Heat and Mass Transfer Model for a Counter-Flow Moving Packed-Bed Oxidation Reactor/Heat Exchanger

Particle-based thermochemical energy storage (TCES) through metal oxide redox cycling is advantageous compared to traditional sensible and latent heat storage (SHS and LHS) due to its higher operating temperature and energy density, and the capability for long-duration storage. However, overall system performance also depends on the efficiency of the particle-to-working fluid heat exchangers (HXs). Moving packed-bed particle-to-supercritical CO2(sCO(2)) HXs have been extensively studied in SHS systems. Integrating the oxidation reactor (OR) for discharging with a particle-to-sCO(2) HX is a natural choice, for which detailed analysis is needed for OR/HX design and operation. In this work, a 2D continuum heat and mass transfer model coupling transport phenomena and reaction kinetics is developed for a shell-and-plate moving-bed OR/HX. For the baseline design, the model predicted similar to 75% particle bed extent of oxidation at the channel exit, yielding a total heat transfer rate of 16.71 kW for 1.0 m(2) heat transfer area per channel, while the same design with inert particles (SHS only) gives only 4.62 kW. A parametric study was also conducted to evaluate the effects of particle, air, and sCO(2) flowrates, channel height and width, and average particle diameters. It is found that the respective heat transfer rate and sCO(2) outlet temperature can approach similar to 25 kW and >1000 degrees C for optimized designs for the OR/HX. The present model will be valuable for further OR/HX design, scale-up, and optimization of operating conditions. Graphical Abstract Figure