Abstract
Designing the jet ejector optimally is a challenging task and has a great impact on industrial applications. Three different sets of nozzles (namely, 1, 3, and 5) inside the jet ejector are compared in this study by using numerical simulations. More precisely, dynamics of bubble coalescence and breakup in the multinozzle jet ejectors are studied by means of Computational Fluid Dynamics (CFD). The population balance approach is used for the gas phase such that different bubble size groups are included in CFD and the number densities of each of them are predicted in CFD simulations. Here, commercial CFD softwareANSYS Fluent 14.0is used. The realizablek-εturbulence model is used in CFD code in three-dimensional computational domains. It is clear that Reynolds-Averaged Navier-Stokes (RANS) models have their limitations, but on the other hand, turbulence modeling is not the key issue in this study and we can assume that the RANS models can predict turbulence of the carrying phase accurately enough. In order to validate our numerical predictions, results of one, three, and five nozzles are compared to laboratory experiments data for Cl2-NaOH system. Predicted gas volume fractions, bubble size distributions, and resulting number densities of the different bubble size groups as well as the interfacial area concentrations are in good agreement with experimental results.
Highlights
There are number of industrial processes in which twophase flows, that is, gas-liquid mixture, in a jet ejector are encountered
As we proceed from nozzle to end of jet ejector we are not adding any gas or liquid so it should be parallel to axis
The population balance approach was demonstrated by using the equation of bubble number density for gas-liquid flows using ANSYS Fluent 14.0 to explain the temporal and spatial changes of the gas bubble size distribution
Summary
There are number of industrial processes in which twophase flows, that is, gas-liquid mixture, in a jet ejector are encountered. An attempt has been made to demonstrate the possibility of combining the population balance models with Computational Fluid Dynamics (CFD) for the case of a gas-liquid bubbly flow in the jet ejector. In all these processes gas holdup, εg, and bubble size distribution are important design parameters, since they define the gas-liquid interfacial area available for interfacial area mass transfer (a), which is given by a. Numerical predictions are compared with experiments and the predicated gas interfacial area is in a good agreement with experimental results
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