Microreactors can provide more uniform operation conditions than conventional reactors due to the characteristic advantages related to mass and heat transfer. In our earlier research, a catalyst testing microreactor was used to study the gas-phase partial oxidation of 1-butanol to n-butyraldehyde and subsequently a Au/TiO2 catalyst was selected for kinetic experiments and mathematical modelling in

The reliable prediction of the pressure drop of packed-beds requires an accurate understanding of the packing characteristics. Therefore, packings of spheres, cylinders and hollow cylinders are studied: firstly, developing a reproducible and easily achievable packing generation method by single particle dropping; secondly, evaluating and correlating the average bed porosity as a function of the tube-to-particle

Two-phase flows generally represent an adverse condition for centrifugal pumps. Research about this topic tends to be focused on performance evaluation through experimental approaches, while numerical works are quite scarce. In this paper, the numerical investigation of the gas-liquid flow in a centrifugal rotor is carried out. An Euler-Euler, polydispersed approach is adopted, together with several

Liquid holdup and mass transfer area are critical parameters for packed column design and CO2 capture efficiency prediction. In this paper, a framework was established for modeling the liquid–gas countercurrent flow hydrodynamics in a random packed column with pall rings. Besides the column-averaged information, the radial pall ring distribution, velocity, and liquid holdup profiles are obtained to

The anode surface is known to play an important role in the growth and in mediating electron transfer between electroactive bacteria and the electrodes in power generating microbial fuel cells (MFCs). However, the effect of the surface and its modification on MFC-based biosensor performance has not been studied previously. In this study, our results show that the surface modification influences certain

Velocity distribution plays an important role on the performances of microchannel reactors. In order to obtain an ideal velocity distribution among microchannels, a reverse optimization algorithm is proposed based on a simplified resistance network model, in which the relationship between the pressure drop and resistance is established, and the relationship between the flow rate and the channel velocity

The growth of mesoporous graphene fibers (MGFs) is achieved by the fluidized-bed chemical vapor deposition methodology using MgCO3.3H2O fibers as templates. The regeneration of templates is realized via adding carbonate ions into the pickling filtrate. Besides, regenerated template and graphene possess similar morphologies and comparable qualities with those of initial template and graphene. MGFs present

In order to estimate parameters accurately in nonlinear dynamic systems, experiments that yield a maximum of information are invaluable. Such experiments can be obtained by exploiting model-based optimal experiment design techniques, which use the current guess for the parameters. This guess can differ from the actual system. Consequently, the experiment can result in a lower information content than

The electrostatic induced self-assembly method is successfully applied to prepare core-shell hierarchical structure of BiOI/OMCMB (Oxidized mesocarbon microbead) composites (MB), in which BiOI nanosheets were uniformly immobilized on the surface of OMCMB. The low-priced graphite carbon OMCMB played a crucial role in inducing and assembling the core-shell structure of the MB composites, which not only

The results of tetraethylenepentamine polyalkylated amine oxides (TEPA-R-AO) and hyperbranched polyethyleneimine polyalkylated amine oxides (HPEI-R-AO) as kinetic inhibitors for methane hydrate are reported. Alkyl groups with 2 to 6 carbon atoms and different end-branchings (n-, iso- and tert-) were investigated. In slow constant cooling experiments, the best HPEI-R-AO derivatives outperformed the

With increasing the computational resources, the number of publications about coupled computational fluid dynamics – discrete element method is in the rise in the recent years. This technique is very useful, especially in simulation of fluid-solid flows in process engineering. This paper provides an introduction to CFD-DEM modeling in process engineering systems, including heat and mass transfer and

Three flow types and previous modeling methods for the fibrous porous media (FPM) are summarized. A novel algorithm for modeling FPM structures was proposed to overcome shortcomings of other modeling methods. Carbon fiber felts were observed by a scanning electron microscopy to obtain geometrical information. Lattice Boltzmann method (LBM) was used in simulations for predicting flow properties. Permeability

Due to its significance in oil recovery and droplet microfluidics, breakup of spherical droplets in a constriction (i.e., snap-off) is extensively studied. However, rectangular channels with large aspect ratios are commonly used in real applications, in which droplets usually present pancake shape. Since capillary pressures governing droplet’s snap-off depend strongly on droplet shape, we hypothesize

Presented is a detailed assessment of dispersive mixing and turbulence characterisation of an industrially representative pulsed sieve-plate extraction column (PSEC) obtained using multiphase CFD modelling. The system consists of a 150 mm diameter column with two perforated plates dispersing a 30 vol% dodecane/tributyl phosphate mixture in 3 M nitric acid. Operational conditions were chosen to examine

The fundamental understanding of the multiphase phenomena involved in drying of porous media is still a challenging task. Pore network models (PNMs) reveal the micro-macro interactions. However, PNMs have shortfalls in using true geometry, and in revealing capillary instabilities and film-effects. In this work, Shan Chen representation of Lattice Boltzmann Method (LBM) is applied to elucidate such

