Calculation of Heating Patterns in Microwave Sintering using a 3D Finite-Difference Code

1994 ◽  
Vol 347 ◽  
Author(s):  
James Tucker ◽  
Magdy F. Iskander ◽  
Zhenlong Huang
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Microwave Sintering ◽  
Scale Up ◽  
Companion Paper ◽  
Temperature Pattern ◽  
Measured Temperature ◽  
Limited Information ◽  
Transfer Program

ABSTRACTAnalysis of heating patterns in microwave sintering experiments provide information on the contributions of the various heat transfer components to the overall temperature pattern. Measured temperature patterns provide limited information on overall effects. Numerical simulations provide a cost effective way from which the effect of geometry, material properties and the presence of stimulus such as SiC rods or sheets on the heating pattern can be studied separately. Parametric studies allow us to identify the most significant properties and provide guidelines for the routine successful utilization of microwave sintering experiments. These guidelines may also facilitate the scale up and commercialization of microwave sintering.In this paper we describe a thermal model that calculates the temperature distribution in ceramic samples and insulation under realistic microwave sintering conditions. The calculation process involves a two-step procedure. The first step is to calculate the microwave power deposition in the sample and surrounding insulation. 3D FDTD calculations, described in a companion paper[1,2], are used for this purpose. The other step involves calculation of the temperature distribution using a 3D finite-difference heat-transfer program developed in our Departments[3]. Results illustrating the effect of thickness of insulation and the placement of SiC rod susceptors in picket-fence arrangement are presented.

Dynamic Model for Calculating Heating Patterns During Microwave Sintering

1992 ◽  
Vol 269 ◽  
Author(s):  
James Tucker ◽  
Ray Smith ◽  
Magdy F. Iskander ◽  
Octavio M. Andrade
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Microwave Sintering ◽  
Companion Paper ◽  
Heating Process ◽  
Transfer Program ◽  
Ceramic Samples ◽  
Step Procedure ◽  
Picket Fence ◽  
And Control

ABSTRACTAnalysis of dynamic development of heating patterns during microwave sintering provides vital information on the evolution of the heating process and the contributions from the various components in a complex sintering arrangement (picket fence) to the heat-transfer mechanism. Measured heating patterns often provide overall effects, and it is difficult to isolate and control the various contributions. To this end, results from numerical simulation may be significant.In this paper we describe a thermal model that calculates the temperature distribution in ceramic samples and insulation under realistic sintering conditions. The calculation process involves a two-step procedure. The first step is to calculate the microwave power deposition in the sample and surrounding insulation. 3D FDTD calculations described in a companion paper are used for this purpose [1] The other step involves calculation of the temperature distribution using a 3D finite-difference heat-transfer program developed in our department.Results illustrating the effect of thickness of insulation and the placement of SiC rods in picket-fence arrangement are presented. Also, the need to measure additional parameters such as thermal conductivity and density of green samples as a function of temperature during sintering is discussed.

Effect of Wall Conduction on Combined Free and Forced Laminar Convection in Horizontal Rectangular Channels

1987 ◽  
Vol 109 (4) ◽  
pp. 936-942 ◽  
Author(s):  
G. J. Hwang ◽  
F. C. Chou
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Aspect Ratio ◽  
Finite Difference Method ◽  
Numerical Study ◽  
Fully Developed Flow ◽  
Rectangular Channels ◽  
Laminar Convection

This paper presents a numerical study of the effect of peripheral wall conduction on combined free and forced laminar convection in hydrodynamically and thermally fully developed flow in horizontal rectangular channels with uniform heat input axially, In addition to the Prandtl number, the Grashof number Gr+, and the aspect ratio γ, a parameter Kp indicating the significance of wall conduction plays an important role in heat transfer. A finite-difference method utilizing a power-law scheme is employed to solve the system of governing partial differential equations coupled with the equation for wall conduction. The numerical solution covers the parameters: Pr = 7.2 and 0.73, γ = 0.5, 1, and 2, Kp = 10−4–104, and Gr+ = 0–1.37×105. The flow patterns and isotherms, the wall temperature distribution, the friction factor, and the Nusselt number are presented. The results show a significant effect of the conduction parameter Kp.

