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At the stagnation time, fuel may impact by a variety of paths, including ablator materials, Hohlraum wall, the interaction of the cone-guided lateral surface with imploding fuel, and cone tip material, releasing and mixing their constituent elements into corona plasma and even inside the pure dense fuel. Here, we have parametrically studied the impact of some well-known ionic impurities such as carbon and gold on the physical condition of DT hot spot ignition. The admissible zone of DT hot spot ignition was plotted on the HsTs plane, and it was shown that for a given percentage of gold impurities, the boundaries of the ignition zone gradually increased with increasing internal implosion velocity and at implosion velocities smaller than 1.7×107 cm/s, there exist two individual ignition islands. In the context of the fast ignition approach to ICF, the areal density of hot spots ignition of deuterium-tritium doped with a small concentration of impurity ions of carbon and gold was then extracted by a non-equilibrium ignition model. Accordingly, for a given value in this range, the contour plot of the allowed areal density parameter in the two-temperature model was plotted on the Te-Ti plane. It has been shown that as the impurity fraction increases, the permissible range of ignition decreases rapidly and the ignition conditions become more difficult. The sensitivity of these changes is directly associated with the coefficient of increase in radiation loss power, which is a function of the parameter of the impurity percentage α and the ionization state of the impurity ion, Zimp. Moreover, in each contour plot, the minimum permissible ignition parameter of ion temperature of contaminated DT fuel is also visible.

In this study, the (Cu and Al2O3/water) hybrid nanofluid flow is carried out in a porous cavity. The thermophysical structures of solid materials are used from the available literature to improve the thermal performance of the base fluid. The mathematical model as a porous cavity is mainly used in the distillation process and is vital for the storage of thermal energy. The magnetic field is also employed perpendicular to the flow field and the impact of the magnetic parameter examined versus fluid motion. Similarity variables are used to transform governing equations as simplified partial differential equations. The model is solved using the control volume-based finite element method. Boussinesq–Darcy force is employed for the motion of the fluid flow, and the Koo–Kleinstreuer–Li model is used to assess the characteristics of the hybrid nanofluids. The roles of the Hartmann number, Rayleigh number, porosity factor in the porous medium, and drag fin improve traditional fluids’ thermal distribution presentation. Recent results predict that the two different kinds of nanoparticles speed up the heat transfer through the porous cavity. The percentage analysis shows that the hybrid nanofluids (Cu and Al2O3/water) are prominent in improving traditional fluids’ thermal distribution. Finally, the grid sensitivity test is also carried out for hybrid nanoparticles to demonstrate that the results are asymptotically coherent.

In order to provide technical support and evaluation basis for the development of remediation technology of radioactive contaminated sites and the site selection, design and construction of radioactive waste disposal facilities, the reliable longterm risk assessment for potential nuclear waste repositories and decommissioning of nuclear facilities requires detailed knowledge on the migration behavior of radionuclides in natural, it is necessary to understand the reaction mechanism of radionuclides in the complex geological environment of aquifers. The batch experiments and dynamic undisturbed soil column migration experiments of 90Sr, 137Cs, 238Pu and 241Am were carried out under saturated steadystate flow conditions in fine sand column, a theoretical model of nuclide migration in soil and groundwater environment was constructed, and the irreversible adsorption reaction mechanism of the microinterface was studied through static adsorptiondesorption and dynamic undisturbed soil column migration experiments, and the environmental migration flux of nuclides was calculated. The static adsorption and desorption experiments adopt batch method, and the test medium is fine sand with saturated porous media from an arid mining area in Gansu Province. The fine sand and soil samples according to the solidliquid ratio of 1 g∶9 mL were added into the centrifuge tube, and the nuclide activity concentration was measured after adsorption and desorption equilibriums to obtain the adsorption and desorption isotherms. Dynamic column method used undisturbed soil to ensure the continuity of soil sample medium, original connectivity of void channels and authenticity of stratum. The design and advantages of dynamic column method is to take into account various physical, chemical and biogeochemical reaction processes and complex migration paths of tracers during migration in soil. And the dynamic migration and transformation process of 90Sr, 137Cs, 238Pu and 241Am were studied in saturated porous media with anisotropic timevarying hydrologic characteristics by artificial spraying under controlled laboratory initial conditions and boundary conditions. The results show that the absorption isotherm of 90Sr doesn’t coincide with its desorption isotherm, with an angle at 3238° between them. According to the metastable equilibrium adsorption theory, 90Sr has an irreversible adsorptiondesorption process, and ions exchange is the dominated action for its adsorption. As for 137Cs, 238Pu and 241Am, reversible adsorptiondesorption process are shown, and their adsorptions are mainly attributed to surface complexation. Equilibrium adsorption theory and nonequilibrium adsorption model can be used to describe the migration peak phenomenon of different nuclides in the dynamic soil column experiment, which can be effectively integrated into chemical nonequilibrium and physical nonequilibrium processes. Considering the superposition of convectiondispersion and chemical reaction on solute migration, solute migration equations were established based on the reaction rate equation, and the calculated and measured concentration distribution curves were fitted reasonably to obtain a reaction model that can accurately describe and predict nuclide migration. As for 90Sr, the nonequilibrium adsorption model by transport column was taken into account the firstorder rate coefficient (β) between the dissolved phase and the adsorbed phase. The calculated concentration distribution curve is good agreement with the measured concentration. The fitting results show that the distribution coefficient (Kd) and β of 90Sr in the fine sand aquifer are 085 mL/g and 016 h-1, respectively, in terms of 137Cs, 238Pu and 241Am, the radionuclides concentration distribution curves in equilibrium adsorption and nonequilibrium models are in good agreement with the measured values. Meanwhile the calculated results by two different adsorption models are almost similar, and the Kd are 49×102, 21×104, and 6.0×103 mL/g for 137Cs, 238Pu and 241Am. It shows that the stronger adsorption capacities of the nuclides have the faster rate of the adsorption-desorption in the soil, meanwhile the shorter time for the system reaction equilibrium. At this time, the fitting results of the equilibrium adsorption mode and the nonequilibrium adsorption mode are closer to each other.

