Mass Transfer Conditions Research Articles

On the Non‐Fourier’s Heat and Non‐Fick’s Mass Flux for the Quadratic Convection Flow of a Couple Stress Nanofluid with Wu’s Slip

The overall goal of this paper is to look at how non‐Fick’s and non‐Fourier’s concepts affect the quadratic convection flow of a couple stress nanofluid across an extending surface under Wu’s slip, convective heating, and convective mass transfer conditions. The governing equations in the investigation are also initially stated as higher‐order partial differential equations and thereafter rehabilitated into ordinary differential equations via similarity conversions. Finally, the numerical approach of the bvp5c solver in MATLAB R2019a is engaged to solve the resultant equations. It has been researched and shown using graphs and tables how physical characteristics affect the velocity, temperature, and concentration fields. The results show that the velocity profile along the x‐direction grows with intensifying values of the couple stress, quadratic convection, buoyancy, and third‐order slip constraints, whereas it declines with intensifying values of the fourth‐order slip and magnetic field constraints. Also, the results show that as the velocity ratio constraint is increased, the velocity field along the y‐axis increases. Furthermore, an augment in the values of the quadratic convection constraint and Schmidt number, respectively, causes a diminution in temperature and concentration distributions. The results of the current study can be used to increase lubricant production and reduce machinery deterioration. Furthermore, this theoretical and numerical deliberation has the potential to be beneficial in the field of bio‐fluid dynamics and biomedicine.

The iron “redox battery” in sandy sediments: Its impact on organic matter remineralization and phosphorus cycling

Permeable sandy sediments cover 50–60 % of the global continental shelf and are important bioreactors that regulate organic matter (OM) turnover and nutrient cycling in the coastal ocean. In sands, the dynamic porewater advection can cause rapid mass transfer and variable redox conditions, thus affecting OM remineralization pathways, as well as the recycling of iron and phosphorus. In this study, North Sea sands were incubated in flow-through reactors (FTRs) to investigate biogeochemical processes under porewater advection and changing redox conditions. We found that the average rate of anaerobic OM remineralization was 12 times lower than the aerobic pathway, and Fe(III) oxyhydroxides were found to be the major electron acceptors during 34 days of anoxic incubation. Reduced Fe accumulated in the solid phase (expressed as Fe(II)) before significant release of Fe2+ into the porewater, and most of the reduced Fe (~96 %) remained in the solid phase throughout the anoxic incubation. Fe(II) retained in the solid phase, either through the formation of authigenic Fe(II)-bearing minerals or adsorption, was easily re-oxidized upon exposure to O2. Excessive P release (apart from OM remineralization) started at the beginning of the anoxic incubation and accelerated after the release of Fe2+ with a constant P/Fe2+ ratio of 0.26. After 34 days of anoxic incubation, porewater was re‑oxygenated and > 99 % of released P was coprecipitated through Fe2+ oxidation (so-called “Fe curtain”). Our results demonstrate that Fe(III)/Fe(II) in the solid phase can serve as a relatively immobile and rechargeable “redox battery” under dynamic porewater advection. This Fe “redox battery” is characteristic for permeable sediments and environments with variable redox conditions, making Fe an important player in OM turnover. We also suggest that P liberated before Fe2+ release can escape the “Fe curtain” in surface sediments, thus potentially increasing net benthic P efflux from permeable sediments under variable redox conditions.

