Analysis of Thermal Conduction Effects on Thermoelastic Temperature Measurements for Composite Materials

1992 ◽  
Vol 59 (3) ◽  
pp. 552-558 ◽  
Author(s):  
S. A. Dunn
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Composite Materials ◽  
Surface Stress ◽  
Thermal Conduction ◽  
Dissimilar Materials ◽  
Stress Fields ◽  
Temperature Changes ◽  
The Mathematical Model

Measurement of the temperature changes which occur as a body undergoes a change in stress is becoming a widely used technique for the analysis of surface stress fields. In this paper, an investigation into the effects of thermal conduction on surface thermoelastic temperature changes for composite materials is reported. A mathematical model which shows the effects of thermal conduction is developed, and the results from this model are compared with experimental data. The mathematical model is then extended to solve for heat transfer between two thermally dissimilar materials. It is shown how this model can be used to account for the effects of a surface epoxy layer on the observed thermoelastic temperature changes.

Heat Convection from a Horizontal Cylinder Rotating in a Quiescent Fluid

1986 ◽  
Vol 10 (3) ◽  
pp. 141-152
Author(s):  
H.M. Badr ◽  
S.M. Ahmed
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Horizontal Cylinder ◽  
Heat Transfer Process ◽  
Two Dimensional ◽  
Two Dimensional Flow ◽  
Boussinesq Fluid ◽  
The Mathematical Model ◽  
Quiescent Fluid

The aim of this work is a theoretical investigation to the problem of heat transfer from an isothermal horizontal cylinder rotating in a quiescent fluid. The study is based on the solution of the conservation equations of mass, momentum and energy for two-dimensional flow of a Boussinesq fluid. The effects of the parameters which influence the heat transfer process namely the Reynolds number and Grashof number are considered while the Prandtl number is held constant. Streamline and isotherm patterns are obtained from the mathematical model and the results are compared with previous experimental data. A satisfactory agreement was found.

scholarly journals Simulation of Electromagnetic-Acoustic Heating of the Oil Layer in Laboratory Conditions

2021 ◽  
Vol 16 (1) ◽  
pp. 109-116
Author(s):  
Gulnara R. Izmailova
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
High Frequency ◽  
Additional Term ◽  
Oil Reservoir ◽  
Combined Effects ◽  
Physical Processes ◽  
The Mathematical Model ◽  
Account Heat

This paper describes an experiment to study the combined effects of high-frequency electromagnetic and acoustic fields on a model of an oil reservoir. A mathematical model is described that describes the physical processes that occur in the reservoir. The heat equation takes into account heat transfer with the environment by introducing an additional term. The largest discrepancy between theoretical and experimental data does not exceed 28%. Qualitative coincidence of theoretical and experimental curves indicates the adequacy of the mathematical model.

scholarly journals EXPERIMENTAL STUDIES OF HEAT EXCHANGE DURING WATER COOLING AND STEAM CONDENSATION IN DEMOVER RADIATOR SECTIONS

2021 ◽  
Vol 1 (38) ◽  
pp. 107-114
Author(s):  
V. Mogila ◽  
M. Kovtanets ◽  
M. Morneva
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Mathematical Model ◽  
Cooling System ◽  
Experimental Studies ◽  
Road Transport ◽  
Thermal Calculation ◽  
Mode Of Operation ◽  
Simulation Results ◽  
The Mathematical Model

The Department of Railwayand Road Transport, lift and care system of Volodymyr Dahl East Ukrainian National University, an energy-saving cooling system for diesel locomotives using phase transitions of the coolant has been developed. The proposed cooling system allows to maintain constant optimal temperatures of cooling objects at ambient temperatures ± 40 ºC and in any mode of operation of the diesel engine. For thermal calculation of the radiator section operating in the mode of the steam condenser, the mathematical model of process of heat transfer from steam to walls of a flat tube at condensation is developed that considers geometrical features of section of a tube. The adequacy of this mathematical model is verified by comparing the simulation results with the obtained experimental data. During the tests, the outlet water temperature, inlet and outlet air temperature, and air pressure in front of and behind the radiator were measured. Having the values of wall temperature, steam temperature and condensate, knowing the value of steam consumption and the experimental heat transfer coefficient, it becomes possible to verify the adequacy of the mathematical model by comparing the simulation results with the obtained experimental data. Schemes of bench equipment, test methods, experimental planning and basic calculation dependences required for testing serial radiator sections of a locomotive in the standard mode of operation and in the mode of steam condensers are presented.

