Simulation Of Microwave Heating Research Articles

Study on the Influence of Structural Parameters of Microwave Heating Device on the Heating Effect of Natural Gas Hydrate Reservoir

Abstract The investigation into microwave heating technology for enhancing gas production from hydrate reservoir has attracted wide attention. However, the initial microwave heating device structure still has limitations of low average temperature and uneven temperature distribution in the reservoir during microwave heating. This study has established the microwave heating simulation model, which is validated by the reservoir microwave heating experiment results. Based on the simulation results of microwave heating model, the optimized structure parameters of microwave heating device are obtained: the slots distribution method is cross-distribution, the slot shape is rectangle, the slot angle is 75°, and the slot length is 30 mm. Following microwave heating with the optimized structure for 10 hours, the average temperature within the 1-meter radius of the reservoir rises from 2 °C to 9.52 °C, the maximum temperature in the reservoir is 58.21 °C, and the temperature standard deviation is 9.15 °C. The results mentioned above indicate that the optimized structure can well increase the temperature in the gas hydrate reservoir and the temperature distribution is uniform. This study will further promote the application of microwave heating technology in the actual exploitation of natural gas hydrate.

COMSOL-Based Simulation of Microwave Heating of Al2O3/SiC Composites with Parameter Variations

The process of microwave heating involves the coupling of multiple physical phenomena, specifically including the distribution of the electromagnetic field in the resonant cavity. The electromagnetic effect generates heat and encourages the transfer of heat inside the material. In this numerical study, a 3D computer model of microwave heating of Al2O3/SiC composites using a multimode microwave heating chamber was established based on the simulation software COMSOL Multiphysics 5.6, and the symmetry treatment of the model was carried out, which effectively reduced the amount of model calculations and accurately analyzed the microwave heating characteristics of the samples. The analysis of the microwave heating characteristics of the sample was mainly preformed from the perspective of the electric field distribution in the resonant cavity, the sample heating rate and the sample heating uniformity, and then it was determined how the microwave source power and sample mold selection affect the temperature and electric field parameters of the sample. After experimental verification, the error between the simulation results and the temperature parameters obtained from the actual experiments is less than 2%. This study contributes to further understanding the heating behavior of Al2O3/SiC composites in complex multimode microwave heating environments and can be used to control the dynamic parameters during microwave heating in order to improve the heating rate and heating uniformity of samples.

On‐demand microwave growth of porosity within a granular composite energetic material: Void formation via a dielectric loss phase change binder additive for propellant burning rate control

AbstractThis study demonstrates, for the first time ever, the ability to grow, in an on‐command fashion, porosity within a granular composite energetic material to effect a change in energy output rate. Specifically, the study investigates the change in burning rates of ammonium perchlorate composite propellants as a result of porosity created in situ via microwave field‐driven volatilization of the low boiling point binder additive, ethylene glycol. Theoretical mass densities were measured before and after microwave irradiation finding that the maximum observed %TMD change for tested propellants is 6 %. Propellants were burned at 1.72 MPa to 6.89 MPa pressures, finding that for all propellants, microwave irradiation produced a change in ballistic characteristics. Most propellant formulations demonstrate acceptable burning rate parameters for use within rocket motors; some exhibited a large change in their pressure exponent as well as slope breaks attributed to the onset of convective burning, while microwave irradiation produced no change in burning rate or density in reference propellants without the additive. Microwave heating simulation results are presented to gain insight into the thermal environment of the propellant during microwave irradiation. These results provide valuable insight into propellant formulations that can have their burning rates (and thus the thrust profile for motor grains) altered after casting via microwave irradiation.

