Electromagnetic Heating Research Articles

A new approach for improving the quality of the carbon anode for aluminum electrolysis – An impregnation-baking process

Prebaked carbon anode is the primary consumable material in the aluminum reduction cell, and its quality directly affects the energy consumption of aluminum production. An impregnation-baking process of the anode was proposed to reduce the anode porosity, improve the quality of the anodes, and reduce additional carbon consumption. The theoretical analysis and industrial testing on the impregnation-baking process were carried out. Firstly, the coal tar pitch was immersed into the anode carbon block through the impregnation process. An anode impregnation model was developed and used for theoretical calculations to analyze the effects of pressure and temperature on the impregnation process. The accuracy of the model was verified experimentally. Secondly, the impregnated anodes were placed in an electromagnetic induction heating furnace for baking to carbonize the immersed pitch. The thermogravimetric and pyrolysis kinetics methods were used to analyze the baking process of the impregnated anodes. Finally, the impregnated-baked anodes were compared with common anodes regarding their impact on the technical and economic indicators of the aluminum electrolysis process in industrial tests. The results showed that the physicochemical properties of the impregnated-baked anodes were significantly improved, with the bulk density increase of 0.1 g/cm3, air permeability reduction of 0.54 nPm, compressive strength enhancement of 9.43 MPa, and electrical resistivity decrease of 10 uΩ·m. The anode service life was increased from 31 to 35 days, the current efficiency was increased by 0.44 %, and the operating voltage was reduced by 17 mV, which improved economic benefit significantly.

Alternative Methods of thermal Oil Recovery: A Review

Oil production from fields with hard-to-recover reserves always remains a challenge for the oil and gas industry, mainly due to one special factor – the high viscosity of oil, which implies low mobility of oil in a porous medium. Over time, traditional methods of increasing oil recovery become less effective due to a decrease in readily available oil reserves and the complexity of geological conditions for field development. In this regard, the need to use innovative methods to increase oil recovery is becoming more urgent. In recent decades, research in this area has shown significant progress, various methods have been introduced to reduce the viscosity of oil. One of the most effective and actively developing approaches in this area is thermal methods of enhanced oil recovery. They are based on the injection of thermal energy into the reservoir in order to reduce the viscosity of oil and, consequently, increase mobility, which in turn will greatly facilitate the displacement of oil from the rock to the surface.
 Despite certain successes achieved in the use of various methods of increasing oil recovery in the production of heavy oil, the problem of finding alternative methods remains relevant.
 This article presents the review of alternative methods of enhanced oil recovery, including principle of operation of electromagnetic heating of the reservoir, the influence and effectiveness of radio waves and microwave frequencies on the reservoir and the properties of oil, ultrasonic exposure, advantages and disadvantages of alternative methods, comparing them with traditional methods, analyzing the productivity of fields where alternative methods of enhanced oil recovery were used.

Energy Efficiency Comparison in Heating Water Using Gas, Electric, and Induction Cooktops and Determination of Container Emissivity Coefficient

A 1.315 kg stewpan is used to boil 1 kg water using three different type of cooktops, that is, gas, electric, and induction. The power of the electric cooktop is 600 W, a gas cooktop uses the maximum setting (large burner in control knob), and the induction cooktop has maximum power of 1200 W. We have observed two different settings of power: 600 W and 1200 W. In the first setting, we compared induction and electric cooktops, while in the second induction and gas cooktops were compared. We obtained energy efficiency about 67.24% and 56.2% for the first setting and 74.03% and 38.55% for the second, which shows that induction cooktop always gives better performance compared to the other cooktops. Besides this, we also investigated the energy leak from the stewpan to the environment through radiation, which should be the same, since all four observations were using the same container to heat the water.
 Keywords: energy efficiency, heating water, induction cooktops, container emissivity coefficient

Research on the heating effect evaluation of the electromagnetic induction heating system at low temperature based on the electrochemical-thermal coupling model