A multi-component lumped kinetic model of non-isothermal and non-linear reactive liquid chromatography was formulated and approximated numerically to demonstrate thermal effects on reaction kinetics, adsorption equilibria, and conversion-separation studies in thermally insulated, packed bed, chromatographic reactors. The considered model is constituted of systems of non-linear convection diffusion reaction partial differential equations for mass and energy balances in the bulk phase coupled with differential equations for mass and energy balances in the stationary phase. In this work, a total variation bounded (TVB) Runge-Kutta local-projection discontinuous Galerkin finite element method (DG-FEM) was derived and proposed for the numerical solutions of the model equations. The developed numerical method is robust, explicit, capable of resolving sharp discontinuities and is second-order accurate. System parametric studies treating heterogeneously catalyzed reversible reactions were performed through numerical simulations. The coupling between thermal and concentration fronts, the influence of temperature on reactor efficiency, and the conversion-separation of products are demonstrated through several consistency tests. The results, which authenticate the accuracy of the (DG-FEM) method, will be beneficial for interpreting mass and energy profiles in non-equilibrium and non-isothermal liquid chromatographic reactors and provide deeper insight into the sensitivity of the conversion-separation process. [ABSTRACT FROM AUTHOR]

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[Display omitted] • The thermal rate constants of title reactions are calculated within the framework of two models. • By comparison with the available experimental data, the features of the H-atom tunneling mechanisms are revealed. • The time of H-atom tunneling and the half-life of the methyl radical umbrella are estimated. The ratio of these values is used as a semi-quantitative description of the tunneling dynamics. • The interrelation of the non-equilibrium approach with TST dynamic models is discussed. Within the framework of the non-equilibrium approach, the thermal rate constants of the methyl radical with methane (reaction (1)) and C H and O H bonds of methanol (respectively, reactions (2) and (3)) were calculated in the experimental temperature range: 450–800 K for reaction 1 and 350 – 550 K for reactions (2) and (3); geometry optimization level B3LYP/6-31+G**, SP calculation levels CСSD(T)/6-311++G** for reaction (1) and CСSD(T)/6-311G** for reactions 2 and 3.The analysis of the obtained results demonstrates differences in the dynamics of the H-atom transition. The possibility of describing the dynamic situation in terms of the tunneling time of the H atom and the half-life of the umbrella oscillation of the methyl radical is discussed. [ABSTRACT FROM AUTHOR]

The results of a theoretical study (energy calculation level CCSD(T)/6–311++ G**//B3LYP/6–31 + G**) of methane with methyl radical gas-phase reaction kinetics [Comp. Theor. Chem. 1125 (2018), Comp. Theor. Chem.1179 (2020) 112,767] were used to analyze the Arrhenius equation in the temperatures range 2000–10 K. A discussion within the framework of the previously proposed (Russ. Bull. Int. Ed. 2008, 57, 1842–1849) model, which is a modification of the non-equilibrium Marcus model, is based on direct ab initio calculations of the structure and energy of the varied activated reaction complex in a wide range of distances between the reactants. The Arrhenius equation is analyzed in terms of the change with temperature parameters in the reaction rate constant equation. The results obtained make it possible to distinguish three temperature ranges (2000–900, 900–100 and 100–10 K), which are qualitatively different from each other in the nature and degree of influence of various variable factors on the Arrhenius plot. [ABSTRACT FROM AUTHOR]

The effect of magnetic field inclination and double lid‐driven on the mixed convection in a square cavity is investigated based on the local thermal non‐equilibrium model. The cavity was filled with a copper–water micropolar nanofluid saturated with a porous medium. The top and bottom walls are considered moving to the left or right directions at a constant velocity. In the current work, the ranges of parameters are as follow: Hartmann number (0 ≤ Ha ≤ 50), length of the heat source (0.2 ≤ B ≤ 0.8), Richardson number (0 ≤ Ri ≤ 10), Reynolds number (0 ≤ Re ≤ 100), location of the heat source (0.3 ≤ D ≤ 0.7), vortex to molecular viscosity ratio (0 ≤ Δ ≤ 2), Nield number (1 ≤ Q ≤ 100) and solid volume fraction (0 ≤ φ ≤ 0.1). It was found that the heat transfer decreases as the dimensionless heat source location and the Nield number increase. Also, the growing in the Nield number enhances the rate of the heat transfer for the porous phase and increases the thermal equilibrium state of the system. [ABSTRACT FROM AUTHOR]

A numerical investigation into the fluid flow and heat transfer process in a 3D-printed shell-and-tube heat exchanger was carried out. The shell side of the heat exchanger was inserted with octahedral lattice frame porous material to enhance the heat transfer. In order to avoid establishing a complex grid system, the porous material of the shell side was modeled by a porous media model. The non-equilibrium model was adopted for the modeling of the heat exchange between the solid and fluid in porous media. An experimental investigation was carried out to validate the feasibility of this approach. The result indicates that the simplified approach is capable of providing an appropriate prediction of the pressure drop and heat transfer efficiency with moderate computational resources. The average error of pressure loss and heat transfer effectiveness is within 4% and 6.1%. [ABSTRACT FROM AUTHOR]

