Mapping Bubble Formation and Coalescence in a Tubular Cross-Flow Membrane Foaming System

Membranes

Karin Schroën¹  Jolet de Ruiter¹  Boxin Deng¹  Tessa Neef¹ 

[1] Food Process Engineering Group, Department of Agrotechnology & Food Science, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands;

关键词: cross-flow membrane foaming (CFMF);    whey protein;    (sub)millisecond;    bubble formation;    bubble coalescence;    convective transport;   

DOI  :  10.3390/membranes11090710

来源: DOAJ

【 摘 要 】

Membrane foaming is a promising alternative to conventional foaming methods to produce uniform bubbles. In this study, we provide a fundamental study of a cross-flow membrane foaming (CFMF) system to understand and control bubble formation for various process conditions and fluid properties. Observations with high spatial and temporal resolution allowed us to study bubble formation and bubble coalescence processes simultaneously. Bubble formation time and the snap-off bubble size ($D_0$) were primarily controlled by the continuous phase flow rate ($Q_c$); they decreased as $Q_c$ increased, from 1.64 to 0.13 ms and from 125 to 49 µm. Coalescence resulted in an increase in bubble size ($D_{coal}>D_0$), which can be strongly reduced by increasing either continuous phase viscosity or protein concentration—factors that only slightly influence $D_0$. Particularly, in a 2.5 wt % whey protein system, coalescence could be suppressed with a coefficient of variation below 20%. The stabilizing effect is ascribed to the convective transport of proteins and the intersection of timescales (i.e., μs to ms) of bubble formation and protein adsorption. Our study provides insights into the membrane foaming process at relevant (micro-) length and time scales and paves the way for its further development and application.

【 授权许可】

Unknown