The extremely fast electromagnetic induction heating system (EIHS) was recently introduced to improve the poor charge and discharge performance of lithium-ion batteries (LiBs) at low temperature. In this work, aimed to investigate the heating effect of EIHS, the accurate electrochemical-thermal coupling model, validated against the charging capacity calibration with various C-rates and HPPC tests at different environments, was developed in depth to reflect the electrochemical and heat transfer behaviors of the LiB exposed to external cool air during the electromagnetic induction heating process. When the copper coil was subjected to a sinusoidal alternating current (SAC) excitation at 10 A, 3 kHz, the LiB can be warmed up to 293.15 K from 243.15 K within 742 s with an even heat generation inside the LiB. The impact of the SAC parameters on the needed heating time was illustrated with time maps, a series of contours suggested that the heating velocity increase with the increase of both the amplitude and frequency. As compared with the low-temperature state, the internal resistance had a more than 3-fold decrease, which can improve the discharging voltage platform and terminal voltage output, thus increasing the pulse power and usable capacity. Neither noticeable capacity retention difference before and after the heating cycles nor obvious capacity loss discrepancy between the normal charge-discharge and heating cycle tests was found at the end of the 200 heating cycles, so the EIHS can achieve a good tradeoff among temperature rising effect, working behaviors and LiB cycle lifespan, which had a considerable potential to enhance the applicability of EVs (electric vehicles) in frigid weather. Moreover, a better heat transfer condition, higher material thermal conductivity and lower specific heat capacity play an important positive role on the improvement of temperature rising performance.

Enhancing Biodiesel Production from Nyamplung Oil: Kinetic Analysis of Transesterification via Electromagnetic Induction Heating

Enhancing Biodiesel Production from Nyamplung Oil: Kinetic Analysis of Transesterification via Electromagnetic Induction Heating

A combined theoretical, computational, and experimental investigation to evaluate performance of suitable thermocouple for microwave processing

Accurate temperature measurement during any microwave processing of material is a contentious issue. While thermocouples are routinely utilized in conventional heat furnaces, their presence in microwave cavities may cause complications such as localized distortion of electromagnetic field, heat dissipation, thermal instabilities, microwave breakdown, and significant inaccuracies in temperature measurement. Therefore, in the present investigation thermocouple effects are discussed by providing the results of temperature estimation by various thermocouples for microwave cladding systems. The present study theoretically and experimentally explored the impact of multiple thermocouples on temperature measurements during microwave heating. COMSOL simulation models were developed to explore microwave and thermocouple interaction during microwave heating. Simulation models were used to assess the effects of the microwave power intensity, thermocouple orientation, and geometry on temperature measurement. The investigation outcomes can be utilized as a guide for selecting appropriate thermocouples in the applications of microwave cladding and other microwave-based manufacturing processes.

Natural catalysis-based clean hydrogen production from shale oil: An in-situ conversion enabled by electromagnetic heating

Employing electromagnetic(EM)-assisted catalytic heating to produce hydrogen (H2) directly from petroleum reservoirs is an emerging technology for decarbonizing fossil fuel industry. Transforming hydrocarbons to clean H2 in situ will enable pure hydrogen extraction to surface while simultaneously sequestering carbon underground with the assistance of downhole hydrogen membrane separation technology. Here, we aim to characterize the role of shale rocks in enhancing EM heating and catalyzing shale oil conversion to hydrogen as natural catalysts under EM irradiation. Flow-through experiments are well designed and conducted in a customized microwave reactor system. We also identified for the first time that shale rocks exhibit a “thermal runaway” (TR) phenomenon which occurs at a temperature of 280 °C. After TR happens, the energy needed for heating shale samples to a high enough temperature is significantly reduced under EM irradiation. Further, we identified that metal-rich minerals in shale rocks play an evident natural catalytic effect on shale oil conversion to hydrogen. As a result, hydrogen with a percentage of 1 mol.% starts to be generated at a measured temperature of 253–421 °C in the presence of shale rocks and is a dominant gas in the generated gas products at high temperatures. The highest production rate and concentration of H2 gas are 178 sccm and 77 mol.% from the conversion of 0.4 g of shale oil, respectively. Importantly, CO2 generated during the process is negligible. This work lays a foundation for leveraging the abundant shale rocks and their natural catalytic effect for more efficient, cost-effective, in-situ hydrogen production directly from shale reservoir via the EM-assisted catalytic heating technology we recently proposed.