Numerical Simulation of Microwave Heating of Cylindrical Shaped Biomass Material

Numerical Simulation of Microwave Heating of Cylindrical Shaped Biomass Material

Microwave sintering of Ti(C,N)-based cermets: Study of the magnetic effect on metal phase

For microwave heating of Ti(C,N)-based cermets, this paper presents a microwave heating simulation study of pure Ti(C,N) ceramics and Ti(C,N)-based cermets using Comsol software. S-parameter inversion is employed to determine the equivalent relative permittivity of Ti(C,N)-based cermets with varying metal contents. The pairwise Ni metal plate model is utilized to investigate the law of mutual coupling voltage between metal plates. It was found that vigorous electric field intensity is generated around the metal particles of Ti(C,N)-based cermets, and high electric field intensity is generated between the metal particles. Model slice analysis and mechanism analysis are combined to reveal the following phenomena: (1)The surface of metal particles in Ti(C,N)-based cermets excites induced electromagnetic fields; (2)High mutual coupling voltages are generated between metal particles; (3)The reflection effect of metal particles on microwaves can increase the electric field intensity between metal particles. By statistically analyzing the temperature data of pure Ti(C,N) ceramics and Ti(C,N)-based cermets during the initial 30-min microwave sintering period, the temperature difference changing law can be concluded: (1)During the initial 30 min of microwave sintering, the temperature difference between the two gradually increased with time; (2)At 30 min, the temperature difference between the two reached 111 °C.

Study on microwave heating energy supplement technology for gas hydrate reservoir

This study proposes a microwave heating energy supplement technology for gas hydrate reservoir. The microwave radiation simulation model of the leaky coaxial antenna is established by HFSS. Based on the simulation results of microwave antenna structure parameters on the radiation performance, the optimized shape, angle, length, width and fillet of the slot are rectangle, 80°, 38 mm, 12 mm and 2 mm, respectively. To compare the heating performance of microwave antenna before and after optimization, a microwave heating simulation model for hydrate reservoir is developed, which is validated by experimental results. The comparison results illustrate that, after microwave heating 10 h with the optimized antenna structure, the average temperature within a 1-m radius of natural gas hydrate reservoir increases to 10.613 °C, which is about 5.5 °C higher than that before the optimization. The aforementioned results suggest that the optimized microwave antenna structure significantly increases the temperature of the hydrate reservoir, providing the necessary energy to drive hydrate decomposition. The proposed microwave energy supplementation technique holds promise for advancing the efficient development of natural gas hydrates, the further investigation of effect of which on gas production within hydrate reservoirs is needed for future application.

3D Multiphysics simulation of microwave heating of bulk metals with parametric variations

Microwave processing of metal base material is a novel and energy-efficient technique. Microwave heating of bulk metal is an emerging method with cost, time, and energy savings over conventional heating methods. This numerical study uses the finite element method-based COMSOL Multiphysics tool to analyse the microwave heating properties of a bulk metal sample. Further in this study, the effects of tooling design assembly and microwave power parameters have been analysed for temperature profile and electric field distribution. The outcome of parametric variations has been analysed in terms of electric field distribution, heating uniformity, temperature gradient, and energy requirement. Experimental results coincided with simulated results in terms of time-temperature characteristics within ±5% error. The heating uniformity of bulk metal can be achieved at low power with small-size component whereas high power creates thermal heterogeneity with high energy consumption. The cylindrical casket geometry shows uniform field distribution with rapid heating of the specimen compared to prismatic geometry. Susceptor's dielectric properties have a significant effect on the homogeneity of the process, and the heating efficiency of the irradiated specimen. The present simulation model can be used to control the heating rate of bulk metal considering various dynamic parametric properties for a complex microwave hybrid heating process.

Microwave pretreatment of biomass for conversion of lignocellulosic materials into renewable biofuels

