# Sedimentation of microparticles in Highly Concentrated Non-Newtonian Emulsions
## 4 Evaluation of Sedimentation Intensity as a Function of System Parameters  
Based on the detailed analyses presented in the previous section, it is possible to draw more general conclusions determining the effect of solids-particle concentration and emulsion oil-phase concentration on the sedimentation process. Dimensionless height, which is the ratio of the height of the sediment layer h\({}_{\rm sk}\) and the total height of the sample h\({}_{\rm c}\), and dimensionless diameter, which is the ratio of the average diameter of the solid particles d\({}_{\rm p}\) and the average diameter of the emulsion oil droplet d\({}_{\rm e}\), were used as comparison parameters. Figure 13a shows the dependence of dimensionless height on dimensionless diameter at different solid-phase concentrations. The lines connecting the measurement points have an increasing character for small values of dimensionless diameters; then, the maximum value of dimensionless height is reached, and with further increase in the value of d\({}_{\rm p}\)/d\({}_{\rm e}\) ratio, there is a gentle decrease in the value of dimensionless height of the sediment. This means that during the sedimentation process at certain emulsion and bed parameters, there is a certain maximum at which, for a given particle size of the solid, the height of the sediment layer at a given time will be the highest, and thus, the sedimentation process will occur fastest. This means that, in order to ensure the stability of three-phase (water/oil/solid) products (e.g., food products), one should avoid a fineness of the solid particles at which the sedimentation process is more intense. A smaller fineness (relative to a given size of oil droplets), as presented in Section 3, would obviously provide more stability to the system, as the solid particles, due to their small weight, would be able to stay on (between) the emulsion droplets (see Figure 5a). However, solids' large fragmentation is associated with high energy expenditure and is sometimes not economically justified. Therefore, it will be more practical to keep the solids-particle size above that at which the maximum sediment height is reached. In this situation, the solids particles, due to their large size, can get stuck on (between) the emulsion droplets (see Figure 5c). Figure 12: Scheme of movement of solid particles through the emulsion structure at different sizes of emulsion oil droplets: (**a**) small oil droplets, (**b**) medium emulsion oil droplets, and (**c**) large oil droplets. As can be observed from the graph in Figure 13a, as the solid concentration in the system increases, the maximum sediment height shifts toward larger particle sizes. This means that in systems with a large number of solids particles, the particle size may be slightly larger than for systems with lower concentrations to maintain system stability. The concentration of the emulsion itself is also not insignificant. Figure 13b shows a plot of the dependence of dimensionless sediment height on a dimensionless diameter during sedimentation in emulsions with different internal phase concentrations. In this system, a peak can also be observed at certain values of diameter ratios, above which the values of dimensionless sediment height decrease. However, in this case, there was no significant effect of emulsion concentration on the value of maximum sediment height. However, an increase in emulsion concentration affects the maintenance of emulsion stability at large particle sizes (relative to oil droplet size). For example, for the sedimentation process at a ratio of average particle diameters to oil droplet size of 90, approximately 30% less dimensionless sediment height was recorded in the 70% concentration emulsion than when sedimenting these diameter sizes in the 60% concentration emulsion. This indicates that modifying the concentration of the oil phase in the system affects the sedimentation of solids.