Performance analysis of a self-condensation compressed carbon dioxide energy storage system with vortex tube

Abstract

The development of low-carbon society needs a high renewable share in energy sector. Energy storage technologies play a crucial role to handle the relevant issues caused by the fluctuant renewables penetration. Compressed carbon dioxide energy storage is recognized as a promising technology thanks to the favorable thermophysical properties of carbon dioxide. In order to realize the condensation process of low pressure carbon dioxide without the support of extra cold source, a self-condensation compressed carbon dioxide energy storage system with vortex tube is proposed. The vortex tube acts as the condensation device in such system. Results indicate that the condensation process is more sufficient when the vortex tube inlet temperature close to the critical temperature of carbon dioxide. Under design condition, the system energy density, roundtrip electrical and exergy efficiencies are 5.43 kWh/m3, 53.45% and 61.83%, respectively. Meanwhile, the pressure increasement of low pressure storage tank has a positive effect on roundtrip efficiency, but a negative effect on energy density. The pressure increasement of high pressure storage tank has positive effect on both energy density and roundtrip efficiency. Higher compressor isentropic efficiency results in higher roundtrip efficiency and reduced energy density, whereas higher turbine isentropic efficiency implies raised roundtrip efficiency and energy density. The increase of ambient temperature can enhance both the roundtrip efficiency and energy density.