摘要:

AbstractA review of existing literature for the purpose of comparing correlations which allow the explicit predictiosn of gas holdup in two‐ or three‐phase bubble columns shows wide disagreement concerning the effect of various variables. Further, various correlations, apparently of equal validity, show equally wide disagreement in the predicted absolute values of gas holdup among three test systems; water‐air, hydrocarbon solvent—air, and trichloroethytene air. Some possible reasons for these disagreements are discussed.Extensive gas holdup data obtained in a 0.30 m diameter column for the three test systems were correlated statistically for the transition and the turbulent region. The resulting correlation gives agreement with experiment to within ±20%, with most data showing ± 10% agreement. The proposed correlation was also tested against thirteen data sets (from eight researchers) which corresponded to its region of validity and gave good agreement. Three additional relevant data sets were not satisfactorily

ISSN:0008-4034    

DOI:10.1002/cjce.5450640501

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe size distribution of bubbles and the liquid circulation in a bubble column with a draught tube and sieve plate were studied experimentally. The size of bubbles is well correlated with the previous result of the authors; the size distribution data are fitted reasonably well by a logarithmic normal probability distribution. Gas holdup in the draught tube and annulus and pressure drop were measured and correlations for these parameters are obtained.An energy balance is used to predict liquid circulating velocity using gas holdup and pressure drop correlations. Reasonable agreement is found between the calculated and measured circulating velocity.

ISSN:0008-4034    

DOI:10.1002/cjce.5450640502

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

年代:1986

数据来源: WILEY

摘要:

AbstractL'électrophorèse à écoulement continu utilise un champ électrique pour séparer, selon leur mobilité, les constituants d'un échantillon introduit dans un fluide porteur. Au cours de cette séparation, des difficultés telles que l'électro‐osmose ou la convection thermique perturbent la qualité de la séparation.Cette publication analyse les divers paramètres influençant le fonctionnement hydrodynamique de la cellule d'électrophorèse. Les équations de modélisation et les conditions de frontières correspondantes, leur conditionnement et leur résolution par une méthode aux différences finies, conduisent à mettre en évidence l'effet des perturbations hydrodynamiques g

ISSN:0008-4034    

DOI:10.1002/cjce.5450640503

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

年代:1986

数据来源: WILEY

摘要:

AbstractTransient laminar forced convection of Newtonian fluids inside circular ducts and parallel‐plate channels subjected to stepwise variations of wall temperature is considered. Approximate analytical solutions are developed by making use of the generalized integral transform and the classical Laplace transform techniques. Higher order solutions are given for the case of a step change in wall temperature. A second‐order accurate finite‐difference solution is developed to assess the accuracy of the available approximate solutions. The Sign‐Count method is used to solve the resulting eigenvalue problems and determine as many eigenvalues and eigenfunctions as needed. Results are presented for the local Nusselt number, average fluid temperature and the wall heat flux over a wide range of the dimensionless axial coo

ISSN:0008-4034    

DOI:10.1002/cjce.5450640504

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe laminar mixed convection heat transfer of a non‐Newtonian fluid modelled by a power‐law constitutive equation is studied. The equations of motion subject to the Boussinesq approximation and an axially uniform heat flux and peripherally uniform wall temperature condition are discretized by finite difference approximation and are solved by the successive relaxation method. Dual solutions with two‐cell and four‐cell patterns have been observed in certain regions of the parameter space. The secondary flow caused by the buoyancy force has a shear thinning effect for pseudoplastic fluids. The Nusselt number, however, always increases with increasing Grashof

ISSN:0008-4034    

DOI:10.1002/cjce.5450640505

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

年代:1986

数据来源: WILEY

摘要:

AbstractTransient population density curves from a continuous MSMPR crystallizer obtained in response to an application of external non‐homogeneous forcing functions (like changes in feed concentration or flowrate) were used to deduce simultaneously nucleation and growth kinetics. Several simplified parameter estimation procedures were examined using simulated experimental observations of population densities and gave consistent results. Results however obtained from an experiment performed in a small continuous MSMPR crystallizer for the precipitation of calcium oxalate showed apparent scatter in all the algorithms. Methods using transient population density information by themselves may be useful to determine and also to provide an independent check on the reliability of kinetic parameter estimate

