Population Balanced Model Crystallization CFD simulation

Description

Population Balanced Model (PBM) Crystallization CFD simulation, ANSYS Fluent Training

Description

The crystallization process is a fundamental phenomenon in which solute particles come together to form a solid crystal structure. Modeling the crystallization process using a population balance model (PBM)is a powerful tool for a detailed understanding of crystal growth, nucleation, and size distribution. It considers super-saturation, temperature, mixing conditions, and impurities. By solving the population balance equation, researchers can simulate and predict the behavior of crystals during the crystallization process.

Modeling the crystallization process using a population balance model provides valuable insights into crystal growth, nucleation, and size distribution. This approach finds applications in pharmaceuticals, chemicals, food, materials science, and energy storage industries. Researchers can optimize product quality, enhance process efficiency, and contribute to advancements in various industrial sectors by understanding and controlling the crystallization process.

The geometry of the present project was designed using ANSYS design modeler and mesh in ANSYS meshing. The mesh type is structured, and the total element number equals 89,244.

Crystallization PBM CFD simulation Methodology

The Eulerian multiphase model was employed in this simulation not only to model the two phases of the mixture (containing water liquid, Ca, and CO3 ions) and Calcium-Carbonate but also to activate the population balance model. Four different classes of bins were considered in this project, with the ratio of exponent set to 1. The minimum diameter was also set to 0.0008 m. Nucleation and growth rates were activated, and constant values of 2e+10 and 2e-11 were set for each one, respectively.

Moreover, the Laminar model was used to simulate the flow equations. 2-D geometry was considered. The present problem is considered complex due to its nature, which includes not only the mixing of different species but also a chemical reaction between two species of Calcium and Carbonate ions. Furthermore, the crystallization modeling through PBM is also considered; activating these models causes the problem to be highly complex. This calls for a multi-stage simulation process. Therefore, three different stages are considered for each mixing, reaction, and crystallization process. The transient study is performed since the PBM model is a time-dependent method.

Conclusion

As shown, different contours, including the phases’ velocity inside the domain, distribution of different classes of bins, and changes in a fraction of each bin, are shown. The heterogeneous reaction contour shows that the reaction between the Ca and Carbonate ions occurs precisely over the line where the two ions are mixed. Moreover, suppose the contours of different bin classes are viewed. In that case, one can easily understand how the nucleation and growth phenomena have worked, as the volume fraction of each bin has expanded in the domain, indicating that the solid phase of calcium carbonate has formed. Furthermore, suppose the number density histogram plot is viewed. In that case, one can see that it is possible to increase the number of bins and consider smaller bin sizes, as the value of number density is almost zero. In contrast, the number density of the smallest bin is enormous. This can be interpreted in the way that not all tiny bins and particles are considered. Therefore, considering smaller values for the minimum diameter in the PBM settings can solve this problem.

 

This video is the 2nd episode of the Population Balanced Model Training Course.