Effect of interparticle force on the hydrodynamics of gas-solid fluidized beds was investigated using the combined method of computational fluid dynamics and discrete element method (CFD-DEM). The cohesive force between particles was considered to follow the van der Waals equation form. The model was validated by experimental results from literature in terms of bed voidage distribution and Eule...

Two-phase flow regimes are affected by conduit position, alignment, geometry, flow direction, physical characteristics, and flow rate of each phase as well as the heat flux toward the boundaries. Due to the importance of two-phase flow, numerous regimes have been identified. The first step in studying micro-bubble formation inside a venturi tube is to recognize the type of flow regimes. In this...

a modified model has been analytically developed to describe the induction time of an elliptic air bubble in contact with an elliptic hydrophobic oil droplet. the role of hydrophobicity was revealed in the slippage of liquid over the surfaces of bubble and droplet. in this condition, the analytical relationships for pressure distribution and consequently hydrodynamic resistance force through th...

Gas holdup and bubble size are important parameters for simulation and designing in bubble column reactors. Because based on these parameters, the available gas-liquid interfacial area is defined for mass transfer. In this paper, the results of applying magnetic fields on the velocity field and volume fraction of gas holdup are reported. Hydrodynamics of the bubble column in the reactors is inv...

Reliable estimation of the porous membranes neck-pore size distribution (NPSD) is the key element in the design and operation of all membrane separation processes. In this paper, a new approach is presented for reliable of NPSD of porous membranes using wet flow-state bubble point test data. For this purpose, a robust method based on the linear regularization theory is developed to extract NPSD...

Nucleate boiling heat transfer coefficients may be strongly reduced by scale formation, even for conditions where the bulk foulant concentration is well below the saturation concentration. Due to the mechanism of micro-layer evaporation, the local concentration at the heat transfer surface can be considerably increased, causing the formation of scale and changes in bubble frequency and bubble d...

The bubble effectiveness in liquid phase cylohexane non-catalytic oxidation process is discussed in this paper. Then the bubble effectiveness and a new proposed kinetic model are used in the mathematical model of the industrial reactor for the cyclohexane non-catalytic oxidation process. Furthermore, simulation and optimization based on this reactor model are carried out. The results of sim...

frothers havea profoundeffectonbubble size and also flotation efficiency. in present study the effect of type and dosage of frothers on the flotation response of coarse particles of quartz was investigated.  therefore, flotation response of coarse particles using frothers such as mibc, pine oil, poly propylene glycol with concentration of 0, 25, 50 and 75 g/t, was obtained respectively. for all...

the bubble effectiveness in liquid phase cylohexane non-catalytic oxidation process is discussed in this paper. then the bubble effectiveness and a new proposed kinetic model are used in the mathematical model of the industrial reactor for the cyclohexane non-catalytic oxidation process. furthermore, simulation and optimization based on this reactor model are carried out. the results of simulat...

The purpose of this study is to investigate and identify the periods of formation and bursting of speculative bubbles in Iran's capital market by creating a state space model and two-mode switching regime (mode 1 is bubble growth and burst stage and mode 2 is the time of bubble loss) during the period from April 2011 to March 2018. The Oxmetrics 7 software is used to investigate the existence o...