ISSN:0008-4034    

DOI:10.1002/cjce.5450640506

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

年代:1986

数据来源: WILEY

摘要:

AbstractA computational procedure using a modification of Boston and Sullivan's “inside‐out” multistage multicomponent separation algorithm (1974) is developed. In order to improve convergence behavior for problems involving mixtures with highly nonideal liquid phases, a two‐parameter model is used to describe liquid‐phase compositional effects upon theK‐factor. The quasi‐Newton methods of Mehra et al. (1983) and Nghiem (1983) are applied to solving various sets of solution variables in the proposed algorithm. Activity coefficients are calculated using the UNIQUAC activity‐coefficient model (1975) with parameters obtained from the UNIFAC group‐contribution method (1975). The computational procedure is applicable to distillation, absorption and reboiled‐absorption configurations. The proposed algorithm was implemented in a FORTRAN 77 program and tested on the Honeywell DPS 8/70M computer at the University of Calgary. Inclusion of the liquid‐phase model resulted in improved convergence behavior for nonideal systems in which the original “inside‐out

ISSN:0008-4034    

DOI:10.1002/cjce.5450640507

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe University of Toronto Tervel Separator was used to fractionate ground, defatted rapeseed meal into protein enriched, and high‐fibre products suitable for inclusion into food products and feed respectively. The meal was screened into fractions of a narrow range of particle size and classified at air speeds chosen to utilize as much of the collection area of the separator as possible. The meat‐rich and hull‐rich cuts were chosen arbitrarily, the cut point being a compromise between pure meat fraction and the greatest possible yield of the meat‐rich fraction. All meat‐rich samples had an increased protein content compared to the original oil‐free meal (43.1%). The 300/425 μm, 425/600 μm, and 600/850 μm meat‐rich fractions had a protein content (moisture‐, and oil‐free basis) of 54.4%, 55.6% and 49.5%, respectively. These meat‐rich fractions contained 28.7%, 20.9% and 15.3% of the protein present in the feed material for a total protein recovery of 64.9% in approximately 55% of the meat weight. The protein‐rich fraction is competitive with dehulled soya meal on the

ISSN:0008-4034    

DOI:10.1002/cjce.5450640508

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

年代:1986

数据来源: WILEY

摘要:

AbstractDirect wood liquefaction of pine sawdust (Pinus radiata) in a hydrogen donor solvent (tetralin), was studied in a 0.5 L autoclave using Co‐Mo/γ‐Al2O3and Pt/γ‐Al2O3supported catalysts. Uncatalyzed as well as Raney Nickel catalyzed runs were also performed for comparison purposes. Reaction temperature was kept at 673 K and total system pressure at 10 MPa in all cases. Weight ratio of solvent to solid loaded was 2:1, the gas phase being either H2or N2. Independent runs were also performed with cellulose and lignin which are the main wood constituents. Reaction products were characterized by means of gas chromatography and solvent fractionation using specific s

ISSN:0008-4034    

DOI:10.1002/cjce.5450640509

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

年代:1986

数据来源: WILEY

摘要:

AbstractThe objective of this investigation is to show that rapid hydrolysis can be achieved by passage of aqueous cellulosic suspensions (2–10% solids) through capillaries followed by sudden decompression and post‐treatment under dilutes acid conditions.Through detailed experimentation within the 200–240°C temperature range and at low sulfuric acid concentrations (0.2–1.0% w/w) it was found that liquefaction of the cellulose proceeds via extensive formation of soluble oligomeric intermediates.A simple kinetic model has been developed to explain the liquefaction‐saccharification patterns of the cellulose. The sequence considered is:Cellulose → Oligo‐derivatives → Glucose → Decomposition productsQuantitative values of the rate constants have been determined and a discussion on the selectivity of the overall reaction seq

ISSN:0008-4034    

DOI:10.1002/cjce.5450640510

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

年代:1986

数据来源: WILEY