In this study, CO2 reactive-absorption process is modeled into the NaOH-NH3-H2O solution in an absorption column. A non-equilibrium or rate-based model is used to simulate the process performance, and the predicted results are compared with the experimental data. In this model, the steady and nonlinear film models are utilized for high and low solubility components, respectively. The average relative deviation (ARD%) is decreased from 9.73 to 4.36 by increasing the number of column stages from 20 to 60 in the simulation. On the other hand, the predicted values by the film and enhancement factor models are compared, and it was concluded that the film model was more accurate than the other. The effects of axial position through the column and initial NaOH concentration on the liquid flow rate, mole fraction of components, and temperature of the gas and liquid phases are also investigated. As a main result, the temperature of the liquid phase and the CO2 concentration in the liquid phase decrease by increasing the axial position through the column. [ABSTRACT FROM AUTHOR]

The Maxwell–Boltzmann distribution is a hallmark of statistical physics in thermodynamic equilibrium linking the probability density of a particle’s kinetic energies to the temperature of the system that also determines its configurational fluctuations. This unique relation is lost for Hot Brownian Motion, e.g., when the Brownian particle is constantly heated to create an inhomogeneous temperature in the surrounding liquid. While the fluctuations of the particle in this case can be described with an effective temperature, it is not unique for all degrees of freedom and suggested to be different at different timescales. In this work, we report on our progress to measure the effective temperature of Hot Brownian Motion in the ballistic regime. We have constructed an optical setup to measure the displacement of a heated Brownian particle with a temporal resolution of 10 ns giving a corresponding spatial resolution of about 23 pm for a 0.92 μm PMMA particle in water. Using a gold-coated polystyrene (AuPS) particle of 2.15 μm diameter we determine the mean squared displacement of the particle over more than six orders of magnitude in time. Our data recovers the trends for the effective temperature at long timescales, yet shows also clear effects in the region of hydrodynamic long time tails.

This study presents a conceptual Dual‐Permeability Non‐Equilibrium (DPNE) model that accounts for both physical and chemical non‐equilibria to describe the reactive solute transport through a porous medium. A semi‐analytical solution of the DPNE model is derived in the Laplace domain, which is then numerically inverted to obtain concentrations in different domains at different times and depths. The derived semi‐analytical solution is validated using experimental data and existing analytical (for simple problems) and numerical solutions. The Global Sensitivity Analysis (GSA) is performed to identify model parameters with an impact on nonreactive tracer breakthrough curves (BTC) for a selected data set. A sensitivity‐based calibration of the DPNE model's parameters is carried out to simulate a BTC with multiple inflection points. The DPNE model can better describe the experimental datasets than the model based on the dual‐porosity (MIM) concept with first‐order mass transfer. Since the DPNE model considers detailed sorption and mass transfer dynamics, it is suitable for process‐based investigations. Key Points: Semi‐analytical solution for non‐equilibrium solute transport in a dual‐permeability porous system with an immobile region is presentedThe global sensitivity analysis is carried out for input parameters for a non‐reactive soluteAn insight into intra‐ and inter‐aggregate mass transfers is presented [ABSTRACT FROM AUTHOR]

A numerical investigation into the fluid flow and heat transfer process in a 3D-printed shell-and-tube heat exchanger was carried out. The shell side of the heat exchanger was inserted with octahedral lattice frame porous material to enhance the heat transfer. In order to avoid establishing a complex grid system, the porous material of the shell side was modeled by a porous media model. The non-equilibrium model was adopted for the modeling of the heat exchange between the solid and fluid in porous media. An experimental investigation was carried out to validate the feasibility of this approach. The result indicates that the simplified approach is capable of providing an appropriate prediction of the pressure drop and heat transfer efficiency with moderate computational resources. The average error of pressure loss and heat transfer effectiveness is within 4% and 6.1%.

A total variation bounded (TVB) Runge–Kutta local-projection discontinuous Galerkin (RK-LDG) finite element method is applied for numerically approximating the non-isothermal and non-equilibrium model of liquid chromatography. The model comprises a system of convection-diffusion partial differential equations (PDEs) coupled with algebraic and ordinary differential equations (ODEs). The suggested numerical scheme is explicit in nature and has the potential to capture sharp peaks and abrupt changes in the solution profiles. A number of case studies are carried out for single and two-component elution. The influence of temperature on the column efficiency and separation of mixture components is analyzed. Furthermore, important parameters are identified that influence the performance of the column. The results of the proposed method are authenticated against the high-resolution finite-volume scheme (HR-FVS). [ABSTRACT FROM AUTHOR]

Biomass-based gasification is an attractive and promising pathway for hydrogen production. In this work, a biomass-based hydrogen production system integrated with organic Rankine cycle was designed and investigated to predict the performance of hydrogen production yield and electricity generation under various operating conditions. The modified equilibrium model presented desirable results for the produced syngas compositions compared with the experimental data. Hydrogen yields from four types of biomass (wood chips, daily manure, sorghum, and grapevine pruning wastes) were compared under the same operating condition, with wood chips exhibiting the maximum hydrogen yield of 11.59 mol/kg. The effects of gasification temperature, equivalence ratio, and steam-to-biomass ratio on the hydrogen yield and electricity generation were investigated by using the response surface method. Furthermore, the system was optimized using a genetic algorithm based on the response surface model. A preferred optimal solution with a hydrogen yield of 39.31 mol/kg and an output power of 3,558.08 kW (0.99 kW h/kg) was selected by the linear programming technique for multidimensional analysis of the preference method.

