Modeling and parameter sensitivity analysis of fluidized bed solid particle/sCO2 heat exchanger for concentrated solar power plant

Abstract Supercritical Carbon Dioxide (sCO2) Concentrated Solar Power (CSP) based on Brayton cycle is considered to be the main development direction of CSP technologies in the future due to its high efficiency, compact structure and low cost. In the system, the solid particle/sCO2 heat exchanger, which uses solid particle and sCO2 as the heat transfer fluids, is the key equipment for energy conversion, and its performance will directly affect the system efficiency. In this paper, a comprehensive model of solid particle/sCO2 heat exchanger is clearly proposed based on the discretized lumped parameter method. In order to improve the reliability as well as the prediction accuracy, the dynamic characteristics of the developed model are fully investigated by a step disturbance of the inlet mass flow and temperature. Besides, in order to improve the design level, the influence of key parameters on the performance of solid particle/sCO2 heat exchanger is also extensively studied. The results show that the 15% step disturbance of inlet temperature can cause no more than 7% variation of the outlet temperature, while the 15% step disturbance of inlet mass flow can only result in no more than 1.2% variation of the outlet temperatures; the small diameter and low number of tubes are beneficial to obtain higher heat transfer coefficient for sCO2 side; the small particle size and low fluidizing gas velocity are conducive to the improvement of heat transfer coefficient for particle side. In order to verify the validity of the proposed models, the simulation results are compared with both the design points and published experimental data, and the results show the model has a high accuracy. Conclusions of this paper are good references for the design, optimization of solid particle/sCO2 heat exchangers.