Mass Transfer Biot Number Research Articles

Significance of Rosseland’s radiative heat transfer and dissipative heat on MHD viscous flow over a slandering sheet in the presence of Darcy-Forchheimer and Lorentz forces

The main emphasis of this research is to investigate computationally an innovative viscous, time-independent, and Darcy-Forchheimer flow of an electrically based incompressible nanofluid on a slandering stretched surface. The thermal conductivity and viscosity of this flow will be discussed. Incorporating an outer heat source into the thermal transfer process enhances the effect of dissipative heat and thermal radiation. When chemical processes are included, the effects of heat and solvent transport are influenced by the use of convective constraints at boundary. The flow characteristics are governed by the mathematical form which is further transferred to ordinary differential equations (ODEs) via appropriate assumptions regarding similarity variables and stream functions. The analytical technique for such highly nonlinear equations sometimes doesn't work effectively due to the strong nonlinearity. As a result, these transformed ODEs are solved numerically by means of bvp4c approach. Graphs depict the impacts of different substantial factors on velocity, temperature, and solutal concentration distributions. Numerical computations of physical quantities including magnetic parameters, inertial coefficient, permeable coefficient, thickness factor, heat transfer Biot number, Radiation parameter, Prandtl number, Eckert number, mass transfer Biot number, Schmidt number, heat source factor, and chemical reaction are evaluated and tabulated. The current findings are compared to previously known results, and they are in great agreement. The main outcomes of the study are thoroughly explained in the results and discussion section. Heat transfer Biot number raises the energy distribution and mass transfer Biot number strengthened the concentration profile while wall thickness quantity reduces the temperature and concentration of fluid as well. The enhanced variable viscosity is augmented by the longitudinal velocity profile and the rate of shear stress.

Simulation of fluid flow and heat-moisture transfer mechanism in packed bed based on double-diffusion model

Based on the discrete element method (DEM), four packed beds composed of soybean kernels with diameters of 6.4, 6.8, 7.4 mm, and the mixture of three kinds of particles were established. Then, a double-diffusion heat and mass transfer model between the grain pile and the interstitial air was established based on the local mass and thermal non-equilibrium (LMTNE) mechanism. Finally, employing particle-resolved computational fluid dynamics (PRCFD), the heat and mass transfer between the grain kernels and air during the drying process in the four packed beds were numerically resolved. It was found that the packed bed formed by stacking particles of different diameters had a minimum porosity of 0.4547. The radial porosity of the packed bed oscillates and decreases toward the central axis, while the tortuosity of the airflow path oscillates and decays toward the periphery. The mass transfer Biot number for soybean kernels with diameters of 6.4, 6.8, and 7.4 mm were 2.38 × 106, 2.44 × 106, and 2.53 × 106, respectively. This indicates that the mass transfer rate in the grain pile primarily depends on the magnitude of the moisture diffusion coefficient within the grain kernels. Compared with mass diffusion, thermal diffusion occurs much faster, which results in temperature gradients in packed beds only existing in the first 5 min of drying, and the drying rate in the early stage is higher than that in the later stage. Most importantly, the airflow characteristics, heat and moisture content are not in local equilibrium in the packed bed, and should be considered when designing drying systems.

Investigation of Heat and Mass Transfer in the Process of Convective Heat Treatment and Drying of Thermal Insulation Materials and Approximate Equation of the Drying Curve

