Thermodynamic and operational analysis of small-scale Brayton cycle based Carnot batteries

In the era of energy transition, there is an increasing need for electricity storage technology. A technology that has been drawing attention for the past few years is the Brayton cycle based pumped thermal electricity storage (PTES). Currently, the research on the thermo-economics of large-scale Brayton PTES systems is relatively well-developed. However, in the context of small-scale applications (i.e., less than 1 MW), the research is still limited and lacking. This thesis focuses on studying the thermodynamic and operational performance of small-scale packed bed Brayton PTES. The research starts with the development and validation of a thermodynamic model. An analysis of the system transient behavior over a charge/discharge cycle is carried out. The round trip efficiency of the reference design is found to be 32.7 %. A parametric analysis is then performed as well as an uncertainty quantification. The operational limits and control strategies of the packed bed PTES are discussed, and solutions for extending the operating time at rated power are proposed. Incomplete charge cycles are also studied. The difficulties of establishing an economic analysis are discussed, highlighting the need for further investigation. Overall, this thesis provides insights into the thermodynamic and operational performance of smallscale packed bed Brayton PTES systems, contributing to the development of packed bed PTES as an alternative solution for other small-scale electrical energy storage.