The problem of the unit slope of the Brønsted plot for the proton transfer reaction from the "hard" CH-acids is considered by the example of a series of gas-phase deprotonation reactions of substituted benzenes with the CH2CN– anion. The discussion is conducted within the framework of the theory of non-equilibrium reactions. The use of intramolecular reorganization (IMR) method allows calculate directly the structure and energy of the activated complex. A comparison is made of two models. In model 1, as with the standard approach, proton tunnelling process is associated with the system potential V(r) (r is proton coordinate), whereas in model 2, it is associated with the potential of reaction zone X (including the breaking (A‒H) and formed (H‒B) bonds), VX(r). The VX energy has been calculated using the Mayer's APOST program, designed to calculate the mono- and diatomic components of the system energy. The accepted level of calculation of the energies V and VX (HF/6-31G**//HF/3-21G**) has been determined by APOST program capabilities. Key feature of model 2 is almost complete insensitivity of the proton tunneling frequency, νt, to changes of reaction energy ΔE00. The end result is an increase of the Brønsted coefficient α from 0.67 (for model 1) to 0.83. It is shown that when going from the gas phase to the solution (reaction in DMSO medium), α value increases to 0.97. [ABSTRACT FROM AUTHOR]

• Non-equilibrium approach for supersonic expansion of carbon-dioxide was presented. • Phase-change intensity was calibrated on the basis of 150 experimental points. • High quality of the motive nozzle mass flow rate prediction was obtained. • Field results were analysed having regard vapour quality and velocity distribution. A non-equilibrium approach was proposed for highly accurate modelling of the expansion process during two-phase flow in the convergent-divergent motive nozzle of an R744 ejector. Comprehensive mapping of the coefficients used in the source terms of the additional transport equation of the vapour quality was provided on the basis of four ejector geometries. The calibration range contained motive pressures from 50 bar to 70 bar, where the prediction quality of the homogeneous equilibrium (HEM) and relaxation (HRM) models, was unsatisfactory. The calibrated model was validated on the basis of experimental mass flow rate data collected from 150 operating points. The mapping results were utilised for final model derivation in the form of an approximation function for R744 expansion. The validation process resulted in satisfactory relative error below 10% for the vast majority of the cases. Moreover, 70% of the simulated cases were considered with a mass flow rate discrepancy below 7.5% in the inaccuracy. Finally, the selected cases were compared and discussed with the HEM approach on the basis of field results. [ABSTRACT FROM AUTHOR]

The diffuse and constricted arc attachment modes to the anode of an argon wall-stabilized transferred arc are investigated using a 2D chemical non-equilibrium model. Detailed argon chemical kinetic processes and self-consistent effective binary diffusion coefficient approximation treatment of diffusion are coupled with a single-fluid, two-temperature model to investigate the plasma characteristics of the near-anode region. The diffuse and constricted arc attachment modes to the anode are obtained self-consistently by changing the gas flow rates. The results show that the high current density and associated self-induced magnetic field of the constricted arc attachment give rise to a large Lorentz force near the anode, resulting in an anode jet. The convection process dominated by the cathode jet is conducive to the radial transport of electrons in the diffuse arc attachment mode, while in the constricted arc attachment mode the direction of electron transport due to the convection caused by the anode jet is opposite to that in a diffuse arc attachment. The effect of diffusion on electron transport is relatively small in the arc central region, while it becomes important in the arc fringe. The recombination processes, especially the dissociative recombination reactions, restrict the electron radial diffusion in the arc fringe. The diffusion current density is the main component of current density in front of the anode due to the steep gradient of electron pressure. It is found that when the diffusion current is not considered, the electric field and Joule heating in front of anode promote a more constricted arc attachment. [ABSTRACT FROM AUTHOR]

The amine regenerator of acid removal unit in South Pars Gas Complex, Assalouyeh, Iran was modeled. This model was fitted to assess the large scale columns and allow application of solar thermal energy for production of low pressure steam. Heat transfer fluids including Therminol oil, sulfur, or salt melt could be applied to yield thermal energy from a solar collector and to store and transfer it to the reboiler of columns. The Angstrom model was adopted here to simulate solar irradiance. Solar irradiance data for the city of Assalouyeh, during the years of 2009-2014, were collected and applied. The results indicated that based on a reboiler duty of around 21.8 MW, a solar collector area of 148,000 m2 was required with a mass of heat transfer and storage medium of 1247255 kg oil, 1787732 kg salt melt and 3803686 kg sulfur, respectively. This model was applied as an analytical tool to explore and describe the following two problems encountered during real plant operation: fouling in the amine heat exchangers and increasing regenerator pressure.