Effect of Nanofluid Properties on Magnetohydrodynamic Pump (MHD)

2011 ◽  
Vol 403-408 ◽  
pp. 663-669 ◽  
Author(s):  
Azadeh Shahidian ◽  
Majid Ghassemi ◽  
Rafat Mohammadi
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Al2o3 Nanoparticles ◽  
Nacl Solution ◽  
Navier Stokes Equations ◽  
Side Walls

A Magnetohydrodynamic pump uses the Lorentz effect. It is based on the injection of an electric field into two electrodes located at facing side walls of a channel. The purpose of this study is to numerically investigate the effect of Nanofluid properties on the flow field as well as the temperature distribution in a MHD pump. To solve the non-linear governing differential equations, a finite difference based code is developed and utilized. The temperature and velocity are calculated by solving the energy and Navier-Stokes equations. Result shows that temperature stays almost constant with magnetic field. Furthermore velocity and temperature behaviours are similar for each period. However heat transfer inside the MHD pump varies with nanofluid (NaCl solution and Al2O3 nanoparticles) in comparison with the NaCl solution.

Application of Steady State and Transient IR-Thermography Measurements to Film Cooling Experiments for a Row of Shaped Holes

2005 ◽  
Author(s):  
Dennis Brauckmann ◽  
Jens von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Film Cooling ◽  
Measured Temperature ◽  
Ir Thermography ◽  
Adiabatic Wall ◽  
Test Plate ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
The Heat Transfer Coefficient

This paper presents experimental investigations for the measurement of the adiabatic film cooling effectiveness as well as the heat transfer coefficient distribution in film cooling experiments with a row of fanshaped holes on a flat plate. The temperature distribution on the flat plate is measured using infrared-thermography (IR). Adiabatic wall effectiveness data are obtained using a high-temperature plastic material. Although a low thermal conductivity material is used, the measured temperature distribution is not identical with the adiabatic temperature distribution. The measured temperature field shows influences of 3D heat conduction inside the test plate. The effects of the heat conduction inside the test plate are modeled using the FE-method to re-evaluate the adiabatic wall temperature and to calculate the coolant gas exit temperature, which is used for the adiabatic film cooling effectiveness. For the measurement of the heat transfer coefficient ratio with and without film cooling (hf/h0) a transient method is used. Temperature transients on the test surface are initiated by switching the coolant flow and are recorded using IR-thermography. The measured wall temperature histories are converted into heat flux values assuming a semi-infinite wall model during the experiment.

scholarly journals Implementation of One Dimensional Finite Difference Heat Conduction Method to Quantity Heat Transfer through Lightweight Cellular Mortar

2018 ◽  
Vol 7 (2.23) ◽  
pp. 103 ◽  
Author(s):  
Md Azree Othuman Mydin ◽  
Mazlina Musa
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Finite Difference ◽  
Initial Approximation ◽  
Heat Emission ◽  
Cement Matrix ◽  
Measured Temperature ◽  
Experimental Procedure ◽  
Temperature Growth ◽  
One Dimensional

This paper accounts the origin of Finite Difference technique (one dimensional) to determine thermal performance of lightweight cellular mortar. This paper will also assimilate the execution of the technique and the reasoning of thermal properties model of lightweight cellular mortar. For this work, a one dimensional finite difference heat conduction simple excel program had been developed to foresee the temperature enlargement via the width of the lightweight cellular mortar system, based on initial approximation of the thermal conductivity properties in relation to the temperature growth in the model as a function of the cellular mortar porosity and the effect of radiation and heat emission surrounded by the voids inside the cement matrix. The accuracy of the developed simple model was then evaluated by equalling prophesied and measured temperature growth assimilated from prototype heat transfer assessment on lightweight cellular mortar system to facilitate the temperature growth of the sample premeditated by the program meticulously bouts those verified through the experimental procedure.   

The Effects of Turbulence and Stator/Rotor Interactions on Turbine Heat Transfer: Part I—Design Operating Conditions

1989 ◽  
Vol 111 (1) ◽  
pp. 87-96 ◽  
Author(s):  
M. F. Blair ◽  
R. P. Dring ◽  
H. D. Joslyn
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Finite Difference ◽  
Large Scale ◽  
Reynolds Numbers ◽  
Companion Paper ◽  
Operating Conditions ◽  
Strong Impact ◽  
Analytical Program ◽  
Turbine Model

A combined experimental and analytical program was conducted to examine the effects of inlet turbulence, stator–rotor axial spacing, and relative circumferential spacing of first and second stators on turbine airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approximately 5× engine), ambient temperature, stage-and-a half rotating turbine model. The data indicate that while turbine inlet turbulence can have a very strong impact on the first stator heat transfer, its impact in downstream rows is minimal. The effects on heat transfer produced by relatively large changes in stator/rotor spacing or by changing the relative row-to-row circumferential positions of stators were very small. Analytical results consist of airfoil heat transfer distributions computed with a finite-difference boundary layer code. Data obtained in this same model for various Reynolds numbers and rotor incidence angles are presented in a companion paper (Part II).