Copper-substituted magnetite as a Fenton-like catalyst boosted with electromagnetic heating

Copper-substituted magnetite samples Fe3-xCuxO4 (x = 0.0; 0.02; 0.05; 0.1) were synthesized using the co-precipitation method. XRD data revealed that the synthesized samples retain the cubic spinel structure of magnetite. The obtained materials were tested as heterogeneous Fenton catalysts to destroy organic pollutants and inactivate bacteria. The model organic pollutants were oxytetracycline, Congo Red dye, and Methylene Blue dye having neutral, anionic, and cationic nature, respectively. These organic pollutants differ in their adsorption on magnetite surface: oxytetracycline < Congo Red < Methylene Blue. The same order stays for their decomposition rates. The copper-substituted magnetite catalysts also ensure effective inactivation of E.coli bacteria. A contact time of 60 min is sufficient to reduce the number of bacteria by 6-log. In all tests, the catalytic activity of magnetite increases with the increase in Cu content. The maximum catalytic activity was recorded for the Fe2.9Cu0.1O4 sample. Since the copper-substituted magnetite samples are ferromagnetic, they absorb a high-frequency electromagnetic field. Electromagnetic heating results in a significant increase in catalytic activity: the rate constants of the studied catalytic reactions are increased by 1.5–5 times. Thus, copper-doped magnetite is a hetero-Fenton catalyst capable of increasing activity by electromagnetic heating. The adjustable catalytic activity may be useful in water disinfection, where bacterial load varies greatly.

A Digital Twin Development Framework for an Electrical Submersible Pump (ESP)

Premature failure of a sub-system can be critical for an industrial Cyber-Physical System (CPS). A digital twin (DT) assisted predictive maintenance procedure can reduce the risk of costly unplanned maintenance. This study presents a generalized DT development framework for an Electrical Submersible Pump (ESP) that can assist in predictive maintenance. The framework is applied on a single-phase ESP as a proof of concept. The maximum winding temperature of the selected ESP is simulated using a multiphysics simulation tool with transient electromagnetic and transient heat transfer solvers. The simulation parameters were refined using data captured through an ESP free-run experiment. Simulating the total energy loss in the ESP stator and rotor and the transfer of heat from the outer fluid domain facilitates a relationship between the measurable external temperature and the maximum temperature in the stator winding. Following a design of experiments (DOE) approach, a series of simulations were run to establish a statistical model for the winding temperature in terms of the fluid temperature, the time duration a particular temperature was persistent, and the initial maximum stator winding temperature. As the instantaneous maximum stator winding temperature is related to the remaining useful lifetime, it was shown using a case study that the proposed framework can prognosticate the ESP failure, assisting effective decision-making for predictive maintenance of a CPS.

Choice modelling of eCooking adoption by households in Ghana

ABSTRACT The use of electric cooking appliances, also referred to as eCooking devices, presents a practical and sustainable solution for achieving universal access to clean cooking facilities by 2030. A choice modelling analysis on the factors that influence the selection of an eCooker in Ghana has been conducted to facilitate market expansion for organisations seeking to offer clean cooking services. The study utilised Analytical Hierarchy Process (AHP), Fuzzy-TOPSIS, and Data Envelopment Analysis (DEA) methodologies to assess and rank electric cookers based on crucial factors such as kWh consumption rate, cooking efficiency, affordability, time-saving features, ergonomics, space utilisation capabilities, compatibility with cookware types, ease of cleaning and maintenance procedures, accessibility, among others. The rate of consumption was identified as the most critical factor, emphasising the significance of energy efficiency in the decision-making process. The analysis showed that the induction stove was optimal, considering both Fuzzy-TOPSIS and DEA evaluations. Although the induction stove may consume a considerable amount of electricity, its efficiency, performance, and other attributes make it the preferred choice. This study presents a systematic approach to assessing and ranking electric cooking stoves in Ghana, offering valuable insights for both consumers and policymakers.