For the conversion of lignocellulosic material into renewable biofuels the microwave pretreatment of raw material is a new and promising technology. This work presents a numerical simulation of microwave heating of materials derived from sugar cane, african palm and green algae in microwave domestic oven. The power absorption of biomasses is studied in cylindrical and spherical shapes, with volumes varying from 10−5 m3 to 100 × 10−5 m3, as function of humidity (from 20% to 80%). Maxwell equations were employed to calculate the microwave electromagnetic field distribution in the microwave cavity and in the samples, coupled to heat equation when the humidity is varied. Penetration depth varied from 2 × 10−2 to 10 m and tanδ from 2 × 10−3 to 7 × 10−1 as function of humidity. Plots of electric field and temperature distribution inside the oven were done for sugar cane, palm oil and green algae for cylindrical and spherical samples for 30% and 65% of humidity in the samples. The coefficient of variation (COV) varied between 0.05 and 0.18. The rate of heating efficiency was evaluated using the degree of thermal runaway ΔT (5K<ΔT<75K) and evolution of average temperature T‾ (300K<T‾<370K) and their relationship with the energy absorbed by the samples and COV, respectively. The comprehensive evaluation coefficient, that describes the usability of a specific lignocellulosic material in industry, varied between 0.3 and 10.0, was calculated for the biomasses shapes and sizes as function of power and humidity.

Assessment of microwave susceptors for optimum temperature rise using parametric numerical simulation

Microwave hybrid heating or indirect microwave heating has been an important development in the processing of metals using microwave energy. In this method of heating, a “susceptor” is used to absorb and convert microwave energy into thermal energy which is utilized for materials processing. Few of these processing applications are sintering, joining, cladding, casting, and composite development. However, the precise selection of a susceptor for a given process is challenging and requires a thorough understanding of the microwave heating phenomenon. In addition, predicting temperature rise in a microwave cavity is a complex task. Numerical simulation can serve to solve these two significant problems. In this work, parametric simulation of microwave heating of three major susceptor materials; silicon carbide, alumina, and coal has been carried out using a multiphysics approach. Initially, a model was developed to validate the simulation procedure. The results were in good agreement with the available data in published literature. Thereafter, the effect of microwave power, position of susceptor block, and time of irradiation on temperature rise in these materials were investigated. On comparing these susceptor blocks after altering the parametric combinations, coal exhibited the formation of hot spots and uneven temperature field with a maximum temperature of 901°C. On the contrary, the temperature attained in silicon carbide (529°C) and alumina (616°C) were lower but distributed in a relatively uniform field across the block. Regression models have also been built to correlate maximum temperature achieved with the parametric variation of parameters. It has been found that microwave power and the time of microwave irradiation have a significant coactive effect on the maximum temperature reached by the material. While the rise in the position of the susceptor block from the base leads to an adverse effect on the temperature rise. The study demonstrates that indirect microwave heating can be harnessed using the proper selection of susceptors as per the temperature requirement of the process. The regression models can be used for the accurate prediction of temperature attainment for given power input, position, and time.

Implementation of a multi-layer radiation propagation model for simulation of microwave heating in hydrate reservoirs

PurposeThis paper aims to present the implementation of a multi-layer radiation propagation model in simulations of multi-phase flow and heat transfer, for a dissociating methane hydrate reservoir subjected to microwave heating.Design/methodology/approachTo model the induced heterogeneity due to dissociation of hydrates in the reservoir, a multiple homogeneous layer approach, used in food processes modelling, is suggested. The multi-layer model is incorporated in an in-house, multi-phase, multi-component hydrate dissociation simulator based on the finite volume method. The modified simulator is validated with standard experimental results in the literature and subsequently applied to a hydrate reservoir to study the effect of water content and sand dielectric nature on radiation propagation and hydrate dissociation.FindingsThe comparison of the multi-layer model with experimental results show a maximum difference in temperature estimation to be less than 2.5 K. For reservoir scale simulations, three homogeneous layers are observed to be sufficient to model the induced heterogeneity. There is a significant contribution of dielectric properties of sediments and water content of the reservoir in microwave radiation attenuation and overall hydrate dissociation. A high saturation reservoir may not always provide high gas recovery by dissociation of hydrates in the case of microwave heating.Originality/valueThe multi-layer approach to model microwave radiation propagation is introduced and tested for the first time in dissociating hydrate reservoirs. The multi-layer model provides better control over reservoir heterogeneity and interface conditions compared to existing homogeneous models.