Inverse Heat Transfer Solution of the Heat Flux Due to Induction Heating

2004 ◽  
Vol 127 (3) ◽  
pp. 555-563 ◽  
Author(s):  
Jie Luo ◽  
Albert J. Shih
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Finite Difference ◽  
Cross Section ◽  
Induction Heating ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Measured Temperature ◽  
Induction Heat ◽  
Inverse Heat Transfer

The explicit finite difference formulation of an inverse heat transfer model to calculate the heat flux generated by induction is developed. The experimentally measured temperature data are used as the input for the inverse heat transfer model. This model is particularly suitable for a workpiece with low cross section Biot number. Induction heating experiments are carried out using a carbon steel rod. The finite difference method and thermocouple temperature measurements are applied to estimate the induction heat flux and workpiece temperature. Compared to measured temperatures, the accuracy and limitation of proposed method is demonstrated. The effect of nonuniform temperature distribution, particularly in the heating region during the induction heating, is studied. Analysis results validate the assumption to use the uniform temperature in a cross section for the inverse heat transfer solution of induction heat flux. Sensitivity to the grid spacing, thermocouple location, and thermophysical properties are also studied.

Characteristics of Heat Transfer During Machining With Rotary Tools

2004 ◽  
Vol 126 (2) ◽  
pp. 404-407 ◽  
Author(s):  
H. A. Kishawy and ◽  
A. G. Gerber
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Rotational Speed ◽  
Measured Temperature ◽  
Tool Rotational Speed ◽  
Radial Temperature ◽  
Conservation Of Energy ◽  
Finite Volume Discretization ◽  
Heat Partitioning ◽  
Good Agreement

In this paper a model is developed to analyze heat transfer and temperature distribution resulting during machining with rotary tools. The presented model is based on a finite-volume discretization approach applied to a general conservation of energy statement for the rotary tool and chip during machining. The tool rotational speed is modeled and its effect on the heat partitioning between the tool and the chip is investigated. The model is also used to examine the influence of tool speed on the radial temperature distribution on the tool rake face. A comparison between the predicted and previously measured temperature data shows good agreement. In general the results show that the tool-chip partitioning is influenced dramatically by increasing the tool rotational speed at low to moderate levels of tool speed. Also, there is an optimum tool rotational speed at which further increase in the tool rotational speed increases the average tool temperature.

FDTD Modeling of Realistic Microwave Sintering Experiments

1994 ◽  
Vol 347 ◽  
Author(s):  
Zhenlong Huang ◽  
Magdy F. Iskander ◽  
James Tucker ◽  
Hal D. Kimrey
Keyword(s):  
Numerical Simulation ◽  
New Technology ◽  
Microwave Sintering ◽  
Scale Up ◽  
Solution Procedure ◽  
Uniform Grid ◽  
Transfer Program ◽  
Microwave Cavities ◽  
Electromagnetic Power ◽  
Variable Mesh

ABSTRACTComputer modeling and numerical simulation provide a valuable tool for providing guidelines towards a successful routine experimentation with microwave sintering of ceramics. It is also expected that continued efforts in numerical simulation will lead to establishing procedures for the scale up and commercial utilization of this new technology.In this paper, we utilize the FDTD technique to model sintering ceramics in multimode microwave cavities. The role of using process stimulus such as SiC rods on improving the uniformity of the microwave sintering process are also simulated. To help experimentally validate the obtained results, the FDTD electromagnetic power deposition results were combined with a 3D heat transfer program to calculate temperature distribution in samples and surrounding insulation. Results from the FDTD codes and comparisons with experimental measurements of sintering experiments are presented.To improve the efficiency of the simulation and achieve more accurate results, we developed a variable mesh FDTD code to help focus the numerical results and hence improve the resolution in critical sites inside the sintering oven. Detailed solution procedures are described. We solved some test geometries with the uniform grid and the developed variable mesh codes and compared the obtained results to validate and check the accuracy of the solution procedure. Results from these comparisons are presented.

Sign in / Sign up

Export Citation Format

Share Document