Design and performance of a multistage fluidised bed heat exchanger for particle-receiver solar power plants with storage

This paper presents an analytical model of a multistage fluidised bed heat exchanger for particle-based solar power plants. This model was developed as an applicable design tool for similar devices. It enables a parametric analysis of the heat exchanger performance to be conducted as a function of the operating specifications of the plant power block, the heat exchanger geometry and the fluidised bed properties, among other parameters. A 50 MWe solar plant with a two-stage Rankine cycle operating at 535 degrees C was used to analyse the heat exchanger design. The results indicate that for the proposed application, improverhents in the thermal behaviour mostly depend on the addition of preheating and superheating stages. The most efficient configuration includes seven fluid bed stages with a thermal efficiency of 99.3% and a global heat exchange efficiency of 49.7%. With such a configuration, a maximum solid temperature difference of 387 degrees C may be achieved between the heat exchanger entrance and its exit for particle inlet temperature of 650 degrees C, thus enabling the best utilization of the thermal energy stored in the solid particles. (C) 2016 Elsevier Ltd. All rights reserved.