Performance map and theoretical analysis of Carnot battery technology via novel reversible Rankine-based cycle

Carnot battery technology offers a good solution for storing the energy for later use. There are various types of Carnot batteries, and the Rankine-based cycle stands out due to its efficiency in power generation. Carnot battery can be configured as a stand-alone system, in which the heat pump and heat engine are installed separately. This approach, though, necessitates additional components, leading to high initial investment costs. As an alternative approach, a reversible system that reduces the number of components can be a promising alternative. This article reported the analysis of the Carnot battery implemented via a novel reversible Rankine-based thermodynamic cycle (so-called RRTC). This RRTC system is designed using one expander for both the organic Rankine cycle and heat pump modes (i.e., a throttle valve in the heat pump mode is replaced by an expander). The mathematical modeling simulation and its results are described, highlighting the performance map of the RRTC. Simulations were made for nine selected working fluids, focusing on their thermal properties. Among nine working fluids studied, R152a emerged as the most promising for RRTC applications due to its superior power-to-power performance of 1.57, surpassing other working fluids for which performances below 1.50 were obtained. The results show that a relative difference below 10% was likely observed between simulation results with and without Baumann's correlation. Moreover, Ba(OH)2·8 H2O and acetamide offer a less phase change material mass required in the storage system, achieving thermal energy storage mass sizing ratio of 0.35–1.55 and 0.39–1.71, respectively.