Numerical simulation of milk fouling: Taking fouling layer domain and localized surface reaction kinetics into account

Numerous theoretical and numerical models have been developed to characterize milk fouling in heat exchangers. Though they helped us understand the fouling process, they lack consideration of fouling layer structure and its evolution. In this work, aiming at a more reliable predictive tool, milk fouling is modeled in a simplified 2D heat exchanger. A unique feature of this fully-coupled multi-domain multi-physics model is that the dynamic change of fouling layer structure can be explicitly taken into account while bulk and surface reaction kinetics for β-lactoglobulin (β-LG) are coupled with momentum, mass and heat transfer. The structural evolution of the deposit is expressed via a continuously varying geometry of the fouling layer domain. Protein fouling deposition can then be modeled based on local information along the deposit surface. Model based analyses revealed a two-stage growth behavior with diffident dominant control factors. The role of different deposition kinetics on the overall fouling of the heat exchanger was also considered as a test case.