Gated recurrent unit-based data-driven model for predicting pot temperature in induction cooking systems

On an induction cooker, accurate pot temperature monitoring can cut down on energy use and prevent overheating. It can be challenging to create a mathematical model for predicting pot temperature, though, because of the different materials and sizes of the pots and the intricate electromagnetic coupling between the induction coil and the pot. To solve this problem, this paper offered a data-driven model that forecasts pot temperature by the inverter module's measured temperature. We used thermocouples in contact with the bottom surfaces of the pots and inverters to record time-series data on the temperatures of the devices to make accurate predictions. This information was gathered under a variety of circumstances, including various pot sizes and materials, various power and temperature settings, and various water levels. We used a gated recurrent unit-based autoencoder to reduce noise in the inverter temperature that was brought on by the cooling fan operation. The data-driven model was then trained using a variety of machine learning and deep learning techniques, including support vector machines, decision trees, linear regression, artificial neural networks, and gated recurrent units. Finally, we compared the predicted and measured pot temperatures to validate the data-driven models that had been learned. According to the statistical findings, there was a 3 °C or so median temperature difference between predicted and actual temperatures.

Graphene synthesis by electromagnetic induction heating: Domain size and morphology control

In this paper we discuss the effect of hydrogen and methane content during low-pressure chemical vapor deposition (LPCVD) of graphene on inductively heated copper foils. By increasing the H2/CH4 ratio by a factor of 5 from 25 to 125, different graphene morphologies ranging from dendritic fractals to compact hexagonal islands are obtained. In addition, increasing the hydrogen concentration allows the nucleation rate to be slowed down by a factor of ∼10 thereby high-quality regular hexagonal graphene single crystals of significant size of 0.1 mm are found. From these measurements, we estimate the activation energy for graphene nucleation in low-pressure CVD (2 eV) and propose a phenomenological law for graphene nucleation. As compared to conventional CVD methods, considerable advantages of inductive heating are outlined, and some fundamental aspects of this approach are discussed.

Robust, planning-based targeted locoregional tumour heating in small animals.

Objective.To improve hyperthermia in clinical practice, pre-clinical hyperthermia research is essential to investigate hyperthermia effects and assess novel treatment strategies. Translating pre-clinical hyperthermia findings into clinically viable protocols requires laboratory animal treatment techniques similar to clinical hyperthermia techniques. The ALBA micro8 electromagnetic heating system (Med-logix SRL, Rome, Italy) has recently been developed to provide the targeted locoregional tumour heating currently lacking for pre-clinical research. This study evaluates the heat focusing properties of this device and its ability to induce robust locoregional tumour heating under realistic physiological conditions using simulations.Approach.Simulations were performed using the Plan2Heat treatment planning package (Amsterdam UMC, the Netherlands). First, the specific absorption rate (SAR) focus was characterised using a homogeneous phantom. Hereafter, a digital mouse model was used for the characterisation of heating robustness in a mouse. Device settings were optimised for treatment of a pancreas tumour and tested for varying circumstances. The impact of uncertainties in tissue property and perfusion values was evaluated using polynomial chaos expansion. Treatment quality and robustness were evaluated based on SAR and temperature distributions.Main results.The SAR distributions within the phantom are well-focused and can be adjusted to target any specific location. The focus size (full-width half-maximum) is a spheroid with diameters 9 mm (radially) and 20 mm (axially). The mouse model simulations show strong robustness against respiratory motion and intestine and stomach filling (∆T90≤0.14°C).Mouse positioning errors in the cranial-caudal direction lead to∆T90≤0.23°C. Uncertainties in tissue property and perfusion values were found to impact the treatment plan up to 0.56 °C (SD), with a variation onT90of 0.32 °C (1 SD).Significance.Our work shows that the pre-clinical phased-array system can provide adequate and robust locoregional heating of deep-seated target regions in mice. Using our software, robust treatment plans can be generated for pre-clinical hyperthermia research.

Efficient Extraction and Analysis of Nanoplastics by Ionic Liquid-Assisted Cloud-Point Extraction Coupled with Electromagnetic Heating Pyrolysis Mass Spectrometry.

