scholarly journals Time dependent temperature distribution model in layered human dermal part

2013 ◽  
Vol 8 (2) ◽  
pp. 66-76
Author(s):  
Saraswati Acharya ◽  
DB Gurung ◽  
VP Saxena
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
The Body ◽  
Distribution Model ◽  
Unsteady State ◽  
One Dimensional ◽  
Engineering And Technology ◽  
Governing Differential Equation ◽  
Subcutaneous Tissues ◽  
Sweat Evaporation

The paper developed application of finite element method with linear function in the study of temperature distribution in the layers of dermal part-stratum corneum, stratum germinativum, papillary region, reticular region and subcutaneous tissues as elements. The method is applied to obtain the numerical solution of governing differential equation for one dimensional unsteady state bio-heat transfer using suitable values of parameters that effect the heat transfer in human body. The numerical results obtained are exhibited graphically for various atmospheric temperatures for comparative study of temperature distribution profiles. The loss of heat from the outer surface of the body to the environment is taken due to convection, radiation and sweat evaporation. Kathmandu University Journal of Science, Engineering and Technology Vol. 8, No. II, December, 2012, 66-76 DOI: http://dx.doi.org/10.3126/kuset.v8i2.7327

Modeling the Effects of Heat Transfer Processes on Material Strain and Tension in Roll to Roll Manufacturing

2013 ◽  
Author(s):  
Youwei Lu ◽  
Prabhakar R. Pagilla
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Distribution Model ◽  
Tension Zone ◽  
Governing Equations ◽  
Flexible Materials ◽  
Transfer Processes ◽  
Roll To Roll ◽  
Average Modulus ◽  
The Web

This paper develops governing equations for material strain and tension based on a temperature distribution model when the flexible materials (often called webs) are transported on rollers through heat transfer processes within roll-to-roll (R2R) processing machines. Heat transfer processes are employed widely in R2R systems that contain process operations such as printing, coating, lamination, etc., which require heating/cooling of the moving web material. The heat transfer processes introduce the thermal expansion/contraction of the material and changes in the elastic modulus. Thus, the temperature distribution in the moving material affects the strain distribution in the material. Because of change in strain as well as modulus as a function of temperature, tension in the material resulting from elastic strain is also affected by heating/cooling of the web. To obtain the temperature distribution, two basic heat transfer modes are considered: web wrapped on a heat transfer roller and the web span between two consecutive rollers. The governing equations for strain is then obtained using the law of conservation of mass considering the temperature effects. Subsequently, a governing equation for web tension is obtained by assuming the web is elastic with the modulus varying with temperature; an average modulus is considered for defining the constitutive relation between web strain and tension. Since it is difficult to obtain measurement of tension using load cell rollers within heat transfer processes, a tension observer is designed. To evaluate the developed governing equations, numerical simulations for a single tension zone consisting of a heat transfer roller, a web span, and a driven roller are conducted. Results from these numerical model simulations are presented and discussed.

Numerical Analysis for Heat and Mass Transfer of Granular Flow in a Duct by the Discrete Particle Simulation

2009 ◽  
Author(s):  
Tomohiko Yamaguchi ◽  
Kuniyasu Kanemaru ◽  
Satoru Momoki ◽  
Toru Shigechi ◽  
Ryo Fujiwara
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Energy Equation ◽  
Continuous Phase ◽  
Particle Simulation ◽  
Two Dimensional ◽  
Discrete Particle ◽  
One Dimensional ◽  
Discrete Particle Simulation ◽  
Dimensional Simulation

