Showing papers in "Chemical Engineering Science in 1997"
TL;DR: In this paper, the limitations of the Fick's law for describing diffusion are discussed and it is argued that the Maxwell-Stefan formulation provides the most general and convenient approach for describing mass transport which takes proper account of thermodynamic non-idealities and influence of external force fields.
1,323 citations
TL;DR: In this article, a combined approach of discrete particle method and computational fluid dynamics (DPM-CFD), in which the motion of individual particles is obtained by solving Newton's second law of motion and gas flow by the Navier-Stokes equation based on the concept of local average, is presented.
853 citations
TL;DR: In this paper, a new discretization method for solving population balance equations for simultaneous nucleation, growth and aggregation of particles is proposed, which combines the best features of the discretisation technique (Kumar and Ramkrishna, 1996, Chem. Engng. 51, 1311-1337), i.e., designing discrete equations to obtain desired properties of a size distribution directly, applicability to an arbitrary grid to control resolution and computational efficiency, with the method of characteristics to offer a technique which is very general, powerful and overcomes the crucial problems of numerical
377 citations
TL;DR: In this article, the influence of the capillary diameter, unit cell length and gas hold-up on measured kLa and kSa coefficients was correlated by simple correlation, which showed that in both cases the mass transport is mostly determined by the liquid slug length and velocity.
310 citations
TL;DR: In this paper, a detailed hydrodynamic model for gas-liquid two-phase flow is presented, which is based on a mixed Eulerian-Lagrangian approach and describes the time-dependent two-dimensional motion of small, spherical gas bubbles in a bubble column operating in the homogeneous regime.
302 citations
TL;DR: In this paper, high-speed video imaging was used to characterize liquid flow patterns and velocity distributions inside liquid slugs were determined by particle imaging velocimetry (PIV).
296 citations
TL;DR: In this article, an equation for mixing time recently published by BHR Group can be related to a basic turbulence model and it is also shown that this equation is superior to those based on a theory linking mixing time to the flow generated by the impeller.
292 citations
TL;DR: In this article, a dynamical, two-phase flow model in two-and three-space coordinates is presented, where the gas-liquid flow is modeled by a Navier-Stokes system of equations in an Eulerian representation.
267 citations
TL;DR: The results showed that the concentration of the undissociated form of acetic acid should not exceed 5 gl−1 in the medium for growth to occur, which led to an increased ethanol yield on glucose and the biomass and glycerol yields decreased by 45 and 33%, respectively.
266 citations
TL;DR: The axial dispersion coefficient was determined for each run and was found to be proportional to the frequency at which particles circulate around the bed, and to be strongly dependent on particle size but independent of drum diameter as discussed by the authors.
266 citations
TL;DR: In this paper, the authors examined the effect of design and working parameters of bubble column reactors on the formation and stability of the homogeneous and the heterogeneous bubbling regimes and demonstrated the existence of direct links between the variations of RTD characteristics of both phases and values of bubble-bed voidage and induced by the changes of bubbling mode.
TL;DR: In this paper, Vortmeyer et al. measured radial velocity profiles below the bed at empty tube velocities of air of 05 m/s
TL;DR: In this article, the equations of motion of the particles and the interstitial fluid are averaged using a soft spatial averaging procedure, thus generating equations relating local average values of the fluid pressure, the fluid velocity, and the velocity and angular velocity of the particle.
TL;DR: In this article, the coagulation kinetics of particles and aggregates are determined by the floc structure and by the hydrodynamic and colloidal interactions between the colliding particles.
TL;DR: In this article, the transition from the homogeneous to the heterogeneous flow regime in bubble columns can be quantitatively found with high accuracy by analysing the chaotic characteristics of the pressure fluctuation signal (PFS).
TL;DR: In this article, the authors proposed a feasible structure to describe the environment within which micromixing and chemical reaction take place and applied it to predict the yields of fast complex reactions in plug-flow static mixers and in a semibatch stirred tank reactor under conditions where neither macromixes nor turbulent dispersion were limiting.
TL;DR: In this paper, a reduced-order nonlinear observer design approach is presented, which allows adjustment of the rate of the decay of observer error and is easy to use and is straightforward to prove analytically that the observer-error dynamics are globally asymptotically stable.
TL;DR: In this paper, the axial and tangential liquid velocity components are measured with confidence, especially close to the wall, and axial normal stress shows a minimum at a radial position of 0.8 of the column radius which has not been reported before.
TL;DR: In this article, the Gibbs energy of a mixture of CH4, C2H4, CH2H2, H2, C6H6 and H2 was calculated at thermodynamic equilibrium.
TL;DR: In this paper, the authors present improved methods for the design of distributed effluent treatment systems and extend the concepts to retrofit cases, where the treatment network is developed in a staged approach by repeated use of targets and design.
TL;DR: In this paper, a hierarchy of models consisting of a Eulerian-Eulerian two fluid model, a discrete bubble model and a volume tracking or Marker Particle model is discussed.
TL;DR: In this article, a simple model to predict the hydrodynamic behavior of a three-phase internal air-lifted reactor is developed, which predicts liquid circulation, gas hold-up and minimum gas supply rates for solids suspension.
TL;DR: In this article, a new approach is presented for the modelling of a fluidized-bed membrane reactor (FBMR), which considers the two-phase nature of the FBMR and the parallel reactions taking place in stream methane reforming, as well as selective permeation through the walls of membrane tubes immersed in the bed.
TL;DR: In this paper, a model based on penetration theory has been developed to calculate the dynamic absorption rate of sulfur dioxide into a droplet of limestone slurry, which includes both instantaneous equilibrium reactions and reactions with finite rates; limestone dissolution, sulfite oxidation, gypsum crystallization and the hydrolysis reaction of CO2.
TL;DR: In this paper, a flow and contacting model is developed to represent a CFB and best estimates of contacting efficiencies are presented for the turbulent, fast fluidized, and pneumatic transport regimes of the CFB.
TL;DR: In this article, the fundamental principles of electrical capacitance tomography (ECT) are presented, and the recent developments in the use of a back-projection algorithm applied to solve an inverse problem are discussed.
TL;DR: In this article, the esterification kinetics of acetic acid with methanol in the presence of hydrogen iodide as a homogeneous acid catalyst was studied with isothermal batch experiments at 30-60°C.
TL;DR: In this paper, a geometric framework for studying optimal reactor design is developed for a given feed and a prescribed kinetics (perhaps involving many reactions), focus is on the full set of product composition vectors that can be produced in principle by means of all possible steady-state designs that employ only reaction and mixing (including designs that transcend current imagination).
TL;DR: In this article, the mass transfer characteristics in a cross-flow rotating packed bed (RPB) have been studied and three different types of mass transfer processes in crossflow RPB were studied.
TL;DR: In this article, the associated perturbed-anisotropic-chain-theory (APACT) and the statistical associating-fluid-theoretic (SAFT) were applied to predict the phase equilibrium of water/hydrocarbon mixtures, with emphasis on liquid-liquid equilibria (LLE).