Study Of Mass Transfer Research Articles

The study of heat and mass transfer during dehydration of gelatin from waste products of hydrobionts

Fish processing waste is rich in collagen and promising as a source of raw materials for the production of gelatin. Gelatin today remains one of the most popular collagens in various industries, while the main share in the Russian gelatin market is occupied by imported products. Given there are structural, mechanical and foam structural characteristics of gelatin extract, including from fish processing waste, one of the ways to increase the effectiveness of dried gelatin technology will be its radiation dehydration in foamy form. The formation of a stable foam structure leads to a significant intensification of the moisture removal operation due to the growth of the phase contact surface during transfer and exchange of thermal energy and substance, a decrease in adhesion between the drying object and the working surface of the unit and, as a result, to simplification of the separation of the dehydrated material from it and the elimination of the energy-intensive crushing operation finished products. The purpose of this research was to develop rational drying regimes of gelatin extract based on the study of kinetic laws of choosing ways to intensify the process of moisture removal. Foamed gelatin extract was dried in the form of round rods with volumetric convective and convective-radiation energy supply. Based on the results of experimental and analytical studies of convective and convective-radiation foam drying of gelatin, practical recommendations are given on the hardware design of the drying process, including the design of a complex convective-radiation drying installation, which is applicable both to the production of dry gelatin and similar complex properties thermolabile elastic-viscous, gel-like and paste-like materials.

Theoretical and experimental studies of molecular (atomic) exchange at the installation for measuring and analyzing the residual gas medium UID-2

The paper presents the results of studies of mass transfer in the measuring circuit of the UID-2 installation (installation of pressure measurement and analysis of the residual gas medium in the electro-vacuum devices), which consists of two parallel vacuum paths, in the volumes of which are placed a total pressure transducer and a monopolar mass spectrometric sensor, limited by pairs of inlet and outlet diaphragms. Using the Monte-Carlo method, estimates of the average density of the distribution of the number of molecules within specified intervals of the number of collisions of the latter with surfaces of characteristic dimensions of these volumes are obtained.The experimental results obtained within the accuracy of the experiment are consistent with the calculated data on the protective properties of diaphragms that prevent the negative influence of the heated cathode of the gauge transducer on the gas composition of the analytical sample during the quantitative and qualitative analysis of the residual gas medium in the electro-vacuum devices based on the implementation of the destructive method.

Numerical study of heat and mass transfer in MHD flow of nanofluid in a porous medium with Soret and Dufour effects

AbstractThis article models the transport mechanism of mass and heat energy under temperature and concentration gradients. Mathematical models in the form of partial differential equations based on conservation laws for fluid flow and transfer of heat and mass subjected to thermal diffusion and diffusion thermos, heat generation porous medium, and buoyancy forces are developed under boundary layer approximations. These models along with models of nanostructures are solved numerically using the shooting method with the Runge–Kutta method of order five. Convergent solutions are obtained and are used for parametric analysis regarding thermal enhancement of a working fluid having nanoparticles of CuO, Al2O3, and TiO2. Numerical experiments are performed and it is observed that the transport of heat is accelerated when the compositional gradient is increased. Similarly, a significant rise in the transport across concentration is noted when the temperature gradient is increased. The magnetohydrodynamic flow experienced retardation when the porous medium parameter and Hartmann number are increased. The temperature increased when the friction force produced heat and that heat is distributed to the particles of the fluid. Hence, viscous dissipation is responsible for widening the thermal boundary layer region.

Utilizing Low-Voltage Pulsed Electric Fields for Mass Transfer Intensification of Drops in Liquid–Liquid Extraction

Low-voltage pulsed electric fields, corresponding to field strengths of 2–16 V/cm, were utilized for mass transfer intensification of drops in a liquid–liquid extraction process. The chemical system of kerosene–acetic acid–water was used in which mass transfer resistance lies mainly in the kerosene phase. The applied frequencies were within 100–1000 Hz. In a hydrodynamic study, the circulating state of drops was confirmed based on different criteria and their terminal velocity precisely followed the Grace model. A mass transfer study of drops, on the other hand, revealed the strong impact of a pulsed electric field with the average and maximum enhancements of 30.3 and 70.5%. This can be attributed to the interfacial instability due to switching poles in the pulsed electric field. An optimum frequency of about 300 Hz corresponded to the applied voltages. Applying a direct electric field also had desired effects but in a lower extent. The provided mass transfer coefficient data were reproduced based on the Kumar and Hartland correlation together with a developed correlation of the enhancement factor in terms of dimensionless field strength, frequency, and the drops’ Reynolds number. The maximum deviation between experimental and predicted Sherwood numbers was ±5%.

