Laws Of Mass Transfer Research Articles

Simulation of the micro-gas desublimation crystallization during pressurization of cryogenic propellant

The desublimation crystallization of trace impurity gas at the temperature of liquid hydrogen and liquid oxygen is a common problem in cryogenic engineering, which usually leads to the failure of cryogenic liquid transportation. Liquid hydrogen and liquid oxygen are important aerospace propellants. In the pressurization process of cryogenic liquid propellant, a small amount of water vapor and other gases in the pressurized gas would appear desublimation and crystallization at low temperature. Inevitably, as the tail gas of hydrogen combustion, water vapor sometimes diffused into cryogenic liquid. This kind of desublimation crystallization was accompanied by heat and mass transfer, accompanied by gas-solid phase transition, moving boundary, random and extremely complicated crystallization growth process. It was of great engineering practical significance to study the heat and mass transfer mechanism and law of this complex desublimation phase change phenomenon for the progress and development of engineering technologies such as refrigeration, cryogenics and aerospace. In this paper, based on the homogeneous desublimation theory, the pressurization system of liquid oxygen tank with oxygen containing trace water vapor was taken as the research object, and the basic data of ice crystal formation and growth during pressurization, such as crystallization quantity, crystallization speed and size distribution, were calculated theoretically. It provided a theoretical basis for the experimental study of the real dynamic characteristics and laws of desublimation crystallization in the propulsion system. The research methods and conclusions in this paper also had some guiding significance for the use of liquid hydrogen in the storage, transportation and use of the hydrogen energy.

Performance optimization of non-isothermal endoreversible chemical pump via Lewis analogy

By considering heat and mass transfer (HMT) coupling, an endoreversible non-isothermal chemical pump cycle model is established and the optimal performance is studied herein. Assuming that the HMT follows Lewis analogy (heat transfer (HT) process obeys Newton's HT law and mass transfer (MT) process obeys diffusion MT law), rate of energy-pumping (Σ) and its corresponding vector coefficient of performance (χT and χμ, which are defined herein) are deduced analytically. Based on the general optimization results, the special examples of endoreversible Carnot heat pump with Newton's HT law and the endoreversible isothermal chemical pump with diffusion MT law are further deduced. The effects of heat flux rate (q1) and mass flux rate (g1) on the optimization results are analyzed. The Σ increases with the increases of q1 and g1. The surface of Σ to [χT,χμ] is a monotonically decreasing plane, and the Σ decreases with the increases of χT and χμ. The special cases of endoreversible Carnot heat pump with Newton's HT law and endoreversible isothermal chemical pump with diffusion MT law are further obtained. The Σ and χμ obtained by endoreversible non-isothermal chemical pump are larger than those obtained by endoreversible isothermal chemical pump. Coupling effect of HMT increases Σ and χμ, but correspondingly decreases χT.

Numerical investigation of mixed convective flow of micropolar Casson fluid with Cattaneo–Christov heat flux model on an inclined vertical stretching surface

Abstract It is vitally critical to understand the dynamics of the non-Newtonian fluids model from an engineering and industrial perspective. Many industrial and technical activities, such as the extrusion of polymer sheets, the manufacturing of paper, and the development of photographic films, require non-Newtonian fluids. Energy transportation has numerous industrial applications, and classical heat and mass transfer laws do not accurately anticipate thermal and solute relaxation times. This study applies the modified Ohm law to heat and mass transport, utilizing Fick’s and generalized Fourier concepts. And the primary purpose of this study is to explore the characteristics of heat and mass transport in the magnetohydrodynamics-mixed convective flow involving a micropolar Casson fluid across the vertically inclined starching surface with multiple slip effects. Moreover, the study considers additional factors like thermal radiation, heat generation, chemical reactions, and the influence of thermophoretic to analyze both energy and nanoparticle concentration aspects comprehensively. To simplify the flow analysis, the original flow model is transformed into a couple of ordinary differential equations (ODEs) by employing relevant similarity transformations. These ODEs establish a system that is solved numerically by using the Bvp4c solver through MATLAB. It is worth noticing that a more substantial estimation of the thermal and concentration relaxation parameters decays the fluid temperature and nanoparticle concentration, respectively, and the growth of the material parameter reduces the drag force, which consequently augmenting the fluid velocity. Furthermore, the enhancement occurs in the skin friction due to greater estimation of the micropolar parameter, while the Casson fluid parameter causes the opposite trend.

