Framework for correlating the effect of temperature on nonelectrolyte and ionic liquid activity coefficients

A power‐law expression is proposed for correlating the temperature dependence of infinite‐dilution activity coefficients ( ) for nonelectrolyte solute–solvent binary pairs and for pairs including an ionic liquid: , where θ_ij = 0 for Lewis–Randall ideal solutions, θ_ij = 1 for classic enthalpy‐based Scatchard–Hildebrand regular solution and van Laar models, and ?5 < θ_ij < 5 for most real binaries. The exponent θ_ij is a function of partial molar excess enthalpy ( ) and entropy ( ) such that . Real binaries are classified into seven types corresponding to distinct domains of and θ_ij. The new method provides a framework for correlating phase‐equilibrium driven temperature effects for a wide variety of chemical and environmental applications. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3675–3690, 2014     

Forced convection boiling in a stator–rotor–stator spinning disc reactor

Boiling of a pure fluid inside the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, average temperature driving force and mass flow rate . The average boiling heat transfer coefficient h_b increases a factor 3 by increasing ω up to 105 rad s^?1, independently of and . The performance of the srs‐SDR, in terms of h_b vs. specific energy input ?, is similar to tubular boiling, where pressure drop provides the energy input. The srs‐SDR enables operation at Wm , yielding values of h_b not practically obtainable in passive evaporators, due to prohibitively high pressure drops required. Since h_b is increased independently of the superficial vapor velocity, h_b is not a function of and the local vapor fraction. Therefore, the srs‐SDR enables a higher degree of control and flexibility of the boiling process, compared to passive flow boiling. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3763–3773, 2016     

Predicting effective conductivities based on geometric microstructure characteristics

Empirical relationships between effective conductivities in porous and composite materials and their geometric characteristics such as volume fraction , tortuosity τ and constrictivity β are established. For this purpose, 43 virtually generated 3D microstructures with varying geometric characteristics are considered. Effective conductivities are determined by numerical transport simulations. Using error‐minimization the following relationships have been established: and (simplified formula) with intrinsic conductivity σ₀, geodesic tortuosity and relative prediction errors of 19% and 18%, respectively. We critically analyze the methodologies used to determine tortuosity and constrictivity. Comparing geometric tortuosity and geodesic tortuosity, our results indicate that geometric tortuosity has a tendency to overestimate the windedness of transport paths. Analyzing various definitions of constrictivity, we find that the established definition describes the effect of bottlenecks well. In summary, the established relationships are important for a purposeful optimization of materials with specific transport properties, such as porous electrodes in fuel cells and batteries. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1834–1843, 2016     

NMR spectroscopic study of chemical equilibria in solutions of formaldehyde,water, and butynediol

Liquid mixtures of formaldehyde, water, and butynediol are complex reacting multicomponent systems in which formaldehyde forms oligomers both with water and butynediol. ‐ and ‐NMR spectra of these mixtures are elucidated. The species distribution of the oligomers is quantitatively determined by ‐NMR spectroscopy. The measurements cover temperatures from 293 to 366 K, overall formaldehyde mass fractions from to , and overall butynediol mass fractions from to . A mole fraction‐based and an activity‐based model of the chemical equilibrium in the studied system are developed and chemical equilibrium constants are reported. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4442–4450, 2017     

Mass transfer coefficient of tubular ultrafiltration membranes under high‐flux conditions

The effect of suction flow on the mass transfer coefficient of tubular ultrafiltration membranes, in particular that under a high‐flux condition, was studied. We pointed out that is proportional to under turbulent conditions, and that the proportional constant, b, exceeds 0.023 when the effect of suction flow is not negligible. We conducted the velocity variation method using ultrafiltration membranes with MWCOs of 20k and 100k and dextrans having molecular weights of 40,000 and 70,000 at the conditions, where exceeded . We demonstrated that the effect of suction flow includes not only flux but also the diffusion coefficient of solute, and that the ratio of the flux to the diffusion coefficient, expressed as , is an important index. Finally, we concluded that , when is smaller than , giving the Deissler equation itself, and that , when exceeds . © 2017 American Institute of Chemical Engineers AIChE J, 64: 1778–1782, 2018     