The solid-gas or liquid-gas two phase flow has many industrial applications such as spray drying, pollution control, transport systems, fluidized beds, energy conversion and propulsion, material processing, and so on. Though the solid-gas multiphase flow has been studied experimentally and numerically, the transport phenomena have not been cleared due to its complexity, computational time and economical costs for the hardware. In this study the heat and mass transfer of solid-gas collision dominated flow is analyzed by the Discrete Particle Simulation (DPS), a kind of the Dispersed Element Method (DEM)[1]. This method describes the discrete phase and the continuous phase by Lagrange and Euler methods respectively, and has been used to simulate the multiphase flow of various geometrical systems. In order to analyze the thermal field we took account of the energy equation and heat conduction between colliding particles. The heat transfer rate is summation of conductive heat transfer and convective heat transfer. Furthermore, the fluid flow has a two dimensional velocity profile, because the void fractions are analyzed as two dimensions. But momentum space has not been resolved by the two dimensional simulation. We call this method, the quasi two-dimensional simulation in this paper. To obtain the temperature distribution of the continuous phase the energy equation is solved in addition to the momentum equations. We treated the interaction between continuous and discrete phases as one and two way couplings. The positions, the momentum and the temperature information of particles and the velocity and the temperature distribution of the fluid were obtained as functions of time from results of these numerical simulations. When the hot air that is suspending small glass particles flows in a duct from bottom up, we traced the particles and got the temperature distribution of fluid and compared with the former results of one-dimensional flow. At the beginning, the cooler particles decrease the fluid temperature near the bottom of the vessel. The temperature profile of the particles obtained by the one-dimensional simulation is as same as quasi two-dimensional simulation. After 0.5 second the particles cool the downstream air. At 1.2 second, particles do not decrease the air temperature because the temperatures of particles are close to the inlet temperature of the air.

Quasi-Steady-State Temperature Distribution in Periodically Contacting Finite Regions

1981 ◽  
Vol 103 (4) ◽  
pp. 739-744 ◽  
Author(s):  
B. Vick ◽  
M. N. O¨zis¸ik
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Temperature Distribution ◽  
Interface Temperature ◽  
Quasi Steady State ◽  
Exact Analytical Solutions ◽  
One Dimensional ◽  
Steady State Temperature ◽  
Regular Cycle

Heat transfer across two surfaces which make and break contact periodically according to a continuous regular cycle is investigated theoretically and exact analytical solutions are developed for the quasi-steady-state temperature distribution for a two-region, one-dimensional, periodically contacting model. The effects of the Biot number, the thermal conductivity and thermal diffusivity of the materials and the duration of contact and break periods on the interface temperature and the temperature distribution within the solids are illustrated with representative temperature charts.

Analysis of Heat Transfer in Particle Velocity Sensor with Three-Wire Configuration

2020 ◽  
Author(s):  
Zhu Linhui ◽  
Shen Jienan ◽  
Zeng Yibo ◽  
Guo Hang
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Forced Convection ◽  
Analytical Model ◽  
Particle Velocity ◽  
Structure Design ◽  
Distribution Model ◽  
Thermal Perturbation ◽  
Velocity Sensor ◽  
Perturbation Field

Abstract Particle velocity sensor (PVS) plays an important role in determining the type and location of a sound source. In this presentation, analytical model of heat transfer in PVS with a three-wire (SHS) configuration was first presented. By comparing with the thermal diffusion motion, the forced convection exerts a smaller influence on the temperature distribution. Thus, variation in forced convection could induce the formation of a thermal perturbation field. The overall temperature distribution model of a PVS is made up of a steady temperature field and a thermal perturbation field. With the derived model, PVS with SHS configuration has smaller thermal noise and higher signal-to-noise ratio in comparision with a two-wire (SS) configuration under the same conditions. Optimized parameters of structure design and heating power could be obtained via the analysis model. Also, this model gives optimal output performance and frequency-dependent characteristic curve. Numerical results are found to be in good agreement with the analytical solutions and experimental data, which verify the correctness of analytical model and numerical method. The study provides a basis for a theoretical and numerical analysis.