Oxygen permeation mass transfer modeling and onion-like micromechanical modeling to predict the effect of multilayered interface on oxidation resistance and mechanical properties of composites

To predict oxidative damage of interfaces and fibers under high temperature aerobic environment and mechanical strength of composites before and after oxidation, oxygen permeation mass transfer modeling and onion-like micromechanical modeling of multilayered interface were proposed. The oxygen mass transfer theory and oxidation damage theory of PyC interface were used to establish the two models. The oxidative damage of PyC interface was extended to (PyC-SiC)n multilayered interface, and transformation of SiC phase and microcracks caused by thermal mismatch were also considered. The law of oxygen permeation mass transfer and the evolution of fiber oxidative damage in the “Carbon fiber/(PyC-SiC)n multilayered interface” region were revealed. The mechanical strength of composites under different interface layers was researched, resembling an onion-like wrapping in layers from the core outwards. Furthermore, Cf@(PyC-SiC)n/SiC(n = 1/2/3/4) composites were prepared by chemical vapor infiltration (CVI) method. The mechanical properties of the composites were tested before and after oxidation. A comparison was made between the experimental and predicted tensile strengths before and after oxidation. The predicted results of tensile strength were found to be in good agreement with the experimental ones. In addition, the results show that PyC-SiC multilayered interface has a positive effect on the tensile strength of the composites, mainly as the cracks are deflected and branched by the multilayered interface to promote the multistage pull-out of the fibers. With the increase of interface number, the oxygen diffusion path was lengthened and zigzagged, reducing the oxidative damage of fiber and interface.

Определение коэффициента теплопроводности деревянных клееных конструкций с учетом макроструктуры и плотности древесины

The paper considers calculated and experimental methods of determining the thermal conductivity coefficient of wooden glued structures. The author shows that when designing the thermal protection of building enclosure structures in the form of CLT-panels or wooden glued laminated timber, one uses reference data on the thermal conductivity coefficient for pine or spruce. In practice, the value of the thermal conductivity coefficient may be less than the reference value; as a consequence, the thickness of the building enclosing structures is overestimated. This is not reasonable in terms of material intensity of construction. When considering wood as an anisotropic material, the peculiarities of the macrostructure and differences in the density of individual layers, as well as the wood species, should be taken into account when determining the parameters of structures. Based on the physical description of the thermal conductivity process and the fundamental laws of heat and mass transfer, the author proposes that it is necessary to adjust the results of calculations to the actual values of the thermal conductivity coefficient of multilayer wooden glued structures. The paper presents the results of experimental determination of the thermal conductivity coefficient of pine and aspen wood using steady-state and unsteady heat flow methods. It is shown that, depending on the density and wood species, experimental values of the thermal conductivity coefficient from 0.102 to 0.115 W·m-1∙K-1 can be obtained.

A comparative study of passive drug diffusion through human skin via intercellular and sweat duct route: effect of aging.

A method of drug delivery that could provide control over medicine reaching the bloodstream for systemic circulation would be of immense importance. This work presents a comparative study of the temporal and spatial variation of drugs diffusing passively through two separate routes of human skin, namely intercellular (ICR) and sweat duct route (SDR). An analysis is carried out for two age groups (young < 40years and old > 60years of age). Governing equations based on Fick's law for mass transfer have been solved numerically using an in-house developed code. The code has been validated thoroughly with numerical and experimental work from the literature. Each skin route is modeled into three compartments sandwiched between the donor and receiver compartments. To understand the role of diffusion and partition coefficient on drug permeation, four drugs, namely hydrocortisone, trans-cinnamic acid, caffeine, and benzoic acid, are considered. The drug diffusion rate is found greater through ICR as compared to SDR. Further, the amount of drugs diffusing through both routes increases with age. Desirable drug characteristic is inferred to be a lower value of partition coefficient and a higher value of diffusion coefficient. This study could lead to real-time assessment of drugs reaching the bloodstream and beyond.

