Comparative analysis of thermal performance of electrothermal energy storage and liquid energy storage based on carbon dioxide
The electrothermal carbon dioxide energy storage and liquid carbon dioxide energy storage systems have the characteristics of a wide application range and high energy storage density;hence,they are research hotspots in the field of compressed gas energy storage technologies.However,the differences in energy storage forms and processes of the above systems result in differences in the energy storage efficiency and energy density of these systems,which have not been systematically studied to date.Consequently,in this study,the energy storage principle and process configuration characteristics of the abovementioned systems are described.Subsequently,a thermodynamic analysis model is established to characterize the performance indexes and irreversible loss distribution characteristics of these systems under the set working conditions.Further,the influence of key parameters on the performance of these systems is discussed.The results show that the electrothermal carbon dioxide energy storage system converts the pressure energy into cold energy of working medium to store it,obtaining a higher energy storage density(7.36 kWh/m3)as compared to that of the liquid carbon dioxide energy storage system;additionally,the liquid carbon dioxide energy storage system directly stores the pressure energy through a high-pressure tank to avoid additional turbomachinery loss,thus showing a higher energy storage efficiency(63.60%)as compared to that of the electrothermal carbon dioxide energy storage system.Additionally,this study shows that increasing the isentropic efficiency and outlet pressure of the compressor significantly improves the performance of the liquid carbon dioxide energy storage system.Further,it shows that increasing the isentropic efficiency leads to the improvement of electrothermal carbon dioxide energy storage system.Hence,this study's results provide technical support for carbon dioxide energy storage technology path selection and performance improvement.
electrothermal carbon dioxide energy storageliquid carbon dioxide energy storagethermodynamic analysis
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