Sag in commercial thermoforming

Our previous analytical solution gives sag advancing implicitly as , or for , sag advances with the cube root of time for a thin wide rectangular Newtonian isothermal sheet. This previous analytical work applies to sheets that are pinned along just two edges, and not all the way around. Corresponding sagometer experimental results confirmed this cube root relation. This work compares the prediction with measured commercial thermoforming behavior on rectangular sheets that are, of course, pinned all the way around. Then sag parallel superposition is used to extend for a sheet pinned all the way around. We evaluate sag parallel superposition using a finite element method (FEM) employing ANSYS Polyflow. The equation assumes sagging sheet cylindricity, and from our FEM we find that this assumption is reliable when . We compare sag measured in commercial thermoforming, using high‐impact polystyrene (HIPS) sheets that are pinned all the way around, by extending with parallel superposition. It is found that the time evolution of the commercial sag follows nearly exactly the same shape as the isothermal prediction. We measure sag runaway, and although the isothermal analysis , predicts the sag runaway time accurately, our isothermal theory overpredicts the amount of sag in the nonisothermal commercial operation by as much as a factor of 14. It is also shown how to use sheet sag measurements from commercial thermoforming to deduce the Newtonian viscosity of a thermoforming resin at a temperature that is above its softening point. © 2013 American Institute of Chemical Engineers AIChE J, 60: 1529–1535, 2014     

Maldistribution susceptibility of monolith reactors: Case study of glucose hydrogenation performance

In this work an ultrafast electron beam X‐ray modality was applied for the first time to characterize the gas–liquid Taylor flow inside each channel of an opaque honeycomb monolith structure ( ) for and . Significant spatial and temporal deviations in the phase holdup as well as in the gas bubble and liquid slug lengths were found. To evaluate the impact of Taylor flow maldistribution on the reactor performance, the data of more than unit cells were used to simulate the reactor productivity in the hydrogenation of glucose. The results verify that a monolith reactor solely designed by using superficial velocities and empirical correlations for gas bubble and liquid slug lengths fails significantly in achieving high product selectivity and the desired conversion. The developed methods are a solid base to design and select proper distributors ensuring the favorable flow configurations for specific chemical processes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 4346–4364, 2016     

Quantitative relationships between microstructure and effective transport properties based on virtual materials testing

The microstructure influence on conductive transport processes is described in terms of volume fraction ε, tortuosity τ, and constrictivity β. Virtual microstructures with different parameter constellations are produced using methods from stochastic geometry. Effective conductivities are obtained from solving the diffusion equation in a finite element model. In this way, a large database is generated which is used to test expressions describing different micro–macro relationships such as Archie's law, tortuosity, and constrictivity equations. It turns out that the constrictivity equation has the highest accuracy indicating that all three parameters are necessary to capture the microstructure influence correctly. The predictive capability of the constrictivity equation is improved by introducing modifications of it and using error‐minimization, which leads to the following expression: with intrinsic conductivity . The equation is important for future studies in, for example, batteries, fuel cells, and for transport processes in porous materials. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1983–1999, 2014     

Property prediction and consistency analysis by a reference series method

Data analysis and prediction of pure component properties of long‐chain substances is considered. The emphasis is on homologous series and properties for which insufficient data are available. A two‐stage procedure is recommended, whereby a linear (or nonlinear) quantitative structure–property relationship (QSPR) is fitted to a “reference” series, for which an adequate amount of precise data is available. This QSPR should represent correctly both the available data and the asymptotic behavior of the property. In the second stage a quantitative property‐property relationship (QPPR) is derived to represent the predicted property values of a “target” series in terms of the property values of the reference series. The procedure is applied for properties which are highly correlated with the number methylene groups in homologous series: and . It is shown that the method is very useful for consistency analysis of property data and enables a reliable prediction of and , and, thus, also of for long‐chain substances. © 2012 American Institute of Chemical Engineers AIChE J, 59: 420–428, 2013     

