| Mechanics of bubble collapse in binary mixture with simultaneous heat and mass transfer has been investigated. The flow field surrounding a collapsing bubble undergoing buoyancy-driven motion was solved using computational fluid dynamics techniques prior to heat and mass transfer analysis. The alteration of the bubble shape is considered throughout the bubble collapsing process with the vapor-liquid interface treated as a free surface. Adaptive grid generation with clustering control is used to discretize the physical domain of interest. A curvilinear coordinate system is employed to keep track of the changing bubble shape, and the moving boundary feature is considered as an integral part of the governing equations. A computer code was developed to solve for the axisymmetric flow around a collapsing bubble with moving free surface.; Through the visualization of instantaneous velocity, temperature and concentration field, the bubble collapse is examined in a progressive fashion with detailed bubble volume and shape degeneration presented. The impact of the initial bubble size, Reynolds number, Weber number, the degree of subcooling of the bulk liquid on the bubble collapsing rate is investigated parametrically.; The bubble collapsing rate, heat and mass transfer coefficients at the interface, velocity, temperature and species concentration field surrounding the bubble, and computer-based visualization of the bubble collapsing process have been reported. As the result of the numerical modeling, correlations have been proposed to characterize the heat and mass transfer process pertaining to bubble absorption. There are reasonable agreements with similar experimental or semi-empirical results. The computer simulation contributes to reveal the fundamental mechanism of the bubble collapse in the binary solutions and provides a guideline for designing the absorber in the ammonia-water GAX heat pump system. |
