Thermal efficiency gains enabled by using CO2 mixtures in supercritical power cycles

The present paper explores the utilisation of dopants to increase critical temperature Carbon Dioxide (sCO 2 ) as a solution towards maintaining high thermal efficiencies sCO cycles even when ambient temperatures compromise their feasibility. To this end, impact adopting CO -based mixtures on performance power blocks representative Concentrated Solar Power plants is explored, considering two possible dopants: hexafluorobenzene (C 6 F and titanium tetrachloride (TiCl 4 ). analysis applied well-known cycle - Recuperated Rankine less common layout Precompression -. latter found capable fully exploiting interesting features these non-conventional working fluids, enabling up 2.3% higher than simple recuperative configuration. Different scenarios for maximum pressure (250–300 bar), turbine inlet (550–700 ° C) fluid composition (10–25% molar fraction dopant) are considered. results in work show that -blends with 15–25%(v) cited enable well excess 50% minimum 50 C. verify potential gain, most pure have been optimised at (32 C C), proving superiority proposed blended technology applications. • blends temperatures. For given layout, sCO2 4–5 pp efficiency cycles. better exploit CO2– C6F6 blends. best-performing blend depends temperature. Cycle dopant composition/fraction independent optimisation variables.