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Reimbert, C.G.; Jorge, M. C.; Minzoni, Antonmaria A.; Vargas, Cristóbal

doi:10.1023/a:1020876331367

Cited by 3 publications

(1 citation statement)

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“…Increasing use of microwaves in material processing is mainly due to faster processing time, which corresponds to the occurrence of maxima in average absorbed power (often termed as resonance). Thus, a series of articles has been devoted to reveal strong dependencies of average absorbed power on characteristic sample dimensions determined by wavelength (λ m ) and penetration depth ( D p ) of the material. − Another important aspect of microwave-assisted material processing is nonuniformity in temperature distribution within the sample, which may lead to hot-spot formation. ,, Because nonuniformity in temperature arises from nonuniformity in absorbed-power distribution (termed as spatial resonances), which may not have one-to-one correspondence with average absorbed power, efficient use of microwaves not only depends on average absorbed power but also needs a priori knowledge about spatial patterns of power distribution, which forms the basis of the current research.…”

Section: Introductionmentioning

confidence: 99%

Detailed Material-Invariant Analysis on Spatial Resonances of Power Absorption for Microwave-Assisted Material Processing with Distributed Sources

Bhattacharya

Basak

2007

Ind. Eng. Chem. Res.

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This paper presents a comprehensive, closed-form-based material-invariant analysis on the occurrence and characterization of spatial resonances in microwave-induced absorbed-power distribution within a material. We have shown that occurrence of resonance depends on competitive interactions between sinusoidal and exponential position dependencies characterized by wave number (N w) and penetration number (N p) confining the resonating regime of absorbed power within thick- (N p ≫ 1) and thin-sample (N w ≪ 0.5) asymptotic limits, where it has been shown for the first time that the thick-sample limit depends on distribution of microwave source (φ0) while the thin-sample limit is invariant of φ0. Within the resonating regime, distribution of microwave source (φ0) and wave number of surrounding free space (N w,0) have shown to play an important role in deciding resonating features of absorbed power in addition to N w and N p, which in the literature have been considered to be the only governing factors for resonance. For example, absorbed power for the case of one-side incidence (φ0 = 0 or 1) shows resonance only if N w,0 ≈ , where locations of resonating peaks are strong function of N w,0 in addition to N w and N p. On the other hand, for both-side incidence with equal power input from left and right sides (φ0 = 1/2), occurrence of resonance as well as locations of resonating peaks are independent of N w,0. For intermediate φ0, the absorbed power shows resonance if N w, N p, N w,0, and φ0 satisfy the condition C n ,3 ≠ 0 as given in this work. We have performed a detail analysis for all the cases in order to quantify various resonating features of absorbed power and derived correlations for predicting the locations of resonating peaks, which are shown to be in good accordance with actual positions.

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Section: Introductionmentioning

confidence: 99%

Detailed Material-Invariant Analysis on Spatial Resonances of Power Absorption for Microwave-Assisted Material Processing with Distributed Sources

Bhattacharya

Basak

2007

Ind. Eng. Chem. Res.

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Generalized scaling on forecasting heating patterns for microwave processing

Bhattacharya

Basak

2007

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).A closed form analysis based on Finite Fourier Transformation (FFT) has been carried out to predict the heating characteristics in the presence of microwave induced volumetric heat sources. A scaling analysis shows that temperature distributions within a material during microwave heating evolve in two stages, namely small time and large time. The inverse of square of second eigenvalue along with thermal diffusivity determines the threshold time scale between these two regimes. During small time evolution, the spatial temperature distribution follows absorbed power profiles, whereas the temperature distributions are slaved by first eigenfunction and independent of volumetric heat distribution at large time evolution. In all the cases, the variation of temperature within the material is guided by a dimensionless number N G 5 L 2 q 0 /kT ref . For N G ( 1, almost uniform temperature distributions are attained and a lump parameter model can be used. In contrast, nonuniformity in absorbed power distributions amplifies in temperature distribution for materials with N G ) 1, where there exists a possibility of local hot spot formation if absorbed power exhibits local maxima. The applicability of this analysis has been illustrated to forecast heating characteristics within various materials American Institute of Chemical Engineers AIChE J, 54: 56-73, 2008 Keywords: microwave heating, modeling, analytical solution, Finite Fourier Transformation IntroductionMicrowave radiations within frequency range 300 MHz-300 GHz are commonly used for material processing due to their ability to generate volumetric heat sources. [1][2][3][4][5] Volumetric heating results in enhanced processing rate and various applications, based on microwave radiations have been reported by earlier researchers. A number of experimental, as well as theoretical/numerical studies have been carried out for microwave heating, thawing, drying, material processing etc. [1][2][3][4][5][6][7][8][9][10][11][12][13] Ayappa et al. 1,2 carried out theoretical and numerical studies of microwave power and temperature dynamics in presence of uniform plane wave. The numerical predictions of temperature within one and two-dimensional (2-D) samples were obtained using finite element method (FEM). Further, FEM has also been used by Basak and Ayappa 5 and Bhattacharya et al. 6 for microwave thawing of 1-D samples in the presence of uniform plane wave. Liu et al. 7 carried out theoretical studies on evaluation of microwave power in lossy dielectric materials within 3-D cavities. They obtained electric and magnetic fields using finite difference time domain (FDTD) algorithm. Later Liu et al. 8 extended FDTD algorithm to evaluate power and temperature within polymeric materials inside a ridge waveguide. FDTD method was further used by Zhang et al. 9,10 for analyzing microwave heating of tissues and natural convection within 3-D waveguides.Correspondence concerning this article should be addressed to T. Basak at tanmay@ iitm.a...

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Analysis of hyperbolic Pennes bioheat equation in perfused homogeneous biological tissue subject to the instantaneous moving heat source

Kabiri

Talaee

2021

SN Appl. Sci.

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The one-dimensional hyperbolic Pennes bioheat equation under instantaneous moving heat source is solved analytically based on the Eigenvalue method. Comparison with results of in vivo experiments performed earlier by other authors shows the excellent prediction of the presented closed-form solution. We present three examples for calculating the Arrhenius equation to predict the tissue thermal damage analysis with our solution, i.e., characteristics of skin, liver, and kidney are modeled by using their thermophysical properties. Furthermore, the effects of moving velocity and perfusion rate on temperature profiles and thermal tissue damage are investigated. Results illustrate that the perfusion rate plays the cooling role in the heating source moving path. Also, increasing the moving velocity leads to a decrease in absorbed heat and temperature profiles. The closed-form analytical solution could be applied to verify the numerical heating model and optimize surgery planning parameters.

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Cited by 3 publications

References 4 publications

Detailed Material-Invariant Analysis on Spatial Resonances of Power Absorption for Microwave-Assisted Material Processing with Distributed Sources

Detailed Material-Invariant Analysis on Spatial Resonances of Power Absorption for Microwave-Assisted Material Processing with Distributed Sources

Generalized scaling on forecasting heating patterns for microwave processing

Analysis of hyperbolic Pennes bioheat equation in perfused homogeneous biological tissue subject to the instantaneous moving heat source

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