Drag coefficient of single bubbles rising in biotechnologically relevant fluids containing (in)organic compounds

Abstract

Understanding the dynamics of bubbles in broth is crucial for various biotechnological processes conducted in bubble columns, such as the manufacturing of cultured meat. In this study, the drag coefficient of individual bubbles ascending in sodium chloride, sodium sulphate, albumin, and egg-white protein solutions was determined. This was accomplished by extracting bubble characteristics, such as the equivalent diameter and terminal velocity, from images captured by a camera system, utilizing bubble detection by a software suite. The obtained terminal velocities and computed drag coefficients were then compared to existing predictive models developed by Clift, Fan and Tsuchiya, Ishii and Zuber, and Peebles and Garber. This comparative analysis was conducted to assess the accuracy of these models in predicting bubble behavior in contaminated water. The results indicated that the drag coefficient of single bubbles rising in salt and protein solutions is higher compared to when ascending in demineralized water. The drag coefficient of single bubbles rising in protein solutions predicted by the drag model of Ishii and Zuber aligned well with the experimentally derived drag coefficients. However, both drag models tended to underpredict the drag coefficient of bubbles ascending in protein solutions. In the case of salt solutions, the drag coefficient predictions by Peebles and Garber approached the experimentally derived drag coefficients more closely although both models tended to overpredict the drag coefficient of bubbles ascending in salt solutions. Additional data acquisition of bubbles within the same size distribution rising in the examined salt and protein solutions is needed to validate and further refine these observations.