AICHE Journal
0001-1541
1547-5905
Mỹ
Cơ quản chủ quản: WILEY , Wiley-Blackwell
Lĩnh vực:
Environmental EngineeringChemical Engineering (miscellaneous)Biotechnology
Phân tích ảnh hưởng
Thông tin về tạp chí
The AIChE Journal is the premier research monthly in chemical engineering and related fields. This peer-reviewed and broad-based journal reports on the most important and latest technological advances in core areas of chemical engineering as well as in other relevant engineering disciplines. To keep abreast with the progressive outlook of the profession, the Journal has been expanding the scope of its editorial contents to include such fast developing areas as biotechnology, electrochemical engineering, and environmental engineering. The AIChE Journal is indeed the global communications vehicle for the world-renowned researchers to exchange top-notch research findings with one another. Subscribing to the AIChE Journal is like having immediate access to nine topical journals in the field. Articles are categorized according to the following topical areas: Biomolecular Engineering, Bioengineering, Biochemicals, Biofuels, and Food Inorganic Materials: Synthesis and Processing Particle Technology and Fluidization Process Systems Engineering Reaction Engineering, Kinetics and Catalysis Separations: Materials, Devices and Processes Soft Materials: Synthesis, Processing and Products Thermodynamics and Molecular-Scale Phenomena Transport Phenomena and Fluid Mechanics.
Các bài báo tiêu biểu
A theoretically correct mixing rule for cubic equations of state Abstract A new mixing rule developed for cubic equations of state equates the excess Helmholtz free energy at infinite pressure from an equation of state to that from an activity coefficient model. Use of the Helmholtz free energy insures that the second virial coefficient calculated from the equation of state has a quadratic composition dependence, as required by statistical mechanics. Consequently, this mixing rule produces the correct low‐ and high‐density limits without being density‐dependent. As a test, the mixing rule is used for ternary mixtures of cyclohexane + benzene + water, ethanol + benzene + water and carbon dioxide + n‐propane + water, and all the constituent binaries. The new mixing rule and a simple cubic equation of state can be used for the accurate correlation of vapor‐liquid and liquid‐liquid equilibria for binary mixtures. Using the parameters obtained from binary systems, the phase behavior of ternary mixtures can be predicted. Also, unlike previous empirical mixing rules, this theoretically based mixing rule is equally applicable and accurate for simple mixtures containing hydrocarbons and inorganic gases and mixtures containing polar, aromatic and associating species over a wide range of pressures. This mixing rule makes it possible to use a single equation of state model with equal accuracy for mixtures usually described by equations of state and for those traditionally described by activity coefficient models. It is the correct bridge between these two classes of models.
Tập 38 Số 5 - Trang 671-680 - 1992
Dispersion‐free solvent extraction with microporous hollow‐fiber modules Abstract Extensive studies on dispersion‐free solvent extraction have been carried out using modules made with either hydrophobic or hydrophilic microporous hollow‐fiber membranes. Membrane and boundary layer resistances have been characterized for both kinds of hollow fiber using solvent extraction systems with a wide variation of distribution coefficients and interfacial tensions. It has been found that the Graetz solution for a constant wall concentration describes satisfactorily mass transfer on the lumen side of a hollow‐fiber device. A correlation of the form N Sh D h L ]N N
Tập 34 Số 2 - Trang 177-188 - 1988
Effective and coupled thermal conductivities of isotropic open‐cellular foams Abstract The effective and the coupled thermal conductivity of the solid microstructure of open‐cellular foams and an accompanying saturation fluid are defined in a conceptual representation of conductive heat transfer in a two‐phase system of which the phases are in a thermal nonequilibrium state. The effective and coupled thermal conductivities were determined from a close observation of the relationship between microscopic and macroscopic temperature distributions. Temperature distributions were obtained from the numerical solution of the three‐dimensional (3‐D) conduction equation in a representative geometrical model of the foam solid microstructure and the fluid pores. Empirical correlations are provided for the effective and coupled thermal conductivities in terms of the solid and the fluid thermal conductivity and foam porosity. Thermal radiation was not considered in the energy transfer process. © 2004 American Institute of Chemical Engineers AIChE J, 50: 547–556, 2004
Tập 50 Số 3 - Trang 547-556 - 2004
Steady‐state and transient analysis of a CH<sub>4</sub>–catalytic partial oxidation reformer Abstract In this work dynamic and steady‐state CH4 partial oxidation tests, performed in an insulated lab‐scale reactor over a Rh‐based catalyst supported onto Al2 O3 spheres, are presented and discussed. To gain insight in the complex observed phenomena a previously developed 1D heterogeneous mathematical model of adiabatic reactor was applied to data analysis. The model implemented an indirect reaction scheme independently derived in previous works. In experiments at low flow rates the heat dispersion significantly affected the steady‐state response of the reactor; the process was governed by thermodynamics. By increasing the flow rate the catalytic bed progressively heated up and the adiabatic behavior was approached as a result of the predominance of the reaction enthalpy release over the heat losses; a kinetic effect of contact time was observed. Under these conditions start‐up dynamics of the process were acquired. The temporal evolution of the product distribution along with the shape of axial temperature profiles at steady state were consistent with the occurrence of an indirect reaction path leading to the formation of synthesis gas. A sensitivity analysis showed that the description of the temperature profiles and conversion/selectivity performances at steady state is greatly influenced by the rate of the reforming reactions; the simulation of the reactor start‐up dynamics is highly sensitive to the initial solid temperature. The comparison between measured temperature profiles and model predictions suggested that the thermocouple measurements were mainly influenced by the temperature of the flowing gas. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Tập 52 Số 9 - Trang 3234-3245 - 2006
Modeling the partial oxidation of methane in a short‐contact‐time reactor Abstract Partial oxidation of methane in monolithic catalysts at very short contact times offers a promising route to convert natural gas into syngas (H2 and CO), which can then be converted to higher alkanes or methanol. Detailed modeling is needed to understand their complex interaction of transport and kinetics in these systems and for their industrial application. In this work, the partial oxidation of methane in noble‐metal (Rh and Pt)‐coated monoliths was studied numerically as an example of short‐contact‐time reactor modeling. A tube wall catalytic reactor was simulated as a model for a single pore of the monolithic catalyst using a 2‐D flow field description coupled with detailed reaction mechanisms for surface and gas‐phase chemistry. The catalytic surface coverages of adsorbed species are calculated vs. position. The reactor is characterized by competition between complete and partial oxidation of methane. At atmospheric pressure, CO2 and H2 O are formed on the catalytic surface at the entrance of the catalytic reactor. At higher pressure, gas‐phase chemistry becomes important, forming more complete oxidation products downstream and decreasing syngas selectivity by about 2% at 10 bar. Temperature (from 300 to ∼ 1,200 K), velocity, and transport coefficients change very rapidly at the catalyst entrance. The dependence of conversion and selectivity on reactor conditions was examined.
