Hydrodynamics heat/mass transfer

Hancox, W. T., and W. B. Nicoll, 1971, A General Technique for the Prediction of Void Distributions in Non-Steady Two-Phase Forced Convection, Int. J. Heat Mass Transfer 14 1377 1394. (3) Haramura, Y., and Y. Katto, 1983, A New Hydrodynamic Model of CHF Applicable Widely to Both Pool and Forced Convection Boiling on Submerged Bodies in Saturated Liquids, Int. J. Heat Mass Transfer 26(3) 387 399. (2)... 

It only operates in continuous mode and uses catalyst particles of a slightly larger size than in BCR an upward flow of L maintains S in suspension, but the L velocity should be slower than the S settling velocity. Stability also requires a very narrow particle size distribution. Hydrodynamics and mass transfer depend on G/L flow ratio. G velocity is usually rather slow, with bubbles rising through a continuous L phase. Heat removal is restricted to use of wall exchangers. 

Basic A, Dudukovic MP. Hydrodynamics and mass transfer in rotating packed beds. In Heat and Mass Transfer in Porous Media Conference Proceedings, 1992 651-662. 

Understanding of a multiphase chemical reactor involves chemical (catalysis) kinetics, hydrodynamics and heat/mass transfers at scales... 

Kryukov, A., Levashov, V., Sazhin, S. (2004). Evaporation of diesel fuel droplets ki-neHc versus hydrodynamic models. Int.. Heat Mass Transfer 47,2541-2549. 

W. M. Kays, and E. Y. Leung, Heat Transfer in Annular Passages Hydrodynamically Developed Turbulent Flow with Arbitrarily Prescribed Heat Flux, Int. J. Heat Mass Transfer, (6) 537-557, 1963. 

Y. Haramura and Y. Katto, A New Hydrodynamic Model of Critical Heat Flux, Applicable Widely to Both Pool and Forced Convection Boiling on Submerged Bodies in Saturated Liquids, Int. J. Heat Mass Transfer (26) 389-399,1983. 

S. Jayanti and G. F. Hewitt, Hydrodynamics and Heat Transfer in Wavy Annular Gas-Liquid Flow A Computational Fluid Dynamics Study, Int. J. Heat Mass Transfer (40) 2445-2460,1997. 

Fluidization is one of the most commonly used techniques for drying particulate solids. The technique reiies on a high-velocity hot gas stream that creates a fluid bed with speciai hydrodynamic and heat/mass transfer characteristics. Aithough weil entrenched in industry, fluid bed dryers have the following disadvantages that limit their appiication ... 

There are several industrially important gas-liquid-solid reactions such as carbonation of lime,coal liquefaction etc.,where solids take part in the reaction.The common type of reactor for these reactions is normally a gas-liquid-suspended solid column with or without mechanical agitation.An extensive literature is already available on the hydrodynamic,mixing,mass transfer,and heat transfer characteristics of these reactors,and critical reviews have been published in recent years(1-3). 

Wu RL, Lim CJ, Grace JR, Brereton CMH. Instantaneous local heat transfer and hydrodynamics in a circulating fluidized bed. Int J Heat Mass Transfer 34 2019-2027, 1991. 

Trickle-bed reactors, wherein gas and liquid reactants are contacted in a co-current down flow mode in the presence of heterogeneous catalysts, are used in a large number of industrial chemical processes. Being a multiphase catalytic reactor with complex hydrodynamics and mass transfer characteristics, the development of a generalized model for predicting the performance of such reactors is still a difficult task. However, due to its direct relevance to industrial-scale processes, several important aspects with respect to the influence of external and intraparticle mass transfer effects, partial wetting of catalyst particles and heat effects have been studied previously (Satterfield and Way (1972) Hanika et. al., (1975,1977,1981) Herskowitz and Mosseri (1983)). The previous work has mainly addressed the question of catalyst effectiveness under isothermal conditions and for simple kinetics. It is well known that most of the industrially important reactions represent complex reaction kinetics and very often multistep reactions. Very few attempts have been made on experimental verification of trickle-bed reactor models for multistep catalytic reactions in the previous work. 

Certain hydrodynamical problems, as well as mass-transfer problems in the presence of surface-active agents, have been investigated theoretically under steady-state conditions (L3, L4, L10, R9). However, if we take into account the fact that in gas-liquid dispersions, the nonstationary term must appear in the equation of mass- or heat-transfer, it becomes apparent that an exact analysis is possible if a mixing-contacting mechanism is adopted instead of a theoretical streamline flow around a single bubble sphere. 

The geometry of the reactor is of great importance owing to the fact that it is necessary to obtain good heat and mass transfer characteristics while working with laminar hydrodynamic conditions in order to assume a sufficient residence time compared to the reaction time. 

Before putting a HEX in operation, it is necessary to characterize its properties in terms of heat and mass transfer, pressure drop, and hydrodynamics. A number of experimental methods have been presented and exemplified. These data are important to perform simulations and to define optimal operating conditions. 

Hydrodynamics, Heat and Mass Transfer in Inverse and Circulating Three-Phase Fluidized-Bed Reactors for WasteWater Treatment... 

Recent research development of hydrodynamics and heat and mass transfer in inverse and circulating three-phase fluidized beds for waste water treatment is summarized. The three-phase (gas-liquid-solid) fluidized bed can be utilized for catalytic and photo-catalytic gas-liquid reactions such as chemical, biochemical, biofilm and electrode reactions. For the more effective treatment of wastewater, recently, new processing modes such as the inverse and circulation fluidization have been developed and adopted to circumvent the conventional three-phase fluidized bed reactors [1-6]. 

To provide the pr equisite knowledge for designing the three-phase fluidized-bed reactors with new modes, the hydrodynamics such as phase holdup, mixing and bubble properties and heat and mass transfer characteristics in the reactors have to be determined. Thus, in this study, the hydrodynamics and heat and mass transfer characteristics in the inverse and circulating three-phase fluidized-bed reactors for wastewater treatment in the present and previous studies have been summarized. Correlations for the hydrod3aiamics as well as mass and heat transfer coefficients are proposed. The areas wherein future research should be undertaken to improve... 

In chemical micro process technology with porous catalyst layers attached to the channel walls, convection through the porous medium can often be neglected. When the reactor geometry allows the flow to bypass the porous medium it will follow the path of smaller hydrodynamic resistance and will not penetrate the pore space. Thus, in micro reactors with channels coated with a catalyst medium, the flow velocity inside the medium is usually zero and heat and mass transfer occur by diffusion alone. 

A systematic, rational analysis of both isothermal and nonisothermal tubular systems in which two fluids are flowing must be carried out, if optimal design and economic operation of these pipeline devices is to be achieved. The design of all two-phase contactors must be based on a firm knowledge of two-phase hydrodynamics. In addition, a mathematical description is needed of the heat and mass transfer and of the chemical reaction occurring within a particular system. 

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