The results of the study of heat treatment in the drying processes of thin thermal insulation materials based on the most general laws of convective drying of wet bodies with the establishment of the equation of the drying curve are presented. The numerical values of heat and mass transfer Biot numbers for the period of decreasing drying rate are established, too. Based on the study and analysis of numerous sources, the ranges of changes in the Lykov, Posnov, and phase transformation criteria for the processes of heat treatment of ceramics, asbestos, felt, and clay plates have been approximately determined. It is demonstrated that for values of Biot numbers less than one, for Lykov criteria value of 0.05–0.13 and for Posnov criteria value of 0.03–0.08 for drying modes with a temperature of 90–120 ° C, the task of drying, as a heat and mass transfer process, is external, and internal transfer does not affect the conditions of interaction of the material surface with the environment. It is also shown that the drying of thin materials takes place when the Biot number is less than one and, under the conditions of an external problem, the similarity criteria do not affect convective drying. The intensity of moisture evaporation from the body surface is determined by the value of the heat transfer coefficient in the Biot number and the regime parameters of the process. It has been established that the processes of drying materials are low-intensity processes. Based on the elements of the theory of thermal regular regime, the rate of heating of a wet body and the rate of decrease in moisture content are determined. The problem of constructing drying curves without conducting experiments to determine the duration of drying of thermal insulation materials based on approximate equations is considered; this problem is of interest for the practice of drying. The constructed drying curves do not coincide with the actual curve with an error of 4–5 %.

Significance of heat and mass transport in peristaltic flow of Jeffrey material subject to chemical reaction and radiation phenomenon through a tapered channel

Abstract Using mathematical modeling and computational analysis, this study aims to examine the peristaltic blood flow of a non-Newtonian material in a tapered channel with radiative heat flux and response mechanisms. By utilizing a long-wavelength approximation, ignoring the wave number, and performing under conditions of low Reynolds number, closed form solutions for the velocity, temperature, and concentration fields are achieved. Several governing parameters and their effects on the system were analyzed, and relevant diagrams were provided. Increasing the Biot number, Jeffrey material, and thermal radiation parameter of the heat and mass transfer mechanism increases the velocity profile. When the heat source/sink parameter and the heat transfer Biot number increase, the temperature profile improves. The resultant concentration distributions are enhanced when mass transfer Biot number, heat radiation, and chemical processes are all raised. We observe that the pressure rate decreases in all three pumping zones when the heat transfer Grashof number and heat transfer Biot number rise. This is because the pressure rate is affected by the Grashof number and Biot number of heat transmission. The increase in thermal radiation parameter and heat transfer Biot number results in a slower rate of heat transfer than when Prandtl number and heat source/sink parameter increases. When the Soret number, Schmidt number, Biot number, and heat source/sink parameter are all raised, the mass transfer coefficient also rises. This rate, however, decreases as the heat radiation and chemical reaction parameters rise. The findings presented in this study have interesting implications for other aspects of human physiology. The preponderance of organs are permeable. Furthermore, fluids render the location of natural boundaries uncertain. The presented mathematical model can be used to derive predictions about the behavior of various systems. For the study of cancer treatment in biological systems, a mathematical model that includes nanoparticles, viscosity dissipation, and rotation holds much promise. Model development incorporated Soret–Dufour effects and thermal analysis of the digestive system.

Influence of ultrasound-pretreated convective drying of Roselle (Hibiscus sabdariffa L) leaves on its drying kinetics and nutritional quality

The drying kinetics and the nutritional qualities of Roselle (Hibiscus sabdariffa L) leaves as affected by ultrasound pretreatment during hot air drying were investigated in this work. Ultrasound frequency and power at 20 kHz and 600 W, respectively, were used for the experiment. Roselle leaves were subjected to ultrasound pretreatment in distilled water for 0 min (untreated), 5 min (UD5), 10 min (UD10) and 15 min (UD15) before hot air drying. The result showed that UD15 samples had about 47% reduction in drying time compared with the untreated samples. The effective moisture diffusivity of the treated and untreated samples ranged from 1.21 to 3.29 × 10−1m2/s. The Page and Logarithmic models best described the drying behavior for the untreated and treated samples respectively. The values of the mass transfer Biot number (ratio of internal mass transfer resistance to external mass transfer resistance) for all the samples ranged from 0.9032 to 1.2391. The samples of UD10 and UD5 had the highest amount of carotenoid and vitamin C contents, respectively, amongst the untreated and treated samples. The total color change of the treated samples were significantly lower than the untreated samples after drying. Drying of Roselle leaves is usually done using convective drying method with its attendant's effects such as long drying time, loss of nutrients and high energy usage. But this work showed that application of ultrasound pretreatment during drying of Roselle leaves can significantly reduce the drying time and at the same time retain the nutritional quality of the dried treated samples.