Cattaneo-Christov heat and mass fluxes model of Casson fluid employing non-Fourier double diffusion theories with ion slip and Hall effects

It is vitally important to comprehend non-Newtonian fluids flow behaviour from an industrial perspective. Non-Newtonian fluids are needed for a number of industrial and technical processes, including the production of paper, photographic films, and polymer sheet extrusion. There are several industrial applications for heat and mass transfer. However, thermal and solute relaxation time phenomena can't be predicted by classical heat and mass transfer laws (Fourier and Fick laws). This work aims to apply the modified Ohm law to thermal and mass transfer which are based on Fick's and generalized Fourier principles, respectively. The current study examines the three-dimensional Darcy-Forchheimer flow of non-Newtonian fluid “Casson fluid” via porous medium with ion slip and Hall effects across a stretched sheet. Thermophoresis and Brownian motion aspects are also considered. The diffusion phenomena are modelled using the Boungrino model. The modified Buongiorno model (MBM) for nanofluids is used to investigate the enhancement of heat transport. Together with practical nanofluid properties, it covers the mechanics of thermo-migration and random motion of nanoparticles. By adding the appropriate similarity transformations, this collection of (PDEs) that reflect the mathematical model is transformed into an (ODEs) system, which it is subsequently resolved utilizing the Lobatto IIIA technique's powerful computing capabilities via Matlab software. Data visualisations and numerical examples are presented considering many physical restrictions affect the fluctuation of velocities, temperatures, concentration, dimensionless shear stress, Nusselt number, and Sherwood number. According to certain findings, the existence of Hall and ion slip effects, and other factors contribute to an increase in horizontal velocity distribution. Furthermore, Fourier's law produces a wider temperature distribution than the Cattaneo-Christov heat flux model.

Mass transfer research on solid-liquid separation of extracted coal tar residue based on diffusion model

A large amount of coal tar residue (CTR) produced in the process of coal coking and tar processing is recognized as hazardous industrial waste with a high carbon content and strong carcinogenic polycyclic aromatic hydrocarbons. Through solvent extraction, CTR can be separated into economically valuable tar and fixed carbon, and waste recycling can be realized. In this paper, a mathematical model of CTR solid-liquid extraction is established based on a diffusion model and experiments, and the mass transfer law, mass transfer equation, and influence of different conditions of solid-liquid separation of CTR from toluene extraction are studied. First, the empirical formula is used to derive the change in the mass transfer coefficient kf outside the particles during extraction, and the kf gradually decreases as the extraction progresses. The particle swarm optimization is used to obtain the best effective diffusion coefficient Deff, inside the particles, which is 9.65 × 10−14 m2/s. The effective diffusion coefficient, Deff, was determined and corrected based on experimental data. A second-order function was fitted to describe the variation of Deff with temperature. MATLAB software was used to solve the model the concentration change law and extraction law during extraction were obtained. According to the model simulation, the influence of different conditions such as agent residue ratio, stirring speed, particle radius, and temperature on the extraction process is calculated.