We consider a two-phase incompressible non-equilibrium flow in fractured porous media in the framework of Kondaurov's model, wherein the mobilities and capillary pressure depend both on the real saturation and a non-equilibrium parameter satisfying a kinetic equation. The medium is made of two superimposed continua, a connected fracture system, which is assumed to be thin of order , where is the relative fracture thickness and an -periodic system of disjoint cubic matrix blocks. We derive the global behavior of the model by passing to the limit as , assuming that the block permeability is proportional to , while the fracture permeability is of order one, and obtain the global –model. In the -model we linearize the cell problem in the matrix block and letting , obtain a macroscopic non-equilibrium fully homogenized model, i.e. the model which does not depend on the additional coupling. The numerical tests show that for sufficiently small, the exact global -model can be replaced by the fully homogenized one without significant loss of accuracy. [ABSTRACT FROM AUTHOR]

The problem of conjugate natural convection flow in a layer of porous media confined by two vertical thermally-conductive thick surfaces is studied. The local thermal nonequilibrium approach is employed for modelling the porous layer allowing for a difference in temperature between the porous structure and the fluid inside it. The basic equations for this investigation are transformed into a set of dimensionless equations. Then, the resulting equations are solved numerically by employing the finite element method. The obtained results are compared with published results in the open literature and are found to be in good agreement. The effects of the wall thermal conductivity parameter, fluid and porous interfacial convective heat transfer parameter and the Rayleigh number on the thermal behavior of the cavity are studied and analysed. The results show that increasing all of the above mentioned parameters results in increasing the heat transfer in the cavity. [ABSTRACT FROM AUTHOR]

Highlights • A square enclosure with particles (base fluid and nanoparticles) is considered. • A novel two-component dissipative particle dynamics (DPD) model is presented. • Heat transfer enhancement in natural convection using Al 2 O 3 -water nanofluid is studied. • It was found that, for high Rayleigh numbers, most parts of the hot wall experienced deterioration in heat transfer. Abstract The current paper presented a novel two-component dissipative particle dynamics (DPD) model to investigate heat transfer enhancement in natural convection using Al 2 O 3 -water nanofluid. This DPD model used two different types of particles to represent the base fluid particles and the nanoparticles. The energy and momentum interaction between nanofluid particles were incorporated within the new DPD model via modifying the DPD collisional heat flux and the friction parameter, respectively. The model was used to investigate the effect of nanoparticle volume fraction on heat transfer enhancement within the cavity. The study covered a wide range of nanoparticles (1% ≤ φ ≤ 7%) and three Rayleigh numbers were considered, which are Ra = 104, Ra = 5 × 104, and Ra = 105. In general, the DPD results reported a minor deterioration in heat transfer due to the presence of nanoparticles. By looking at the local distribution of enhancement along the hot wall of the cavity, it was found that, for high Rayleigh numbers, most parts of the hot wall experienced deterioration in heat transfer accompanied with some enhancements that were registered near the top wall of the cavity. Also, the results revealed that for the case of low Rayleigh numbers some enhancements were observed using low volume fraction of nanoparticles (φ ≤ 4%), however further increase in volume fraction of nanoparticles caused a deterioration in heat transfer. [ABSTRACT FROM AUTHOR]

Highlights • Non-equilibrium model was applied to an actual cryogenic column. • Commonly-used mass transfer models were evaluated in calculating cryogenic distillation. • Simulated results were verified by measured data and Aspen plus. Abstract Reliable heat and mass transfer model plays a significant role on design and calculation of the distillation process. Since the cryogenic fluids of oxygen, nitrogen and argon have obviously different thermal physical properties compared to the room temperature ones, it is of great necessity to evaluate the feasibility of the existing heat and mass transfer models in the cryogenic distillation calculation. In this study, a non-equilibrium model (NEM) based on the FORTRAN compiler is implemented to investigate the actual cryogenic distillation process in a structured packing column (SPC) of the air separation unit (ASU) with capacity of 17,000 Nm3/h. The complete conservation equations for materials, mass and energy in the phases are numerically solved based on the Thomas algorithm. The commonly used mass transfer coefficient models with different diffusion coefficients, as well as the heat transfer model, are evaluated in the performance prediction of the cryogenic SPC. The multiple imports and exports of the model are validated by the limited available measurements, while the calculated distributions of the component molar fraction, temperature, pressure and flow rates along the column are compared with those from the Rate-based module of Aspen plus simulation. The comparisons verify the solving strategy and help to understand the reliability of the existing basic transfer correlations for future cryogenic distillation calculation. [ABSTRACT FROM AUTHOR]

In the proposed paper, non-equilibrium and equilibrium models of heat and moisture transfer through wet building materials are presented and compared. In the former, the mass transfer between liquid and gaseous moisture results from the difference between the partial pressure of water vapor and its saturation value. In the second model, the equilibrium between both phases is assumed. In the non-equilibrium model, liquid moisture can be in the continuous (funicular) or discontinuous (pendular) form. The transfer of moisture for each proposed model is tightly coupled with the energy transfer, which is assumed to be an equilibrium process. The time step and grid size sensitivity analysis of both numerical models are performed primarily. The verification of the model is based also on the numerical data available in literature. Finally, obtained with considered models, temporal variations of moisture content in three locations in the computational domain are compared. Reasonable conformity of results is reported, and discrepancies related to differences in formulations of models are discussed.

