Optimization of the integration of fluidized bed particle heat exchanger in sCO2-based solar tower plants

Next generation solar tower plants aim at increasing the maximum achievable temperature thanks to the adoption of advanced heat transfer media and sCO2 cycles. In this context, the Horizon Europe Powder2Power project aims at demonstrating at MW-scale the adoption of fluidized particles as heat transfer medium in CSP plants. This work focuses on the numerical model for the sizing and simulation of the sCO2-particles multistage heat exchanger to be used for the overall plant analysis. The developed model adopts reliable heat transfer correlations available in the literature to size the heat exchanger based on the target thermal duty and pressure losses. A sensitivity analysis is presented to study the effect of the main design parameters on the component size and efficiency. The model is then used in a case study for the complete techno-economic optimization of fluidized particle based CSP plants. Results show that the temperature differences at the cold- and hot-end of the heat exchanger greatly influences the minimum number of stages and that an increase in the number of stages leads to a reduction in the total heat transfer surface. The economic optimization highlights that the fluidized bed heat exchanger represents a marginal share of the plant overall cost and thus that there is no convenience to adopt a component with a little number of stages and penalize the efficiency and that the stage number in real plants would be likely more constrained by other technical aspects related to components manufacturing.