Investigations of the Mass Transfer and Flow Field Disturbance Regulation of the Gas–Liquid–Solid Flow of Hydropower Stations

With the continuous depletion of fossil fuels, all countries attach importance to clean and sustainable development. The real-time state monitoring of multiphase flows is vital for enhancing hydropower station energy conversion. However, the material mass transfer mechanism and flow field disturbance regulation strategy faces significant challenges. To solve these problems, a computational fluid mechanics and discrete element method (CFD-DEM) coupling modeling and solution method based on a particle porosity model was proposed, and the mass transfer mechanism of gas–liquid–solid mixing flows was obtained under dynamic whirl intensity regulations. Combined with the user-defined function (UDF), the interphase forces and void ratios of fluids and particles were calculated to obtain the material mass transfer laws under dynamic disturbance regulations. The evolution characteristics of the particle flow pattern were tracked during the material mixing process. The results show that the mixed flow field had a high material transport efficiency under intensive whirl regulation, especially for the particle aggregation in the center of the reaction vessel. The maximum peak velocity and energy values of the particle transport process were 3.30 m/s and 0.27 × 10−3 m2·s−2. The higher whirl regulation improved the material transport process and conveying efficiency and enhanced the particle mixing effect in the reaction space. Relevant research results can provide theoretical references for material mass transfer mechanisms, dynamic regulation strategies, and particle flow pattern identifications and can also provide technical support for hydropower energy conversion.

Performance investigation and mass transfer enhancement of a novel cone-type solar seawater still

There are some disadvantages in the operating process of the basin solar seawater still (BSSS), such as long mass transfer distance, large heat indolence, huge floor space, and poor bearing pressure ability. A novel cone-type solar seawater still (CTSSS) is presented to overcome the weaknesses of the BSSS in this study. The CTSSS has the characteristics of seawater liquid film evaporation, short mass transfer distance, the condensation sleeve is parallel to and above the evaporation sleeve, and the condensation area is larger than the evaporation area. In order to clarify the performance of the CTSSS, the influence mechanism of feed seawater mass flow rate, heating power and heating temperature on the fresh water yield of the CTSSS was analyzed, the method of enhancing the mass transfer of the binary mixed gas in the CTSSS was explored, and the law of heat and mass transfer of the binary mixed gas in the annular enclosed small space was investigated. The results indicated that the maximum fresh water yield of the CTSSS is 62.7 g/20 min at the feed seawater mass flow rate of 400 g/h when the input power is 200 W, which is 4.5% higher than that when the feed seawater mass flow rate is 300 g/h. The performance ratio (PR) of the CTSSS is increased as the heating power, the PR of the CTSSS is 0.65 when 180 W heating power is employed. The steady state fresh water yield of the CTSSS with mirror condensation sleeve at 85°C is 84.6 g/20 min, which is 12.1% higher than that with non-mirror condensation sleeve Compared with the CTSSS with non-mirror condensation sleeve, the value of proportions of radiative heat transfer in the total heat transfer of the CTSSS with mirror condensation sleeve decreased by 6.6%, and the value of proportions of evaporative heat transfer increased by 6.4%. This study would provide a reference for small-scale decentralized application of solar desalination in remote areas.

Power maximization for a discrete-model of multistage dynamic irreversible isothermal-chemical-engine with linear mass-transfer law

Power maximization for a discrete-model of multistage dynamic irreversible isothermal-chemical-engine (IICE) with a linear mass-transfer-law is investigated by applying discrete-maximum-principle and dynamic-programming method with conditions of fixed initial-time and fixed initial key-component-concentration (KCC). Relationships among the maximum power (MPO), final-KCC and process-period for discrete multistage dynamic IICE system are discussed in detail. Results show that when final-concentration and process-period are fixed, there does exist an optimal control-strategy for MPO, and internal-irreversibility factor has a significant effect on the MPO, but the corresponding optimal-concentration-configurations are the same. When final-time and final-concentration are fixed and free, respectively, there does exist an optimal final-KCC for MPO, and change of internal-irreversibility factor has effects on MPO and the corresponding optimal-KCC configurations now; the more total stage-number of chemical-engines is, the more closely optimization results of discrete-model tend to those of the corresponding continuous-model. When final-time and final-concentration are free and fixed, respectively, numerical example shows that for the discrete multistage dynamic IICE system with total stage-numbers of N=25 and N=50, respectively, total MPOs are with relative errors of 1.66% and 3.33%, respectively, comparing with that for the continuous-model of multistage dynamic IICE system. Both the model established and the mothed adopted herein are effective.

