Investigation of Thermal Processes in Gas‐Thermal Spraying of Metal‐Ceramic Coatings

The features of the thermal regime of gasthermal deposition of metalceramic coatings have been studied. The procedure of calculation of the temperature field of a multicomponent coating throughout the process of formation has been developed. The quantitative dependences of the character of heating of the deposited particles and melting of the substrate on the thermophysical properties and chemical composition of the material, the intensity of heat exchange, and the technological parameters of the process have been established. The thermal conditions of spraying of powder compositions, which ensure improved strength characteristics of the coating–substrate system, have been determined.     

Determination of the Chemical Potential of Mass‐ and Heat‐Transfer Processes in Porous Bodies

The problem of determining the chemical potential of mass and heattransfer processes for porous bodies of a classical shape (an infinite plate, a sphere, etc.) is considered; the solution obtained is illustrated with examples of the nonisothermal extraction and nonisothermal adsorption purification of vegetable oils.     

Heat and Mass Transfer in a Two‐Component Developed Turbulent Gas‐Vapor‐Droplet Flow

A calculation model is developed and a numerical study is made of the heat and mass transfer characteristics in a turbulent gas–vapor–droplet flow moving in a round tube. The model takes into account the evaporation of droplets, the diffusion of vapor into air, and the acceleration of a carrier flow. Distributions of the parameters of the twophase flow are obtained with respect to the tube radius for different initial concentrations of the gas phase. Heat and masstransfer calculations are compared to the experimental and numerical works. On the whole, the evaporation of the droplets in the vaporgas flow leads to the intensification of heat transfer as compared to a onecomponent vapordroplet flow and singlephase flow of vapor.     

Modeling of Heat and Mass Transfer in Systems of Radiation‐Evaporation Thermal Protection

Results of theoretical and experimental studies of models of different systems of radiationevaporation thermal protection are presented; the overalldimensionweight parameters of these systems and of systems of passive radiation thermal protection are compared.     

Mathematical Model of Dynamic Heat‐ and Mass‐Exchange Processes in a Glassmaking Furnace

Theoretical foundations have been developed and a mathematical model of dynamic heat and massexchange processes in a glassmaking furnace has been constructed, which makes it possible to calculate and visualize nonstationary temperature fields in the furnace volume and nonstationary fields of velocities of convective glassmass flow in the molten bath. Test calculations for a specific structure of a glassmaking furnace which have shown the effectiveness of the model constructed have been performed.     

Some Three‐Dimensional Effects of Heat and Mass Transfer in a Fire within a Building

Results of a numerical investigation of heat and mass transfer at the initial stage of a fire within a building in combustion of a liquid fire load, performed with the use of a threedimensional mathematical field model, are presented. Formulas approximating the calculation results are proposed for estimation of the maximum time of operation of an opening to release the gas from the building and determination of the size of the zone within which a change in the position of the fire load causes no marked changes in the parameter of heat and mass transfer. Threedimensional inhomogeneities in the temperature and velocity fields, which have a profound impact on the problems of providing fire safety for buildings, are revealed.     

Heat and Mass Transfer in Condensation of Harmful Air‐Polluting Substances on the Phytocenosis Surface

A mathematical model for the condensation of harmful airpolluting substances on the phytocenosis surface is formulated. Results of a numerical study of the problem of heat and mass transfer are presented. The temperature and concentration fields, the time dependence of the condensation rate, and the distribution of the condensate film over the phytocenosis surface are obtained.     

Modeling of Processes of the Formation and Transformations of Nanoclusters in a Rapidly‐Cooling Mixture of a Vapor and an Inert Gas

Abstract

As the initial state, we consider a high‐temperature vapor consisting of atoms (or a mixture of atoms and small clusters). It is assumed that during a rapid expansion of the vapor and its mixing with a buffer gas (e.g., helium), it cools down to the temperature when the dissociation of clusters run slowly, while the processes of nucleation (association) of particles dominate. Such approach was employed, e.g., for modeling of processes of formation of carbon nanoclusters (CNC) in a carbon arc.     

Local Forecast of the Heat‐Moisture State of the Soil Surface as a Problem of Energy and Mass Transfer in the System of Soil–atmosphere

Consideration is given to the dynamic problem of forecasting a frost on the soil surface, namely, of establishing the fact and the moment of the water–ice and water vapor–ice phase transitions at the soil–atmosphere interface, in calculating the evolution of the heatmoisture state of the viscousbuffer layer of air and the nearsurface layer of soil that are adjacent to this interface. The results obtained can be used for prediction of ice formation on runways of airfields and on roads.     

Experimental Study of the Velocity of Sound in Liquid n‐Tetradecane at Temperatures from 303.15 to 433.15 K and Pressures to 100 MPa

The velocity of sound in liquid ntetradecane has been studied experimentally in the interval of temperatures from 303 to 433 K and pressures to 100 MPa. The maximum measurement error amounts to 0.1%. Experimental data on the velocity of sound in liquid ntetradecane in the region of the state variables p = 50–100 MPa and T > 373 K have been obtained for the first time. It has been shown that the new data demonstrate the reliability of the structure–property quantitative correlation proposed earlier for the acoustic quantity in the series of nalkanes.     

Mass Transfer,Gas Holdup,and Kinetic Models of Batch and Continuous Fermentation in a Novel Rectangular Dynamic Membrane Airlift BioreactorOA

Compared with conventional cylinder airlift bioreactors(CCABs) that produce coarse bubbles, a novel rectangular dynamic membrane airlift bioreactor(RDMAB) developed in our lab produces fine bubbles to enhance the volumetric oxygen mass transfer coefficient(kLa) and gas holdup, as well as improve the bioprocess in a bioreactor. In this study, we compared mass transfer, gas holdup, and batch and continuous fermentation for RNA production in CCAB and RDMAB. In addition, unstructured kinetic models ...