ISSN:0001-1541    

DOI:10.1002/aic.690150202

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

ISSN:0001-1541    

DOI:10.1002/aic.690150207

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractA theoretical study has been made on the effect of pulsations in the flow field on interphase mass transfer. The phenomenon is of interest in studies of the cardiovascular system as well as in traditional engineering applications. The physical situation studied corresponds to fully developed flow in a long conduit with a periodic pressure gradient. The mass transfer problem was solved analytically for low amplitude pulsations for the two limiting cases of very small and very large frequencies. In addition, several numerical solutions were developed in the intermediate region where the asymptotic solutions are least accurate. The solutions taken together give a good quantitative overall view of the phenomenon.One of the most interesting and unexpected results is that at very low frequencies it is possible for a pulsatile flow to yield a lower interphase mass flux than a steady Poiseuille flow with the same velocity.

ISSN:0001-1541    

DOI:10.1002/aic.690150208

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractLiapunov's direct method is used to establish a finite region of asymptotic stability for nonlinear systems with an arbitrary number of state variables. The procedure is a geometric one in multidimensional space which uses the Fletcher‐Powell minimization technique to find the maximum time derivative of the Liapunov function on the closed Liapunov hypersurface. Three detailed examples are presented, the first being the classical 2‐variable CSTR with heat transfer and the third being a 32‐variable 16‐stage model of an adiabatic tubular reactor with axial di

ISSN:0001-1541    

DOI:10.1002/aic.690150209

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractEntanglement theories for polymer solutions resemble those developed for solid rubbers. These rubberlike theories are extremely successful qualitatively; they give a good indication of the type of response observed experimentally in concentrated solutions. Quantitatively the theories are not so useful; in general they predict constant viscosities in simple shearing motions and ever‐increasing tensile stress in steady elongational flow.If it is supposed that the lifetime of the entanglements is limited partly by a maximum allowable strain magnitude, and that the network ruptures locally whenever this magnitude is exceeded, greatly improved quantitative predictions are observed. For polyisobutylene‐cetane solutions, where the critical strain magnitude appears to be about 3, excellent prediction of the steady shearing viscosity curve is available starting from the measured dynamical response to small sinusoidal strains and the critical strain magnitude. Normal stress effects are also well represented; in elongational flow the tensile stress shows a slight maximum. It thus appears that the notion of network rupture is useful in guiding the selection of continuum theories for polymer fluid descript

ISSN:0001-1541    

DOI:10.1002/aic.690150210

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractDrag coefficients of aerodynamically smooth spheres varying in diameter from 0.0625 to 1.004 in. and in density from 0.195 to 7.80 g./cc. were obtained at acceleration rates ranging from 120 to −30 ft./sq.sec. The particles were subjected to relative turbulence intensities of 7 to 35% and to ratios of Eulerian macroscale to particle diameter of about 0.4 to 5.Quantitative measurement of particle drag coefficients was made possible by the use of a new particle tracing technique which permits the resolution of time to the nearest tenth of a millisecond. The resulting data extend farther into the supercritical flow regime than any other measurements previously reported.The variation in drag coefficient with Reynolds number indicates a continuous alteration in the flow pattern around a sphere in this region. The effect of turbulence is, essentially, to increase supercritical drag, although this effect was found to diminish with increasing Reynolds number. Possible mechanisms for the effects of Reynolds number and turbulence on the particle drag coefficient are suggeste

ISSN:0001-1541    

DOI:10.1002/aic.690150211

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractCalculations of the molar heat and entropy of adsorption for pure methane and pure ethane on silica gel at 25°C. show the heterogeneity of the adsorbent when plotted as functions of the spreading pressure. Plots are given for the activity coefficient of methane and ethane in the adsorbed phase based on experimental data for the entire range of compositions at 25°C. up to a maximum pressure of 1,400 lb./sq.in.abs. Similar results were obtained at 5, 15, and 35°C. The activity coefficients deviate from unity at intermediate compositio

ISSN:0001-1541    

DOI:10.1002/aic.690150212

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractA shell progressive kinetic model is used to determine the temperature rise in a spherical pellet for a gas‐solid diffusion controlled reaction. The effects of heat and mass transfer resistances in the gas film as well as inside the pellet are investigated. The predicted temperature rise may be severe enough to cause sintering to catalyst pellets in which reactions such as combustion of coke occu

ISSN:0001-1541    

DOI:10.1002/aic.690150213

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractElectrochemical techniques are developed to study the details of the flow around a single particle in a packed bed. Initial work has been done with a dumped bed of 1 in. spheres. Results are presented on the variation of the mass transfer coefficient and the shear stress around the surface of one of the spheres, the overall mass transfer rates to a sphere in a bed of inert spheres, and the effect of Reynolds number on the local mass transfer coefficient and the shear stress.

ISSN:0001-1541    

DOI:10.1002/aic.690150214

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY

摘要:

AbstractMonocrystals of calcium tartrate tetrahydrate, neodymium‐doped calcium tartrate tetrahydrate, and cuprous chloride have been grown by controlled diffusion in silica gel using both metathetical and decomplexation reactions. Conditions for the optimum growth of the crystals are given and it is shown how thepH of the gel, the temperature of its formation, the concentration of the reactants which make up the gel, and the concentration of the reactants which result in the crystal are important in attaining good single crystal products. Crystals have been grown up to 11 mm. on edge in three to four weeks, and in many cases take on a form which, to all outward appearances, seem to have been cut and polishe

ISSN:0001-1541    

DOI:10.1002/aic.690150215

出版商:American Institute of Chemical Engineers    

年代:1969

数据来源: WILEY