Prospects of Application of Ultramicroelectrode Ensembles for Voltammetric Determination of Compounds with Close Standard Electrode Potentials and Different Diffusion Coefficients

The spherical diffusion that occurs when using ultramicroelectrodes (i.e., electrodes with a characteristic size of 1–10 µm) contributes to a higher mass transfer rate. This leads to equalization of the depletion rates of the near-electrode layer due to the electrochemical reaction and to the supply of the product from the solution depth. This is the reason why, for ultramicroelectrodes, a limiting size of the spherical layer exists in which the concentration gradient is localized (diffusion layer). Thus, a stationary mass transfer mode is achieved, which is expressed in the sigmoidal CV curve’s shape. In ultramicroelectrode arrays, when the diffusion hemispheres are separated, a steady-state diffusion is realized. However, with a decrease in the interelectrode distance, which leads to the diffusion spheres intersection, a mixed regime arises, which is not fully time-independent. The resulting voltammogram’s shape change can serve as an analytical signal in the study of substances with differing diffusion coefficients, since the diffusion layer growth rate and, consequently, the area of intersection of neighboring spheres, depends on it. This work shows the applicability of voltammetry using ensembles of ultramicroelectrodes operating in the transient mode for the analysis of mixtures of electrochemically active compounds with close electrode reaction parameters, such as exchange currents and electrode potential. Ferrocenemethanol esters are used as an example. The applicability of cyclic voltammetry on the UME array for analysis of mixtures was illustrated by means of finite element modelling. The reliability of the modelling results was experimentally proved for ferrocenemethanol esters with glycine and triglycine.

Identifying diffusion limiting current to unravel the intrinsic kinetics of electrode reactions affected by mass transfer at rotating disk electrode

Rotating disk electrode systems are widely used to study the kinetics of electrocatalytic reactions that may suffer from insufficient mass transfer of the reactants. Kinetic current density at certain overpotential calculated by the Koutecky-Levich equation is commonly used as the metrics to evaluate the activity of electrocatalysts. However, it is frequently found that the diffusion limiting current density is not correctly identified in the literatures. Instead of kinetic current density, the measured current density normalized by diffusion limiting current density (j/jL) has also been frequently under circumstance where its validity is not justified. By taking oxygen reduction reaction/hydrogen oxidation reaction/hydrogen evolution reaction as examples, we demonstrate that identifying the actual diffusion limiting current density for the same reaction under otherwise identical conditions from the experimental data is essential to accurately deduce kinetic current density. Our analysis reveals that j/jL is a rough activity metric which can only be used to qualitatively compare the activity trend under conditions that the mass transfer conditions and the roughness factor of the electrode are exactly the same. In addition, if one wants to use j/jL to compare the intrinsic activity, the concentration overpotential should be eliminated.

The effect of mass transfer conditions during plastic stage on sulfur removal from high organic-sulfur coal

A gas coal (B) was used to study the effect of volatiles on sulfur removal from a high organic-sulfur coking coal (A) from the perspective of mass transfer conditions. The mass transfer driving force and resistance of volatiles were analyzed in terms of fluidity development, permeability of coal plastic stage to gas flow, and volatile matter release. Carbonization using vertical and horizontal stacking modes of two coals were designed according to the release directions of volatiles during pyrolysis. Three pyrolysis temperatures (450, 475 and 510 ºC) were used to study mass transfer conditions. The semicokes were cut into pieces at fixed intervals along vertical and horizontal directions to determine the spatial sulfur distribution in semicoke. The gas coal volatiles helped the removal of sulfur within a limited distance that was related to the mass transfer conditions of volatiles, whereas permeability determined the mass transfer resistance of volatiles and their driving force was controlled by the amount and rate of volatile matter release.

A study on the upper limit efficiency of solar still by optimizing the mass transfer