Numerical simulation and experimental study of heat and mass transfer in cylinder-like vegetables during vacuum cooling

Vacuum cooling is an established technology widely applied on the processing of harvested vegetables. For the purpose of investigating heat and mass transfer in vacuum cooling of cylindrical vegetables, a mathematical model was established and eggplants were selected as research target. Comparison of simulated and experimental data was conducted for the validation of the mathematical model. Additional simulation was carried out to study the influence of pressure reduction rate on the temperature variation. The results show that the maximum error of temperature and weight loss are 14.2% and 18.3%. It is also found that temperature difference tends to be smaller when the pressure reduction rate increases. Data obtained from the simulation are consistent with experimental value, and the present study on influence of pressure reduction rate is helpful to the optimization of vacuum cooling process.

Adsorption and mass transfer studies of methylene blue onto comminuted seedpods from Luehea divaricata and Inga laurina.

In this work, comminuted seedpods of the forest species Luehea divaricata (LDPR) and Inga laurina (ILPR) were used as alternative and environmental-friendly adsorbents for the methylene blue (MB) removal from aqueous solutions. Batch adsorption experiments were carried out at the native pH of the solution (pH = 8.7), with curves of removal and adsorption capacity crossed at 0.75gL-1, having 125mgg-1 for LDPR and 115mgg-1 for ILPR. The kinetic models of pseudo-first-order (PFO) and HSDM-Crank were the most adequate to represent MB dye concentration decay data for both biosorbents. The equilibrium curves were better adjusted by the Langmuir model for both adsorbents, with maximum adsorption capacity increased from 279 to 325mgg-1 for LDPR, and 199 to 233mgg-1 for ILPR, as a function of an increase in temperature from 298 to 328K. The thermodynamic parameters showed that both systems are spontaneous with a dominance of physisorption. Mass transfer analysis indicates that the external mass transfer is the limiting step, with Bi < 0.5. Surface diffusion increased with the adsorption capacity, presenting linear and exponential behavior for the ILPR and PLPR adsorbents, respectively. Both materials proved to be efficient in treating a simulated effluent with similar industrial wastewater characteristics, reaching superior values at 70% of color removal.

Numerical modeling of segmented flow in coiled flow inverter: Hydrodynamics and mass transfer studies

A novel CFD modeling approach was developed to investigate the hydrodynamics and mass transfer in a gas–liquid slug flowing through microscale coil and coiled flow inverter channels. One straight slug model was formulated by adding a virtual centrifugal body force. The model was validated in terms of the helicity and secondary flow magnitude. The secondary flow magnitude was shown to be a power function of the Dean number, and a new correlation was proposed. The mass transfer across the interface was compared to that obtained in previous studies. The new model described the temporal and spatial distribution of species in the slug reasonably well. The volumetric mass transfer coefficient kLa in the coil was found to be 1.5 times higher than that in the straight channel, and the enhancement in kLa reached a maximum at a modified Dean number of 1.2.

Extensive analyses of mass transfer, kinetics, and toxicity for hazardous acid yellow 17 dye removal using activated carbon prepared from waste biomass of Solanum melongena

The present study was focused on the synthesis of brinjal waste activated carbon (BWAC) from the dry woody part of brinjal plant by chemical activation method. The BWAC was used as adsorbent to remove acid yellow 17 (AY-17) from the synthetic solution. For BWAC synthesis, phosphoric acid was used as a chemical reagent for chemical activation at a ratio of 1:1, followed by pyrolysis of chemically treated biomass in N2 atmosphere at high temperatures in a vertical reactor for improved chemical and surface properties of BWAC. The BWAC was characterized by several techniques such as BET surface area, pore distribution, SEM, FTIR, XRD, and point of zero charge (pHPZC). Various affecting parameters such as equilibrium time, initial pH, BWAC dose, AY-17 concentrations, and temperature for dye removal by BWAC were also investigated in the batch experiment. The maximum of 99.58% removal of AY-17 dye by BWAC occurred at pH 3. More than 97% dye was removed by BWAC from aqueous solution for initial 15 mg/L AY-17 dye concentration with other conditions such as 2 g/L dose, 5.00 ± 0.2 pH, 80 min equilibrium time, and 25 °C temperature. Therefore, further experiments were carried out at pH 5. Equilibrium data were fitted with the isotherm models such as Langmuir, Freundlich, and Temkin, and according to the correlation coefficient (R2), the Langmuir model was best fitted among them. The experimental kinetic data was well-validated with the pseudo-second-order kinetic model. The mass transfer studies of the dye onto BWAC were described by three models, such as Weber-Morris (intra-particle diffusion), Banghum’s, and liquid film diffusion models, and the result reported that all steps were involved for the adsorption process. The order for the rate-determining step, according to R2, was intra-particle diffusion > Bangham’s model > liquid film diffusion model. Recovery and recycling of dye-treated BWAC with desorption efficiency of ~ 73% was possible by 1 M NaOH treatment after 5th cycles. The simulated dye solution after treatment by BWAC was used in seed germination for toxicity assessment.