Modeling comparison and theoretical study of mass transfer characteristics for desiccant coated air channel under isothermal dehumidification

Coupled heat and mass transfer phenomena are encountered in desiccant coated dehumidifier, and their numerical modeling is becoming indispensable. In this study, three conjugate heat and mass transfer models were compared to clarify the effects of interparticle mass transfer and local kinetic non-equilibrium on modeling accuracy, and the models were validated by experiment results of silica gel and FAM Z01 coated dehumidifiers with single one air channel. Furthermore, a parametric study on the separate mass transfer characteristics of the dehumidifier under isothermal dehumidification was conducted based on one of the improved models. Results demonstrated that the effect of interparticle mass transfer should be involved, while the local kinetic non-equilibrium tends to be considered for desiccants with steep isotherm shape. Parametric study revealed that as air velocity increases, both air- and solid-side mass transfer change significantly, while desiccant layer thickness, interparticle porosity and isotherm shape mainly affect solid-side mass transfer. The average mass transfer Biot numbers Bim of desiccant layer with relative low thickness of 0.1 mm under various parameters are in the same order of magnitude as 1, indicating that the mass transfer resistance on solid side cannot be ignored generally.

Comprehensive analysis of intermittent drying. A theoretical approach

Intermittent drying is a promising technique that may improve drying performance, when compared to stationary drying. An intermittent drying is composed of a succession of cycles, each of them consisting in an active drying period followed by a tempering period. It is typically characterized by two parameters: the duration of the cycles tc and the ratio of the duration of the drying period of a cycle to the total duration of the cycle χ. In this work, we derive two general models of the intermittent drying of a solid material, corresponding to different physical situations: a continuous model, to describe a situation where liquid water is continuously distributed through the material, and a shrinking core model, to describe a situation where the material is divided into a humid core and a dry zone. With these models, we provide a thorough analysis of the influence of the parameters characterizing the intermittent drying of a material on the dynamics of this drying, over wide ranges of values of these parameters. The results allows the identification of three possible regimes in the dynamics of an intermittent drying, when it is compared to a stationary one, what is summarized into an operational diagram that could be useful to select the best parameters for an intermittent drying process. Notably, the results show that one of these regions (with small values of tc and χ) corresponds to high energy efficiency, without significantly increasing the total drying time compared to continuous drying, if the external resistance to mass transfer is negligible. The models also exhibit that the external mass transfer Biot number, Bim, has a strong influence on the dynamics of an intermittent drying; the influence of tc and χ on drying performance is mitigated as Bim decreases. Finally, the models are used to shed new light on experimental data from the literature, regarding the intermittent drying of several products, for different operating conditions. The investigation of the influence of the operating conditions and the product properties on the drying performance shows that strategies such as varying the intermittency ratio or using inherently intermittent dryer can enhance the drying kinetics.

Insight into the Significance of Hall Current and Joule Heating on the Dynamics of Darcy–Forchheimer Peristaltic Flow of Rabinowitsch Fluid

This paper aims to present the significance of the Hall current and Joule heating impacts on a peristaltic flow of a Rabinowitsch fluid through tapered tube. The Darcy–Forchheimer scheme is used for a porous medium; a mild stenosis is considered to study the impacts of radiative heat transfer and chemical reactions. Convective conditions are postulated for heat and mass transfer. In the meantime, the slip conditions are presumed for the velocity distribution. Soret and Dufour features bring the coupled differential systems. The hypotheses of a long wavelength and low Reynolds number are employed to approximate the governing equations of motion, and finally the homotopy perturbation method is adopted for numerical study. Pumping characteristics are revealed and the trapping procedure correlated with peristaltic transport is elucidated. The present study is very important in many medical applications, such as the gastric juice motion in the small intestine and the flow of blood in arteries. The mechanism of peristaltic transport with mild stenosis has been exploited for industrial applications like sanitary fluid transport and blood pumps in heart-lung machine. The influences of various physical parameters of the problem are debated and graphically drawn across a set of figures. It is noted that the axial velocity is reduced with the increase of the Hartmann number. However, enhancing both the Rabinowitsch parameter and the Forchheimer parameter gives rise to the fluid velocity. As well, it is debated that Rabinowitsch fluid produces a cubic term of pressure gradient. Therefore, the relation between mean flow rate and the pressure rise does not stay linear. It is recognized that the temperature rises with the enhancement of both Dufour number and Soret number. Furthermore, it is illustrated that the concentration impedes with the increase of the mass transfer Biot number. Also, it is revealed that the trapped bolus contracts in size by enlarging the maximum height of stenosis.

