Showing papers on "Packed bed published in 1972"
TL;DR: In this paper, the heat transfer between a fluid flowing through a packed bed and the wall is interpreted according to a one-dimensional model characterized by an overall heat transfer coefficient, hw and by two-dimensional models with one parameter, the effective thermal conductivity, ke or two parameters, the Effective Thermal Conductivity (ETC) λe and αw.
360 citations
TL;DR: In this article, the hydraulic radius model was applied to laminar flow in a packed bed and assuming that mass transfer in the packed bed is analogous to that between a pipe surface and a stream of liquid with steady velocity profile, liquid-phase mass transfer from the packed solid sphere was analyzed and an approximate solution was proposed.
Abstract: Applying the hydraulic radius model to laminar flow in a packed bed and assuming that mass transfer in the packed bed is analogous to that between a pipe surface and a stream of liquid with steady laminar velocity profile, liquid-phase mass transfer from the packed solid sphere was analyzed and an approximate solution is proposed. Further liquidfilm mass transfer coefficients were measured for benzoic acid-water system. From these results, together with previous data, it was found that the proposed equation agrees with data in Re'^10, both this equation and Carberrys equation can be applied for ]0100.
118 citations
TL;DR: In this paper, a simplified analysis of wall friction and its effect on porosity and permeability is presented, and the effects of stress distribution on the structure and uniformity of the packing are examined.
Abstract: The effect of side-wall friction on the uniformity of packing of beds in compression-permeability cells is examined. A large portion of pressure applied to the top of a compressible bad is absorbed in wall friction, resulting in a nonuniformly packed bed. A simplified analysis of wall friction and its effect on porosity and permeability is presented.
All experimenters involived in flow through porous media are urged to examine the effects of stress distribution on the structure and uniformity of the packing. In general, compressible beds of small particles will be strongly affected by the walls.
87 citations
TL;DR: In this article, the maximum achievable rates of heat transfer between a wall surface and a fluidized bed have been further studied in order to control the particle residence times more precisely than is possible in a fluidised bed.
69 citations
TL;DR: In this article, the Peclet number for axial heat transport, which includes effects of all significant heat transport mechanisms, has been obtained in the form of empirical relation for estimation of PEClet number.
55 citations
18 citations
TL;DR: It has been shown that a 5-m gas Chromatographic column (60–80 chromosorb G 1 per cent w / w SE 52) is comparable in terms of resolution and time of analysis to a capillary column.
18 citations
TL;DR: In this paper, the heat transfer results of Agnew and Potter were re-analyzed using additional data obtained from mass transfer experiments carried out with geometrically identical beds.
16 citations
16 citations
Patent•
30 Jun 1972
TL;DR: In this paper, the authors proposed a method for the extraction of soluble solids from roast and ground coffee using a compacted (packed) bed of solid particles during extraction of solids.
Abstract: Channeling of solvent in a compacted (packed) bed of solid particles during extraction of soluble material from the particles can be minimized or substantially eliminated by operating the system such that the viscosity of the extracting fluid (solvent) within the interstices formed between solid particles at every point in the porous packed bed progressively decreases in the direction of increasing concentration of soluble material in the solvent Temperature control is one method of effecting the proper viscosity profile of the extracting fluid throughout the packed bed during the extraction process The method, with respect to the extraction of soluble solids from roast and ground coffee provides an effective means for obtaining a high concentration of coffee solids in the effluent extract and at a high yield and relatively short residence time thus avoiding the need for further concentrating the extract prior to dehydration in the production of soluble coffee powder
13 citations
TL;DR: The Carman channel model for flow in packed beds is shown to apply for the minimum fluidization velocity and homogeneous fluidized beds in this article, and the channel model also provides correlations for mass transfer in the laminar flow region and heat and mass transfer for turbulent flow in a packed bed.
Abstract: The Carman channel model for flow in packed beds is shown to apply for the minimum fluidization velocity and homogeneous fluidized beds. The channel model also provides correlations for mass transfer in the laminar flow region and heat and mass transfer for turbulent flow in a packed bed. Tube bundle data for pressure drop and heat transfer are also evaluated as a packed bed with the channel model.
TL;DR: In this article, the distribution of residence times, DRTs, and contact times, DCTs were measured for ethene reacting with hydrogen, and the ethane thus formed on a palladium catalyst supported on aluminium silicate in an isothermal packed bed reactor at temperatures between 60 and 200°C.
TL;DR: In this paper, heat transfer in packed beds is modeled to account for the heat transfer between the particles and the gas phase, the conduction through the solid phase of particles, and the mixing or dispersion within the gas phases in the void structure of the porous media.