This study investigated the effects of practice schedule and task specificity based on the perspective of adaptive process of motor learning. For this purpose, tasks with temporal and force control learning requirements were manipulated in experiments 1 and 2, respectively. Specifically, the task consisted of touching with the dominant hand the three sequential targets with specific movement time or force for each touch. Participants were children (N=120), both boys and girls, with an average age of 11.2years (SD=1.0). The design in both experiments involved four practice groups (constant, random, constant-random, and random-constant) and two phases (stabilisation and adaptation). The dependent variables included measures related to the task goal (accuracy and variability of error of the overall movement and force patterns) and movement pattern (macro- and microstructures). Results revealed a similar error of the overall patterns for all groups in both experiments and that they adapted themselves differently in terms of the macro- and microstructures of movement patterns. The study concludes that the effects of practice schedules on the adaptive process of motor learning were both general and specific to the task. That is, they were general to the task goal performance and specific regarding the movement pattern. [ABSTRACT FROM AUTHOR]

This work deals with fluid dynamic simulations of high enthalpy flows. Thermochemical non-equilibrium, typical of such flows, was modelled by using the well known multi-temperature model developed by Park. The non-equilibrium model was implemented in a 2D finite volume solver of the Euler equations and was assessed by comparing the results with available experimental measurements. Several test cases concerning 2D and axisymmetric expansion nozzles were performed by varying gas composition and stagnation temperature. [ABSTRACT FROM AUTHOR]

The two-phase flow following the blowdown of pipeline carrying flashing liquid is numerically investigated by using thermodynamic equilibrium and non-equilibrium models. Model equations are solved numerically by the finite volume method. The values of fluxes at cell boundaries are obtained by AUSM+-up. To obtain proper values for the coefficients of dissipation, both single phase liquid and two phase shock tube problems are investigated. The transient release from the pressurized pipeline is studied for two cases of long and short pipes. Comparison of the predictions against experimental data reveals non-equilibrium model performs a little better than equilibrium model in the prediction of temporal variations of pressure and void fraction of the long pipe. However, equilibrium model totally overestimates pressure and void fraction of the short pipe. The relative error of equilibrium model in the prediction of pressure variation with time exceeds 50% and it is 20% for non-equilibrium model. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3214-3223, 2017 [ABSTRACT FROM AUTHOR]

We consider a thermodynamic consistent multi-component model in multi-dimensions that is a generalization of the classical two-phase flow model of Baer and Nunziato. The exchange of mass, momentum and energy between the phases is described by additional source terms. Typically these terms are handled by relaxation procedures. Available relaxation procedures suffer from efficiency and robustness resulting in very costly computations that in general only allow for one-dimensional computations. Therefore we focus on the development of new efficient and robust numerical methods for relaxation processes. We derive exact procedures to determine mechanical and thermal equilibrium states. Further we introduce a novel iterative method to treat the mass transfer for a three component mixture. All new procedures can be extended to an arbitrary number of inert ideal gases. We prove existence, uniqueness and physical admissibility of the resulting states and convergence of our new procedures. Efficiency and robustness of the procedures are verified by means of numerical computations in one and two space dimensions. [ABSTRACT FROM AUTHOR]

The modeling of plasma torch operation has advanced greatly in the last 15 years due to a better understanding of the underlying physics, development of commercial, open-source computational fluid dynamics softwares, and access to high performance and cloud computing. However, the operation mode of the electric arc in plasma torches is controlled by dynamic, thermal, electromagnetic, acoustic and chemical phenomena that take place at different scales and whose interactions are not completely understood yet. Even though no single model of plasma torch operation fully addresses these phenomena, most of these models are useful tools for parametric studies, if their use is reinforced by knowledge of torch operation and the model predictions are validated against experimental data. To increase the level of predictability of the current models, several further steps are needed. This study examines the issues remaining to be addressed in the modeling of plasma spray torch operation and the current critical aspects of these. [ABSTRACT FROM AUTHOR]

Arid grazing systems can behave according to both equilibrium and non- equilibrium models, depending on spatial and temporal scales. Regarding spatial aspect, key resource areas with access to water bodies can indeed be in equilibrium with livestock while rainfall dependent areas can be non- equilibrium. It is important to understand the application range of each of the models, since associated management is different. We studied the plant communities on a Mongolian Gobi site, paying particular attention to the communities connected to the water table. We found evidence that the vegetation structure on the main river’s fl oodplain is shaped by grazing, meaning that it is in the equilibrium model condition. This vegetation type covers 7.61% of our study site. We therefore concluded that from a spatial viewpoint, at least 7.61% of our site behaves according to the equilibrium model.

Spontaneous condensation processes are common in the industry and have a significant impact on the aerodynamic characteristics of turbines. The spontaneous condensation process of moist air in a high-speed turbo-expander was investigated experimentally and numerically. Temperature and humidity of the moist air into the turbo-expander were controlled independently in a psychrometric chamber. A liquid fraction of 0.8% was achieved at the turbo-expander outlet which was corresponding to a relative humidity of 76.9% at 303.2 K. The non-equilibrium condensation model was validated against the experimental results, and the maximum relative deviations of outlet temperature, absolute humidity, and moist efficiency were 0.16%, 3.23%, and 2.15%, respectively. Based on numerical simulations, the nucleation process and droplet distribution in the turbo-expander were studied. Compared with the suction surface, the nucleation region near the pressure surface was more extensive. The effect of inlet temperature, humidity, and pressure was compared. The inlet pressure had the most significant impact on the nucleation initial position, and the inlet temperature mainly determined the nucleation rate and droplet number. The wetness loss due to the vapor condensation mainly occurred in the impeller, and the efficiency drop could reach 2.17% when the pressure ratio was 2.1. • Spontaneous condensation processes of moist air in the turboexpander are studied. • The aerodynamic parameters distribution with condensation process is analyzed. • Effect of inlet temperature, humidity, and pressure on the condensation process. • Inlet relative humidity of 76.9% at 303.2 K leads to a liquid fraction of 0.8%. [ABSTRACT FROM AUTHOR]

