Analysis of Microwave Heating for Composite Dielectric Food Substances Supported on Ceramic Materials

2005 ◽  
Author(s):  
Tanmay Basak ◽  
A. Meenakshi
Keyword(s):  
Heating Rate ◽  
Thermal Processing ◽  
Preliminary Analysis ◽  
Average Power ◽  
Ceramic Materials ◽  
Uniform Heating ◽  
Small Thickness ◽  
Resonance Modes ◽  
Time Plot ◽  
Oil Thickness

A detailed theoretical analysis has been carried out to study efficient heating of 1D composite dielectric samples due to microwaves. Current study involves processing of beef with oil layers with/without support and three cases are considered where oil layer is followed by beef layer (case 1), beef layer is followed by oil layer (case 2) and oil-beef layers are exposed to microwaves at both the sides (case 3). For cases 1 and 2, microwaves are incident at the left face only and the support is generally attached with the oil layer. A preliminary analysis has been carried out for beef-oil composite without any support for all cases and it is observed that identical average power in beef sample occurs for small thickness of oil layer irrespective of either oil or beef directly exposed to microwaves (case 1 or 2) and for greater thicknesses of oil layer, the food composite would exhibit greater average power for case 1. The maxima in average power corresponding to resonances occur at various sample thicknesses for all cases with and without supports and two dominant resonance modes R1 and R2 are considered where the average power at R1 mode is greater than that at R2 mode for all cases. The detailed spatial distribution for various cases illustrates that for small oil thicknesses, heating rate is less and greater heating rate would correspond to larger oil thicknesses. However, the excessive heating in beef sample may correspond to thermal runaway which are also illustrated by ΔTb (difference between the maximum and minimum values of temperature) in beef samples vs time plot. The similar analysis has been extended for all cases with oil layer directly attached with ceramic supports (Al2O3 and SiC). Based on the detailed analysis, the suitability of the support would be guided by factors such as optimal oil thickness, uniform heating and enhanced thermal processing within the beef sample.

Influence of Ceramic Supports on Efficient Microwave Heating of Porous Dielectrics

2005 ◽  
Author(s):  
Tanmay Basak ◽  
K. Aparna ◽  
A. Meenakshi ◽  
A. R. Balakrishnan
Keyword(s):  
Average Power ◽  
Thermal Runaway ◽  
Test Cases ◽  
Uniform Heating ◽  
Heating Rates ◽  
Resonance Modes ◽  
Heating Effects ◽  
Al2o3 Support ◽  
The Face ◽  
Time Plot

A detailed theoretical analysis has been carried out to study efficient heating of 1D porous dielectric samples due to microwaves. The heating effects are analyzed for two types of porous material: beef-air (b/a) and beef-oil (b/o) with and without ceramic supports (Al2O3 and SiC). Three test cases for porosity (φ) 0.3, 0.45 and 0.6, are considered. The effective dielectric properties are obtained using Fricke’s complex conductivity model with air and oil being the discontinuous media. The maxima in average power corresponding to resonances occur at various sample thicknesses for all porous materials with and without supports and two dominant resonance modes R1 and R2 are considered where the average power at R1 is larger than that at R2. It is observed that the maxima at R1 mode decreases significantly with porosity for samples with and without supports. It is interesting to observe that average power absorption is enhanced for samples (b/a and b/o) in presence of Al2O3 support whereas the average power is smaller with SiC support. The detailed analysis on spatial distribution of electric field, power and temperature illustrate that runaway heating is observed at the face which is not attached with support for b/a samples, and the intensity of thermal runaway is increased with porosity whereas the less thermal runaway is observed for b/o samples with all porosity regimes. The thermal runaway is less pronounced for SiC supports. The thermal runaway is also represented by ΔTb (temperature difference) vs time plot which illustrates that greater magnitudes of ΔTb occur with φ = 0.6 for b/a samples. In contrast, ΔTb vs time distribution is almost identical with porosity for b/o samples. Based on the analysis, it may be recommended that b/o samples with all porosity regimes would exhibit uniform heating rates with Al2O3 and SiC supports, whereas b/a samples may be heated with minimal thermal runaway heating corresponding to Al2O3 support at the left face.