Analytical Solution for Temperature Distribution in a Multilayer Body With Spatially Varying Convective Heat Transfer Boundary Conditions on Both Ends

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Long Zhou ◽  
Mohammad Parhizi ◽  
Ankur Jain
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Conduction ◽  
The Body ◽  
Theoretical Understanding ◽  
Linear Algebraic Equations ◽  
Spatially Varying

Abstract Analytical modeling of thermal conduction in a multilayer body is of practical importance in several engineering applications such as microelectronics cooling, building insulation, and micro-electromechanical systems. A number of analytical methods have been used in past work to determine multilayer temperature distribution for various boundary conditions. However, there is a lack of work on solving the multilayer thermal conduction problem in the presence of spatially varying convective heat transfer boundary condition. This paper derives the steady-state temperature distribution in a multilayer body with spatially varying convective heat transfer coefficients on both ends of the body. Internal heat generation within each layer and thermal contact resistance between layers are both accounted for. The solution is presented in the form of an eigenfunction series, the coefficients of which are shown to be governed by a set of linear, algebraic equations that can be easily solved. Results are shown to be in good agreement with numerical simulation and with a standard solution for a special case. The model is used to analyze heat transfer for two specific problems of interest involving spatially varying convective heat transfer representative of jet impingement and laminar flow past a flat plate. In addition to enhancing the theoretical understanding of multilayer heat transfer, this work also contributes toward design and optimization of practical engineering systems comprising multilayer bodies.

Numerical Simulations and Research of Heat Transfer in Pneumatic Pulsator

2015 ◽  
Vol 16 (3-4) ◽  
pp. 157-160 ◽  
Author(s):  
Jacek Wernik ◽  
Krzysztof J. Wolosz
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Numerical Simulations ◽  
Loose Material ◽  
Rational Design ◽  
Convection Heat Transfer ◽  
The Body ◽  
Frictional Heat ◽  
Experimental Stand ◽  
Flow Phenomena

AbstractIn loose material beds above silo outlets or in vertical channels immovable vaults can occur limiting or making impossible the downward movement of the loose material. To prevent vault creation or to destroy vault by aeration and separation of the loose material from encasing walls, a pneumatic pulsator can be applied. In order to optimize the head design, the flow phenomena were numerically simulated and the channels were preliminarily designed. The data obtained from simulation were also used as a basis for setting up an experimental stand to validate simulation results. During air flow in the channels due to frictional heat is produced, which is discharged from the pulsator to the environment. To increase the heat transfer in pneumatic pulsator, the external surfaces of channel are finned. Numerical simulations carried out conduction and convection heat transfer in the fins, and the results illustrated the temperature distribution on the surface of the body, the temperature distribution in the fins, stress distribution, value of factor of safety, the static displacement of the body and the distribution of air temperature along with the speed vectors. The results were compared with experimental and analytical results that confirm their correctness. The results confirm the rational design of the body in terms of thermal. The obtained temperature distribution using CFD agrees approximately with the values measured during the tests.

scholarly journals Performance analysis and optimization of rectangular fin arrays used in plate-fin heat exchangers

2020 ◽  
pp. 213-213
Author(s):  
Weicheng Wu ◽  
Hassan Soliman
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Performance Analysis ◽  
Aspect Ratio ◽  
Analytical Solutions ◽  
Heat Exchangers ◽  
Two Dimensional ◽  
One Dimensional ◽  
Independent Parameters

This paper deals with longitudinal rectangular fin arrays used in plate-fin heat exchangers. The temperature distribution and rate of heat transfer were obtained using one dimensional (1-D) and two-dimensional (2-D) solutions. The ranges of independent parameters within which the 1-D solution was within 1% from the 2-D solution were determined. Simple analytical solutions were determined for the rate of heat transfer, fin effectiveness, and augmentation factor. The aspect ratio at which the rate of heat transfer reached a maximum was determined, as well as the corresponding effectiveness and augmentation factor.