Effect of an Oscillating Grid on Hydrodynamics and Gas-liquid Mass Transfer in an Aquarium

This experimental study describes the effect of the oscillating grid on hydrodynamics and mass transfer in an aquarium. The contribution of the two driving elements CO2 and oscillating grid is identified. Depending on the operating conditions, either these two effects add up and promote the circulation and transport of the liquid, or these effects are opposite, the liquid velocity is then reduced. On the other hand, with regard to gas-liquid mass transfer, the use of the grid is beneficial since, under certain operating conditions; the mass transfer coefficient is increased compared to that obtained without the grid. Analysis of the various energy contributions in the unit shows that the presence of the grid is justified only in cases where the CO2 flow rate must remain low. Flow characterization was performed using Particle Image Velocimetry (PIV) technique. The results were compared with previous studies. In order to perform the concentration field measurements by planar laser induced fluorescence (PLIF) technique and simultaneous PIV and PLIF measurements, the test bench was modified. The observations of velocity and concentration fields are in adequacy with the previous studies and allow to validate the bench. The necessary tools have been put in place, the study of mass transfer can continue.

Enhanced Heat and Mass Transfer Study on the Tubular Fixed-Bed Reactor with Helical Fins Around the Inner Heating Pipe for Methanol Steam Reforming Reaction

Enhanced Heat and Mass Transfer Study on the Tubular Fixed-Bed Reactor with Helical Fins Around the Inner Heating Pipe for Methanol Steam Reforming Reaction

Production of modified sunflowers seed shells for the removal of bisphenol A.

In this present study, an abundant, available lignocellulosic biomass, sunflower seed shells, SSS, was used as a precursor to prepare an effective eco-adsorbent by treatment with H2SO4. A study of the surface characteristics of raw and acid-treated SSS (ACS) has shown that the addition of H2SO4 greatly affected the physicochemical properties of the obtained eco-adsorbent, improving the BET surface area from 6.106 to 27.145 m2 g−1 and surface oxygen-rich functional groups. Batch experiments were performed to assess the removal efficiency of a phenolic compound, bisphenol A (BPA), on the adsorbents. Several parameters were evaluated and are discussed (contact time, pollutant concentration, adsorbent dosage, and pH), determining that the adsorption efficiency of BPA onto SSS was notably improved, from 20.56% to 87.81% when a sulfuric acid solution was used. Different canonical and stochastic isotherm models were evaluated to predict the experimental behaviour. A dynamic study was performed based on the models of reaction kinetics and those of mass transfer. The results showed that the adsorption kinetics of BPA obey the fractal like-kinetic model of Hill for all experimental conditions. The equilibrium data are well suited to the Hill–Sips isotherm model with a determination coefficient >0.999. The kinetic modelling also indicates that the adsorption processes of BPA onto ACS are exothermic and proceed through a physical mechanism. A mass transfer study, using simplified models, proved that the process is controlled by intraparticle and film resistances to mass transfer of the BPA.

