A computational study has been carried out to assess the influence of pressure on the flow behaviors in dense gas-fluidized beds. Therefore the discrete particle simulation approach has been employed to study the regime transitions, local two-phase flow structures and the energy dissipation distribution. The results show that high pressure reduces the incipient fluidization velocity, widens the...

Nanopowders are applied in a wide range of processes, and their use continues to increase. Fluidization is one of the best techniques available to disperse and process nanoparticles. However, nanoparticles cannot be fluidized individually; they fluidize as very porous agglomerates. Often, it is needed to apply an assisting method, such as vibration or microjets, to obtain proper fluidization. I...

Fluidized beds are used in a variety of process industries because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Minimum fluidization velocity is an important factor in understanding the hydrodynamic behavior of fluidized beds, and this characteristic may be modified through high frequency (sound) vibrations. The effects caused by sound wave frequ...

Melosh [1996] has suggested that acoustic fluidization could provide an alternative to theories that are invoked as explanations for why some faults appear to be weak. We show that there is a subtle but profound inconsistency in the theory that unfortunately invalidates the results. We propose possible remedies but must acknowledge that the relevance of acoustic fluidization remains an open que...

in this study, a laboratory scale continuous plug flow fluidized bed dryer was designed and constructed. a backward-curved centrifugal fan with a 4 kw electromotor was selected based on the maximum pressure drop in the minimum fluidization state and the ability to produce the velocity required for fluidization of the most granular agricultural materials. the fluidization chamber was a rectangul...

The fluidization behavior of silica gel was tested in a fluidized bed under different sound pressure levels and sound frequencies. It has been found that the particle mixtures can be fluidized smoothly with sound assistance at low sound frequency owing to the sound energy disrupting large size of agglomerates. The minimum fluidization velocity was found to decrease with increasing sound frequen...

............................................................................................................................. xi CHAPTER 1: INTRODUCTION ................................................................................................ 1 1.1 Motivation ............................................................................................................................. 1 1....

A mathematical model for the fluidization of polydisperse suspensions is developed. The stationary concentration configurations for a given fluidizing velocity are analyzed and a mixing condition for bed inversion is derived. A central finite difference scheme is applied to the simulation of the fluidization of a bidisperse suspension. The numerical simulations agree with the experimentally rep...

In this study hydrodynamics of a fluidized bed reactor with fumed silica nano particles was modeled using CFD method. Hydrodynamics parameters such as gas and solid velocity and void fraction have been investigated. The minimum fluidization velocity was around 0.0115 m/s at solids volume fraction of 0.0077. Fluidization process was involving a high expansion ratio of bed and without large bubbl...

The present work is focused on the study of fluidization behaviour of biomass and sand mixtures in a laboratory scale test set up. The biomass materials used during the experimentation were rice husk, bagasse and sawdust. Two different particle sizes of silica sands were used in forming the mixture. The percentages of biomass in the mixtures were 2%, 5%, 10% and 15% by weight. The minimum fluid...