Experimental and numerical thermal analysis for direct microwave heating of silicon carbide

AbstractA comparison between experiment and numerical simulation of microwave heating of a parallelepipedic silicon carbide (SiC) sample is presented. Using a‐2.45 GHz single‐mode cavity, the evolution of the surface temperature is first experimentally studied for different orientations of the sample. A finite element analysis of this electromagnetic‐thermal coupled problem is then conducted with the COMSOL Multiphysics®software. Despite the different approximations of our model, a good agreement between experimental and numerical results is found, confirming that the heating of SiC depends only on the electric field. The effect of sample orientations and the cavity length on heating is also highlighted and analyzed.

Numerical analysis of microwave heating: Fundamentals and applications

In recent years, microwave-assisted materials processing applications are on the rise in terms of novel processes being developed and increased coverage of materials that can be processed. In general, the studies have been of experimental nature. Since microwave heating has extensive application in food processing at an industrial scale, literature on the research involving numerical studies is available in this domain. It is primarily focussed on determination of the distribution of temperature and the rate of heating of a food sample. The evolution in materials processing applications using microwaves has paved the way for exploring numerical analysis to predict and control the response parameters required for efficient material processing. This paper presents the theoretical background of electromagnetic wave propagation along with the heat transfer mechanism required in the numerical studies of microwave heating. The steps for this multiphysics-based numerical analysis are also discussed. An account of the state of microwave heating simulation research is presented as well. The unpredictability of microwave heating mechanisms coupled with fast-developing novel applications makes microwave heating simulation quite challenging. In addition, the merits of such numerical analysis present a case for extensive future research.

Arbitrary Lagrangian-Eulerian method for computation of rotating target during microwave heating

In a particular condition, moving elements are typically used to improve heating uniformity during microwave heating. However, due to the complexity of mathematical models, the simulation of moving elements during microwave heating process remains a challenge. In this paper, a novel continuous algorithm based on Arbitrary Lagrangian-Eulerian method is developed to compute this heating process. By introducing the ALE method, the mesh of moving domain are set as a function of space coordinate and time, the mesh of surrounding domain is free deformation under the action of the moving domain, ensuring the accuracy and continuity of calculation by remesh the deformed configuration. A 2-D model and a 3-D model with a rotating turntable are used to illustrate the proposed method in detail. The change of temperature was measured by experiments to verify the rationality and accuracy of the proposed method. This method can be used in microwave heating simulation of other food movements and assist microwaveable food product development.

Boosting Algorithms Applied to Microwave Heating Simulation

Boosting Algorithms Applied to Microwave Heating Simulation

Classical molecular dynamics simulation of microwave heating of liquids: The case of water.

We perform a complete classical molecular dynamics study of the dielectric heating of water in the microwave (MW) region. MW frequencies ranging from 1.0 to 15.0 GHz are used together with a series of well-known empirical force fields. We show that the ability of an empirical force field to correctly predict the dielectric response of liquids to MW radiation should be evaluated on the basis of a joint comparison of the predicted and experimental static dielectric constant, frequency-dependent dielectric spectra, and heating profiles. We argue that this is essential when multicomponent liquids are studied. We find that both the three-site OPC3 and four-site TIP4P-ϵ empirical force fields of water are equally superior for reproducing dielectric properties at a range of MW frequencies. Despite its poor prediction of the static dielectric constant, the well-known SPCE force field can be used to accurately describe dielectric heating of water at low MW frequencies.

Thermal regime of slotted channel with moving incompressible liquid under microwave conditions

The article studies mathematical simulation of microwave heating of flow in a slotted channel. The internal heat sources, which are proportional to the absorbed microwave energy, obey the Bouguer law. The stationary temperature distributions in the liquid, wall inner surface andmiddle of the wall along the channel have been found from the balance of heat supply and heat release. The maximum temperature values over channel cross sections have also been determined. The heat transfer to the flow was realized in the nonboiling convective regime. The microwave power was selected such that themaximum temperatures and heat fluxes did not exceed themaximumallowable values for the materials.