Soret and Dufour effects on a Casson nanofluid flow past a deformable cylinder with variable characteristics and Arrhenius activation energy

In this study, the effects of variable characteristics amalgamated with chemical reaction and Arrhenius activation energy are analyzed on a two-dimensional (2D) electrically conducting radiative Casson nanoliquid flow past a deformable cylinder embedded in a porous medium. The surface of the cylinder is deformable in the radial direction i.e., the z-axis. The impression of Soret and Dufour's effects boosts the transmission of heat and mass. The flow is analyzed numerically with the combined impacts of momentum slip, convective heat, and mass conditions. A numerical solution for the system of the differential equations is attained by employing the bvp4c function in MATLAB. The dimensionless protuberant parameters are graphically illustrated and discussed for the involved profiles. It is perceived that on escalating the velocity slip parameter and porosity parameter velocity field depreciates. Also, on escalating the radiation parameter and heat transfer Biot number a prominent difference is noticed in an upsurge of the thermal field. For growing values of Brownian motion and thermophoretic parameters, temperature field augments. On escalating the curvature parameter and porosity parameter, drag force coefficient upsurges. The outcome of the Soret number, mass transfer Biot number, and activation energy parameter is quite eminent on the concentration distribution for the sheet in comparison to the deformable cylinder. A comparative analysis of the present investigation with an already published work is also added to substantiate the envisioned problem.

Transient Convective Heating Transport of the Micropolar Fluid Flow Between Asymmetric Channel with Activation Energy

Here modelling and computations are presented to introduce the concept of activation energy involved in the micropolar fluid between the porous vertical channel with the boundary conditions of third kind. The fluid is considered to be gray, absorbing-emitting but non scattering medium. The resulting system of equations are solved numerically by Crank-Nicolson implicit finite difference method. The effect of various physical parameter such as activation energy, micropolar parameter, reaction rate, Reynolds number, Schmidt number, heat and mass transfer Biot numbers on the velocity, temperature and concentration field are discussed by means of pictorial representation.

Peristaltic motion of Maxwell fluid subject to convective heat and mass conditions

This article concentrates on peristalsis of Maxwell fluid in a symmetric channel with heat and mass convective conditions. Analysis is given in presence of viscous dissipation. The relevant problems statements are constructed and solved for the series solutions of stream function, temperature and concentration. Regular perturbation technique is adopted for small wave number. Heat transfer coefficient is also derived. Results of temperature, concentration and heat transfer coefficient are graphically analyzed. Trapping phenomenon is studied. It is observed that heat and mass transfer Biot numbers have opposite effects on fluid temperature and concentration. Concentration distribution decays with the increase in Schmidt number and Soret number. Heat transfer coefficient has oscillatory behavior and magnitude of heat transfer coefficient increases when heat transfer Biot number enhances. In addition, similar trapping pattern is observed for relaxation parameter and wave number.

Effects of ultrasound pretreatments on the drying kinetics of yellow cassava during convective hot air drying

