摘要:

AbstractThis paper describes a selection of the statistical methods which are available for designing and analyzing experiments for the purpose of choosing between rival mathematical models and for estimating their parameters. To exemplify how rival models might arise an approach to the writing of reaction rate expressions for chemical kinetic situations is given.

ISSN:0008-4034    

DOI:10.1002/cjce.5450520301

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe sliding phenomenon which is reported to impose a restriction upon the slope of slurry pipelines is investigated experimentally. Two different types of behavior which could be called “sliding” were observed.At pipe inclianations greater than 22° to the horizontal, fully settled layers of solid particles would slide with shear occurring at or near the pipe wall. The critical angle of inclination increased as the particle size decreased.When the slurry was not fully settled, a natural convective flow process was observed to move the slurry down a pipe incline. This flow occurred at much lower pipe inclinations. Concentration profiles measured near the bottom of a pipe incline showed little effect of slurry type or concentration, provided the slurry contained a significant amount of slowly settling solids. In this case, pipe slope was the most important vari

ISSN:0008-4034    

DOI:10.1002/cjce.5450520302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe paper deals with the deagglomeration process in viscous fluids. The process is that in which aggregates of particles suspended in fluids are broken in a shear field. A mathematical model is proposed to predict the equilibrium particle size distribution as a function of shear stress, the initial particle size distribution and the agglomerate strength distribution. Experimental work was performed to test the model. A concentric cylinder apparatus provided the shear field and a procedure was developed to determine the agglomerate size distribution. Artificial agglomerates were prepared by a novel method. Within the limitations of experimental and sampling errors, the calculations agree with experimental results.

ISSN:0008-4034    

DOI:10.1002/cjce.5450520303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThis paper describes the design, construction and performance of a high temperature thermal regenerator of annular geometry with radial air flow present. This regenerator has possible application to the efficient exploitation of high temperature gas reactions and in particular to the fixation of atmospheric nitrogen for which this investigation was made. A mathematical model is formulated for the transient heat transfer between a fluid and an annular solid matrix with reversing flows and is solved numerically. The model is used to predict and analyse the operating performance of the regenerator over a range of flow rates (650 Kg/hr maximum), flow reversal periods (100 seconds maximum) and core temperatures (1431°C maximum). The model is tested by comparison of the theoretical and observed regenerator effectiveness, internal bed temperature profiles and the bed pressure drop under conditions of cyclic equilibrium. Apparent effective heat transfer coefficients for the regenerator packing are obtained and compared with an empirical correlation based on independant measurements

ISSN:0008-4034    

DOI:10.1002/cjce.5450520304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThis paper reports experimental observations on peak (critical) heat fluxes on stainless steel ribbons exposed to flow currents under submerged distilled water jets at subcooled and saturated conditions at near atmospheric pressures. A theoretical correlation is proposed based on certain modifications to the treatment of pool boiling hydrodynamic theory.

ISSN:0008-4034    

DOI:10.1002/cjce.5450520305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractA recently reported investigation indicates several inaccuracies in the methodology of compression‐permeability (C‐P) testing which suggest that previously reported agreement between C‐P and filtration data may be fortuitous. Until now, there has been no separate and direct confirmation of each of the two assumptions necessary to obtain a unique correspondence between C‐P and filtration data.The first assumption that the specific filtration resistance is a function solely of cumulative‐drag‐stress is generally accepted. Direct proof requires that the parabolic filtration equation, which is derived primarily on this assumption, describes both incompressible and compressible cake behavior. Most materials produce compressible cakes and “a priori” screening to find an incompressible cake requires identification of a material (Geon) that produces a cake with a linear axial pressure distribution. Results show that the parabolic filtration equation fits both types of cake behavior but an equation based on constant filtration resistance describes only incompressible cake behavior. To engineering accuracy and for dilute slurries, the assumption is verified.The second assumption that the cumulative‐drag‐stress equals the cake pressure drop is a macroscopic force balance and experimental verification requires a filter chamber designed to measure both of these quantities. A theoretical development, based on integral averaging, and experimental results both indicate that the ratio of cumulative‐drag‐stress to cake pressure drop correlates extremely well with cake porosity.A unique one‐to‐one correspondence between C‐P and filtration data is not possible without “a priori” knowledge of filter cake porosity. Previously reported agreement between C‐P and filtration data can probably be attributed to the L/D dependence of C‐P specific filtration resistances. Consequently, C‐P data can be used as a research tool to simulate filtration data but predicted filtration times based solely o

