency of the mixture is simulated in next-generation CSP plant.•The mixture enables +2 % electric efficiency gain compared to pure sCO2.