Flow regime evolution mechanism and falling flux prediction model for bypass injection of viscous liquid in vertical T-junction

The gas–liquid two-phase flow in T-junction serves as a fundamental theoretical foundation for studying mass and heat transfer laws in industrial applications, including oil and gas resource development and material mixing in the chemical industry. We designed a T-junction pipeline consisting of a vertical gas flow pipe and a horizontal liquid injection pipe and conducted experiments to investigate gas–liquid two-phase flow with liquid bypass injection. The experimental results indicate that there are two critical states for the downward flow of liquid at the injection point at different gas velocities: Critical Downward Flow(CDF) and All Downward Flow(ADF). Based on liquid falling state and response law of falling flux, the liquid falling conditions were categorized into three regions: region without liquid falling (flux ratio = 0), region of all liquid falling (flux ratio = 1) and transition region(flux ratio from 0 to 1). Through analyzing the dynamic characteristics of gas–liquid two-phase flow at the connection point and considering the zero shear stress state of the pipe wall and flow pattern transition, a CDF criterion for the liquid was established. The flooding state of gas–liquid countercurrent was used as the limit condition for ADF, and a criterion for ADF was developed based on experimental data. Under varying liquid viscosity conditions, compared with experimental data, the error of the CDF criterion model is less than 5 %, and the error of ADF criterion model is less than 15 %. A liquid falling flux prediction model was established based on the two extreme states of liquid falling, and its accuracy was verified through experimental results, challenging the existing theoretical criterion of liquid falling flux ratio being limited to “either 0 or 1”.

Thermal modelling of microwave dehydration of fruit slice

The thermal modelling of microwave dehydration of papaya fruit slice was established. The mathematical modelling used approximation equations of the Heat and Mass Transfer laws, the development of internal heat resulting from the transformation of electromagnetic energy was investigated. MATLAB was used for coding the Partial Differential Equations (PDE) of the coupled system, to obtain the plots. The projected temperature, along with the mass loss while drying was analysed. Using Energy2D Computational Fluid Dynamics (CFD) model of the radiation in a box (microwave oven) procedure, the temperature at each point of the slice and moisture content was investigated. From the results it's significant that temperature was higher at the surface corner of the leading edge and lower at the symmetry leading edge. The depletion of water is more efficient when the surface temperature is higher and the surface moisture is lower than it is at the surface corner. The proposed model's capability to provide information on moisture and temperature at all times, a crucial aspect of food safety, allowing for the discovery of the region within the fruit. Hence, using the created model, it is possible to anticipate how temperature and moisture will vary over time.

Numerical and experimental investigation of 3D flow field bipolar plates for PEMFCs by metal 3D printing

The bipolar plate is one of the core components of a proton exchange membrane fuel cell (PEMFC). Its flow field structure directly affects the drainage and heat dissipation performance of the cell, as well as the transmission and distribution of the reaction gas. Compared with conventional 2D flow fields, novel 3D flow fields can provide superior gas–liquid mass transfer performance, significantly improving the performance of PEMFCs. However, traditional manufacturing processes fail to meet the associated molding needs, due to the complex structure of such plates. This research aims to investigate the metal 3D printing process, mass transfer law, and efficiency of 3D flow field bipolar plates, focusing on the influence of structural parameters on the gas–liquid mass transfer performance, by combining CFD multi-phase flow numerical simulations and experiments. The results indicate that the use of a 3D stepped flow field enhances the convection effect in the vertical direction due to the increase in Z-directional inflow, thus promoting oxygen transfer and reducing the accumulation of water. In particular, better gas–liquid mass transfer performance is achieved when the number of steps is 4. At 0.55 V, the measured power density of the Stepped-IV cell reached as high as 6727 W/m2, which is about 26 % higher than the conventional parallel flow field. This study provides an important technical and theoretical reference for the design and preparation of novel 3D complex flow fields.