Nanoplastics have attracted much attention due to their potential hazards. However, analysis of nanoplastics remains challenging. In this study, ionic liquid-assisted cloud-point extraction (IL-assisted CPE) was developed to enrich nanoplastics in the aqueous environment and further coupled with electromagnetic heating pyrolysis mass spectrometry. The use of trace ILs improves the extraction efficiency of CPE for nanoplastics. The effects of ILs (types, contents), nanoplastic properties (type, size), and environmental factors (aging time, humic acid content) were systematically investigated to evaluate the applicability. The limits of detection of poly(methyl methacrylate) (PMMA) and polystyrene (PS) were determined to be 1.78 and 2.67 μg/L, respectively. Real environmental samples including lake water, rainwater, and influent and effluent from wastewater treatment plant were analyzed with good accuracy (79.58-116.87%) and satisfactory precision (RSD ≤ 11.99%). A possible mechanism for ILs being absorbed into the ordered surfactant micellar and generating larger micelles to synergically enclose hydrophobic nanoplastics was proposed. This work provides a simple and efficient approach to the extraction and analysis of nanoplastics in aqueous environments.

Enhancing energy efficiency and cost redemption through solar-powered electric vehicles with induction cooking system for mobile hospitality in India

Enhancing energy efficiency and cost redemption through solar-powered electric vehicles with induction cooking system for mobile hospitality in India

Heating uniformity improvement of the intermittent microwave drying for carrot with simulations and experiments

AbstractHeating uniformity is always a concern in microwave drying for foodstuff, where unsatisfied product quality could be caused by over‐ or inadequate‐heating. To deal with this concern, multi‐physics field rotation simulation models and intermittent microwave drying modes were designed and evaluated in this study. Four drying modes with different intermittent time ratios (R1/2, R1/3, R1/4, and R1/5) were first applied in drying experiments. Their effects on temperature distribution, drying characteristics, and quality aspects (chromatic aberration, rehydration ratio, vitamin C content, and sensory evaluation) for carrot samples were compared and analyzed. The results revealed that the carrot quality in R1/4 mode drying was increased by up to 64% in comparison with the other three modes. The root‐mean‐square error of the moisture ratio was maintained at a lower value, and a better consistency was also achieved in R1/4 mode. To further improve the drying performance and efficiency, a novel stage intermittent‐time control strategy was attempted, that is, an appropriate strategy was used in each drying stage. With this method, the best drying effect could be obtained. The above work can promote a deeper understanding of the drying kinetic and provide novel operation strategies in the microwave drying of food products.Practical applicationsA multi‐physics field rotational simulation model (MFRSM) coupled with an intermittent microwave drying process, including electromagnetic heating, heat, and mass transfer, was developed to characterize the drying process of rotating samples in an intermittent microwave dryer. The MFRSM was helpful to analyze the continuous microwave drying process of the sample and deepen the understanding of the internal heat and mass transfer process of the sample. Four modes with different intermittent schedules were designed, and simulation models were also established. The drying characteristics in different modes were analyzed; a long intermittent time could affect the drying efficiency on account of the driving force, while a short intermittent time would reduce the product quality because of the continuous high temperature. R1/4 mode was founded in terms of drying efficiency and drying quality. An optimized stage intermittent‐time control strategy (R‐IO mode) was designed. The drying time in the three stages was shortened by 25% in total compared with R1/4 mode. Meanwhile, the vitamin C retention, the taste quality of the dried products were improved. These works are expected to provide benefits for the understanding of the intermittent microwave drying modes on drying kinetic using the MFRSM. It can also be useful in the development of an IMD for food materials.

A theorem of existence of solution for the nonlocal formulation of the problem of microwave heating

Microwave electromagnetic heating are widely used in many industrial processes. The mathematics involved is based on the Maxwell’s equations coupled with the heat equation. The thermal conductivity is strongly dependent on the temperature, itself an unknown of the system of P.D.E. We propose here a model which simplifies this coupling using a nonlocal term as the source of heating. We prove that the corresponding mathematical initial-boundary value problem has solutions using the Schauder’s fixed point theorem.