Abstract: Heat transfer in packed beds can be mathematically modeled to account for the heat transfer between the particles and the gas phase, the conduction through the solid phase of particles, and the mixing or dispersion within the gas phase in the void structure of the porous media. To solve the resulting differential equations numerically is not easy. The solution for sinusoidal gas temperature input assumes linearity of the logarithm of the temperature with time. If, in addition, linearity with distance can be assumed, then the solution can be vastly simplified to finding the real root of a fourth-order algebraic equation.
TL;DR: In this paper, a smoothed version of the discontinuous steady states of the packed bed model is obtained and the initial conditions from which they evolve are studied, showing that there is a trade-off between the conductivities of fluid and wall in the way that high values of one or the other can promote fully ignited steady states.
Patent•
07 Jun 1972
TL;DR: In this paper, a packed bed of an oxygen-accepting solid is used for the production of oxygen or enriched air employing a 4-step cyclic operation: pressurization, oxidation, depressurization and reduction.
Abstract: Process and apparatus for the production of oxygen or enriched air employing a packed bed of an oxygen-accepting solid, e.g. a barium oxide with MgO and CaO, for example BaO2-DQL. The process is substantially adiabatic with respect to the bed, and is characterized by 4-step cyclic operation: Pressurization, oxidation, depressurization, and reduction. The pressure during the oxidation portion of the cycle ranges from 14 - 385 psia, and during reduction from 1 - 45 psia, wherein the ratio of pressure during oxidation to that during reduction is between 1.6 and 15. The half-cycle time, that is the time the reactor is maintained in either oxidizing or reducing mode ranges from 30 seconds to 360 seconds, and the space velocity ranges from 200 - 5,000 SCF/cu. ft. bed-hour. The bed may be operated either cocurrently or counter-currently in either an upflow or downflow mode, and the process temperature may range from 1250 DEG - 1600 DEG F. The air used in the process is dried and rendered CO2-free by conventional means.
TL;DR: In this article, a finite difference scheme of equations was developed capable of analog solution for a simple but realistic model of dispersion, absorption, and desorpiation of dye within a cylindrical packed bed of fibers.
Abstract: Commencing with a simple but realistic mathemati cal model of dispersion, absorption, and desorp tion of dye within a cylindrical packed bed of fibers, a finite difference scheme of equations was developed capable of analog solution.By varying the main kinetic and mass-transfer pa rameters, the dynamic response of the system was determined and preferred changes of operating values were indicated.We suggest that these methods could be widely ap plied in the study of systems involving mass trans fer and reaction; to determine the individual effect of descriptive physical parameters on a pro cess without recourse to complex mathematical procedures.
TL;DR: In this article, the influence of a fluid-solid interaction on the performance characteristics of a single liquid phase packed bed catalytic reactor at low Reynolds numbers has been investigated, and a simple theoretical model is suggested which allows for the influences of fine scale dispersion as well as more gross mixing phenomena associated with packing irregularities.
01 May 1972
Abstract: The purpose of this study is to find the influence of a local Obstruction on heat transfer between one particle in a-p packed bed and the coolant gas which is forced through it. A method is chosen and developed, giving average as well as local heat transfer coefficients in the case of a packed bed containing spherical particles of constant diameter.
The results show:
- an important decrease of the average cooling of a sphere near the obstruction. The measurements can be correlated by an expression such as: Nu = A.ReB where Nu is the Nusselt number, Re the Reynolds number and A, B constants depending upon the type and the amount of obstruction.
- important local variations of the heat transfer coefficient over the surface of a sphere.
This work was conducted for the “gas cooled breeder reactor association” and presented at the Thermohydraulics Specialist Meeting at Windscale on May 17-19, 1972, in connection with the ENEA GCFR Programme.
TL;DR: Consecutive reaction in a packed-bed reactor of two-enzyme system is analyzed and the effects of four dimensionless kinetic parameters, K, K 1, W and W 1, on the general substrate conversion are investigated.
TL;DR: In this paper, a pyrometallurgical method for partial separation of hafnium from zirconium has been investigated, which involves continuous reaction between a flowing gas mixture of ZIRconium tetrachloride and HFO with solid sodium chloride in a packed bed reactor.
Abstract: A pyrometallurgical method for partial separation of hafnium from zirconium has been investigated. The method involves continuous reaction between a flowing gas mixture of zirconium tetrachloride and hafnium tetrachloride with solid sodium chloride in a packed bed reactor. The solid-vapour reaction enriches the vapour phase with respect to zirconium tetrachloride. This may be attributed to a more favourable reaction for hafnium tetrachloride. The influence of a number of parameters, e.g. temperature, gas flow rate, particle size and bed length, has been studied. Decreases in flow rate and particle size and increase in bed length are found to favour separation, while temperature has little effect. A simple equation has been derived to explain the experimental observations.