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Multiphase flows are widely encountered in many chemical reactor processes. Multiphase flow reactors in the form of bubble columns are used in many industrial applications such as hydrogenation of heavy oils, fermentation processes, Fischer-Tropsch reactors, etc. Past work in the modeling of these flows was based on empirical correlations. Even though these correlations fit the data well, they were applicable for narrow ranges of experimental parameters. Moreover, detailed information regarding the local flow parameters was not available through these correlations. The present study attempts to overcome some of these deficiencies. It must also be pointed out that detailed experimental data for three-phase flows through bubble columns are scarce in the literature. These flows are very complex, and understanding them would greatly help in the design and scale-up of the chemical process reactors.

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This paper investigates on three-dimensional thermal deformation of aluminum casting tire mold applying metal casting method by numerical analysis and experiment. In this study, the numerical analysis was performed based on finite element method (FEM) in order to predict thermal deformation in tread part of tire mold by completely cooling about 50°C. For the numerical analysis, “COMSOL Multiphysics 3.3 Ver.” a commercial program for heat transfer and thermal-structural analysis, was used. In order to verify the results calculated by the numerical analysis, the experiment was carried out applying metal casting method on the same condition of numerical analysis. For the experiment, the temperature profile inside the aluminum casting tire mold was measured using thermocouples by completely cooling. When the temperature profile calculated by the numerical analysis and measured by the experiment were compared with each other, it appeared that was a slight temperature difference between the two results by latent heat of aluminum alloy, but their cooling patterns were almost similar.

This study presents the effect on accelerating heat transfer of phase change material (PCM) when the ultrasonic vibrations were applied. Applying ultrasonic waves in a medium may cause the flow velocity of the medium to increase: an effect known as acoustic streaming. Hence, the objective of the present study was to investigate the melting process of a PCM from a heated vertical wall for the following: one without ultrasonic vibration (natural melting) and the other ultrasonic vibrations. The heat flow was measured in the absence of and in the presence of acoustic streaming. The streaming created by ultrasonic vibrations was visualized by a particle image velocimetry (P1V) and a thermal infrared camera. The experimental results revealed that acoustic streaming could accelerate the melting process as much as 2.5 times. Also, total consumed electricity was saved about 2.3 ~ 2.8 Wh, compared to the rate of natural melting. Moreover, we investigate the relationship between acoustic pressure variations and enhancement of heat transfer applying for coupled finite element-boundary element method (Coupled FE-BEM) as a numerical analysis. From the result study, as the acoustic pressure increases, the higher enhancement ratio of heat transfer is obtained. In the end, acoustic pressure variations are related to the acceleration of heat transfer by ultrasonic vibrations.