• The assumption of local equilibrium between coal matrixes and fracture within the representative elementary volume is removed. • Local non-equilibrium index is introduced to define the transformation from equilibrium to non-equilibrium models. • The current Equilibrium Coal Multiphysics is upgraded to Non-Equilibrium Coal Multiphysics. Current permeability models are normally derived on the assumption of local equilibrium between coal matrixes and fracture within the representative elementary volume (REV) during gas extraction/injection. Under this assumption, the gas pressure and its associated swelling strain will distribute uniformly throughout the entire REV irrespective of the equilibration process between coal matrixes and fracture. This uniform distribution has long been considered as the reason why current permeability models cannot explain permeability data as widely reported. Significant efforts have been made to resolve this issue for the last decade but all these efforts ignore the transient nature of local equilibration evolution from initial to ultimate equilibrium states. In this study, we developed a concept of local non-equilibrium index (LNEI) to define a complete permeability model under the influence of gas extraction/injection. The application of this concept transforms equilibrium permeability models to non-equilibrium ones. Equilibrium models represent only two end points (before gas extraction/injection and after the completion of gas extraction/injection) while our non-equilibrium one represents the complete evolution of coal permeability between two end points. Our non-equilibrium model is degenerated to replicate all equilibrium models as reported in the literature and used as a key cross-coupling relation to formulate the non-equilibrium multiphysics model. Our non-equilibrium multiphysics model is verified against two rare experimental data sets and applied to predict the effects of the local equilibration process on both the evolution of coal permeability and the gas production under field conditions. [ABSTRACT FROM AUTHOR]

The objective of this work is to develop a thermodynamic model considering non-stoichiometric restrictions. The model validation was done from experimental works using a bench-scale fluidized bed gasifier with wood chips, dairy manure, and sorghum. The model was used for a further parametric study to predict the performance of a pilot-scale fluidized biomass gasifier. The Gibbs free energy minimization was applied to the modified equilibrium model considering a heat loss to the surroundings, carbon efficiency, and two non-equilibrium factors based on empirical correlations of ER and gasification temperature. The model was in a good agreement with RMS <4 for the produced gas. The parametric study ranges were 0.01 < ER < 0.99 and 500 °C < T < 900 °C to predict syngas concentrations and its LHV (lower heating value) for the optimization. Higher aromatics in tar were contained in WC gasification compared to manure gasification. A wood gasification tar simulation was produced to predict the amount of tars at specific conditions. The operating conditions for the highest quality syngas were reconciled experimentally with three biomass wastes using a fluidized bed gasifier. The thermodynamic model was used to predict the gasification performance at conditions beyond the actual operation. [ABSTRACT FROM AUTHOR]

A mathematical model is formulated and numerically approximated to simulate reaction and separation occurring jointly in a chromatographic column. To cover realistic problems, the reversibility of the reactions and the occurrence of temperature gradients are considered. The model is formed by a system of convection–diffusion–reaction partial differential equations coupled with differential and algebraic equations. The presence of nonlinear transport dominated terms in mass and energy balance equations and stiffness of the reaction terms are the main sources of instabilities if simple numerical schemes are applied. In this work a high resolution finite volume scheme is applied to accurately solve the model equations. The numerical case studies, treating two stoichiometrically different reactions, demonstrate the degree of coupling concentration and thermal fronts. The impact of several key parameters on process performance is illustrated. The results obtained are seen as very useful to understand the velocities and shapes of concentration and thermal fronts in chromatographic reactors. They reveal potential for improving reactor performance exploiting the unavoidable non-isothermal operation. [ABSTRACT FROM AUTHOR]

We study an immiscible incompressible two-phase, such as water–oil flow through a-periodic double porosity media. The mesoscopic model consists of equations derived from the mass conservation laws of both fluids, along with a generalized Darcy law in the framework of Kondaurov’s non-equilibrium flow model. The mobility functions as well as the capillary pressure function for each component of the porous medium are the functions of the saturation and an additional non-equilibrium parameter, which satisfies a kinetic equation coming from the definition of the Helmholtz free energy. The fractured medium consists of periodically repeating homogeneous blocks and fractures, where the permeability ratio of matrix blocks to fracture planes is of order. Using the method of two-scale asymptotic expansions, we derive the macroscopic model of the flow which is written in terms of the homogenized phase pressures, saturation, and the non-equilibrium parameter. For small relaxation times, we compare our model with the global models obtained earlier by H. Salimi and J. Bruining. We show the novelty of our macroscopic double porosity flow model. [ABSTRACT FROM AUTHOR]

The paper deals with the global Kondaurov double porosity model describing a non-equilibrium two-phase immiscible flow in fractured-porous reservoirs when non-equilibrium phenomena occur in the matrix blocks, only. In a mathematically rigorous way, we show that the homogenized model can be represented by usual equations of two-phase incompressible immiscible flow, except for the addition of two source terms calculated by a solution to a local problem being a boundary value problem for a non-equilibrium imbibition equation given in terms of the real saturation and a non-equilibrium parameter. [ABSTRACT FROM AUTHOR]