Solar still is an green energy, low-cost and easy-to-maintain desalination system. Enhancing the mass transfer is a very important strategy for improving solar still. However, the analysis of the upper limit performance of the solar still related to the optimized mass transfer is lacking. In this work, by assuming the most ideal heat and mass transfer condition in solar still, the theoretical upper limit performance of solar still is given. The theoretical results reveal that the mass transfer in solar still is sensitive to the inner air circulation. The mass transfer in the solar still reaches up to the upper limit quickly when the air circulation is enhanced. By enhancing the mass transfer process, the theoretical upper limit of the energy efficiency in solar still is around 87%, 91.5%, and 94.5%, respectively, for the input power density at 300 W/m2, 500 W/m2, and 700 W/m2. Experimental results show that in a solar still with the basin size at 25 cm × 25 cm, the theoretical upper limits can be approached by only using 0.2 W ∼ 0.6 W of fan power. Compared to the efficiency of conventional solar still without modification, the upper limit energy efficiency is 48%, 28%, and 20% higher, respectively, under 300 W/m2, 500 W/m2, and 700 W/m2 input power density. Meanwhile, to reach the upper limit, the total extra cost of the modification can be as low as 3 $ by using a fan in solar still. This work offers a new understanding of the mass transfer process and provides an effective and economical optimizing way not only for the solar still but other themal systems with heat and mass transfer.

Design and performance verification of a fast-reaction thermogravimetric analyzer

Ca(OH)2/CaO fluidized thermochemical heat storage can provide considerable heat storage power, and is a promising large-scale energy storage technology. Owing to the limitations of existing gas–solid reaction kinetics research equipment, there is a lack of Ca(OH)2/CaO reaction kinetics research under fluidization conditions, with a lack of reliable reference data for the design and operation of fluidized bed reactors. In response to the above-mentioned problem, and through our research, we developed a fast-reaction thermogravimetric analyzer to provide samples with excellent heat and mass transfer conditions close to fluidization. The fast-reaction thermogravimetric analyzer enables the reaction of Ca(OH)2 to mainly take place under isothermal conditions by rapidly moving the high-temperature reactor, as well as inputting purge gas at a high flow rate to provide excellent mass transfer conditions for the sample, while obtaining real-time and reliable mass data for thermal analysis kinetics studies. Through an in-depth performance verification, the apparent activation energy of char combustion in a TGA (144.82 kJ/mol), fast-reaction thermogravimetric analyzer (88.32 kJ/mol), and fluidized bed reactor (47.23 kJ/mol) were obtained by the model-free method (iso-conversional). The comparison of data proved that the fast-reaction thermogravimetric analyzer could obtain kinetic parameters similar to a fluidized bed reactor, which was also verified using other materials. Therefore, the fast-reaction thermogravimetric analyzer developed in this study can provide a new solution for studying the reaction kinetics of fluidized thermochemical heat storage for Ca(OH)2/CaO, in addition to acting as a reliable reference for the design and operation of fluidized bed reactors.

Experimental study and kinetic modeling of continuous flow conversion of fructose to 5-(chloromethyl)furfural using micro- and millistructured coiled flow inverter

5-(chloromethyl)furfural (CMF) can be derived from renewable feedstocks and is considered as potentially biorenewable platform chemical. Experimental investigations and kinetic modeling of the conversion of d-fructose with aqueous HCl to CMF by a reactive extraction was undertaken with a continuous flow setup. Experiments were performed under variation of extraction solvents, reaction temperatures, fructose concentrations, and reactor diameters for various residence times so that time evolution of species concentration allowed for detailed kinetic analysis. Anisole, a solvent ranked as “recommended” by the CHEM21 selection guide was found to be an environmentally more benign alternative to the typically employed chlorinated extraction solvents. A maximum CMF yield of 79 % was obtained at 90 °C within a residence time of 265 s. Kinetic modeling under non-limiting mass transfer conditions showed general consistency of experimental data with the view that the reactions take place solely in the aqueous phase and that CMF is formed consecutively via 5-(hydroxymethyl)furfural (HMF) from fructose. Under these conditions no side-product formation from CMF and HMF was discernible. Activation energies for conversion of fructose to HMF of 94 ± 8 kJ/mol, of HMF to CMF of 85 ± 6 kJ/mol, and for conversion of CMF to HMF of 74 ± 25 kJ/mol were observed. To the best of our knowledge this study provides the first detailed kinetic investigation of biphasic CMF synthesis under variation of several experimental parameters in continuous flow.