The Analysis of Non-Fourier Heat Transfer Mechanism on Thermal Conductivity for Nanofluids

2007 ◽  
Author(s):  
Jurij Avsec ◽  
Maks Oblak
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Conductivity ◽  
Mathematical Model ◽  
Analytical Calculation ◽  
Heat Transfer Mechanism ◽  
Influence Of Temperature ◽  
The Mathematical Model ◽  
Brown Motion ◽  
Good Agreement

The paper features the mathematical model representing the analytical calculation of thermal conductivity for nanofluids. The mathematical model was developed on the basis of statistical nano-mechanics. We have made the detailed analysis of the influence of temperature dependence on thermal conductivity for nanofluids. On this basis are taken into account the influences such as formation of nanolayer around nanoparticles, the Brown motion of solid nanoparticles and influence of diffusive-ballistic heat transport. The analytical results obtained by statistical mechanics are compared with the experimental data and they show relatively good agreement.

scholarly journals MATHEMATICAL MODELING OF HEAT TRANSMISSION THROUGH THE ENCLOSURE CONSTRUCTION

2020 ◽  
pp. 29-39
Author(s):  
A. Grazhdankin ◽  
V. Ivanchenko ◽  
A. Pis'menskiy
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Temperature Distribution ◽  
Dissimilar Materials ◽  
Building Envelope ◽  
Transfer Resistance ◽  
Space Planning ◽  
Air Temperatures ◽  
The Mathematical Model ◽  
Stationary Heat Transfer

Currently, the main direction of energy saving in mass construction is the energy efficiency of structural and space-planning solutions of buildings and structures. To evaluate the thermotechnical qualities of the enclosure, it is necessary to know the value of the heat transfer resistance and the temperature in any plane of the enclosure at given air temperatures on one and the other side of the enclosure. To understand and describe the processes of heat transfer, as well as to determine the temperature distribution inside the enclosing structures, Tabunshchikov Y.A. and Brodach M.M. derived a mathematical model of heat transfer through the enclosing structure. When considering one-dimensional heat transfer perpendicular to the wall surface at the internal borders between dissimilar materials of the building envelope, it is assumed that the temperature functions T (x) and the heat flow Q (x) are continuous. The article presents an analytical and numerical solution of a boundary value problem for stationary heat transfer through a multilayer enclosing structure, as well as a comparison of the obtained solution with the current regulatory documentation. An experimental study is conducted in the laboratory to compare the theoretical, obtained in the mathematical model of heat transfer given in the article, and the experimental temperature distribution, which shows greater convergence of the results and confirms the validity of the mathematical model.

Systems Actuated by Shape Memory Alloys: Identification and Modeling

2021 ◽  
Vol 1 (2) ◽  
pp. 12-20
Author(s):  
Najmeh Keshtkar ◽  
Johannes Mersch ◽  
Konrad Katzer ◽  
Felix Lohse ◽  
Lars Natkowski ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Constitutive Model ◽  
Shape Memory Alloys ◽  
Numerical Simulations ◽  
Shape Memory ◽  
Transfer Equation ◽  
Mechanical Parameters ◽  
Heat Transfer Equation ◽  
The Mathematical Model

This paper presents the identification of thermal and mechanical parameters of shape memory alloys by using the heat transfer equation and a constitutive model. The identified parameters are then used to describe the mathematical model of a fiber-elastomer composite embedded with shape memory alloys. To verify the validity of the obtained equations, numerical simulations of the SMA temperature and composite bending are carried out and compared with the experimental results.

Application of a Bubble-Induced Turbulence Model to Subcooled Boiling in a Vertical Pipe

1999 ◽  
Author(s):  
Mahmut D. Mat ◽  
Yüksel Kaplan ◽  
Olusegun J. Ilegbusi
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Liquid Phase ◽  
Turbulence Model ◽  
Transport Equations ◽  
Subcooled Boiling ◽  
Vertical Pipe ◽  
Void Fractions ◽  
Turbulence Production ◽  
The Mathematical Model

Abstract Subcooled boiling of water in a vertical pipe is numerically investigated. The mathematical model involves solution of transport equations for vapor and liquid phase separately. Turbulence model considers the turbulence production and dissipation by the motion of the bubbles. The radial and axial void fractions, temperature and velocity profiles in the pipe are calculated. The estimated results are compared to experimental data available in the literature. It is found that while present study satisfactorily agrees with experimental data in the literature, it improves the prediction at lower void fractions.

