Computer Modeling of Microwave Heating Processes for Food Preservation

Koutchma, Tatiana; Yakovlev, Vadim V.

doi:10.1201/9781420053548-29

Cited by 6 publications

(6 citation statements)

References 58 publications

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“…Fig. 3 shows how microwave energy absorbed by the graphite sample in the batch reactor depends on the sample's height; the energy efficiency is calculated here as the derivative of the reflection coefficient computed at the input port of the system [33]- [34]. One can see that the larger the sample's volume, the more energy is absorbed.…”

Section: Resultsmentioning

confidence: 99%

“…The value of such a modeling tool would be even higher for larger samples in larger reactors operating, in contrast to the considered MiniFlow reactors, on their higher modes with multiple minima/maxima of the electric field. The electromagnetic modeling technique used in the present study is proved to be (i) fully capable of accurately handling high modes of arbitrarily-shaped closed microwave systems and (ii) advantageous in solving in multiphysics modeling in microwave power engineering [32]- [34]. However, as seen from the results of this paper, for more precise computations, the electromagnetic-thermal model should also be coupled with a solver accounting for exothermic chemical reactions (in this case, oxidation) as a source of an additional heat.…”

Section: Discussionmentioning

confidence: 99%

“…Computer simulation of electromagnetic and thermal processes in both MiniFlow reactors was carried out in accordance with the computational scheme for an iterative solution of the electromagnetic-thermal two-way coupled problem [32]- [34]. Aiming to reach a high level of adequacy in representing microwave heating scenarios, this advanced technique accounts for temperature-dependent electromagnetic and thermal material parameters of the heated material and upgrades their values in all relevant grid cells after Simulations were run on a Dell T-4700 workstation (64-bit Windows XP) with 16 GB RAM and two quad-core Intel Xeon 3.20 GHz processors.…”

Section: Computational Techniquementioning

confidence: 99%

“…While precise reproduction of the entire geometry of a microwave system and accuracy of the applied numerical technique can be considered necessary conditions for sensible computer simulations of microwave heating, for reasonably adequate computational studies of a particular process, the developed model should be supplied with reliable input data on temperature-dependent media parameters of all the materials involved [34], [36]. Therefore, to mimic microwave heating of graphite powder in the MiniFlow reactors, the electromagnetic and thermal properties (i.e., dielectric constant ε′, the loss factor ε″, specific heat C p , density ρ, and thermal conductivity k) of Teflon, Pyrex and graphite powder should be specified in the models in the considered temperature range.…”

Section: Materials Parameters Of Graphite Powdermentioning

confidence: 99%

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Microwave-induced temperature fields in cylindrical samples of graphite powder – Experimental and modeling studies

Moon

Yang

Yakovlev

2015

International Journal of Heat and Mass Transfer

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Microwave heating of graphite powder is the key process of a number of promising applications and emerging technologies ranging from kiln crucibles to synthesis of graphene. However, this process is typically studied in terms of structural parameters of the resulting products, whereas the prime electromagnetic and associated temperature characteristics remain insufficiently studied. In this paper, we investigate microwave heating of graphite powder in a batch (non-resonant) and waveguide (resonant) reactors using multiphysics (electromagnetic-thermal) modeling and experimentation. Temperature-dependent material parameters of graphite power are determined from measurements and appropriate physical models. Non-uniform temperature fields and their trend for relatively quick homogenization are shown to be conditioned by high values of the loss factor and thermal conductivity. These parameters are also found to be responsible for the effect of postmicrowave heating. It is demonstrated that processing of graphite power in a resonant reactor may be convenient for controlling the heating rate and the level of temperature uniformity.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Computational Techniquementioning

confidence: 99%

Section: Materials Parameters Of Graphite Powdermentioning

confidence: 99%

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Microwave-induced temperature fields in cylindrical samples of graphite powder – Experimental and modeling studies

Moon

Yang

Yakovlev

2015

International Journal of Heat and Mass Transfer

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“…The university partner has developed an advanced modeling technique capable of simulating thermal processes in hybrid systems of combined heating by heat radiation and microwaves. Simulation of heating scenarios in the systems of hybrid heating requires certain advancement beyond the current state-of-the-art in multiphysics modeling currently adopted in microwave power engineering [2][3][4]: such a technique should account for thermal radiation within the accurately and precisely reproduced geometry of the cavity. Appropriate approaches were employed in [5,6], where Robin (convective) boundary conditions (BC) were applied at the sample walls with the effective heat exchange coefficient based on approximate formulas describing natural convection for several simplified geometries.…”

Section: Modelingmentioning

confidence: 99%

Energy Efficient Microwave Hybrid Processing of Lime for Cement, Steel, and Glass Industries

Fall¹,

Yakovlev²,

Sahi³

et al. 2012

Self Cite

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that a production size MAT rotary calciner was not feasible, and a different approach was adapted. The concept of a microwave post heat section located in the upper portion of the cooler was devised and well received by the industrial lime company and an industry expert. Commercialization of this technology will require 1) continued pilot scale calcining demonstrations, 2) involvement of lime kiln companies, and 3) involvement of an industrial microwave equipment provider. Ceralink identified two builders of lime kilns whom could be approached to partner with for continued technology and equipment development. Eventually, Ceralink would plan to license and transfer the technology to the kiln builders once the technical aspects are finalized. The lime company could then implement the MAT post heating sections in new builds and pursue retrofit of existing lime kilns in order to improve efficiency. Retrofits would likely be attractive to lime manufacturers, as the purchase of a new lime kiln is on the order of a $30 million dollar investment, where as a MAT retrofit might be on the order of $1 million. Ceralink would receive a royalty from the kiln builder. Current scale-up designs indicate that four 100kW microwave generators (915 MHz frequency) will be required to provide sufficient energy to a chute measuring 6ft in diameter and 4 ft. long to finish calcining the limestone before the limestone is cooled. This is scale for a production size rotary calciner with 600 ton/day output. Ceralink has identified a microwave equipment supplier who could supply the required microwave equipment and engineering work to assist with design and integration.

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Applicability Study of Classical and Contemporary Models for Effective Complex Permittivity of Metal Powders

Kiley¹,

Yakovlev²,

Ishizaki³

et al. 2012

Journal of Microwave Power and Electromagnetic Energy

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Microwave thermal processing of metal powders has recently been a topic of a substantial interest; however, experimental data on the physical properties of mixtures involving metal particles are often unavailable. In this paper, we perform a systematic analysis of classical and contemporary models of complex permittivity of mixtures and discuss the use of these models for determining effective permittivity of dielectric matrices with metal inclusions. Results from various mixture and core-shell mixture models are compared to experimental data for a titanium/stearic acid mixture and a boron nitride/graphite mixture (both obtained through the original measurements), and for a tungsten/Teflon mixture (from literature). We find that for certain experiments, the average error in determining the effective complex permittivity using Lichtenecker's, Maxwell Garnett's, Bruggeman's, Buchelnikov's, and Ignatenko's models is about 10%. This suggests that, for multiphysics computer models describing the processing of metal powder in the full temperature range, input data on effective complex permittivity obtained from direct measurement has, up to now, no substitute.

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Computer Modeling of Microwave Heating Processes for Food Preservation

Cited by 6 publications

References 58 publications

Microwave-induced temperature fields in cylindrical samples of graphite powder – Experimental and modeling studies

Microwave-induced temperature fields in cylindrical samples of graphite powder – Experimental and modeling studies

Energy Efficient Microwave Hybrid Processing of Lime for Cement, Steel, and Glass Industries

Applicability Study of Classical and Contemporary Models for Effective Complex Permittivity of Metal Powders

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