The role of wettability of nonideal nozzle plate: From drop‐on‐demand droplet jetting to impact on solid substrate

The dynamics of drop‐on‐demand (DoD) droplet formation and subsequently impact on the solid substrate are investigated using a three‐dimensional (3‐D) multirelaxation‐time (MRT) pseudopotential lattice Boltzmann (LB) model. The wettability of nonideal nozzle plate and solid substrate is modeled by a geometric scheme within the LB framework. The dynamics of droplet formation are explored in a range of the inverse of Ohnesorge number , , and , and the Reynolds number , , and . For , no satellite droplet is observed and the wettability of nozzle plate greatly influences the velocity and length of jetting fluids. For , the filament breakup and recombination are observed. The moment of filament breakup is delayed with advancing contact angle increasing. For with , the primary and satellite droplets could not be recombined with and which agree with the literature. Whereas with , the recombination occurs. The dynamics of subsequent oscillating droplet impact on the substrate are similar to that of equilibrium droplet which could obtain high‐resolution printed features. Consequently, considering with large and numbers, the printable range could be extended which could help increase the printing frequency and boost the production outputs of inkjet printing. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2837–2850, 2018     

Kinetics of the absorption of carbon dioxide into aqueous ammonia solutions

Experiments were performed in a customized double stirred tank reactor to study the kinetics of CO₂ absorption into NH₃ solutions at concentrations ranging from 0.42 to 7.67 kmol·m^?3 and temperatures between 273.15 and 293.15 K. The results show that the reactive absorption was first order with respect to CO₂ but fractional order (1.6–1.8) with respect to ammonia. Experimental data can be satisfactorily interpreted by a termolecular mechanism using and . © 2016 American Institute of Chemical Engineers AIChE J, 62: 3673–3684, 2016     

Intensification of convective heat transfer in a stator–rotor–stator spinning disc reactor

A stator–rotor–stator spinning disc reactor is presented, which aims at intensification of convective heat‐transfer rates for chemical conversion processes. Single phase fluid‐rotor heat‐transfer coefficients h_r are presented for rotor angular velocities rad s^?1 and volumetric throughflow rates m³s^?1. The values of h_r are independent of and increase from 0.95 kWm^?2K^?1 at ω = 0 rad s^?1 to 34 kWm^?2K^?1 at ω = 157 rad s^?1. This is a factor 2–3 higher than values achievable in passively enhanced reactor‐heat exchangers, due to the 1–2 orders of magnitude larger specific energy input achievable in the stator–rotor–stator spinning disc reactor. Moreover, as h_r is independent of , the heat‐transfer rates are independent of residence time. Together with the high mass‐transfer rates reported for rotor–stator spinning disc reactors, this makes the stator–rotor–stator spinning disc reactor a promising tool to intensify heat‐transfer rates for highly exothermal chemical reactions. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2307–2318, 2015     

Determination of kinetics in batch cooling crystallization processes—A sequential parameter estimation approach

A comprehensive methodology to carry out a sequential parameter estimation approach has been developed and validated for the determination of the kinetic parameters of the crystallization of a generic organic compound. The strength of the approach lies in the thorough design of isothermal experiments which facilitate the isolation and/or decoupling of the different crystallization phenomena. This methodology has been applied for the parameter estimation of primary and secondary nucleation, growth and agglomeration kinetics. The resulting crystallization model has been able to reproduce the quantiles , and of the volume‐based particle size distribution of an independent seeded validation experiment with an error below 10 μm. The deviation in the prediction has been increased in the case of an independent unseeded experiment, although errors below the uncertainty of the measurement have been always obtained. The methodology here proposed is intended to be an efficient strategy for rapid modeling of batch crystallization processes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3992–4012, 2016     