ISSN:0008-4034    

DOI:10.1002/cjce.5450520306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractPublished procedures for calculating the maximum throughput of mutually saturated phases in rotating disc contactors, based on the slip‐velocity concept, are compared against a set of experimental data from two sources. The results of the comparison are expressed as the standard relative deviation of the calculated and experimental continuous phase velocitie

ISSN:0008-4034    

DOI:10.1002/cjce.5450520307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractExperimental results are presented for cyclic reflux operation of an electrosorption — desorption separation process. Solute is alternately absorbed by, or desorbed from, a stack of multilayer ion‐selective membranes in a modified electrodialysis cell by periodically reversing the polarity of the applied electric field. Solution passes through a single set of flow channels parallel to the membrane sheets, and the flow alternates in direction synchronously with the electric current cycle. An axial concentration gradient is set up within the cell so that dialysate is produced at one end of the stack and concentrated solution at the other.Two cell designs are described, one containing a single stack of membranes, the other built in a modular arrangement with up to eight stacks in series. The effect of nine system parameters on the separation of aqueous NaCl solutions is reported for the first unit. Separation factors of up to 40 were obtained. For the second unit, the effect of channel length, displacement cycle, applied voltage and initial concentration on the rate of separation, the final separation factor, and the current consumption are reported. This unit has longer channels, more uniform flow distribution and less axial dispersion than the earlier design and gave separation factors>103with NaCl solution. Applications of the process to continuous separation in open systems are discus

ISSN:0008-4034    

DOI:10.1002/cjce.5450520308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractA theoretical study is reported on the use of d.c. and r.f. plasma jets as chemical reactors for the processing of minerals in the form of a fine powder. The temperature and flow fields of the jet are calculated by solving the integral boundary layer equations. Single particles trajectories are obtained by solving the Basset‐Odar equations. A multi‐particle model is then developed for a feed of known particle size and injection velocity distributions under low loading conditions. Calculators are made on the thermal decomposition of molybdenum disulphide (5 to 30‐micron equivalent diameter). The parameters investigated are the free jet velocity, the mean injection velocity, and the reactor ambient conditions. The results are presented as the probability density distributions of the gas loading, particle temperature, and conversion at different levels downstream of the n

ISSN:0008-4034    

DOI:10.1002/cjce.5450520309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY

摘要:

AbstractThe addition reaction between the compacted powders of phthalic anhydride and p‐nitroaniline was studied. Both the reactants of equal particle size, were mixed in 1‐to‐1 molar ratio and compacted. Three particle sizes — 0.0065 cm, 0.0178 cm and 0.0376 cm and three compaction pressures — 302.0 kgf/cm2, 785.0 kgf/cm2and 1208.0 kgf/cm2were used for the study. Conversions were measured at 80°, 90°, 100°, 110° and 120°C for 1/2, 1, 2, 4, 8, 12, 16, 20 and 24 hours. The reaction rate changed to a constant value, after an initial phase boundary process. The mole percentage conversions increased with decrease in particle size, increase in compaction pressure corresponding to a decrease in the initial porosity of the compact. It was also observed that the final porosity of the compact increased with increase in reaction temperature. Combination of Jander's model and parabolic rate law was used to calculate the values of the reaction rate constant equivalent. The activation energy was calculated to be 14 to 34 kilocalories

ISSN:0008-4034    

DOI:10.1002/cjce.5450520310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1974

数据来源: WILEY