Stages of steady diffusion growth of a gas bubble in strongly supersaturated gas-liquid solution

Gas bubble growth as a result of diffusion flux of dissolved gas molecules from the surrounding supersaturated solution to the bubble surface is studied. The condition of the flux steadiness is revealed. A limitation from below on the bubble radius is considered. Its fulfillment guarantees the smallness of fluctuation influence on bubble growth and irreversibility of this process. Under the conditions of steadiness of diffusion flux three stages of bubble growth are marked out. With account for Laplace forces in the bubble intervals of bubble size change and time intervals of these stages are found. The trend of the third stage towards the self-similar regime of the bubble growth, when Laplace forces in the bubble are completely neglected, is described analytically.Comment: 22 page

Homogeneous bubble nucleation limit of lead

Liquid heavy metal coolant in a fast reactor, as well as in accelerator driven systems, is exhibited to large thermal and pressure shocks which can cause cavitation in the coolant. Here we calculated the work of the critical bubble formation in the lead coolant and the nucleation rate in terms of the generalized Gibbs approach. It is demonstrated that such approach provides a more adequate description of the process of bubble nucleation as compared with the classical nucleation theory.Теплоносители на основе жидких тяжелых металлов в быстрых реакторах и реакторах, управляемых ускорителем, подвержены значительным тепловым и гидравлическим ударам, что может приводить к кавитации теплоносителя. Рассчитаны работа образования критических пузырьков в свинцовом теплоносителе и скорость их зарождения в рамках обобщенного подхода Гиббса. Показано, что такой подход обеспечивает более адекватное описание процесса зарождения пузырьков по сравнению с классической теорией нуклеации.Теплоносії на основі рідких важких металів у швидких реакторах і реакторах, керованих прискорювачем, схильні до значних теплових і гідравлічних ударів, що може призводити до кавітації теплоносія. Розраховані робота утворення критичних пухирців в свинцевому теплоносії та швидкість їх зародження в рамках узагальненого підходу Гіббса. Показано, що такий підхід забезпечує більш адекватний опис процесу зародження пухирців в порівнянні з класичною теорією нуклеації

Theory of the nonsteady diffusion growth of a gas bubble in a supersaturated solution of gas in liquid

Using a self-similar approach a general nonsteady theory is elaborated for the case of the diffusion growth of a gas bubble in a supersaturated solution of gas in liquid. Due to the fact that the solution and the bubble in it are physically isolated, the self-similar approach accounts for the balance of the number of gas molecules in the solution and in the bubble that expells incompressible liquid solvent while growing. The rate of growth of the bubble radius in its dependence from gas solubility and solution supersaturation is obtained. There is a nonsteady effect of rapid increase of the rate of bubble growth simultaneous with the growth of the product of gas solubility and solution supersaturation. This product is supplied with a limitation from above, which also stipulates isothermal conditions of bubble growth. The smallness of gas solubility is not presupposed.Comment: 22 pages, 3 figure