Carnot battery energy storage system integrated with liquid hydrogen exploitation

This thesis presents a steady-state thermodynamic study of an integrated Carnot Battery system that combines a Vapor Compression Refrigeration (VCR) cycle as a charging and an Organic Rankine Cycle (ORC) as a discharging subsystem. The system uses liquid hydrogen (LH₂) as the cold storage medium and n-pentane as the hot thermal storage. The simulation model is developed in Aspen HYSYS v10 with Peng Robinson property methods and with mixed hydrocarbon/argon working fluids (CH₄ + C₂H₆ + Ar) for the VCR and (C₂H₆ + Ar) for the ORC, to evaluates component duties, cycle performance and system round-trip efficiency under steady-state operating conditions. The steady-state simulation converged and gives a VCR coefficient of performance of approximately 3.32, an ORC thermal efficiency of 19.38%, and a round-trip efficiency of 69.7%. Validation against published literature demonstrates good agreement at the system level and supports the reliability of the developed model. A detailed sensitivity analysis shows that multiple operating parameters influence overall performance. In particular, the ORC turbine inlet temperature, ORC and VCR mass flow rate, VCR evaporator temperature, and ORC turbine inlet pressure all affect the overall round-trip efficiency of the system. LH₂ inlet temperature produced no observable effect due to fixed outlet temperature setpoints in the heat exchangers, reflecting a modelling constraint rather than a physical characteristic. The thesis also documents numerical artefacts that arise from the steady-state, decoupled treatment of the two cycles (for example, ηRT values exceeding 100% under certain parameter changes), explains their physical origin, and outlines why they should be interpreted as modelling limitations rather than real performance gains. Overall, the study establishes a clear thermodynamic baseline for a liquid hydrogen assisted Carnot Battery and provide a roadmap for dynamic modelling, experimental validation, and techno- economic assessment is proposed.