A review on processes, mechanisms, and quality influencing parameters for puffing and popping of grains

Ready to eat expanded food grains are gaining popularity in modern days due to their ease to digest, lightness, crispiness and most importantly their ready to eat in nature. The demand for these products is increasing gradually, which tempts researchers to develop products with enhanced quality more diversifications in product and taste. An integrated study on food grain expansion helps to understand these processes. Puffing and popping process expands the grain by many folds. The expansion of grains depends upon heat and mass transfer rates, which take place in the counter direction. Therefore, optimal heat and mass transfer conditions affect the final quality and play an important role. Processing methods and grain characteristics influence these processes. Processing parameter levels and grain characteristics are interrelated. Optimum levels of processing parameters differ with changes in processing methods. This review article explains the effect of processing parameters on product quality and influencing mechanisms. Novelty impact statement This review covers the varietal effect of grains, their conditioning processes, heating methods for expansion, and the effect of these such parameters on the quality of the final product. Quality characteristics such as texture, nutrition, and other organoleptic properties play an essential role in selecting puffing or popping methods and preconditioning parameters for enhancing consumer acceptability. This review summarizes optimal processing conditions and the various quality parameters description to evaluate the quality of the final product.

Solar pyrolysis of biomass - part I: Volatile evolution mechanism

To study the volatile evolution mechanism during solar pyrolysis of biomass, willow pellets with thicknesses of 3 mm, 1 mm and 0.5 mm were used to investigate the dynamic pyrolysis characteristics at heat flux densities of 0.5 and 1.1 MW/m2. The results showed that the larger thickness significantly reduced oil yield (by 23%–35%) and increases gas yield (by 19%–20%), while increasing heat flux density showed a similar trend. These changes in solar pyrolysis behavior and product composition were governed by intra-particle secondary reactions due to the heat and mass transfer conditions. The evolution of heavy compounds (molecular weight ≥ 200 Da) was integrated into the volatile evolution mechanism of solar pyrolysis. Results showed the secondary reactions promoted the cracking, deoxygenation and condensation of sugars and phenolic species, and also led to the growth of condensed aromatic hydrocarbons. A novel dimensionless number (Bi∙Prmass) was proposed in this study to estimate the solar pyrolysis behavior of wood pellets. A smaller Bi∙Prmass indicates that the conversion process is dominated by primary pyrolysis, while a higher value indicates that it is dominated by intra-particle secondary reactions. Depending on the degree of condensation, a critical value of Bi∙Prmass around 0.1 was adopted in this study. This work can provide guidance about operating conditions optimization for solar gasification of biomass.

Regulation of permeability of plastic layer of coking coal by volatiles from coal pyrolysis

The low permeability of plastic layer of coking coal causes the formation of coking pressure, and the evolution of permeability is closely related to the release behavior of volatiles. In this paper, a low-volatile bituminous coal C1 and a high-volatile bituminous coal C2 were selected as research objectives, and a lignite L1 and two semi-cokes produced from the pyrolysis of C2 at two temperatures were used as the contrast. The permeability tests of single coal, binary coal or semi-coke and separated combination were conducted. The influence of volatiles release behaviors on the evolution of permeability of plastic layer was revealed by thermogravimetric and fluidity analyses. The results showed that there was a low permeability plateau stage of plastic layer of C1, while the permeability of plastic layer of C2 was rapidly improved after reaching the lowest. This was related to the difference in the mass transfer conditions of volatiles from two coals. C2 could enhance the mass transfer driving force of volatiles and bring both inert components (semi-coke after pyrolysis) and transferable hydrogen, thus the permeability of plastic layer could be improved without destroying the stability of plastic layer. The hydrogen-rich volatiles released from C2 before its initial softening temperature helped the low permeability of the plastic layer of C1 be formed and reach the maximum. The volatiles released during the plastic stage of C2 helped maintain the low permeability plateau of plastic layer of C1. It was plausible to further improve the permeability of plastic layer of C1 by consuming part of hydrogen-rich volatiles from C2 with prolonging the volatiles’ reaction.