Effect of uniform heating rate on the nature of thermoluminescence of glass

1963 ◽  
Vol 20 (9) ◽  
pp. 476-477
Author(s):  
R. V. Lipchanskaya ◽  
V. S. Aksenov
Keyword(s):  
Heating Rate ◽  
Uniform Heating

Assessment of Heating Rate and Non-uniform Heating in Domestic Microwave Ovens

2012 ◽  
Vol 46 (4) ◽  
pp. 229-240 ◽  
Author(s):  
Krishnamoorthy Pitchai ◽  
Sohan L. Birla ◽  
David Jones ◽  
Jeyamkondan Subbiah
Keyword(s):  
Heating Rate ◽  
Uniform Heating

Ceramic Additive Manufacturing Using VAT Photopolymerization

2018 ◽  
Author(s):  
Diptanshu ◽  
Erik Young ◽  
Chao Ma ◽  
Suleiman Obeidat ◽  
Bo Pang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Thermal Processing ◽  
Biomedical Applications ◽  
Ceramic Materials ◽  
Ceramic Suspension ◽  
Alumina Particles ◽  
Compressive Testing ◽  
The Difference ◽  
Porosity Percentage

The popularity of additive manufacturing for producing porous bio-ceramics using vat photopolymerization in the recent years has gained a lot of impetus due to its high resolution and low surface roughness. In this study, a commercial vat polymerization printer (Nobel Superfine, XYZprinting) was used to create green bodies using a ceramic suspension consisting of 10 vol.% of alumina particles in a photopolymerizable resin. Four different sizes of cubical green bodies were printed out. They were subjected to thermal processing which included de-binding to get rid of the polymer and thereafter sintering for joining of the ceramic particles. The porosity percentage of the four different sizes were measured and compared. The lowest porosity was observed in the smallest cubes (5 mm). It was found to be 43.3%. There was an increase in the porosity of the sintered parts for the larger cubes (10, 15 and 20 mm). However, the difference in the porosity among these sizes was not significant and ranged from 61.5% to 65.2%. The compressive testing of the samples showed that the strength of the 5-mm cube was the maximum among all samples and the compressive strength decreased as the size of the samples increased. These ceramic materials of various densities are of great interest for biomedical applications.

Modification of Banding in Dual-Phase Steels via Thermal Processing

2014 ◽  
Vol 783-786 ◽  
pp. 1067-1072 ◽  
Author(s):  
K. Mukherjee ◽  
L.S. Thomas ◽  
C. Bos ◽  
David K. Matlock ◽  
John G. Speer
Keyword(s):  
Heating Rate ◽  
Thermal Processing ◽  
Thermomechanical Processing ◽  
Rolled Sheet ◽  
Dual Phase ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Cold Rolled ◽  
Dp780 Steel ◽  
Microscopic Techniques

The potential to utilize controlled thermal processing to minimize banding in a DP780 steel with 2 wt pct Mn was evaluated on samples processed on a Gleeble® 3500 thermomechanical processing simulator. All processing histories were selected to result in final dual-phase steel microstructures simulating microstructures achievable during annealing of initially cold rolled sheet. Strip samples were processed to evaluate the effects of heating rate, annealing time, annealing temperature, and cooling rate. The degree of banding in the final microstructures was evaluated with standard light optical microscopic techniques. Results are presented to illustrate that the extent of banding depended on control of both heating and cooling rates, and a specific processing history based on a two-stage heating rate can be used to minimize visible banding in selected final heat treated products.

Microwave Curing of Silicon Carbide Ceramics from a Polycarbosilane Precursor

1994 ◽  
Vol 347 ◽  
Author(s):  
Tzyy-Heng Alex Shan ◽  
Robert Cozzens
Keyword(s):  
Silicon Carbide ◽  
Thermal Processing ◽  
Ceramic Materials ◽  
Sole Source ◽  
Curing Temperature ◽  
Polymeric Precursor ◽  
Microwave Curing ◽  
Silicon Carbide Ceramic ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics

ABSTRACTSilicon carbide ceramic materials have been successfully formed from commercially available polycarbosilane using microwave radiation as the sole source of heat. Conventional thermal processing of the same polymeric precursor was also studied for comparison with microwave processing. Microwave heating enhances crystallinity at much lower curing temperature and within shorter times. Possible explanations for microwave enhanced processing are proposed.

Sintering Study of Al2O3/NbC/Wc Micro-Nanocomposite

2012 ◽  
Vol 727-728 ◽  
pp. 597-602 ◽  
Author(s):  
Vania Trombini ◽  
Karolina Pereira Santos Tonello ◽  
Thais Santos ◽  
José Carlos Bressiani ◽  
Ana Helena de Almeida Bressiani
Keyword(s):  
Mechanical Properties ◽  
Mechanical Strength ◽  
Heating Rate ◽  
Cutting Tools ◽  
Ceramic Materials ◽  
Simultaneous Increase ◽  
Sintering Behavior ◽  
Alumina Matrix ◽  
Hard Metals ◽  
Nanometric Particles

