Mechanism coalescence

Foam persistence increases with rise in BW TDS because the bubbles are stabilized by the combined repelling forces of electrical charges at the steam-water interface that result from the high concentration of dissolved salts. The repulsion effect of similar charges prevents bubble thinning, bubble rupture and coalescence mechanisms from taking place. 

Kapur and Fuerstenau (K6) have presented a discrete size model for the growth of the agglomerates by the random coalescence mechanism, which invariably predominates in the nuclei and transition growth regions. The basic postulates of their model are that the granules are well mixed and the collision frequency and the probability of coalescence are independent of size. The concentration of the pellets is more or less fixed by the packing... 

Fig. 17. Size distributions of pellets generated by the random-coalescence mechanism in the nuclei and transition regions. [From Kapur and Fuerstenau (K6).]...

Fig. 18. Mean granule volume as a function of the agglomeration time in the random-coalescence mechanism. [From Kapur (K2).]...

Fig. 21. Self-similar size distributions of limestone pellets generated by the nonrandom-coalescence mechanism. [From Kappr (K4).]...

Adetayo, A. A., and Ennis, B. J., A Unifying Approach to Modeling Coalescence Mechanisms, in Review, AIChEJ (1996)... 

Figure 7.11. Schematic representation of layer growth (a,b) and the nucleation-coalescence mechanism (c).

In some cases, due to coalescence mechanisms (Oswald ripening), bimodal particle-size distributions are observed. 

A. A. Adetayo, B. J. Ennis, Unifying approach to modeling granule coalescence mechanisms,... 

Thus, the sequence of growth of electrodeposited gold by nucleation-coalescence mechanism has four stages (1) formation of isolated nuclei and their growth to TDC, (2) coalescence of TDC,... 

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