An inherently leakage-free inverted rotating disk electrode (IRDE) design

In electrochemistry, rotating disk electrodes (RDE) are commonly used for the investigation of different electrochemical reaction regimes. The defined mass transfer conditions allow the investigation of rate limiting steps such as adsorption, diffusion or electron transfer. However, when gaseous reaction products are formed, they pose a challenge for a conventional experimental setup, as these gases accumulate on the electrode surface and hinder electrode processes.In this work, a novel experimental setup for an inverted rotating disk electrode (IRDE) cell suitable for the investigation of photoelectrochemical processes is presented. The rotation is achieved through magnetic coupling of magnets inside and outside the cell. This cell design yields construction-inherent leak tightness since the electrolyte reservoir is free from openings on the bottom and sides. Stable electric contact is provided through a spring-loaded tip.The vertical flow profile in the newly developed IRDE was simulated at different rotation speeds using computational fluid dynamics (CFD). The geometry of the cell was adapted in several iterative steps. The final experimental setup was validated comparing the well-studied oxidation of ferrocyanide in the new IRDE setup to measurements in a conventional RDE setup and literature results in a speed range from 100 to 1600 rpm.

Using coarse-grain MD to study the trade-off between surface area and mass transport in aqueous Li-O2 battery using functionalized CNT

The discharge performance of lithium-oxygen battery with ultrahigh theoretical capacity is not satisfactory, and its mass transfer process is restricted by many factors such as cathode structure and hydrophilic/hydrophobic properties. Here, the mass transfer process at the interface composed of hydrophobic carbon nanotubes (CNTs) electrode, hydrophilic carboxylic carbon nanotubes (COOH-CNTs) electrode, composite electrode and aqueous electrolyte was studied by coarse-grain molecular dynamics (CGMD) simulation. The mesoscopic scale simulation method enabled this study to discuss the hydrophilicity/hydrophobicity of the two-phase interface on the cathode side in order to improve the mass transfer and diffusion of reactants. The morphology of hydrophobic/hydrophilic electrode in aqueous electrolyte and the mass transfer conditions of reactants under different hydrophilic conditions were analyzed. The results showed that hydrophobic CNTs exhibited aggregation behavior and formed pore channels in aqueous electrolyte, which was conducive to the transport of ions and dissolved oxygen, while hydrophilic COOH-CNTs had stronger dispersion under aqueous electrolyte conditions, which could provide more reaction sites. Under certain hydrophobic conditions, non-polar force had cutoff effect on the diffusion of dissolved oxygen. The simulation results of electrolyte density showed good consistency with the experimental data, and the oxygen diffusion coefficient obtained was also consistent with the microscopic simulation results. This study was of great significance for the analysis of the mesoscopic morphology and mass transfer characteristics of the oxygen electrode during the charging and discharging process of lithium-oxygen battery.

Lens Evaporation on Immiscible Liquid Surface with an Interfacial Cooling Effect.

A theoretical heat and mass transfer model of volatile liquid lens evaporation on the surface of an immiscible liquid substrate is established in toroidal coordinates. According to the coupled boundary conditions of heat and mass transfer at the lens surface as well as the interfacial cooling effect, the analytical solutions of the temperature field inside the lens and the vapor concentration field around the lens are derived for the first time. Compared with the isothermal model, the change of contact radius calculated by the present model agrees well with the experimental data, especially when the liquid substrate reaches a relatively high temperature. It also reveals that the temperature distribution inside the lens is not uniform, which is similar to the sessile droplet evaporation on a solid substrate surface. In addition, the excess temperature, heat flux, and evaporation flux of the lens–air interface increase monotonically from the lens center to the contact line. Finally, the influences of density ratio and evaporative cooling number E0 on lens mass evaporation rate are analyzed, which shows that the lens mass evaporation rate decreases with increasing density ratio and evaporative cooling number.

