Simulation of Rectangular Microwave Cavity for Thermal...

GEMCCON 2017November 8-10, São Paulo - Brazil

Simulation of Rectangular Microwave Cavity for Thermal

Treatment of ClayFederal University of Campina Grande

Applied Eletromagnéticas and Microwave Lab – LEMA

Authors: João R. A. Zacarias, Glauco Fontgalland, Priscilla K. P. de Melo, Raymundo de Amorim Jr.

08/11/2017 Oral Session 1 1


Outline

• Introduction;• Cavity and Sample Design;• Results;• Future Works Proposals;• Conclusion.



Introduction

• Since the application of microwave to heat materials, an importantissue is to evaluate the efficiency of the process during the materialheating.

• There are several ways to increase the efficiency of a microwaveheating process.

• One helpful way is optimize the size and shape of the heating cavity.

• The cavity dimension is important to save power and microwaveenergy.



Introduction

• The vermiculite is a material usually heated byconventional ovens.

• This micaceous material is used in severalapplications: construction, agriculture, and etc.

• The expanded material presents the advantage to belight, absorption, and isolation. Hence, it’s crucial tosurvey the microwave heating and its efficiency.

• The simulated cavity prototype for heating isrectangular.


Heat


Cavity and Sample Design

• The cavity proposed is rectangularwith the cylindrical sample.

• COMSOL Multiphysics® Version5.0 was used to simulate thedistribution of the electric field,reflection coefficient S11 andheating into the material.

• The vermiculite was used in theproposed simulation.


Fig 1: Simulated cavity in COMSOL®.


Simulation Results


Fig. 2: Non-chamfered cavity.


Cavity Optimization & Results


Improvement

• Improvement of the reflectioncoefficient;

• Expected to reach the highesttemperatures in the sample;

• Faster sample heating.

Fig. 3: Chamfered cavity.


S-Parameters Results


-1.510 dB

-8.536 dB

• In the frequency of 2.45 GHz wecan observe a shortly reductionof reflection coefficient S11considering the chamferedintroduced on the cavity.

• More than 6 dB improvement inthe reflection coefficient. non-chamfered cavity

chamfered cavity

Fig. 4: Comparison between chamfered and

non-chamfered cavity.


Sample Temperature Results


• It can be seen that the finaltemperature in the sample withchamfered cavity increased 27° Cabove the temperature achievedinside the original cavity, withoutchamfered.

ΔT = 27° Cchamfered cavity

non-chamfered cavity

Fig. 5: Temperature response on the vermiculite

sample of the cavities.


In development - Monomode WG test

08/11/2017 Oral Session 1 10

Fig. 6: Monomode aplicator.


In Development - Prototype WG test

08/11/2017 Oral Session 1 11

CAM visorMullite crucible

Vermiculite

Graphite

attenuator


In Development - Control System

08/11/2017 Oral Session 1 12

Single-mode

Applicator

Diodes

Impedance

matching

Data

Acquisition

Microcontroller

Temperature

Computer

Microwave

Power

Variable Microwave

High Power Source

0 to 2,5 kW

Circulator


Conclusion

• Both simulated cavities have different efficiencies.

• The chamfered cavity presented higher performance.

• Such difference represents higher processing speed and lower cost of

production.

• It’s important to consider the prototype and simulation of a cavity for

microwave heating process, to improve its efficiency and ensure

better heating.

08/11/2017 Oral Session 1 13


Thank You!

08/11/2017 Oral Session 1 14

Simulation of Rectangular Microwave Cavity for Thermal...

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