Studying the effects of adsorption, recoalescence and fragmentation in a high pressure homogenizer using a dynamic simulation model

TY - JOUR

T1 - Studying the effects of adsorption, recoalescence and fragmentation in a high pressure homogenizer using a dynamic simulation model

AU - Håkansson, Andreas

AU - Trägårdh, Christian

AU - Bergenståhl, Björn

PY - 2009

Y1 - 2009

N2 - The emulsification in a high pressure homogenizer was studied using a dynamic simulation model based on the population balance equation. The model includes fragmentation, recoalescence and adsorption of macromolecular emulsifier and uses a simple flow model in order to link the hydrodynamics in the homogenizer to the three physical processes mentioned above. A computer model offers an interesting opportunity to study the effect of model assumptions on the overall outcome of the process. The computer model is also an interesting complement to experiments in this case since internal measurements in the active region of homogenization are very hard to carry out, due to small scales and high forces, and information on the spatial position of the different processes is of great importance in design. Based on a set of assumptions, mainly that the turbulent jet responsible for break-up can be described by a one dimensional model and that the macromolecular emulsifiers hindrance of recoalescence can be described by a wall like repulsion, it is shown that the active region of homogenization can be divided into two zones; a narrow zone with fast fragmentation and nearly no recoalescence in the most intense part of the region followed by a recoalescence zone as drop–drop interactions starts to dominate with decreasing turbulence intensity. The effect of operating parameters is seen to be close to the ones found from experiment. The results are discussed in relation to a flow field obtained by a simplistic CFD and assumptions made about hydrodynamics and emulsifier behavior.

AB - The emulsification in a high pressure homogenizer was studied using a dynamic simulation model based on the population balance equation. The model includes fragmentation, recoalescence and adsorption of macromolecular emulsifier and uses a simple flow model in order to link the hydrodynamics in the homogenizer to the three physical processes mentioned above. A computer model offers an interesting opportunity to study the effect of model assumptions on the overall outcome of the process. The computer model is also an interesting complement to experiments in this case since internal measurements in the active region of homogenization are very hard to carry out, due to small scales and high forces, and information on the spatial position of the different processes is of great importance in design. Based on a set of assumptions, mainly that the turbulent jet responsible for break-up can be described by a one dimensional model and that the macromolecular emulsifiers hindrance of recoalescence can be described by a wall like repulsion, it is shown that the active region of homogenization can be divided into two zones; a narrow zone with fast fragmentation and nearly no recoalescence in the most intense part of the region followed by a recoalescence zone as drop–drop interactions starts to dominate with decreasing turbulence intensity. The effect of operating parameters is seen to be close to the ones found from experiment. The results are discussed in relation to a flow field obtained by a simplistic CFD and assumptions made about hydrodynamics and emulsifier behavior.

KW - High pressure homogenization

KW - Emulsification

KW - Recoalescence

KW - Fragmentation

KW - Adsorption of emulsifiers

KW - Population balance equation

U2 - 10.1016/j.foodhyd.2008.10.003

DO - 10.1016/j.foodhyd.2008.10.003

M3 - Article

VL - 23

SP - 1177

EP - 1183

JO - Food Hydrocolloids

JF - Food Hydrocolloids

SN - 0268-005X

IS - 4

ER -