Optimization of electrochemical degradation of organics considering the simultaneous effects of electroactive area and mass transfer on current modulation

In the modulated current (MC) technique, the applied current is reduced during the course of the electrolysis, in order to maintain the process operating at limiting current (Ilim), corresponding to optimized charge and mass transfer conditions. However, despite the efficacy of MC for effluent treatment, a longer electrolysis time is required. This problem can be overcome using a turbulence promoter (TP) to enhance mass transfer and increase the reaction rate. In this work, an attempt was made to further improve the mass transfer, comparing electrolyses performed with plate and mesh BDD electrodes in the absence and presence of a TP. Instead of using the geometric area of the electrode (AG), the electrolyses were performed considering the electrochemical active area (AE) for determination of Ilim, avoiding overestimation of the current applied in the MC mode, since AE < AG, as observed here. The electrolyses were performed in a flow reactor, with phenol as a model organic compound. The process combining MC and a TP enabled 85% reduction of the energy consumption, corresponding to 24.4 kWh per kg of COD removed. This outstanding reduction was attributed to i) high mass transfer obtained due to the reactor design and use of a TP, and ii) 67% improvement of the current efficiency, due to improved mass transfer and the use of more accurate values of Ilim during the modulation. Finally, the efficacy of the MC+TP technique was validated in the degradation of a real wastewater.

Role of gas coal in sulfur regulation from the release behavior and mass transfer condition of volatiles

There were new restrictions on sulfur regulation of high organic-sulfur coal (HOSC: A) brought by the differences in the pyrolysis characteristics of different gas coals (GC: B and C) and the mass transfer conditions of their volatiles. Firstly, the role of volatiles from GC in the sulfur regulation along vertical and horizontal directions was revealed by designing two stacking modes in a cylindrical crucible and using the parallel and cylindrical baffles to block the volatiles’ migration. Secondly, the different performances of volatiles from two different GC on the sulfur regulation were associated with their volatiles’ release behaviors. And finally, the effect of mass transfer conditions of volatiles on the sulfur regulation was discussed and reflected in the sulfur spatial distribution in chars. Contrast experiments with or without parallel and cylindrical baffles indicated that the monodirectional migration of volatiles from GC helped reduce the sulfur contents along both vertical and horizontal directions. The maximum distances of effective sulfur removal by volatiles from GC along vertical and horizontal directions varied respectively within 5 ∼ 15 and 8 ∼ 15 mm as changing GC. The performance of different GC in sulfur removal depended on the good match of its intensive volatiles release to the high permeability of HOSC and the continuous supply of hydrogen-rich volatiles. The effective distance of bi-directional vertical migration of volatiles was shortened to 3 ∼ 6 mm. It was promising to use the effective distance of sulfur removal by volatiles migrating vertically to evaluate the potential of GC as a sulfur regulator. The bi-directional migration of volatiles from GC helped extend the effective distance in the horizontal direction (>15 mm), which was related to the temperature gradient. The proper temperature gradient helped the volatiles of GC spontaneously or forcedly complement the hydrogen-rich volatiles in the HOSC layer. The temperature gradient is promising to maximize the potential of GC as a sulfur regulator and break the limits on sulfur removal by GC’s volatiles.