Novel Electromagnetic Heat Hydrodistillation for Extraction of Essential Oil from Tangerine Peel.

A novel electromagnetic heat method is presented for green extraction of natural compounds from peel residue. In the processing cavity obtained through 3D printing, a core made of amorphous alloy was applied to strengthen the magnetic flux. During the process, an induced electric field was produced in the extract medium owing to an oscillating magnetic field at 50 kHz rather than a pair of electrodes; thus, electrochemical reactions could be avoided. A thermal effect and temperature rise were observed under the field, and essential oil was obtained via this electromagnetic heat hydrodistillation. In addition, the numerical relationships between magnetic field, induced electric field (IEF), induced current density, and temperature profile were elaborated; they were positively correlated with the extraction yield of essential oils. It was found that the waveforms of the magnetic field, induced electric field, and excitation voltage were not consistent. Using a higher magnetic field resulted in high current densities and terminal temperatures in the extracts, as well as higher essential oil yields. When the magnetic field strength was 1.39 T and the extraction time was 60 min, the maximum yield of essential oil reached 1.88%. Meanwhile, conventional hydrodistillation and ohmic heating hydrodistillation were conducted for the comparison; all treatments had no significant impact on the densities. In addition, the essential oil extracted by electromagnetic heat had the lowest acid value and highest saponification value. The proportion of monoterpenoids and oxygen-containing compounds of essential oil extracted by this proposed method was higher than the other two methods. In the end, the development of this electromagnetic heat originating from magnetic energy has the potential to recover high-value compounds from biomass waste.

Analysis of Fine Fault Electrothermal Characteristics of Converter Transformer Reduced-Scale Model

Converter transformer is the key equipment in UHVDC transmission. If a local overheating fault occurs, it will inevitably form a local hot spot on the core, winding or other structural parts. Among these faults, multipoint grounding and interlaminar short circuit faults account for 30–50% of core accidents. The continuous overheating of 150–250 °C will cause ablation on the silicon steel sheet, which will destroy the insulation material and reduce the insulation performance. In severe cases, it will cause thermal expansion, resulting in local deformation or displacement of the core. Considering the scale of size and temperature parameters, the scale model of converter transformer is established based on the principle of constant magnetic flux density. By using the homogenization theory, the scaled model under multipoint grounding and interlaminar short circuit fault is simulated by electromagnetic heat. First, the single-phase four-column model of the core is established according to the scaled principle, and the core is refined. Secondly, taking the refined model as the research object, the magnetic thermal coupling simulation and analysis are carried out under multi-point grounding and interlaminar short circuit fault, and the magnetic density, eddy current loss and temperature distribution on each lamination are obtained. Finally, the correctness of the simulation is verified by the one-dimensional eddy current loss analytical equation, which provides a reference for the local overheating problem of converter transformers.

Hybrid Foams based on Multi‐Walled Carbon Nanotubes and Cellulose Nanocrystals for Anisotropic Electromagnetic Shielding and Heat Transport

AbstractLightweight and mechanically robust hybrid foams based on cellulose nanocrystals (CNC) and multi‐walled carbon nanotubes (MWCNT) with an anisotropic structure are prepared by directional ice‐templating. The anisotropic hybrid CNC‐MWCNT foams displayed a combination of highly anisotropic thermal conductivity and an orientation‐dependent electromagnetic interference (EMI) shielding with a maximum EMI shielding efficiency (EMI‐SE) of 41–48 dB between 8 and 12 GHz for the hybrid foam with 22 wt% MWCNT. The EMI‐SE is dominated by absorption (SEA) which is important for microwave absorber applications. Modelling of the low radial thermal conductivity highlighted the importance of phonon scattering at the heterogeneous CNC‐MWCNT interfaces while the axial thermal conductivity is dominated by the solid conduction along the aligned rod‐like particles. The lightweight CNC‐MWCNT foams combination of an anisotropic thermal conductivity and EMI shielding efficiency is unusual and can be useful for directional heat transport and EMI shielding.