This paper focuses on numerical and practical aspects associated with a parallel implementation of a two-layer zonal wall model for large-eddy simulation (LES) of compressible wall-bounded turbulent flows on unstructured meshes. A zonal wall model based on the solution of unsteady three-dimensional Reynolds-averaged Navier–Stokes (RANS) equations on a separate near-wall grid is implemented in an unstructured, cell-centered finite-volume LES solver. The main challenge in its implementation is to couple two parallel, unstructured flow solvers for efficient boundary data communication and simultaneous time integrations. A coupling strategy with good load balancing and low processors underutilization is identified. Face mapping and interpolation procedures at the coupling interface are explained in detail. The method of manufactured solution is used for verifying the correct implementation of solver coupling, and parallel performance of the combined wall-modeled LES (WMLES) solver is investigated. The method has successfully been applied to several attached and separated flows, including a transitional flow over a flat plate and a separated flow over an airfoil at an angle of attack. [ABSTRACT FROM AUTHOR]

Design and analysis of distillation columns usually takes place by using rigorous equilibrium models, where efficiencies are utilized to enhance the designs obtained and have a better approach to the real performance of the column. A second alternative, based on the mass and heat transfer rates, has been proposed and it is known as the non-equilibrium (or rate-based) model. By employing this approach, the use of supposed values for efficiencies is not necessary. Nevertheless, to the authors’ knowledge, there is not a short-cut design model for analysis of distillation columns with the non-equilibrium model. In this work, the design and optimization of conventional and intensified distillation sequences, with equilibrium and non-equilibrium models for the separation of ternary mixtures, is presented. The multiobjective optimization is performed by a stochastic technique with handling constraints, which is also coupled to a process simulator. This strategy allows analyzing the distillation systems with the complete rigorous models (MESH and MERSHQ equations, respectively). Optimal designs are then compared to determinate relationships between the design parameters of the optimal equilibrium sequences and the optimal non-equilibrium sequences. It has been found that the optimal on heat duty for each analyzed systems is almost the same for both, equilibrium and non-equilibrium models, but with different number of stages. Nevertheless, other design variables have only slight differences between models for an optimal structure. [ABSTRACT FROM AUTHOR]

In this study, the equilibrium and non-equilibrium models for CO 2 absorption from natural gas stream by DEA-promoted potassium carbonate solution in a tray column were developed and compared with each other. The Electrolyte NRTL thermodynamic model was utilized to calculate the activity coefficient in the liquid phase, and the SRK equation of state was used for the gas phase. The non-equilibrium model was based on the two-film theory, and the effect of film discretization was examined. The equilibrium model was based on the theoretical number of stages combined with the concept of Murphree efficiency from 0.1 to 0.3 for three stages in the lower section of the column and 0.4 from stage 4 onwards. A thermodynamic study was performed to describe the equilibrium behavior of the solvent. All the necessary reactions in the liquid phase were considered in all simulations. The models were validated by comparing the obtained results with the published experimental data. Results of absorber column simulation show that the non-equilibrium model gives a better prediction of the temperature and concentration profiles as compared to the equilibrium model. [ABSTRACT FROM AUTHOR]

Grazing-induced degradation is an important issue in semi-arid and arid regions, particularly in key resource areas where livestock concentrate during droughts. However, this concentration assumes a single nomadic strategy, and in practice, pastoralists employ multiple mobility patterns in response to environmental and socioeconomic factors. We surveyed pastoralists to detect variation in herding strategies during a drought, such as key resource selection and travel distance. We defined two groups of strategies: small herds moved a short distance and used key resources; large herds moved a long distance and moved to areas with more abundant rain and plants instead of using key resources. These variations relate to the cost of long-distance travel, and suggest that grazing-induced degradation can occur at multiple scales; degradation of key resources in the study area may occur at a small scale, corresponding with the travel distance for small herds. Our study suggests that interactions between resource spatial heterogeneity and herding strategies at multiple scales should be considered when assessing grazing-induced degradation in highly variable environments. [ABSTRACT FROM AUTHOR]

This study aims at extracting a mathematical expression for describing the moisture loss kinetics from grains dried in the form of a static bed, based on a measured grain moisture profile across the bed, and validating its reliability in predicting the drying times. The target expression for moisture transfer is the Lewis equation with Arrhenius type dependence of the drying rate constant on temperature, thereby reducing the problem to the determination of two coefficients (i.e., Ea and K0) for the drying rate constant. The scheme of numerical solution of the non-equilibrium model of the deep bed drying process is represented as a trained neural network, with the values of the coefficients as inputs and the sum squared error (SSE) in the prediction of moisture content at various bed depths as the output. Training data for the neural network were generated for static bed drying of barley at an airflow rate of 638 kg/m²·h. The two coefficients were estimated by inversion of the trained neural network. The derived expression for drying rate constant was found to give a better prediction of the drying time and drying air temperature profiles at different experimental runs with air flow rates close to 638 kg/m²·h. It underlines the fact that grain moisture loss kinetics, extracted from a known moisture profile across the static bed can reliably be used to predict the batch drying time. [ABSTRACT FROM AUTHOR]

Abstract: In this study, virus transport parameters in porous media were estimated using a hybrid finite volume model coupled with a non-linear least square optimization algorithm. For the study, both non-equilibrium and equilibrium transport model were considered. For the case of estimating two or three unknown parameters with non-equilibrium transport model, presence of distribution coefficient, inactivation coefficients of liquid and sorbed phase results in a non-unique estimate. Similarly, in case of parameter estimation with non-linear equilibrium transport model, a priori estimate of one of the Freundlich isotherm parameter (i.e. n or k f ) along with inactivation coefficients for liquid or sorbed phases is necessary. Finally, the model is applied to estimate the parameters from a column experiment involving virus transport and it was found that non-equilibrium models fit the observed data much better as compared to equilibrium model. [Copyright &y& Elsevier]