Soot oxidation temperature by high frequency electromagnetic energy was proposed using numerical simulation by combining electromagnetic with transient thermal analyses. Equation of electric field distribution in a microwave cavity with perfect electric conductor surfaces and TE10 mode is formulated from Helmholtz equation. The dissipated heat distribution is calculated from the electric field distribution. Six study cases for electric field and dissipated heat distributions were implemented by using ANSYS software based on finite element method. The impact of dielectric sample properties, position, size and shape inside the microwave cavity were predicted. The results from the simulation of electric field and dissipated heat were compared with available data in literature and showed the validity of the analysis. It was found that the electric field forming hot spots at penetration depth and front corners of the soot sample and penetration depth is equal to 12mm but equal to 0 for samples with dimensions less than penetration depth. Dissipated heat pattern depend on electric field pattern and dielectric properties.
This paper presents the simulation of microwave heating by coupling high frequency electromagnetic with transient heat transfer using finite element method edge base of ANSYS software. Helmholtz equation of electric field has been formulated from Maxwell equations to predict electric field and the mathematical model of transient thermal analysis was included. Three cases have been examined numerically to investigate electric field, dissipated heat, temperature distribution and weight loss of soot at operation frequency 2.45 GHz. The simulation results showed that heat is generated from inside to outside of soot. The temperature at penetration depth increased till ignition point and after further heating, maximum temperature was attained, followed by temperature decreases due to mass transport. Maximum electric field was found to be located on the front face for the small samples with dimensions less than penetration depth. The predicted results have been compared with experimental results which show the validity of the simulation.
Abstract. The reduction of the harmful emission soot is necessary in recent years due to the environmental protection regulation. Soot is a carbonaceous matter and a strong absorber of microwave energy. Microwave heating offers the advantage over conventional heating to oxide soot. Where plasma is high electric field that leads to instantaneous temperature rising. This paper proposes a recent concept for soot oxidation using micro-plasma in a microwave cavity. The concept was presented by simulating the electric field using microwave heating and thin metal object. Five cases were examined numerically in a mono-mode TE10 microwave cavity WR430 having closed surfaces of perfect electric conductors working under 2.45 GHz frequency and 1500 W power supply to predict the electric field and dissipated heat distribution. The methodology of prediction was implemented using ANSYS based on FEM. The present prediction results showed higher electric field (400 kV/m) and high dissipated heat (3.7x10 10 W/m 3 ) can be obtained for a soot sample backed with metal rods inserted vertically with gaps not exceeding 1.5 mm between the rods tips. Also increasing the number of metal rods, from 8 to 14 increases the maximum value of electric field formed in the soot sample to 575 kV/m. The simulation results revealed the ability of achieving high electric field by using microwave heating with the assistance of metal objects.
The Microwave oven is a system used to convert the electromagnetic energy to thermal energy when the microwave cavity is loaded with a dielectric material. The ordinary microwave ovens are not supported with complex features for detecting parameters such as temperature, weight, and loaded material availability. Due to the lack of material availability, several laboratory and industrial applications require these features to switch off the oven. The reflections of electromagnetic radiation inside an empty microwave oven lead to oven damage. An overview of the microwave oven characteristics and emergence of electromagnetic radiation inside a microwave oven is presented in this study. The parameters measured inside the microwave oven, methods for power attenuation in a microwave oven, microwave power detector, and microwave oven leakage are discussed as well. Moreover in the methodology of this work, proposed a new technique based on the measurement of leaked microwave power to control the microwave oven. The preliminary results showed that the leakage measurement of electromagnetic power changes with the state/phase of the material inside the microwave oven, which ensured the possibility of the proposed promising technique. This work will be continued to connect the microwave oven with a spectrum analyzer and computer via hardware and software interfaces depending on the methodology of this article. A computer code will be developed to read the measured power and automatically switch off the microwave oven depending on materials state.
Index Terms— Microwave, power, measurement, control.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.