Thermodynamic assessment of a hybrid particle-based concentrated solar power plant using fluidized bed heat exchanger

Abstract In this study, we modify a practical hybrid system developed by National Renewable Energy Laboratory (NREL) and analyze it thermodynamically through energy and exergy methods for analysis, performance assessment and evaluation purposes. In this system, the solid particles are used as the direct heat transfer medium in solar receiver, thermal energy storage and fluidized bed heat exchanger. Furthermore, the hydrodynamic aspects of the fluidized bed (FB) are conducted to reveal the pressure drop and the fluidizing-gas compression power as two important factors in the FB consideration. The present results show that a application of the particle FB heat exchanger in the Rankine power cycle and the pressurized fluidized bed combustion (PFBC) in the air Brayton cycle enable the whole solar plant performance to achieve the energy and the exergy efficiencies of 50% and 53.8% respectively. In addition, the particle energy storage and the solar tower sub-systems potentially can achieve the high energy efficiencies up to 88% and 44.2% and the exergy efficiencies of 96% and 35.1%, respectively. Moreover, highest exergy destructions take place in the PFBC due to chemical reaction and heliostat field and particle receiver due to the high-temperature gradients.