Tập 44 Số 11 - Trang 2465-2477 - 1998
Steps in CH<sub>4</sub> oxidation on Pt and Rh surfaces: High‐temperature reactor simulations Abstract The direct oxidation of CH4 to H2 and CO in O2 and in air at high temperatures over alumina foam monoliths coated with high loadings of Pt and Rh has been simulated using a 19‐elementary‐step model of adsorption, desorption and surface reaction steps with reaction parameters from the literature or from fits to previous experiments. The surface reaction model for Pt is in good agreement with previously reported low‐pressure(0.1 to 1 torr) reactor measurements of CH4 oxidation rates at temperatures from 600 to 1,500 K and of OH radical desorption during CH4 oxidation at 1,300 to 1,600 K over polycrystalline Pt foils. The model predictions for both catalysts are also consistent with product selectivities observed over monolithic catalysts in an atmospheric‐pressure laboratory‐scale reactor, and the differences between Pt and Rh can be explained by comparing individual reaction steps on these surfaces. Because of the good agreement between the model and both low‐and atmospheric‐pressure reactor simulations, a complete energy diagram for methane oxidation at low coverages is proposed. The model results show that under CH4 rich conditions at high temperatures, H2 and CO are primary products of the direct oxidation of methane via a pyrolysis mechanism.
Tập 39 Số 7 - Trang 1164-1177 - 1993
A C<sub>1</sub> microkinetic model for methane conversion to syngas on Rh/Al<sub>2</sub>O<sub>3</sub> Abstract A microkinetic model capable of describing multiple processes related to the conversion of natural gas to syngas and hydrogen on Rh is derived. The parameters of microkinetic models are subject to (intrinsic) uncertainty arising from estimation. It is shown that intrinsic uncertainty could markedly affect even qualitative model predictions (e.g., the rate‐determining step). In order to render kinetic models predictive, we propose a hierarchical, data‐driven methodology, where microkinetic model analysis is combined with a comprehensive, kinetically relevant set of nearly isothermal experimental data. The new, thermodynamically consistent model is capable of predicting several processes, including methane steam and dry reforming, catalytic partial oxidation, H2 and CO rich combustion, water‐gas shift and its reverse at different temperatures, space velocities, compositions and reactant dilutions, using the measured Rh dispersion as an input. Comparison with other microkinetic models is undertaken. Finally, an uncertainty analysis assesses the effect of intrinsic uncertainty and catalyst heterogeneity on the overall model predictions. © 2009 American Institute of Chemical Engineers AIChE J, 2009
Tập 55 Số 4 - Trang 993-1008 - 2009
Modeling the partial oxidation of methane in a fixed bed with detailed chemistry Abstract This work presents a model of a fixed‐bed reactor for the catalytic partial oxidation of methane to synthesis gas at short contact time. The transient model, one dimensional in space, accounts for separate energy equations for the gas and solid phases, interphase heat and mass transfer, internal radiation within the fixed bed, longitudinal gas‐phase dispersion, and detailed surface kinetics. The model is used to analyze the influence of the feedstock composition and temperature on the conversion and selectivity reactor performance. Furthermore, the study also investigates the blowout of the reaction and the impact of reactor geometry on the performance. Reactor scale‐up is discussed and a general criterion is formulated. © 2004 American Institute of Chemical Engineers AIChE J, 50:1289–1299, 2004
Tập 50 Số 6 - Trang 1289-1299 - 2004
Permeation through liquid surfactant membranes Abstract A novel separation technique based on the selectivity of a liquid membrane composed of surfactants and water is described. The permeation mechanism is discussed in terms of surfactant concentration, surfactant structure and chain length, the nature of permeate, and the solubility of permeate in water.
Tập 17 Số 2 - Trang 459-463 - 1971
Analysis of the effect of internal phase leakage on liquid membrane separations Abstract A general physical model of a typical batch extraction system employing liquid surfactant membranes is developed. The model takes into account the continuous‐phase resistance and the interfacial resistance along with permeation through a composite emulsion globule. It also quantifies the loss in extraction efficiencies by leakage of the encapsulated phase due to membrane breakage. The physical model is easily adapted to apply to the case of transport facilitation wherein the solute is reacted in the internal phase to yield products incapable of permeating through the membrane phase. Experimental data on o‐chlorophenol extraction are satisfactorily correlated with the model.
Tập 34 Số 5 - Trang 753-762 - 1988