Hydromechanics for crystal growth from water-salt solutions

This paper presents an overview of the current state of technological problem solving related to controlling of hydrodynamics and mass transfer in crystallizers of complex design (continuous-flowing and non-flowing) during the growth of crystals with technologically important properties (potassium dihydrogen phosphate - KDP and a mixed crystal of nickel and cobalt - KCNSH) from special water-salt solutions. Unlike crystallizers of standard designs for crystal growth from a melt (by Czochralski, Bridgman, etc.), there are also crystallizers of different design for crystal growth from water-salt solutions. According to the designers, the necessary crystal growth conditions are maintained in these crystallizers by creating the best characteristics of the flow, i.e., by controlling its velocity and direction, as well saline saturation solution and temperature. In this work, hydromechanical problems are solved for continuous-flowing and non-flowing crystallizers. The flow visualization through its physical model reveals a multi-vortex and unsteady flow structure due to mixer action, three-dimensional solution inflow and outflow and spatial crystal placement. For this reason, primary attention is given to the studies devoted to the development and application of the mathematical models for hydromechanics and heat and mass transfer based on the complete Navier-Stokes equations in the Boussinesq’s approximation for laminar regimes, as well as to the standard (k-ε)-turbulence model for turbulent regimes. The hydromechanical features associated with the three-dimensional flow complexity are discussed for continuous-flow crystallizers. The possibilities of maintaining the required saline saturation near the growing crystal over a long period of time are analyzed for non-flowing crystallizers. Mathematical models of convective mass transfer are considered in a "solution-crystal" conjugate formulation. The local features of hydrodynamics and mass transfer conditions in solution (saline solution saturation near growing crystal) are analyzed.

Mathematical modeling of memristor resistive switching based on mass transfer full model of oxygen vacancies and ions

A relatively simple mathematical model of dynamic switching of a memristor has been created based on a fairly complete physical model of the processes of stationary mass transfer of oxygen vacancies and ions, considering their generation, recombination and diffusion in electric field in the “metal-oxide-metal” structure with the dominant transport mechanism of electron tunneling through oxygen vacancies. The results of numerical simulation of mass transfer of oxygen vacancies along thickness of the oxide layer of the memristor are presented. The distributions of vacancy concentration during their diffusion in an electric field are found, taking into account the processes of generation and recombination with ions, depending on the applied voltage to the electrodes and on the temperature of the memristor. A good coincidence of the volt-ampere characteristics part found as a result of numerical simulation and a series of experiments is obtained. It is shown that under conditions of more than 600 K memristor temperature, it is possible to neglect the process of ion-vacancy recombination and significantly simplify the procedure for mathematical modeling of memristor resistive switching by eliminating the oxygen mass transfer equation, as well as the recombination term in the stationary equation of oxygen vacancies mass transfer. The developed mathematical model of memristor dynamic switching, including a system of stationary ordinary differential equations, is designed to simulate the operation of large memristor arrays in neuromorphic computing devices and may be preferable in relation to known circuit models that include a certain set of fitting parameters to match the simulation results with the memristor experimental characteristics.

Thermal imaging – A novel method for gas-liquid Interface conditions determination

We suggest monitoring of the interfacial mass transfer activity over the surface of the packing under distillation conditions by a thermal camera. Such a study should reveal zones with imperfect hydrodynamics and decreased mass-transfer intensity, enabling quantification of the fraction of the packing geometrical area, which is ineffective in the interfacial mass exchange.The objective of the present study is to validate that the temperature of a liquid surface measured by the camera is truly the temperature of the interface, which can substantially differ from the liquid bulk temperature under the non-zero heat and mass-transfer conditions. Validation experiments are performed using a water-air system with zero net mass transfer across the interface and non-zero heat transfer induced by cooling of the liquid phase and heating of the gas phase. The interface temperature is indirectly determined from the partial pressure of water in the air above the liquid level.The results show that the temperature reading of the thermal camera is up to 92% determined by the temperature of the interface. Its measurement opens the possibility of determining not only effective interfacial area but also local distribution of the mass-transfer and heat-transfer resistances between the phases.

Experimental study of heat transfer in adsorbed natural gas storage system filled with microporous monolithic active carbon

The study of the thermal state of the monolithic adsorbent layer and internal heat exchange processes during the circulating charging of an adsorbed natural gas storage system was carried out. The correlation between gas flow mode and the heat transfer coefficient between gas and adsorbent is determined under conditions of mass transfer.