Sánchez Martínez, David Tomás2021-10-112021-10-112021-08-28Crespi, F.M., Rodríguez de Arriba, P.E., Sánchez Martínez, D.T., Ayub, A., Marcoberardino, G.Di., Invernizzi, C.M.,...,Manzolini, G. (2021). Thermal efficiency gains enabled by using CO2 mixtures in supercritical power cycles. Energy, 238, 121899-.0360-5442https://hdl.handle.net/11441/126517The present paper explores the utilisation of dopants to increase the critical temperature of Carbon Dioxide (sCO2) as a solution towards maintaining the high thermal efficiencies of sCO2 cycles even when ambient temperatures compromise their feasibility. To this end, the impact of adopting CO2-based mixtures on the performance of power blocks representative of Concentrated Solar Power plants is explored, considering two possible dopants: hexafluorobenzene (C6F6) and titanium tetrachloride (TiCl4). The analysis is applied to a well-known cycle -Recuperated Rankine- and a less common layout -Precompression-. The latter is found capable of fully exploiting the interesting features of these non-conventional working fluids, enabling thermal efficiencies up to 2.3% higher than the simple recuperative configuration. Different scenarios for maximum cycle pressure (250–300 bar), turbine inlet temperature (550–700 °C) and working fluid composition (10–25% molar fraction of dopant) are considered. The results in this work show that CO2-blends with 15–25%(v) of the cited dopants enable efficiencies well in excess of 50% for minimum cycle temperatures as high as 50 °C. To verify this potential gain, the most representative pure sCO2 cycles have been optimised at two minimum cycle temperatures (32 °C and 50°C), proving the superiority of the proposed blended technology in high ambient temperature applications.application/pdf11 p.engCO2 BlendsCSP plantSCARABEUS projectsCO2 PowerCycles Supercritical CO2info:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess10.1016/j.energy.2021.121899