This study investigated the effects of ultrasound pretreatments on the drying kinetics of yellow cassava during convective hot air drying. Sliced yellow cassava samples were pretreated using distilled water with ultrasound (DWU) and ultrasound-assisted osmotic dehydration (ODU) prior to hot air drying. Ultrasound pretreatments were carried out using a probe-type ultrasound having a frequency of 20 kHz at ultrasound power and pretreatment time of 600W and 10 min, respectively. The results showed that ODU samples had the shortest drying time, about 35% reduction in drying time compared to the untreated samples. The effective moisture diffusivities of DWU and ODU samples were significantly (p < .05) higher than that of the untreated. The mass transfer Biot numbers (Bim) for the treated samples were in the range of 0.1 < Bim < 100. The parabolic model fitted best in describing the drying kinetic of DWU samples, while Page model fitted best both for the ODU and untreated samples. Practical Application Yellow cassava is a new breed of cassava that is highly fortified with vitamin A. Convective drying is known to have some adverse effects on agricultural products. However, the use of ultrasound pretreatment before hot air drying can save energy, time, and cost of drying operation. In this work, new information about the drying kinetics and mass transfer of the new breed of cassava (yellow cassava) using ultrasound as pretreatment is obtained. This information is useful in designing and developing a novel ultrasound-assisted dryer for yellow cassava.

Capturing the features of peristaltic transport of a chemically reacting couple stress fluid through an inclined asymmetric channel with Dufour and Soret effects in presence of inclined magnetic field

The primary focus behind this research work is to unfold the heat and mass transfer characteristics of peristaltic transport of hydromagnetic couple stress fluid through a porous medium in an inclined channel of asymmetric kind. Consideration of both Dufour and Soret effects is one of the key factors of this investigation. Simultaneous convective conditions of mass and heat transfer are satisfied by the channel walls. Beneath the presumptions of small Reynolds number along with long wavelength, the governing two-dimensional coupled differential equations are simplified after incorporating dimensionless variables. To calculate the pressure difference, the technique of numerical integration has been employed. Graphical demonstrations for velocity, temperature, concentration profiles have been sketched out under the influence of pertinent flow parameters. Pumping characteristics and trapping phenomenon for some particular kind of waveshapes are also highlighted through contour plots. Noteworthy findings are that near the center of the channel the maximum value of the temperature is attained due to the intensification of heat generation parameter. Also, Dufour number tends to enhance the temperature of the fluid, whereas Soret effect results in a downfall in the concentration field. Heat and mass transfer Biot numbers lead to an elevation in the concentration and temperature profiles, respectively. It is also perceived that a reduction in concentration takes place due to the presence of destructive kind of chemical reaction while a reverse trend is being followed during a chemical reaction of constructive kind. Moreover, both the pressure gradient as well as pressure difference act as increasing functions of the angle of inclination of the channel. Additionally, the general propensity of couple stress fluid parameter is to diminish the volume of the trapped bolus.

Soret and Dufour features in peristaltic motion of chemically reactive fluid in a tapered asymmetric channel in the presence of Hall current

The present work examines heat and mass transfer characteristics of peristaltic motion of Johnson-Segalman fluid in a tapered asymmetric channel along with chemical reaction, by taking into account the Soret and Dufour effects. Effects of Hall current have also been discussed in mathematical modeling and analysis. Following the peristaltic wave procedure, the tapered asymmetric channel is based on the non uniform boundaries having diverse phases and amplitudes. The channel walls show excellent agreement with more realistic convective conditions. The modeled flow problem is directed into ordinary differential equations set with proper utilization of similarity quantities. The estimation of high wavelength as well as small Reynolds number are acknowledged to deduce the equations of Johnson-Segalman liquid model. The adopted solution procedure is constructed via homotopic algorithm. The results have been analyzed for various parameters of interest and sketched for better understanding. The velocity profile reveals decreasing behavior for increasing values of Weissenberg number and Hartman number while converse behavior is found for mean flow rate and Hall parameter. The temperature profile falloffs for heat transfer Biot number and Hartman number whereas it increases for Prandtl number, Brinkman number, Dufour number and Hall parameter. The concentration profile tends to decrease for mass transfer Biot number and increase for Schmidt constant.

