Packed beds energy transport

There may be radial temperature gradients in the reactor that arise from the interaction between the energy released by reaction, heat transfer through the walls of the tube, and convective transport of energy. This factor is the greatest potential source of disparities between the predictions of the model and what is observed for real systems. The deviations are most significant in nonisothermal packed bed reactors. 

Heterogeneous Models. The two-phase character of a packed-bed is preserved in a heterogeneous model. Thus mass and energy conservation equations are written separately for the fluid and solid phases. These equations are linked together by mass and heat transport between the phases. 

Due to the high number of particles in a packed bed, the model for a single particle hes to be simple. Here, an one dimensional approach has been chosen as compromise between accuracy and computing time. The change of a scalar in time within the particle is influenced by diffusion, convection and source terms. Thus, the energy and species distribution over the particle can be described by the general transport equation... 

Numerical simulation results of batch and continuous drying models for slices of peppers in packed beds were presented in this work. The reported models were based on differential mass and energy balances in the dryer along with kinetic equations describing transport phenomena in individual particles and product quality deterioration. The shrinkage problem was... 

V. Heat Transferi Energy Transport and Temperature Profiles in Tubular Packed Bed Reactors... 

The rate-based models usually use the two-film theory and comprise the material and energy balances of a differential element of the two-phase volume in the packing (148). The classical two-film model shown in Figure 13 is extended here to consider the catalyst phase (Figure 33). A pseudo-homogeneous approach is chosen for the catalyzed reaction (see also Section 2.1), and the corresponding overall reaction kinetics is determined by fixed-bed experiments (34). This macroscopic kinetics includes the influence of the liquid distribution and mass transfer resistances at the liquid-solid interface as well as dififusional transport phenomena inside the porous catalyst. 

---