[EN]A thermodynamic model for a steady state pumped heat energy storage in liquid media is presented: it comprises a coupled Brayton-like heat pump and heat engine cycles connected to a cryogenic liquid and a hot molten salt by counter-flow heat exchangers. The model considers non-isothermal heat transfers between
the working fluid and the liquid media and explicitly includes a set of parameters accounting for the main
internal and external losses, heat leak, and pinch point effects for both the heat pump (charge) and heat
engine (discharge) modes. Specific expressions for the main magnitudes in the charge (as the input power
and coefficient of performance) and discharge (as power output and efficiency) modes and the global round
trip efficiency have been analytically derived in terms of isentropic efficiencies of the compressor and turbine,
pressure losses in the heat exchange processes, effectivenesses of the external counter-flow heat exchangers, and
coupling between the working fluid and the storage and cryogenic liquid media. Round trip efficiencies around
of 35 − 40% have been obtained, internal losses being those with main negative influence on the calculated
values. The strong constraints imposed by the pinch point effects and liquid media have been analyzed. The
model provides a thermodynamic assessment of the main involved processes and their interplay for a selected
arrangement (molten salts, cryogenic fluid, and the charge and discharge power blocks) in order to check
parametric strategies for thermodynamic optimization and design. These strategies are based on a reduced set
of parameters of the overall installation and without the high computational costs of dynamical models.
