where Qs and Ṁs,C 4 H 10 are calculated by integrating the heat and C 4 H 10 source terms of the CFD simulation over the particle volume. The surface temperature T surf and mass fraction w surf,C 4 H 10 are evaluated by area averaging temperatures and mass fractions from the CFD simulation over the particle surface. Figure shows that heat and species mass transfer from the particle surface into the fluid phase grows with increasing Re p . The N u p and the Sh p,C 4 H 10 numbers are in excellent agreement with the correlations derived by and , which is in line with the findings of . The used literature correlations are described detailed in the supplementary information (SI Section S7). In addition to the particle Nußelt and Sherwood number, the 99 % boundary layer thickness δ i of temperature (i = T) and CO 2 concentration (i = CO 2 ) at the forward stagnation point is evaluated from the CFD simulations and compared with the definition of temperature and concentration boundary layer thickness according to .