A Bottom-up Transient Theory for Concentration Polarization with Applicability to over-Limiting Current Conditions

Renewable power sources have drawn interest due to scarcity of fossil fuels and associated pollution during their combustion-based power production. Renewables are projected to produce approximately 60% of US electricity generation by 2050, with an expected contribution of 2000 TW-h from wind power alone. To overcome the mismatch between electricity demand and intermittent supply, such power plants require large-scale energy-storage device integrated with them. In contrast to other technologies, redox flow batteries (RFBs) offer independently scalable power and energy capacity that is demanded for such applications. Despite significant achievement in their designs through experimentation and modeling, limited understanding has been established to date concerning their transient response while operating under irregular charge/discharge scenarios in renewable-powered grids and micro-grids. Under such conditions pore-scale mass transport physics and different mechanisms of concentration polarization can occur, but the conventional film law of mass transfer (FLoMT) using a constant Sherwood number cannot capture time-varying diffusion layer thickness near electrode surfaces. Further, the mean solute advection rate through porous RFB electrodes can deviate from the value expected from product of superficial velocity and average concentration inside the electrode if pore-scale concentration polarization is substantial. Consideration of these effects in the present bottom-up theory makes it applicable to over-limiting conditions, while predicting concentration polarization in agreement with experimental observations. We accomplish this by creating theory with similarity to the theory of Ralph White and co-workers for solid-state, particle-scale diffusion in Li-ion batteries [J. Power Sources, 2012, Vols. 214 and 218], while our theory is instead applied to an arbitrary representative volume element of flowing liquid electrolyte inside electrode pores.Here, we present a theory to incorporate these transient effects into a bottom-up transient model (B-UTM) by using frequency-dependent transfer functions (TFs) that are derived from the Fourier transformed pore-scale mass conservation equations (MCEs). These TFs preserve pore-scale mass transfer physics during their embedding into an up-scaled model. One of these TFs is the spectral Sherwood number that extends the film law of mass transfer to transient conditions and that correlates reactive flux with concentration polarization through an output-input relationship in the frequency domain. Another TF named the advective-flux transfer function captures the acceleration/suppression of solute advection rate that arises from the inhomogeneity in pore-scale concentration distributions. We first present validation of this theory using transient RFB experiments where the introduced B-UTM predicts the time evolution of concentration polarization in good agreement. Meanwhile the conventional FLoMT model that uses time-independent Sherwood number and neglects the solute acceleration/suppression effect shows systematically larger polarization (up to 400%), which restricts such models from simulating charging/discharging with applied current near and above the limiting current.The utility of the introduced bottom-up theory is demonstrated by incorporating it into a multi-scale RFB model in which redox-active electrolyte flows through a porous electrode comprised of an array of circular cylinders in crossflow that mimics commonly used carbon felt. The frequency dependence of the introduced TFs obtained from numerical solution of pore-scale MCEs are analyzed for different electrode porosity and Péclet number, where both the TFs reach a non-zero finite value in the limit of vanishing frequency. The non-zero value of the spectral Sherwood number in this limit is identical to the Sherwood number obtained in the pseudo-steady limit (PSL) where transient effects are negligible. With increasing frequency both the TFs show a transition from lagless response to semi-infinite Warburg response with orders higher values compared to that of the PSL. Finally, these TFs are embedded into an up-scaled model to obtain the time-domain response of RFBs operating under a step impulse applied current with different step durations. Numerically obtained concentration polarization and the average reactant concentration inside electrodes is used to construct non-dimensional regime maps showing a regime of over-limiting current. The results show that fast current fluctuations are sustained even when current exceeds the limiting current, which provides a means to increase the utilization of charge capacity of existing flow-based electrochemical devices that are operated under transient conditions. The theory introduced here can find applicability in other flow-based electrochemical devices including electrochemical separations and CO2 capture. Figure 1

