Method for measuring bubble size under low-light conditions for mass transfer enhancement in industrial-scale systems

Shadowgraphy-based image processing studied in the literature on multiphase processes has led to meaningful advances in mass transfer enhancement via interfacial area enlargement. However, the industrial applications of shadowgraphy have been limited due to the requirement of an additional light source at specific locations. To overcome this limitation, in this study, a new bubble size measurement technique in low-light conditions is proposed. The technique uses reflected LED image on the bubble surface to estimate the bubble size in low-light conditions and includes a newly derived measurement correlation model, which was validated with lab-scale experimental data. Furthermore, the proposed model was applied to industrial-scale bubble systems for hydrogen fluoride (HF) removal. Using the bubble properties identified through analysis, the overall mass transfer coefficient (OMTC) was determined as an indicator of HF mass transfer enhancement. The optimal conditions for HF mass transfer were determined by identifying the system with the highest OMTC. By manipulating the pressure difference and flow rate, OMTC was increased by ∼78% of the base case.