Predicting breakthrough of vanadium in fixed-bed absorbent columns with complex groundwater chemistries: A multi-component granular ferric hydroxide−vanadate−arsenate−phosphate−silicic acid system

Granular ferric hydroxide (GFH) is often used for fixed bed adsorbent (FBA) columns in groundwater purification units around the world to remove arsenate contaminations. Groundwater can contain also other toxic (e.g., antimonite and vanadate) and non-toxic oxo-anions (phosphate and silicic acid) that are known to affect FBA lifetimes. Therefore, understanding the breakthrough of toxic compounds intended for removal by FBA is essential to their design, and is important to predict accurately breakthrough curves (BTCs) for FBAs in waterworks to plan future operating costs. Rapid small-scale column tests (RSCCT) and pilot-scale FBA were used to simulate vanadate BTCs for complex groundwater chemistries. The BTCs were simulated successfully using a homogeneous surface diffusion model (HSDM) combining equilibrium chemical adsorption and kinetic mass transfer. Adsorption parameters for various groundwater compositions were predicted using the CD-MUSIC surface complexation model, which was set up for the first time for akaganéite-based granular ferric hydroxide with a competitive multi-solute system. The results indicated that V(V) is less prone to competitive adsorption effects, and use of the homogeneous surface diffusion model to predict the BTCs requires then the kinetic mass transfer Biot number to be used as the only fitting parameter. On the other hand, a concentration overshoot could be observed for the two weaker absorbed oxo-anions arsenate and phosphate because of displacement by the vanadate. Results of pilot scale test column BTCs of vanadate for three waterworks with different groundwater compositions could be favorably extrapolated with a unique Freundlich constant kF of 3.2 derived on basis of the multi-solute CD-MUSIC model, and a unique Biot number of 37 fixed for all three different test sites.

Mesoscale transport-geometry interactions in lithium ion cathode active materials: Particle scale galvanostatic simulations based on X-ray nanotomography data

Simulation results of lithium diffusion in Li(Ni1/3Mn1/3Co1/3)O2 under galvanostatic discharge (intercalation) conditions are presented for a set of cathode active material particles imaged using X-ray nanotomography. A range of operating conditions from 0.5C to 10C are considered. Behavior of these real particles is compared to idealized spherical particles on the basis of dimensionless parameters that link particle morphology, lithium diffusion and reaction kinetics. These parameters include the particle sphericity, a mass transfer Biot number and a mass transfer Fourier number. At lower C-rates, lower Biot numbers, and higher sphericities the spherical particle model proves sufficient, and the spherical particle model predicts minimum concentrations within one standard deviation of the average behavior of the particle ensemble that is analyzed. However, at higher C-rates, higher Biot numbers, and intermediate Fourier numbers the spherical particle model significantly overestimates the state of charge in the active material particles, an error that may underestimate lithium available for plating at the anode and state of charge dependent degradation in cathode materials. The results presented highlight a need and means for more accurate assessment of the influence of microstructural geometry on battery performance under aggressive current conditions.

3D simulation of transport phenomena of onion drying with moving boundary in a vacuum oven

AbstractThis study aimed to perform numerical simulation of the onion drying process considering its deformed geometry. For this purpose, transport phenomena such as heat and mass transfer in the onion structure and water vapor transfer in its porous structure were simulated in 3D form with Darcy's law during the vacuum drying process for onions. The simulated results were validated by experimental data. Heat and mass transfer rates were determined using kinetic data. Simulation of onion drying revealed that deformed geometry should be included in the model to represent the faster removal of water from the onion due to the increase in mass transfer surface area. The influence of drying temperature (313, 323, 333, and 343 K) on drying time and water concentration of onion was insignificant. The mass transfer Biot number revealed that the water vapor removal from onion was controlled by intraparticle mass transfer resistance.Practical applicationsThe main purpose of the vegetable drying industry is to obtain good‐quality dried products accompanied by savings in terms of energy and time. Recently, heat and mass transfer models constructed for drying of vegetables have focused on vegetables such as potato or carrot that provide limited information due to their uniform structure. An onion slice has a porous structure and increasing spaces between its rings; therefore in this study, heat and mass transfer occurring during vacuum drying of an onion was simulated considering the deformed geometry. The analysis of transport phenomenon mechanisms involves valuable information for researchers studying drying of food and large‐scale vacuum dryer designers in which 3D simulation of onion drying revealed that the deformed geometry fitted better to experimental results than undeformed geometry. The results of 3D simulation can be used to predict drying time and energy requirements of the process better than regular numerical modeling and may serve dried onion manufacturers.