In this study, we numerically determined the performance of a microscale separator comprising a lateral and a main channel to separate a two-phase flow. It was aimed to conduct continuous phase through the lateral channel and dispersed phase through the main channel. The continuous and dispersed phases were modeled as incompressible Newtonian fluids with the corresponding interface tracked by the phase-field

The impacts of the entrained droplet size on the pressure drop and heat transfer in annular flow cannot be ignored. However, literature data on the droplet size for higher liquid viscosities are lacking. This paper presents an in-depth study on the characteristics of droplets in annular flow in a 50-mm-inner-diameter vertical pipe, conducted using a particle dynamic analyzer. Afterwards, the effects

Consider a two-layer film flows down a slippery inclined plane where both interface and free surface are contaminated by insoluble surfactants. A detailed linear stability analysis is performed in the presence of several flow parameters. Further, a coupled system of Orr-Sommerfeld equations is derived for the two-layer film flows with a free surface. The analytical calculation is accomplished based

A Multi-phase Particle-in-cell (MP-PIC) method was used to simulate the full-loop co-combustion process of coal and refuse derived fuel (RDF) in a three-dimensional (3D) pilot-scale circulating fluidized bed (CFB) based on the Eulerian-Lagrangian framework. The heat transfer, pyrolysis of volatiles, combustion of gaseous fuel and char, and generation of gaseous pollutants are considered in this model

Mesoscale structures exist inherently in fluidized beds and hence should be taken into account in the constitutive modeling of the drag force. To account for mesoscale effects, previous efforts have been paid on extending the steady-state Energy-Minimization Multi-Scale (EMMS) model to the sub-grid level by introducing acceleration terms into the force balance equations. The EMMS drag models thereof

Surfactant drag reduction has wide applications in energy power and chemical industries. However, the drag reduction ability will be weakened or lost during long-term applications. We studied the surfactant drag reduction in turbulent pipe flow using coarse-grained molecular dynamics simulations and cryogenic transmission electron microscopy experiments. The results show that the weakening/loss of

A strategy for rationally selecting solvent systems of spherical agglomeration is proposed for the first time. It emphasizes that followed by crystallization and phase separation, spherical agglomeration can be achieved only when the solvent system can induce wetting and adhesion which are estimated by the Lifshitz-van der Waals acid-base approach. Especially for wettability of bridging liquid, solvent

Cavitating Venturi tubes play a significant role in mineral processing and their performance depends to a great extent on the presence of solid particles. This work is devoted to experimental and numerical studies of cavitation phenomena in a Venturi tube with different solid mass concentrations (Ws=5∼30 wt%). Numerical simulation is carried out with an axisymmetric 2D CFD-based model available in

Ammonium ionic liquids (ILs) are relatively cheap in synthesis and environmentally benign and despite that they have been very rarely used in gas separation. In this research we used several ammonium ILs as liquid membranes for removal of residual toluene from gas phase. Ionic liquids used in this study were composed of bis(trifluoromethylsulfonyl)imide anion [Tf2N] and trimethylbutylammonium [N1114]

The performances of surfactant-polymer (SP) and alkali-polymer (AP) systems in recovering heavy oil were systematically compared via interfacial tension (IFT), emulsification, and oil displacement experiments. Significant differences of heavy-oil-recovery mechanism by SPs and APs are firstly revealed, those are, ultra-low IFT and oil-in-water (O/W) emulsification dominate using the former, while water-in-oil

Residence time distribution of particles is a critical parameter for proper design of gas-solid fluidized beds, especially in many non-catalytic solid conversion processes where it is highly desirable to match the residence time of a particle and its complete conversion time to achieve the synchronized conversion of particles of different sizes. However, the requisite of considering particle polydispersity

The efficiency of membrane separation processes relies on the performance of fluid flow across the membranes. Herein water transport across carbon nanotube membranes is investigated by means of non-equilibrium molecular dynamics simulations. Particularly the interior/exterior surface wetting effects on water flux are examined. We find that the hydrophilic interior and exterior surfaces can both suppress

Heat and mass transfer enhancement in a convective flow is studied using a variational optimization technique. Entropy generation rate is minimized while allowing to vary the relative weight of the total viscous dissipation in the objective functional to determine optimized velocity and scalar field patterns. The resulting velocity, thermal and mass concentration fields are analyzed as well as the

Perovskite oxide has been emerging as one of the efficient heterogeneous catalysts for advanced oxidation of organic contaminants in wastewater because of their structural integrity and compositional tunability. Herein, we report a new perovskite oxide, La1.15MnO3+δ with excess La, for a lowered average oxidation state of Mn cations and abundant oxygen vacancies, which can be active sites for peroxymonosulfate

Passive acoustic signals from the free fall of water droplets onto a liquid free surface are reported experimentally. The signals are co-registered with video images, permitting the association of the signals with various physical-hydrodynamic events such as the initial impact, first bubble entrainment, fragmentation of small bubbles and the entrainment of a second bubble. An interesting acoustical

We generalize the results on invariances found for linear two-step mechanisms within our joint kinetics approach. A general invariant expression for any linear complex mechanism with at least two single-step substances is obtained, from corrected ratios of the concentration profiles of single-step substances. The invariant expression consist of the product of three factors of different nature: • A