Coupling fluid flow, heat transfer and thermal denaturation-aggregation of beta-lactoglobulin using an Eulerian/Lagrangian approach

Abstract

The transformation of liquid food product under heat treatment is often represented by considering average temperature evolution along the exchanger and by assuming plug-flow. Our aim is to demonstrate that thermal denaturation-aggregation of whey proteins can be more realistically represented by taking into account the different dynamical and thermal histories associated with fluid parcels which progress more or less quickly, far or close to the heating wall, inside the processing unit. A numerical approach is proposed for evaluating the thermal denaturation-aggregation of whey proteins, combining computational fluid dynamics and the population balance equation. The approach is illustrated by the evolution of a suspension of beta-lactoglobulin. Fluid flow and heat transfer are solved through the finite element method in the Eulerian frame, while product transformation is evaluated along representative Lagrangian trajectories. Outlet bulk results show that the product reaches a higher level of transformation than in assuming plug-flow and radially-independent temperature

A numerical model for studying the thermal denaturation-aggregation of whey proteins under continuous thermal processing

“…This study represents the logical continuation of previous efforts (Chantoiseau, Plana-Fattori, Doursat, & Flick, 2012) in modelling the thermal processing of a liquid product containing whey proteins. In that contribution, the coupled physical model neglected the influence of the regime transition near 90 o C for the temperature dependence of the thermal denaturation-aggregation kinetics rate, as well as the progressively shearthinning rheological behavior of the liquid product along its transformation history; both issues were effectively taken into account here.…”

An Eulerian–Lagrangian approach for coupling fluid flow, heat transfer and liquid food product transformation

“…In applying the Eulerian-Lagrangian approach, the discretization of the size distribution into a great number of classes does not add convection-diffusion-reaction equations to the Eulerian algorithm for solving the fluid flow and heat transfer coupled problem; hence the population balance equation can be successfully solved along a number of representative trajectories without demanding an exorbitant increase in computational resources. It has been accomplished by Chantoiseau et al (2012), in studying the thermal denaturation-aggregation of whey proteins in aqueous suspension. The Eulerian-Lagrangian approach can be applied to any chemical engineering problem in which a single velocity field applies to both liquid and dispersed phases, as in oil-in-water emulsions (Almeida-Rivera and Bongers, 2010) and crystallization under batch conditions (Falola and Borissova, 2012).…”

Two-Way Coupling of Fluid-flow, Heat-Transfer and Product Transformation during Heat Treatment of Starch Suspension Inside Tubular Exchanger

“…Work in progress includes the coupling of fluid flow and heat transfer with a more complex transformation process found in liquid food engineering, namely the particle aggregation. Its representation involves the population balance equation, and preliminary results are available (Chantoiseau et al, 2012).…”

“…In other words, fluid parcels moving near the wall are slowed down while those running at the axis are accelerated, justifying the higher maximum axial velocity and the lower minimum residence time values. Offering a complementary point-of-view from modeling work, Chantoiseau et al (2012) had developed a CFD model for studying the thermal denaturation-aggregation of whey protein, by coupling fluid flow, heat transfer and particle aggregation. Those authors put in evidence the importance of radial distributions of state variables (temperature, velocity field and particle sizes) in explaining the size distribution of protein aggregates at the outlet.…”