Numerical study of heat and mass transfer in a desalination system

In today’s world the demand for freshwater, to meet the needs of human activities is growing exponentially. As a result, manufacturers are continuing to make progress in the design and production of efficient desalination and cooling units to optimize and reduce the overall cost of production. In this work, we study the numerical study of the evaporation of a thin liquid film dripping by gravity with constant feed rates in a closed rectangular cavity formed by two parallel flat plates. The wall which supports the liquid film is heated by a constant temperature heating, while the other is kept at a constant and uniform temperature to condense the formed vapor. The results obtained show that the heat transfer in the distillation cell is dominated by the latent heat transfer associated with the evaporation. The results also show that the temperature of the film increases slightly for the heating zone and then decreases over most of the plate for the evaporation zone

Mass Transfer Coefficients in Electrochemical Membrane Process of Iron, Magnesium and Manganese Ions Extraction from Technological Solutions Complicated by Concentration Polarization

The article presents the results of a study of mass transfer in the process of electrochemical extraction of iron, magnesium and manganese ions from technological solutions. Mathematical expressions are obtained, and numerical values of empirical coefficients are determined for theoretical calculation of specific outflow, retention coefficient, and average mass transfer coefficients of the electrochemical membrane process of separation of technological solutions. The dependence of concentration polarization on solution flow rate, pressure gradient, and concentration is analyzed.

Extraction and mass transfer study of Cupressus sempervirens L. oil by hydro-distillation method

Abstract The extraction of Cupressus sempervirens L. or cypress essential oil was studied in this paper. This cypress oil was extracted by using the hydro-distillation method, using a clevenger apparatus. Cupressus sempervirens L. leaves were collected from Hit city in Al-Anbar province – Iraq. The influences of three important parameters on the process of oil extraction; water which used as a solvent to the solid ratio (5:1 and 14:1 (ml solvent/g plant), temperature (30 to 100 °C) and processing time, were examined to obtain the best processing conditions to achieve the maximum yield of the essential oil. Also, the mathematical model was described to calculate the mass transfer coefficient. Therefore, the best conditions, that were obtained in this study, were at 4hr as a reaction time, the temperature of about 100 °C, solvent to solid ratios of 10:1 ml solvent/g plant. The volumetric mass transfer coefficient at ratios 10:1 and 14:1 solvent to solid ratio were 0.017 and 0.007 min−1 respectively. Thus, it took less time to extract the Cupressus Sempervirens L. oil by using the 10:1 compared to using 14:1 solvent to solid ratio. The composition compounds of extracted C. sempervirens L. essential oil was analyzed and identified by Gas Chromatography Mass Spectrometry (GC-MS).

Comparative studies of removal of hazardous dyes, methylene blue (MB) and malachite green (MG) from solutions by low cost activated carbon

The removal of two hazardous dyes, MB and MG newly synthesized economic activated carbon. The adsorbent was synthesized from an agro waste material. The activated carbon has been characterized by XRD, FTIR, SEM, and surface area. A comparative study of the removal of selected dyes was reported. The process of removal for both the dyes is optimized for important parameters. It has been observed that removal of the dyes is maximum in alkaline range of pH. Both for MB and MG, the removal is controlled by first order kinetics. Mass transfer studies for both the dyes have been reported and the values of coefficient of mass transfer are found to be 2.25×10-5 cm/s and 1.92 cm/s respectively at 30°C. The rates of transfer of dyes onto the adsorbent surface were significant both the cases. The process of removal is endothermic and in both the cases higher temperature favoured the removal. Equilibrium data fitted Freundlich adsorption isotherm and the values of constants are found to be 0.59 and 3.01 mg/g for the removal of selected dyes. The results show suitability of the synthesized material for both the systems and can serve as baseline data for dyes removal.

A colorimetric technique to characterize mass transfer during liquid-liquid slug flow in circular capillaries

Continuous slug flow in microreactors are featured by alternative presence of regulate segments of immiscible phases in microchannel or capillaries with lateral dimensions below 1 mm. Due to the high interfacial area and short diffusive distance therein, such microreactors have been widely applied in chemical engineering processes that are sensitive to mass transfer. Therefore, mass transfer rates in microreactors have long been broadly investigated via either typical offline or online methods. Compared to these conventional methods, the colorimetric technique based on the oxidation of resazurin with oxygen enables direct determination of physical mass transfer rates. However, this technique was currently applied only to the gas-liquid system in microreactors, and mostly in rectangular channels due to the simplicity in image processing. Based on this, the current paper showed a demo where the colorimetric technique using resazurin was adapted to a liquid-liquid system for the mass transfer study of flowing droplets within a slug flow capillary. Experimental tips and tricks were summarized, and a sliced color-concentration calibration strategy was proposed to balance analyzing efficiency and accuracy.