Analysis and optimization of pressure retarded osmosis for power generation

Model‐based analysis and optimization of pressure retarded osmosis (PRO) for power generation is focused. The effects of membrane properties (hydraulic permeability and mass‐transfer characteristics), design conditions (inlet osmotic pressures, inlet flows, and membrane area) and operating condition (applied pressure) on power density and efficiency are systematically investigated. A dimensionless design parameter , originally developed in analysis and optimization of reverse osmosis, is used to quantify the effect of dilution in draw solution (DS) as water permeates through membrane. An optimization method is developed to maximize PRO performance. It is shown that dilution and concentration polarization significantly reduce the maximum power density, and the optimal shifts away from . Moreover, power density and efficiency follow opposite trends when varying process conditions including DS flow rate and membrane area. Enhancing membrane properties is crucial to improve the economic feasibility of PRO. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1233–1241, 2015     

A positron emission particle tracking investigation of the scaling law governing free surface flows in tumbling mills

Positron Emission Particle Tracking (PEPT) measurements are used to track the flow of glass beads within a rotating drum fitted with (and without) lifter bars and operated in the cascading and cataracting Froude regimes. After converting the Lagrangian trajectories of a representative radio‐labeled glass bead (the tracer) into Eulerian fields under the ergodic assumption, the bed shape and kinematics are extracted for steady, fully developed flow conditions. Notwithstanding the azimuthal wall effects introduced by the lifter bars, we show a linear scaling of the local flowing layer thickness (h) with local depth‐averaged velocity and a constant average shear for direct measurements spanning the entire flowing layer (not just the central region), and high Froude regimes (cascading and cataracting) not previously investigated by scaling analysis in the literature. © 2016 American Institute of Chemical Engineers AIChE J, 63: 903–913, 2017     

Removal of Hg0 from flue gas using two homogeneous photo‐fenton‐like reactions

Removal of Hg⁰ using two homogeneous Photo‐Fenton‐Like reactions was first investigated in a photochemical reactor. Effects of process parameters on Hg⁰ removal were studied. Free radical and reaction products were analyzed. Removal pathways of Hg⁰ were discussed. Simultaneous removal of Hg⁰, NO, and SO₂ is also studied briefly. The results show that UV power, wavelength, H₂O₂ concentration, and solution pH have great effects on Hg⁰ removal. Hg⁰, and SO₂ concentrations, solution temperature, Fe³⁺, Cu²⁺, , and concentrations also have significant effects on Hg⁰ removal. However, concentrations of CO₂, NO, O₂, Cl^?, , , SiO₂, Al₂O₃, and Fe₂O₃ only have slight effects on Hg⁰ removal. Hg⁰/NO/SO₂ can be simultaneously removed by Photo‐Fenton‐Like reactions. ·OH was captured, and / /Hg²⁺ were also detected. Removals of Hg⁰ by photochemical oxidation and ·OH oxidation play a major role, and removal of Hg⁰ by H₂O₂ oxidation only plays a secondary role in removal of Hg⁰. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1322–1333, 2015     

Pressure drop through platinized titanium porous electrodes for cerium‐based redox flow batteries

The pressure drop, , across a redox flow battery is linked to pumping costs and energy efficiency, making fluid properties of the electrolyte important in scale‐up operations. The at diverse platinized titanium electrodes in Ce‐based redox flow batteries is reported as a function of mean linear electrolyte velocity measured in a rectangular channel flow cell. Darcy's friction factor and permeability vs. Reynolds number are calculated. Average permeability values are: 7.10 × 10^?4 cm² for Pt/Ti mesh, 4.45 × 10^?4 cm² for Pt/Ti plate + turbulence promoters, 1.67 × 10^?5 cm² for Pt/Ti micromesh, and 1.31 × 10^?6 cm² for Pt/Ti felt. The electrochemical volumetric mass transport coefficient, , is provided as a function of . In the flow‐by configuration, Pt/Ti felt combines high values with a relatively high , followed by Pt/Ti micromesh. Pt/Ti mesh and Pt/Ti plate gave a lower but poorer electrochemical performance. Implications for cell design are discussed. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1135–1146, 2018     

