In this study, we measured pressure gradient dP/dz and void fraction αG in spherical particle beds with particle diameters of 4 and 8 mm under stagnant liquid conditions. We obtained an empirical correlation and its uncertainty for the void fraction by using the data reported by Tutu et al. (1984), Chikhi et al. (2016) and ours. The uncertainty of the obtained αG correlation was relatively small and ±2s = ±0.049 (where s is the standard deviation). However, the uncertainty band for the computed dP/dz was relatively large due to the uncertainty in the void fraction, ±2s = ±0.049. Effects of the interfacial friction Fi on computation of dP/dz were also discussed.
