Sensitivity of transcritical cycle and turbine design to dopant fraction in CO2-based working fluids

Abstract Supercritical CO2 (sCO2) power cycles have gained prominence for their expected excellent performance and compactness. Among benefits, they may potentially reduce the cost of Concentrated Solar Power (CSP) plants. Because critical temperature is close to ambient temperatures in areas with good solar irradiation, dry cooling penalise efficiency sCO2 CSP Recent research has investigated doping different materials increase its temperature, enhance thermodynamic cycle performance, adapt it arid climates. This paper investigates use CO2/TiCl4, CO2/NOD (an unnamed Non-Organic Dopant), CO2/C6F6 mixtures as working fluids a transcritical Rankine implemented 100 MWe plant. Specific focus given effect dopant type fraction on optimal operating conditions key parameters that influence expansion process. Thermodynamic modelling simple recuperated employed identify turbine pressure ratio recuperator effectiveness achieve highest each assumed molar fraction. A design model then used define geometry based conditions. It was found any three dopants (TiCl4, NOD, or C6F6) increases cycle’s thermal efficiency. The greatest achieved TiCl4 (up 49.5%). specific work, other hand, decreases C6F6, but NOD. Moreover, unlike two dopants, NOD does not alleviate irreversibility. In terms sensitivity, addition ratio, ratios across turbine. fluid’s density at inlet all well. Conversely, speed sound yet higher Mach numbers are turbines.