Quantitative study of density-driven convection mass transfer in porous media by MRI

CO2 geologic storage in deep saline aquifers is a promising technology to reduce greenhouse gas emissions and maintain the pace of economic development. The dissolution and convection of CO2 injected into brines are the primary trapping mechanisms to enhance storage efficiency and provide long-term storage security. The spatial mass transfer characteristics of convection in porous media remain poorly understood. In this study, two kinds of analogous fluid pairs were used as the equivalents of CO2-saturated brine and in situ brine. Density-driven convection experiments using magnetic resonance imaging (MRI) technology in heterogeneous porous media were performed at various stages, including the diffusion stage, the unstable trigger stage and the convection development stage. Combined with the spatial evolution of the fingers and the change in MRI mean intensity, the local fluid concentration and overall mass transfer behavior could be quantified. Physical quantities associated with mass transfer by convection, such as the mixing layer thickness and scalar dissipation rate at the diffusion stages, the onset time at the unstable trigger stage, the average velocity of the front finger, the finger number, the transverse concentration gradient of the finger, and the sweep area of the finger at the convection development stage, were also analyzed systematically. We found that convective mixing substantially promotes mass transfer over pure diffusion, and the dissolution rate can be further enhanced by improving the injection method at each stage. The range of Ra in this study covers most CO2 capture and storage (CCS) sites and can provide basic data for engineering applications.

Mass transfer study in eductor liquid–liquid extractor: Dimensional analysis and response surface methodology modeling

AbstractIn this work, the mass transfer performance of a new eductor liquid–liquid extractor is investigated experimentally and modeled by dimensional analysis and response surface methodology (RSM) with the utilization of water/acetic acid/toluene system. A correlation is derived for the overall mass transfer coefficient versus the Reynolds number, throat to nozzle area ratio, projection ratio, and the two phases of flow rates ratio. Based on the obtained results, the Reynolds number is known as the most effective parameter. Also, different hydrodynamic and geometrical parameters, giving the same Sauter mean diameter, have different mass transfer coefficients due to differences in droplet size distribution. In addition, the RSM studies show that the effects of the parameters are in the order of the two phases of flow rates ratio, the venturi throat to nozzle tip distance, nozzle diameter, and venturi throat diameter. The maximum overall mass transfer coefficient obtained equals to 0.000278 m/s for the studied system.

Analytical study of heat and mass transfer in MHD flow of chemically reactive and thermally radiative Casson nanofluid over an inclined stretching cylinder

The main purpose of this study is to give a mathematical analysis of heat and mass transfer in a boundary layer flow of Casson fluid over an inclined stretching cylinder in the presence of magnetic nanoparticles. The effects of Casson parameter, curvature of the cylinder, angle of inclination, Buoyancy force, external magnetic field, thermal radiation, Joule heating, viscous dissipation, heat source and chemical reaction are taken into account. Appropriate transformations are incorporated to convert the governing partial differential equations and the boundary conditions suitable for computation. The elegant optimal homotopy analysis method is used to obtain analytic approximations for the resulting system of nonlinear differential equations. The features of flow characteristics such as velocity, temperature and concentration profiles in response to the variations of the emerging parameters are simulated and examined in detail. Extensive analysis is also made to explore the influences of relevant constraints on the rates of momentum, heat and mass transfer near the surface of the cylinder. Among the many outputs of the study, it is found that increasing the non-Newtonian Casson parameter can slowdown the flow velocity and enhance the temperature and concentration profiles. It is also revealed that significant enhancement of wall friction and mass transfer rate can be achieved by increasing the curvature of the cylinder. Further, the analytic approximations obtained by implementing the optimal homotopy analysis method to the present model are in close agreements with previous studies under common assumptions.

Problem of heat transfer in compact heat exchangers using variable thermal resistance

The paper presents the results of a complex of studies, analysis of the efficiency of the heat exchangers of aircraft ACS, as well as developed methods for protecting the heat transfer surface from freezing and thermal stresses. The basis of the work was the results of experimental studies of heat and mass transfer of a three-phase flow of “moist air - supercooled water aerosol” with a negative temperature in the CPFHE channels. As well as previously developed methods for modeling the processes of local heat transfer in compact heat exchangers with two-phase coolants (condenser) and in the presence of thermal stresses at high temperatures of hot air (preliminary heat exchanger). The proposed methods are based on the idea of obtaining a given surface temperature by changing the thermal resistances during the heat transfer process. The improvement of the models consists in taking into account the variable thermal resistances along the length of the hot and cold tract. In particular, the parameters of heat transfer processes defined by the geometry of the fins and flow regimes, as well as local heat and mass transfer processes during phase transitions.