Convective condensation in a stator–rotor–stator spinning disc reactor

Centrifugal intensification of condensation heat transfer in the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, volumetric throughflow rate , and average temperature driving force . For the current range of ω, heat transfer from the vapor bubbles to the condensate liquid is limiting, due to a relatively low gas–liquid interfacial area a_GL. For rad s^?1, a strong increase of a_GL, results in increasing the reactor‐average condensation heat transfer coefficient h_c from 1600 to 5600 W m^?2 K^?1, for condensation of pure dichloromethane vapor. Condensation heat transfer in the srs‐SDR is enhanced by rotation, independent of the vapor velocity. The intensified condensation comes at the cost of relatively high energy dissipation rates, indicating condensation in the srs‐SDR is more suited as a means to supply heat (e.g. in an intensified reactor‐heat exchanger), rather than for bulk cooling purposes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3784–3796, 2016     

Effect of dead volumes on the performance of an industrial‐scale simulated moving‐bed Parex unit for p‐xylene purification

The cyclic steady state (CSS) of the industrial‐scale, seven‐zone, simulated moving‐bed (SMB) unit for p‐xylene (p‐x) purification (Parex unit) with three types of dead volumes—bed lines, push‐around and pump‐around circulation lines, and bed heads—is analyzed. In particular, the effects of the size and level of hydrodynamic dispersion of each dead volume on process performance and on its CSS are studied in detail. The circulation lines change the CSS behavior from ‐periodic to ‐periodic, where is the switching interval and is the number of columns in each adsorbent chamber. A high level of axial dispersion in the bed lines, characterized by Péclet numbers smaller than 100, affects the p‐x purity. Moreover, the bed lines lower the average p‐x concentration in the extract, which reduces the p‐x recovery. If the small time lags introduced by the circulation lines are neglected, it is possible to develop a detailed process model that considers the operation of the Parex unit over a single switching interval as opposed to a full cycle, and whose CSS solution can be efficiently computed using a full‐discretization approach. Finally, it is shown that the volume of the bed heads influences significantly the performance of the Parex unit, and that its impact on the location of the operating point with respect to the boundaries of the separation region can be approximately taken into account using the standard true moving‐bed‐SMB equivalence rules if they are corrected for the presence of extra interparticle fluid. © 2015 American Institute of Chemical Engineers AIChE J, 62: 241–255, 2016     

A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE

This work forms part of a broader study that describes a methodology to validate experimental data of phase equilibria for multicomponent systems from a thermodynamic‐mathematical perspective. The goal of this article is to present and justify this method and to study its application to vapor–liquid equilibria (VLE) and vapor–liquid–liquid equilibria (VLLE), obtained under isobaric/isothermal conditions. A procedure based on the Gibbs‐Duhem equation is established which presents two independent calculation paths for its resolution: (a) an integral method and (b) a differential method. Functions are generated for both cases that establish the verification or consistency of data, δψ for the integral test and δζ for the differential approach, which are statistically evaluated by their corresponding average values [ , ], and the standard deviations [ , ]. The evaluation of these parameters for application to real cases is carried out using a set of hypothetical systems (with data generated artificially), for which the values are adequately changed to determine their influence on the method. In this way, the requirements of the proposed method for the data are evaluated and their behavior in response to any disruption in the canonical variables (p,T, phase compositions). The conditions for thermodynamic consistency of data are: , , , and . In systems with VLLE, in addition to the previous criteria, must occur that: and . The new proposed method has been tested with a set of 300 experimental binary systems, biphasic and triphasic, obtained from published bibliography, and the results are compared with those of other tests commonly used for testing thermodynamic consistency. The results show that the greater rigor of the proposed method is mainly due to the simultaneous verification of various independent variables. As a result, the conditions for the new test are verified for fewer systems than using other tests mentioned in the literature (i.e., Fredenslund‐test and direct of Van Ness). Its unique application is sufficient to ensure the consistency of experimental data, without using other tests. © 2017 American Institute of Chemical Engineers AIChE J, 2017