Simulation of electrical and thermal fields in a multimode microwave oven using software written in C++

Due to multiple reflexions on walls, the electromagnetic field in a multimode microwave oven is difficult to estimate analytically. This paper presents a C++ program that calculates the electromagnetic field in a resonating cavity with an absorbing payload, uses the result to calculate heating in the payload taking its properties into account and then repeats. This results in a simulation of microwave heating, including phenomena like thermal runaway. The program is multithreaded to make use of today’s common multiprocessor/multicore computers.

Preliminary study of improving reservoir quality of tight gas sands in the near wellbore region by microwave heating

The formation damages, such as water blocking and clay swelling, in tight gas reservoir have been recognized as severe problems impairing gas production. To remedy these damages, formation heat treatment (FHT) was taken as one of the effective measures by some researchers. In this paper, the effects of microwave heating on the petrophysical properties of sandstone samples has been investigated. A modified commercial microwave oven was used to heat the core plugs and aluminum tubes were used to accommodate tight sandstone samples in order to confine them and reduce their contact with air. After microwave heating, any alterations in the porosity, permeability, texture, structure, mineralogy, and pore size distribution of tight sandstones were investigated by a series of lab experiments.By subjecting tight sandstone samples to microwave, the surface temperature of sandstone can be elevated to approximately 400 °C or more. The intense heat is effective in changing the structure, texture and mineralogy of the sandstone. The shrinkage or decomposition of minerals, which are shown by XRD analysis, and generation of micro-fractures created more spaces in the samples. By employing Automated Permeameter, porosity and permeability are found increased after heating. Nuclear Magnetic Resonance (NMR) and CT numbers of all samples after microwave heating indicate the increase of porosity as well. Moreover, the NMR T2 distribution reveals the smaller pores diminished, so the incremental porosity of short NMR T2 decreased. Micro-fractures generated between grains or in grains due to decomposition of some cement minerals and clay shrinkage, so the amplitude of long NMR T2 increased. The fractures are visible both in X-ray CT images and in Scanning Electronic Microscopy (SEM) images. By comparing with NMR T2 distribution data, it is found that the presence of micro-fractures accounts for the increased population of pores with T2 larger than 10 ms.The numerical simulation of microwave heating in the borehole indicates that the microwave heating is effective to raise the temperature of reservoir rock to approximately 900 °C within 1 day and to remove the water within a distance of 25 cm from the borehole wall. The efficiency of microwave heating can be further improved by optimizing the downhole microwave device.

Investigation into heat transfer and fluid flow characteristics of liquid two-layer and emulsion in microwave processing

Numerical study of fluid flow and heat transfer within two types of liquid (liquid two-layer and oil–water emulsion) when subjected to microwave energy are discussed. In order to obtain the simulation of microwave heating from room temperature, a 2D comprehensive model was integrated with electromagnetic field, incompressible laminar flow and heat transfer. The effects of layered configuration, layered thickness and dispersed fraction of emulsions were investigated. Temporal profiles obtained using fiber optic sensors at four discrete points were compared with the simulated temperature profiles. The simulated outlet temperatures of liquid had a good agreement with experimental data within the maximum prediction error of 5%. The theory presented in this paper can be effectively used to explain fluid transport during microwave heating system using the rectangular waveguide.

Research of uniformity evaluation model based on entropy clustering in the microwave heating processes

This paper proposes a uniformity evaluation method based on Spectral Clustering and Maximum Information Entropy (ECUEM) for clustering the simulation results in the microwave heating system. The proposed method can effectively evaluate the dataset of the electric field E, the magnetic field H, the temperature field T, and analyze the non-uniformity phenomenon in the microwave heating processes. Compared with other clustering algorithms, the ECUEM can get better clustering results for the dataset in simulation of microwave heating. In particular, in the resonant cavity, the experimental results show that the minimum the evaluation results, the better the materials heating uniformity. In addition, when the ECUEM method is used to analyze the experiment of waveguide moving, the best position (0, 11/20⁎do, 3/14⁎ho) of waveguide can be obtained; at the same time, the uniformity or efficiency of materials microwave heating is the best. Moreover, other rules have been obtained in the microwave heating processes. Thus, the proposed method would provide a new method to guide the researchers who are working in the area of dataset clustering in the microwave heating.