摘要:

The differential forms of heat and work, owing to their dependence upon parameters characterizing the interaction between system and environment (and not only upon the state functions of the system), differ basically from the usual non-exact differentials.

ISSN:0098-6445    

DOI:10.1080/00986449308936120

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In this paper, the results of an experimental study on two phase (air and oil) flow through a crevice between two parallel plates are presented. These results are compared to the predictions of an approximate theoretical model. Four correlations are reported on the dependence of the friction factor on the Reynolds number based on the crevice hydraulic diameter and the crevice height. Each one of these correlations corresponds to a specific value of the oil to air volume ratio (μ) in the range 0≤μ≤0.3 The performance of the theoretical model was deemed acceptable for engineering estimates

ISSN:0098-6445    

DOI:10.1080/00986449308936121

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Heat transfer coefficients have been measured from heat transfer tube bundles simulating heat exchanger configurations and surrounding two-phase and three-phase dispersions in a slurry bubble column. The tube bundles are comprised of a single tube, and five-, seven-, and thirty-seven tubes of 19 mm outer diameter. The Pyrex glass bubble column is 0.305 m internal diameter and 3.30 m tall and is heated electrically by internal heaters to temperatures in the range 298 to 353 K. Air, water and glass beads are used as gas, liquid and solid phases respectively. Heat transfer coefficients are measured for air-water, and air-water-glass bead systems as a function of air velocity up to about 0.3 m/s, and solids concentration up to about 30 weight percent in slurries of glass beads of average diameters 125, 168 and 212 μm at temperatures of 298, 323, 343 and 353 K. The nondimensional correlation available for heat transfer coefficient is also examined and modifications in its form are proposed on the basis of experimental data. Heat transfer coefficient values are compared with the predictions based on correlations due to Deckweret al., Suh and Deckwer, Kimet al., and Pandit and Joshi. These correlations are inadequate and hence a semitheoretical correlation is proposed which synthesizes the data successfully. The influence of tube bundle size on heat transfer coefficient is discussed

ISSN:0098-6445    

DOI:10.1080/00986449308936122

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The effective thermal conductivity of single size and binary mixtures of packed particle beds with stagnant gas at high solid/gas conductivity ratios is determined by a deterministic, unit cell approach. The model results are shown to be in good agreement with experimental data for various gas pressures and solid to gas thermal conductivity ratios up to 1300. A set of correlations for effective conductivity of binary mixtures as a function of gas pressure and particle size is derived. The effect of particle swelling on the effective conductivity of binary mixtures is studied by performing a parametric study of the contact area between the particles

ISSN:0098-6445    

DOI:10.1080/00986449308936123

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An analysis is presented of the fluid dynamics of meniscus coating, in which a horizontal substrate contacts the top surface of a liquid film flowing down an inclined plane, forming a meniscus. The substrate is then moved and a film is entrained on it. The analysis shows the dependence of the entrained film thickness on the substrate translation rate, suspension viscosity, geometry and falling film flowrate. An idealized geometry is assumed which retains the physics of the coating process but which allows a leading-order analytic solution by requiring continuity of the meniscus curvature across three regions: an entrained film flow region near the substrate, static meniscus region and a falling film region down the inclined plane. It is shown that, except for a small term associated with the falling film flow, the film thickness equation is identical to the leading order result for the familiar dip-coating problem. Results of the model agree very well with optical film thickness measurements for films deposited from a Newtonian suspension, and departures from the theory due to non-Newtonian rheology are discussed

ISSN:0098-6445    

DOI:10.1080/00986449308936124

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A forced oscillation method applying reverse-piezo electric effect has been proposed for mass-production of biocatalyst-entrapping polymer gel particles. A jet of aqueous alginate solution flowing out through an orifice was disintegrated into droplets by an oscillating pressure which was exerted by a ceramic plate vibrated by the reverse-piezo electric effect. The droplets formed were immediately solidified into gel particles in calcium chloride solution.

ISSN:0098-6445    

DOI:10.1080/00986449308936125

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The study of the phenol separation-concentration process with the hollow fiber supported liquid membrane technology has been performed. Mixtures of kerosene and CYANEX 923 were used as liquid membrane. The extractant CYANEX 923 is characterized by a high phenol selectivity and an extremely low solubility in the aqueous phase. The introduction of CYANEX 923 in the membrane composition decreases the extractant losses from the pores of the support.

ISSN:0098-6445    

DOI:10.1080/00986449308936126

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A general kinetic transport equation for the description of gas-liquid two-phase flows is presented. This formulation accounts for mechanisms of interfacial area variation due to breakup and coalescence of bubbles. Within this formulation, a model of discrete bubble volumes is applied to the analysis of a column of rising bubbles. Predictions of the development length are in accordance with existing data

ISSN:0098-6445    

DOI:10.1080/00986449308936127

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

An analytical expression for the instantaneous terminal velocity of a two-phase bubble evaporating or collapsing in a less viscous, immiscible liquid at large Reynolds numbers is derived. The predicted results are compared with the experimental data of Sideman and Taitel [1]. There is good agreement between experiment and theory

ISSN:0098-6445    

DOI:10.1080/00986449308936128

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The effect of high molecular weight additives (PVA and gelatin) on barium sulfate precipitation in an MSMPR reactor is investigated. The impeller speed is varied from 0 to 1200 rpm and the additive concentration in the bulk solution is increased up to 5.0 g/1. As the additive concentration is increased, the particle growth rate decreases and the nucleation rate increases. However, the particle morphology is not changed by the additives. The experimental results are explained qualitatively by supposing that the additive is adsorbed on the particle surface and inhibits the mass transfer to the surface.

ISSN:0098-6445    

DOI:10.1080/00986449308936129

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor