Complex Optimization of Processes of Heat Exchange in Gas‐Firing Installations with Utilization of Heat

Results of complex experimental investigations of the processes of combustion and combined heat exchange with separation of radiative and convective components of boilers with utilization of secondary energy resources are presented. The complex optimization is conducted by solving a system of partial differential equations on EC, CM, and IBM computers. For the purpose of controlling the combustion and heatexchange processes automatically, the calculated dependences are given and charts of regimes are composed.     

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.     

Heat‐Transfer Processes in a Plasma Reactor in Destruction of Pesticides

The possibility of using a multijet electric arc plasmachemical reactor for decontamination and destruction of different powder pesticides with an expired effective date and storage life which have not been used in agriculture is studied. Studies of heat transfer are conducted on a setup operating without processing of raw material and with supply of pesticides (isophen and butyl ester of 2,4dichlorophenoxyacetic acid) to the reactor. The composition of waste gases at the reactor outlet is studied.     

Heat Exchange on the Front Surface of a Blunt Body in a High‐Speed Flow Containing Low‐Inertia Particles

The method and results of an experimental investigation of the heat exchange on the front surface of a sphere in a supersonic flow containing particles of diameter d = 0.12–2.4 m and hollow particles of d = 160 m are presented. It has been revealed that in the case where even very small particles of d = 0.15 m are contained in an undisturbed flow and their concentration is low (of the order of a percent), the heat flux in the region of the critical point of the model markedly increases. A comparison of the experimental data with the data of calculations of the heat exchange in the region of the forward critical point which are based on the theory of a twophase laminar boundary layer has been made. A glow near the surface of the model was observed in the experiments conducted in total darkness.     

Numerical Calculation of the Flow Regimes of a Fluid Partially Filling a Horizontal Rotating Heat‐Exchange Cylinder

Consideration is given to a numerical determination of a twodimensional unsteady viscous flow with the free surface in a stationarily rotating horizontal cylinder in which heatexchange processes are carried out. The markerandcell method in a polar coordinate system is used. The features of modeling of the walllayer regime and the circulating flow regime that occur in rapid and slow rotation of the cylinder, respectively, are discussed. Based on the given results of numerical calculations, the influence of the Reynolds number on the character of flow is analyzed.     

Heat Exchange with Horizontal Cylinders in a Centrifugal‐Bubbling Bed

The authors present results of an analysis of experimental data on heat exchange on horizontal cylinders in rotating gasliquid flow. The hydrodynamic parameters of a thin film in a centrifugalbubbling bed have been determined based on the mathematical modeling of a film flow in the case of a highvelocity gasliquid flow about it. Results of a generalization of the data on heat exchange are given, and the hydrodynamic stability criteria for the film flow on the cylinder surface are evaluated.     

Convective Heat Transfer in a Bubble Laminar Flow in a Round‐Cylinder Tube

The problem of heat exchange between a twophase laminar flow in a roundcylinder tube and the isothermal wall of the tube is studied. An exact analytical solution is obtained.     

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.     

Temperature Field of a Half‐Space with a Thermally Thin Coating in Pulse Modes of Heat Exchange with the Environment

Characteristic features of the process of formation of the temperature field at the boundary of a solid body simulated by a homogeneous halfspace with a thermally thin coating are studied by methods of mathematical modeling in realization of the pulsed modes of heat exchange with the environment.     

Heat Transfer in Straight Channels with Two‐Dimensional Cross‐Sectional Profiles under Conditions of Nonisothermal Stabilized Flow of a Fluid

Heat transfer in stabilized regimes of nonisothermal flows in a round tube and in channels with twodimensional convex cross sections is investigated with allowance for the velocity profile of a heating or cooling flow of a fluid. Mathematical models of unsteady processes of cooling by convection and radiation in pulling of rods and plane sheets at a constant velocity and of heat transfer (mass transfer) in a thin runningdown layer of a medium (fluid) are solved.     

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.     

Equalization of the Concentration of a Scalar Impurity in a Flow‐Type Chamber

Experimental and theoretical investigations of the time of equalization of the concentration of an impurity in a rectangular flowtype chamber have been carried out. It has been shown that the process of equalization of the concentration with time is exponential in character. The characteristic equalization time has been computed using the theory of turbulent diffusion. Theoretical results describe experimental regularities with an accuracy of about 10%. The value of the coefficient of turbulent diffusion for different configurations of flows in the chamber has been obtained from a comparison of experimental and calculated results.     

Mathematical Model of a Recuperative Heat Exchanger in a Two‐Dimensional Formulation

A twodimensional model of a recuperative heat exchanger which allows calculation of flows through a heattransfer wall and temperature at any point of it has been developed. The results of the calculations are in satisfactory agreement with experimental data.     

High‐Temperature Radiative‐Convective Heat Exchange on the Surface of Glass‐Reinforced Plastics

The results of experimental investigations of heat exchange on the surface of a thermalprotective material — glassreinforced plastic — in the flows of hightemperature gases have been presented. It has been established that the influence of injection on the value of the heat flux does not exceed 10% in the range of variation of gas temperatures 300–2000 K and Reynolds numbers 350–9800.     

Heat Exchange and Hydrodynamics of Two‐Phase Media under Conditions of Forced Motion in Porous Structures

Experimental data on the heat transfer and resistance of twophase media in porous structures are given. Results of calculating the thermal state of a heat exchanger with a porous insert that is cooled by a twophase flow are presented.     

Investigation of the Processes in Torches for High‐Speed Gas‐Plasma Spraying of Powder Materials with the Use of the Flow‐Rate Method of Action on the Flow

The comparative characteristic of torches with geometric and flowrate methods of control of the characteristics of a twophase flow are given. Based on the mathematical model proposed, the advantage of the flowrate method is shown by calculation. By using particular examples, the estimates of the optimum values are given for the relation of the flow rates in feeding units and for the length of the heating portion for torches with a flowrate method of control of the twophase flow.     

Process of Cooling of a High‐Temperature Two‐Phase Flow

A technique and a design of a transducer for measuring the enthalpy of twophase flows using the thinwall method have been developed. Working formulas for calculating the heat capacity and the enthalpy of a gas flow are substantiated. Results of a test of the transducer in hightemperature flows of powder gases, including those after the packing of a coolant, are presented. The results obtained show that cooling of powder gases due to an endothermic reaction makes it possible to decrease the enthalpy flux by a factor of 5 and the temperature by a factor of 2.     

Influence of a Long Stay of the Heat‐Release Surface in Kerosene on the Critical Heat Flux in Boiling in It under Steady‐State and Step Conditions of Heat Release

Results of experimental investigations of the influence of a long stay of the heatrelease surface in kerosene on the first critical density of the heat flux in boiling under the steadystate and step conditions of heat release are given.