Mass Transfer Analysis of CO2-Water-Rock Geochemical Reactions in Reservoirs

It is difficult to exploit low-permeability reservoirs, and CO2 flooding is an effective method to improve oil recovery from low permeability reservoirs. However, in the process of CO2 flooding, acidic fluids dissolved in formation water will react with rock to cause dissolution and precipitation, resulting in pores and precipitates, changing the evolution law of seepage channels, destroying formation integrity, and affecting the effect of CO2 oil displacement. The change in rock’s physical properties and the mass transfer law between CO2-water-rock are unclear. This paper considers the coupling effects of seepage, mechanics, and chemistry when CO2 is injected into the formation. The mass transfer model of CO2-water-rock in the geochemical reaction process is established on this basis. The physical properties of the reservoir after CO2 injection are quantitatively studied based on the microscopic mechanism of chemical reaction, and the migration law of solute in the reservoir rock during CO2 flooding under the coupling effects of multiple fields is clarified. The experimental results show that with the increase in reaction time, the initial dissolution reaction of formation rocks will be transformed into a precipitation reaction of calcite, magnesite, and clay minerals. The porosity and permeability of the rocks near the well first increase and then decrease. The far well end is still dominated by dissolution reactions, and the average values of formation porosity and permeability show an upward trend. Although the dissolution reaction of CO2-water-rock can improve the physical properties of reservoir rocks to a certain extent, the mutual transformation of the dissolution reaction and precipitation reaction further exacerbates the heterogeneity of formation pore structure, leading to the instability of CO2 migration, uneven displacement, and destruction of formation stability. The research results of this paper solve the problem of quantitative calculation of physical parameters under the coupling effect of multiple fields after CO2 injection into reservoirs and can predict the changes in formation physical properties, which can provide a certain theoretical basis for evaluating formation integrity and adjusting CO2 injection under the condition of CO2 flooding.

Perm School of Lymphologysts: theory, experiment and clinic

The paper narrates the early research on the lymphatic system in the city of Perm (Russia) in 1951 and the systematic study of lymph nodes during the period from 1954 to 1963 under the guidance of Professor Ivan Ivanovich Kositsyn. The second period of experimental lymphology development in Perm is associated with the name of Professor Elizaveta Nikolaevna Oleneva. Her research on the lymphatic vessels of various organs when creating typological models of experimental venous congestion and lymphostasis became the basis for understanding pathological processes in organ interstices. The development of clinical lymphology owes much to Professor Nadezhda Alexandrovna Garyaeva. Close scientific cooperation between the Perm and St. Petersburg lymphological schools led to the development of structural foundations of modern lymphodynamics theory. The discovery of the lymphatic valve tensor muscle determined the role of valves in lymph flow in a historical discussion question. Reconstructive-restorative operations on the thoracic duct for surgical lymphology are significant for the prevention of lymphostasis and thrombosis. The study of mass transfer laws of medicinal substances through the interstitium provided a scientific rationale for lymphotropic therapy at a new level. The terms “intersticiology,” “somatic lymphedema,” and “visceral lymphedema” have been introduced into scientific circulation. Analysis of fundamental lymphostasis research allowed for the development of drug treatment methods for post-radiation fibrosis and lymphedema. The Department of Human Anatomy with a course in clinical lymphology under the leadership of Professor N.A. Garyaeva, developing treatment technologies in gynecology, phthisiopulmonology, surgery, traumatology, pediatrics, and therapy, became the scientific-methodological center in the city of Perm for building knowledge in the field of lymphology. The Lymphatech Clinic, opened in 2007, gave a new impetus to the development of clinical lymphology. The Lymphatech method, providing targeted pharmacological correction of the structures and functions of the lymphatic system, has stood the test of time and proved itself as an essential pathogenetic therapy for many pathologies. Scientific and clinical results are reported and published at international conferences, including the leading journal Lymphology.

