Effect of Bed Particle Size on Thermal Performance of a Directly-Irradiated Fluidized Bed Gas Heater

Abstract

There is a growing interest in a fluidized bed particle receiver that directly irradiates sunlight to particles in the fluidized bed as a solar thermal collector for heating. Thermal performance of directly-irradiated fluidized bed gas heater is strongly affected by the physical properties of the particles. The effect of SiC particle size on heat transfer characteristics in the solar fluidized bed gas heater (50 mm-ID × 100 mm high) has been determined. The outlet gas temperatures showed a maximum value with increasing gas velocity due to the particles motion by bubble behavior in the bed, and the maximum values were found at 3.6 times of Umf for fine SiC and less than 2.0 times of Umf for coarse SiC. Heat absorption from the receiver increased with increasing gas velocity, showing with maximum 18 W for the fine SiC and 23 W for the coarse SiC at 4.5 times of Umf. The thermal efficiency of the receiver increased with increasing gas velocity, but was affected by the content of finer particles. The maximum thermal efficiency of the receiver was 14% for fine SiC and 20% for coarse SiC within the experimental range, but showing higher for the fine SiC at the same gas velocity. A design consideration was proposed to improve the thermal efficiency of the system.

Fluidized Beds for Concentrated Solar Thermal Technologies—A Review

“…FBs have been employed for solar energy applications, considering configurations operating in bubbling, spouted, circulating regimes (see Table 1, Types A-C "ordinary" configurations), and special and novel designs (Types D-J). Early studies successfully pioneered the application of ordinary FBs operated in the bubbling (Flamant, 1982;Bachovchin et al, 1983) and circulating (Koenigsdorff and Kienzle, 1991;Werther et al, 1994) inherent mobility of fluidized particles received further confirmation in subsequent studies (Flamant et al, 1988;Glicksman et al, 1988;Chirone et al, 2013;Pardo et al, 2014;Schwaiger et al, 2014;Salatino et al, 2016;Tregambi et al, 2016;Milanese et al, 2017a;Tregambi et al, 2018a;Briongos et al, 2018;Miller et al, 2018;Bellan et al, 2019a;Tregambi et al, 2019a;Almendros-Ibáñez et al, 2019;Zhang and Wang, 2019;Sulzgruber et al, 2020a;Díaz-Heras et al, 2020b;Sulzgruber et al, 2020b;Park et al, 2020;Wünsch et al, 2020). Moreover, FBs, if properly designed and operated, may provide an appropriate environment for solar-driven heterogeneous chemical processes.…”

Recent Advances in Fluidized Bed Hydrodynamics and Transport Phenomena—Progress and Understanding

“…In recent years, solar receivers based on the fluidized bed concept have attracted considerable interest. The effect of the bed particle size was characterized in [16] for SiC particles. After quantifying the outlet gas temperature, heat absorption, and thermal efficiency as a function of the particle size and gas superficial velocity, the authors proposed novel design considerations.…”