Supercritical CO2 Binary Mixtures for Recompression Brayton s-CO2 Power Cycles Coupled to Solar Thermal Energy Plants

Abstract

In this work, an evaluation and quantification of the impact of using mixtures based on supercritical carbon dioxide “s-CO2” (s-CO2/COS, s-CO2/H2S, s-CO2/NH3, s-CO2/SO2) are made as a working fluid in simple and complex recompression Brayton s-CO2 power cycle configurations that have pressure drops in their components. These cycles are coupled with a solar thermal plant with parabolic-trough collector (PTC) technology. The methodology used in the calculation performance is to establish values of the heat recuperator total conductance (UAtotal) between 5 and 25 MW/K. The main conclusion of this work is that the cycle’s efficiency has improved due to using s-CO2 mixtures as working fluid; this is significant compared to the results obtained using the standard fluid (pure s-CO2). Furthermore, a techno-economic analysis is carried out that compares each configuration’s costs using pure s-CO2 and a mixture of s-CO2/COS with a molar fraction (70/30), respectively, as working fluid where relevant results are obtained. These results show that the best configuration in terms of thermal efficiency and cost is the RCC-RH for pure sCO2 with values of 41.25% and 2811 $/kWe, while for the mixture sCO2/COS, the RCC-2RH configuration with values of 45.05% and 2621 $/kWe is optimal. Using the mixture costs 6.75% less than if it is used the standard fluid (s-CO2).

Design of a 130 MW Axial Turbine Operating with a Supercritical Carbon Dioxide Mixture for the SCARABEUS Project

“…According to the study presented by Tafur-Escanta et al [7], blending CO 2 with carbonyl sulfide (COS) increased the efficiency of the cycle to 45.05%, compared to 41.25% for pure CO 2 , while the specific investment cost decreased to 2621$/kWe for the blended CO 2 cycle compared to 2811$/kWe for the pure CO 2 cycle. The SCARABEUS consortium proposed hexafluorobenzene (C 6 F 6 ), sulfur dioxide (SO 2 ), and titanium tetrachloride (TiCl 4 ) as possible candidate mixtures [8,9].…”

Vortex Patterns Investigation and Enstrophy Analysis in a Small Scale S-CO2 Axial Turbine

“…These features are necessary advantages for the future utilizing vehicles such as flying cars and interstellar spacecraft. Multiple availabilities of many power sources like nuclear power [1][2][3], solar power generation [4,5], gas turbines [6,7], and fuel cells [8][9][10] were frequently proposed dealing with S-CO 2 system in recent years.…”