Analytical Study of Hydro-Pneumatic Processes for Gorlov's Power System

1994 ◽  
Vol 208 (1) ◽  
pp. 67-70
Author(s):  
A I Ryazanov
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Power System ◽  
Analytical Study ◽  
Model Tests ◽  
Air Pressure ◽  
Pneumatic Power ◽  
Time Required ◽  
The Mathematical Model

This paper describes the aerohydrodvnamics of processes in chambers of Gorlov's hydro-pneumatic power system. The mathematical model is developed to determine the main parameters of the processes: water and air velocities, air pressure in the chamber, the periods of time required to fill and empty the chambers and the output of energy during the cycle. The results obtained are in agreement with experimental data and model tests.

scholarly journals MATHEMATICAL MODELING OF LEACHING PROCESS OF RED MUD IN ORDER TO OBTAIN THE KINETICS PARAMETERS

2015 ◽  
Vol 14 (2) ◽  
pp. 90 ◽  
Author(s):  
K. L. M. Dos Passos ◽  
B. M. Viegas ◽  
E. N. Macêdo ◽  
J. A. S. Souza ◽  
E. M. Magalhães
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Red Mud ◽  
Mineralogical Composition ◽  
Raw Material ◽  
Data Conversion ◽  
Kinetics Parameters ◽  
Leaching Process ◽  
Iron Leaching ◽  
The Mathematical Model

The use of the waste of the Bayer process, red mud, is due to its chemical and mineralogical composition that shows a material rich in oxides of iron, titanium and aluminum. Some studies conducted show that this waste can be applied as a source of alternative raw material for concentration and subsequent recovery of titanium compounds from an iron leaching process, which is present in higher amounts, about 30% by weight. To obtain a greater understanding about the leaching kinetics, the information of the kinetic data of this process is very important. In this context, the main objective of this work is the development of a mathematical model that is able to fit the experimental data (conversion / extraction iron, titanium and aluminum) of the leaching process by which is possible to obtain the main kinetic parameters such as the activation energy and the velocity of chemical reactions as well as the controlling step of the process. The development of the mathematical model was based on the model of core decreasing. The obtained model system of ordinary differential equations was able to fit the experimental data obtained from the leaching process, enabling the determination of the controlling step, the rate constants and the activation energies of the leaching process.

scholarly journals Development of condenser mathematical model for research and development of ways to improve its efficiency

2020 ◽  
Vol 18 (4) ◽  
pp. 578-585
Author(s):  
Madina Shavdinova ◽  
Konstantin Aronson ◽  
Nina Borissova
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Water Temperature ◽  
Steam Turbine ◽  
Cooling Water ◽  
Laboratory Research ◽  
Thermal Engineering ◽  
Linear Regression Method ◽  
Cooling Water Temperature ◽  
The Mathematical Model

The condensing unit is one of the most important elements of the steam turbine of a combined heat and power plant. Defects in elements of the condensing unit lead to disturbances in the steam turbine operation, its failures and breakdowns, as well as efficiency losses of the plant. Therefore, the operating personnel need to know the cause of the malfunction and to correct it immediately. There are no diagnostic models of condensers in the Republic of Kazakhstan at the moment. In this regard, a mathematical model of a condenser based on the methodology of Kaluga Turbine Plant (KTP) has been developed. The mathematical model makes it possible to change the input parameters, plot dependency diagrams, and calculate the plant efficiency indicators. The mathematical model of the condenser can be used to research ways for the improvement of the condensing unit efficiency, for diagnostic purposes of the equipment condition, for the energy audit conduction of the plant, and in the training when performing virtual laboratory research. Using static data processing by linear regression method we obtain that the KTP methodology of condenser calculation is fair at cooling water temperature from 20 °C to 24 °C, but at cooling water temperature from 20 °C to 28 °C, the methodology of JSC "All-Russia Thermal Engineering Institute" (JSC "VTI") is used. One of the ways to increase the condenser efficiency has been proposed. It is the heat transfer augmentation with riffling annular grooves on tubes. This method increases the heat transfer coefficient by 2%, reduces the water subcooling of the heating steam by 0.9 °C, and decreases the cooling area by 2%.

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