Modelling thermocline storage for CSP yield assessment and process control simulation

In view of the adoption of thermocline Thermal Energy Storage (TES) systems for Concentrated Solar Power (CSP) plants the thermocline behavior needs to be modeled to correctly predict the plant’s yearly energy yield and to specify and tune plant’s process control (e.g. solar field temperature control requirements, electric production scheduling based on estimation of the TES state of charge, etc.). Indeed the thermocline evolution influences the ratio between the nominal TES capacity and the effective one, therefore the potential degradation of the thermocline, when subject to arbitrary charge/discharge cycles, off-design temperature input from the solar field and/or incomplete charging cycles in periods or low Direct Normal Irradiation (DNI) must be taken into account. This paper illustrates the development of a thermocline TES dynamic model sufficiently accurate to predict the TES behavior but sufficiently simple to allow a fast execution of the simulation in the time domain. The TES model is implemente...