Performance simulation of plate-and-tube evaporative cooling frost-free heat pump heat exchanger

To verify the operational feasibility of the plate-and-tube evaporative cooling frost-free heat pump heat exchanger and its influence factors, a single plate-and-tube was selected as the simulation object, and the VOF model, RNG k-ε model, and self-programmed UDF program were used to control the water vapor transfer mass to verify the influence of air flow rate on the internal flow and heat and mass transfer law of the model. The results show that as the air velocity increases, the percentage of turbulent flow inside the model increases, and the solution coverage on the surface of the plate and tube decreases slightly; the heat and mass transfer increases with the increase of the flow velocity, and the latent heat, sensible heat, and total heat exchange increase with increase the of the flow velocity.

Hot‐air drying of corn kernels: Drying kinetics and quality improvement

AbstractBackground and ObjectivesDuring the hot‐air drying process of corn kernels, excessive stress can cause cracks to develop. For this reason, it's essential to identify the optimum parameters that can minimize stress during hot‐air drying.FindingsIn this study, a three‐dimensional fitness model was established based on the average geometric size of corn kernels. Additionally, a hot‐air drying model was constructed on the basis of heat and mass transfer, stress‐strain theory, and conservation law of heat and mass transfer. Simulated calculations of heat and mass transfer were performed to obtain the temperature and moisture gradient distribution. This distribution was then coupled with a stress model to reveal the variation of drying stress. Verification experiments were conducted on the drying model. The results indicated that the temperature and moisture gradient were symmetrically distributed about the geometric center of corn kernels. At symmetrical positions about the geometric center, their sizes were almost equal but their directions are opposite. The thermal stress and moisture gradient stress showed the fact of larger surface but smaller interior of corn kernels. Furthermore, they both increased rapidly in the initial stage and then slowly decreased. The maximum value of thermal stress was 4.57 kPa, and the maximum value of moisture gradient stress was 0.49 MPa.ConclusionsMass transfer plays a significant role in the hot‐air drying process, and cracks can develop as a result of excessive moisture gradient stress. To mitigate these issues, it's important to increase the air humidity in a controlled manner to significantly reduce the total stress. The maximum error in temperature between simulated and experimental results was 8.5%. This suggests that our drying model can be effectively utilized to explore temperature gradient, moisture gradient, and stress distribution of corn kernels.Significance and NoveltyThis study provides insights into the mechanism of stress generation that occurs during the hot‐air drying process of corn kernels. Our analysis indicates that properly increasing the air humidity can significantly reduce drying stress and consequently prevent the formation of cracks. This ultimately leads to improved product quality and economic value.

Numerical treatment of MHD Al2O3–Cu/engine oil-based nanofluid flow in a Darcy–Forchheimer medium: Application of radiative heat and mass transfer laws

This computational study was designed to examine the effect of alumina and copper on the flow of a nanofluid based on engine oil through a Darcy–Forchheimer porous media. The flow model incorporates the generalized radiative heat and mass transport rules. The Darcy–Forchheimer terms in the momentum equation and radiation term in the energy equation are integral parts of the governing nonlinear Navier–Stokes equations, which are two-dimensional partial differential equations. Under the constraint of the convective boundary, the stated PDEs are transformed into highly nonlinear versions of the ordinary differential equations. In order to solve the final ODEs, the numerical RK-45 approach is combined with the shooting methodology. Important aspects of the governing model include porosity, magnetohydrodynamics (MHD), a convective boundary, thermal radiation, and viscous dissipation. The final findings show that when the Forchheimer number increases, the velocity decreases because of the inertial effect included in the flow model. In addition, the velocity profile is improved due to the increased volume percentage of both kinds of nanoparticles. The temperature varies greatly depending on the volume fraction. A higher Biot number and the resulting convective border cause a greater heat flow than a non-convective barrier. For two particular examples, with and without MHD influence, interesting streamlines and contour graphs are produced.