Ceramic materials based on alumina are considered excellent for produce cutting tools used to machining hard metals. However, low mechanical strength and toughness presented by these materials limit their application. Traditionally particles, such as TiC, TiN and ZrO2, are added to the alumina matrix to improve their mechanical properties, increasing the range of applications. Recent studies have shown that the addition of particles of different sizes in alumina matrix can promote simultaneous increase in mechanical strength and tenacity. In this work sintering behavior of Al2O3micro-nanocomposite containing nanometric particles of NbC and micrometric particles of WC, was studied by dilatometry using heating rate of 20°C/min up to 1800°C. The addition of carbides in alumina matrix is prejudicial to sintering causing an increase in temperature of shrinkage.

scholarly journals A flowline model for Nigardsbreen, Norway: projection of future glacier length based on dynamic calibration with the historic record

1997 ◽  
Vol 24 ◽  
pp. 382-389 ◽  
Author(s):  
J. Oerlemans
Keyword(s):  
Mass Balance ◽  
Heating Rate ◽  
Computer Model ◽  
Flow Model ◽  
Perfect Match ◽  
Greenhouse Warming ◽  
Dynamic Calibration ◽  
Uniform Heating ◽  
Glacier Length ◽  
Historic Record

Historic glacier-length variations are used to constrain a computer model for Nigardsbreen, Norway. A mass-balance history is derived that, when imposed on the flow model, gives an almost perfect match between observed and simulated glacier length since AD 1748. Being calibrated with past changes, the model predicts an 800 m advance of the glacier snout if mass-balance conditions remain as they were for the period 1962–93. Several greenhouse-warming scenarios are imposed to project the glacier’s behaviour into the next century. For a uniform heating rate of 0.02 K a–1, Nigardsbreen would advance slightly until AD 2020, but then a very rapid retreat would start: in AD 2100 glacier volume would be only 10% of the 1950 volume.

THE DIFFERENTIAL THERMAL ANALYSIS OF NATURAL AND SYNTHETIC HYDRATES OF CALCIUM SULPHATE

1960 ◽  
Vol 38 (6) ◽  
pp. 936-943 ◽  
Author(s):  
W. E. P. Fleck ◽  
M. H. Jones ◽  
R. A. Kuntze ◽  
H. G. McAdie
Keyword(s):  
Heating Rate ◽  
Calcium Sulphate ◽  
Endothermic Effect ◽  
Exothermic Effect ◽  
Uniform Heating ◽  
Heating Rates ◽  
Sample Concentration ◽  
Naturally Occurring ◽  
Lower Temperature ◽  
Dehydration Behavior

A variety of naturally occurring forms of calcium sulphate dihydrate produce substantially identical differential thermograms under conditions of uniform heating rate and particle size. These thermograms closely resemble those for synthetic dihydrate and β-hemihydrate, showing four endothermic effects and one exothermic effect below 500 °C. Two of these endothermic effects, at about 170° and 300 °C, respectively, which have not been reported previously, were found to be easily masked by changes in heating rate or sample concentration. Resolution of the several effects was improved by using different heating rates at different stages of the thermogram. Thermograms of the α-hemihydrate were similar, except that the endothermic effect at 300 °C was not evident and the exothermic effect occurred at a much lower temperature than for the dihydrate. No conspicuous differences were found in the temperatures corresponding to the various endothermic and exothermic effects which might be correlated with the general dehydration behavior of the particular material. The endothermic effect at about 170 °C appears to be associated with part of the hemihydrate to soluble anhydrite transition, possibly arising during the removal of the last traces of water.

Microcalorimetry and Kinetics of Biodiesel

2014 ◽  
Vol 592-594 ◽  
pp. 1647-1651
Author(s):  
S.P. Sivapirakasham ◽  
A. Afsal Khan ◽  
Mane G. Yogesh ◽  
R. Anand
Keyword(s):  
Activation Energy ◽  
Kinetic Model ◽  
Heating Rate ◽  
Diesel Fuel ◽  
Fossil Fuel ◽  
Uniform Heating ◽  
Nitrogen Gas ◽  
Gas Atmosphere ◽  
Great Acceptance ◽  
Kinetics Of

Now a day biodiesel becomes best alternative for diesel fuel. Thermogravimetry technique has great acceptance in the field of fossil fuel. The thermal and kinetics properties of diesel and Jatropha biodiesel are analyzed by using popular technique of thermogravimetry. The aim is to study the behavior of diesel, biodiesel and their blends in Nitrogen gas atmosphere at the heating rate of 5K/min, 10K/min and 15K/min from 30°C to 600°C. From study it is found that as heating rate increases peak is shifting toward higher value which shows that there is less uniform heating. The study clearly shows biodiesel is more stable than diesel indicating that transesterification make sample less stable. The Arrehenius Kinetic model is applied to study the activation energy. As percentage of biodiesel increases, stability of sample increases and hence increases in activation energy

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