Gas‐induced liquid film characteristics and sulfonation reaction in falling film reactors

Abstract This study investigates gas‐induced liquid film characteristics in falling film reactors, revealing that interfacial gas shear breaks the classical Nusselt balance. By reshaping the internal velocity profile, it acts as the dominant driver for macroscopic film thinning while exerting a “dampening‐and‐triggering” effect on waves, fundamentally altering momentum exchange. We introduce a novel gas–liquid interfacial shear number to modify the Nusselt solution. The resulting correlation predicts average film thickness within a ±15% error, halving the ±40% error inherent in classical Nusselt predictions at high gas velocities. Traditional theory systematically overestimates film thickness, skewing Hatta number and reaction rate evaluations. Correcting this bias confirms that intense gas shear, coupled with high reactant concentrations, significantly enhances mass transfer and reaction performance. Ultimately, this newly developed correlation provides a crucial theoretical tool for the precise design and evaluation of falling film reactors.