Optimization Analysis of a Power Cycle Using Supercritical CO₂-Based Mixture Working Fluid

Supercritical carbon dioxide cycle (sCO₂ cycle) is an attractive energy conversion technology with advantages of high thermal efficiency, small equipment volume, high safety and environmental friendliness. Though the sCO₂ cycle with closed-loop using pure working fluid has been studied for decades, the thermodynamics of a semi-closed loop using mixed working fluid is still obscure. In this paper, the key equipment and technical characteristics of the circulating power generation system using mixed working fluid are studied, where the calculation of thermodynamic models are implemented by Aspen software. In the results, the parameter analysis and optimization are conducted by analyzing the effects of fuel types, turbine inlet parameters, compressor efficiency, temperature difference at the hot end of the reheater and reheater outlet split ratio on the cycle efficiency. It found that that the cycle net efficiency can be up to 49.3%, and the carbon capture rate is higher than 98%. This study promotes the fundamental understanding of the design of energy conversion technology using mixed working fluid.