scholarly journals Thermoregulation through Skin at Low Atmospheric Temperatures

1970 ◽  
Vol 5 (1) ◽  
pp. 14-22 ◽  
Author(s):  
DB Gurung
Keyword(s):  
Exact Solution ◽  
Temperature Distribution ◽  
Subcutaneous Tissue ◽  
One Dimensional ◽  
Physiological Conditions ◽  
Metabolic Heat ◽  
Metabolic Heat Generation ◽  
Engineering And Technology ◽  
Key Words Thermoregulation ◽  
2000 Mathematics Subject Classification

The metabolic heat generation decreases exponentially if the persistence of cooling in human body is sustained. This phenomena is under consideration in dermis and subcutaneous tissue to study the exact solution of temperature distribution in dermal layers at low atmospheric temperatures. Other suitable variable physiological conditions are taken and the solution has been obtained using laplace tranform in one dimensional case. Key words: Thermoregulation; Human dermal part; Laplace transform. 2000 Mathematics Subject Classification: 92 C 35.   DOI: 10.3126/kuset.v5i1.2843 Kathmandu University Journal of Science, Engineering and Technology Vol.5, No.1, January 2009, pp 14-22

Analysis of Unsteady State Heat Conduction Performance in Anisotropic Materials

2012 ◽  
Vol 217-219 ◽  
pp. 2484-2487
Author(s):  
Shun Yu Su ◽  
Qin Huang ◽  
Jian Chen
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Temperature Gradient ◽  
Heat Conduction Problem ◽  
Separation Of Variables ◽  
Anisotropic Materials ◽  
Unsteady State ◽  
One Dimensional ◽  
Isotropic Materials ◽  
State Heat

The magnitudes of heat flux for both isotropic materials and anisotropic materials can be determined from Fourier’s law. But the mechanism of heat transfer in anisotropic materials is quite different from that in isotropic materials. The thermal conductivities at one point are not equal in all directions for anisotropic materials. The magnitude of heat transfer rate of anisotropic material in one direction is not only relevant to the temperature gradient in this direction, but also relevant to the temperature gradient which is normal to the direction. Basing on one-dimensional unsteady state heat conduction problem in isotropic materials which can be solved by separation-of-variables method, the performance of unsteady state heat conduction in anisotropic materials was analyzed. And the unsteady state temperature field of the anisotropic plane wall was obtained. The results will provide help for the energy conservation of anisotropic materials.

Effects of structural thermal boundary conditions on hypersonic aerothermoelasticity of all-movable control surface

2018 ◽  
Vol 233 (7) ◽  
pp. 2673-2689 ◽  
Author(s):  
Kun Ye ◽  
ZhengYin Ye ◽  
XianZong Meng ◽  
Zhan Qu
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Thermal Stresses ◽  
Stokes Equations ◽  
Thermal Environment ◽  
The Body ◽  
Control Surface ◽  
Aerodynamic Heating ◽  
Thermal Boundary Conditions

Structural thermal boundary conditions are usually simplified in the aerothermoelastic analysis. However, it will influence the heat transfer, the temperature distribution, and the structure stiffness, which have effects on the accurate prediction of the aerothermoelastic characteristics. In this study, an aerothermoelastic framework for hypersonic vehicles is developed, and the effects of structural thermal boundary conditions on aerothermoelasticity of all-movable control surface are investigated. The Reynold’s averaged Navier–Stokes equations are solved by computational fluid dynamics method to obtain the thermal environment. The transient heat transfer, the thermal stress, and the structure mode are analyzed by using finite element method. Finally, the local piston theory is used to calculate the unsteady aerodynamic force, and aeroelastic characteristics are analyzed in the state space. Aerothermoelastic characteristics of three different structural thermal boundaries are investigated in detail, including aerodynamic heating only on control surface; aerodynamic heating on both the control surface and the shaft; and aerodynamic heating on the control surface, the shaft, and the body. The results show that the heat transfer process, the temperature distribution, the thermal stresses, and the natural frequencies of the structure are influenced significantly by structural thermal boundary conditions especially in the shaft. Furthermore, the aerothermoelastic stability margin is affected ultimately.

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