Experimental investigation, modelling, and order of magnitude analysis of oxygen mass transfer in pulsed plate column with -Fe₂O₃ nanofluid

Volumetric oxygen mass transfer coefficient (k(L)a) is an important parameter in the design of various reactors and bioreactors. In the present work, the influence of alpha-Fe2O3 nanofluid on the enhancement of k(L)a is studied in a pulsed plate column (PPC). An enhancement factor of greater than one showed that the nanofluid is favourable in enhancing the mass transfer rate. The effect of pulsing velocity on k(L)a is observed to fall under two regimes: the dispersion regime and emulsion regime. The k(L)a enhancement factor is found to be higher in TiO2 nanofluid than in alpha-Fe2O3 nanofluid, indicating that the type of nanofluid influences the enhancement factor. The order of magnitude analysis showed that localized convection triggered by the Brownian motion of nanoparticles is the phenomenon responsible for k(L)a enhancement. A dimensionless multiple regression analysis (MRA) model was developed to predict k(L)a in the nanoparticle loading range of 0.003-0.019 (v/v%), relating the Sherwood number with oscillating Reynolds number (1200 <= Re-o <= 20,000), gas flow Reynolds number (0.135 <= Re-g <= 0.370), Schmidt number (1300 <= Sc <= 2700), and Brownian Reynolds number (2.81 x 10(-4) <= Re-B <= 5 x 10(-4)). The pseudo-homogeneous model could accurately predict the enhancement until critical loading conditions.