Quantification of gas exsolution of alkane solvents-CO2 mixture in heavy oil with consideration of individual interfacial resistance under nonequilibrium conditions

A novel and pragmatic technique has been developed and validated to quantify gas exsolution of alkane solvent(s)–CO2–heavy oil systems with consideration of interface mass transfer for each gas component under nonequilibrium conditions. Experimentally, constant composition expansion (CCE) tests of three alkane solvent(s)–CO2–heavy oil systems are conducted with a visualized PVT cell under equilibrium and nonequilibrium conditions. The liquid height and pressure of the system are continuously monitored and recorded during experiments to measure, respectively, the bubblepoint pressure, pseudo-bubblepoint pressure, and the entrained gas volume. With the assumption of instantaneous nucleation, a mathematical model which integrates Peng-Robinson equation of state (PR EOS), Fick's second law, and nonequilibrium boundary condition has been developed to quantify not only the amount of the evolved gas and entrained gas, but also the dynamic composition of gas phase as a function of time. Once the deviations between the measured gas volumes and the calculated ones have been minimized, the mass transfer Biot number, individual diffusion coefficient, and interface mass transfer coefficient of each gas component as well as the gas bubble number are determined. Increases in experimental temperature and pressure are found to impose opposite effects on diffusion coefficient during gas exsolution processes. The diffusion of each gas component is found to be faster when the temperature becomes higher or the initial pressure becomes lower. Either CO2 or C3H8 diffuses faster than CH4 in the liquid phase under the same condition. In addition, the interface mass transfer coefficients, with an order of CO2 > CH4 > C3H8, obtained in this study are much higher than those collected in the literature since the nonequilibrium conditions greatly facilitate gas exsolution. The determined mass transfer Biot numbers in this study are large, indicating that the bulk resistance due to molecular diffusion inside the heavy oil dominates the gas exsolution process compared to the interfacial resistance.

Mathematical analysis of non-Newtonian nanofluid transport phenomena past a truncated cone with Newtonian heating

In the present study, we analyze the heat, momentum and mass (species) transfer in external boundary layer flow of Casson nanofluid past a truncated cone surface with Biot Number effect is studied theoretically. The effects of Brownian motion and thermophoresis are incorporated in the model in the presence of both heat and nanoparticle mass transfer Biot Number effect. The governing partial differential equations (PDEs) are transformed into highly nonlinear, coupled, multi-degree non-similar partial differential equations consisting of the momentum, energy and concentration equations via. Appropriate non-similarity transformations. These transformed conservation equations are solved subject to appropriate boundary conditions with a second order accurate finite difference method of the implicit type. The influences of the emerging parameters i.e. Casson fluid parameter (?), Brownian motion parameter (Nb) and thermophoresis parameter (Nt), Lewis number (Le), Buoyancy ratio parameter (N ), Prandtl number (Pr) and Biot number (Bi) on velocity, temperature and nano-particle concentration distributions is illustrated graphically and interpreted at length. Validation of solutions with a Nakamura tri-diagonal method has been included. The study is relevant to enrobing processes for electric-conductive nano-materials of potential use in aerospace and other industries.

Chemical reaction in peristaltic motion of MHD couple stress fluid in channel with Soret and Dufour effects

Abstract This paper looks at the peristaltic motion of MHD couple stress fluid in an inclined asymmetric channel. Simultaneous effects of heat and mass transfer are considered. Soret and Dufour features lead to the coupled differential systems. Channel walls satisfy the convective conditions of heat and mass transfer. Exact solutions for the stream function and pressure gradient are derived. Temperature and concentration are obtained numerically. Graphical illustrations for axial velocity, temperature, concentration and streamline patterns are developed. Physical interpretation of obtained results has been presented. It can be seen that both Soret and Dufour numbers reduce the concentration field while reverse effect is seen towards temperature for both numbers. It is also observed that concentration reduces towards destructive chemical reaction and enhances for constructive chemical reaction. The heat transfer Biot number gives rise to fluid temperature. Further more the mass transfer Biot number decreases the concentration.