Induction Heating Technology Research Articles

Magneto-Thermal Coupling Simulation of Flowing Liquid Induction Heating through Static Mixer-Type Susceptors

As a new non-contact heating technology, induction heating technology has very broad application prospects in the field of fluid food heating. However, its application is inevitably affected by the heat concentration caused by uneven energy distribution. The uneven temperature distribution of the heating process will lead to the decrease in the quality of heating products. Therefore, based on the previous research, in order to improve the uniformity of heat distribution in the heating process, this study selected the susceptor with the greatest potential for efficient and the most uniform heating fluid to carry out the coupling simulation of electromagnetic heat transfer. The susceptor was simulated and optimized in three aspects: different power comparisons, the influence of structural change on temperature distribution uniformity, and the influence of physical property change of metal material on temperature distribution uniformity. The results show that the simulation results are in good agreement with the experimental results, and the error between the experimental and simulation values of the outlet temperature at Kelvin temperature is less than 0.18%. The change of geometric structure had a great influence on the uniformity of temperature distribution, and the uniformity of temperature distribution was inversely proportional to the conductivity. During the simulation, the temperature of the fluid heated by the susceptor was increased from 284.75 K to about 333K. The temperature distribution of the fluid at the outlet of the susceptor was uniform, and the temperature difference was about 1 K.

Role of carbon fiber in the electrothermal behavior and geopolymerization process of carbon fiber-reinforced FA-GBFS geopolymer composite

Carbon fiber-reinforced geopolymer composite (CFGC) can be used as the energy conversion layer of airport pavement, thus converting electromagnetic energy into heat energy via induction heating technology to melt snow and ice on pavement surface. In this study, fly ash (FA), granulated blast furnace slag (GBFS) and carbon fibers were used to prepare carbon fiber-reinforced FA-GBFS geopolymer composite (CFFGC). Then, the modification mechanism of carbon fibers on the electrothermal and mechanical properties of CFFGC was studied, in which important effects arising from the geopolymerization process within CFFGC were focused on. Results show that the gullies on carbon fiber surface can provide nucleation sites for the geopolymerization and calcium silicate hydration reaction in CFFGC, which accelerates the precipitation of reactive Si(OH)4 and [Al(OH)4]- in the raw materials and promotes the generation of geopolymer gels and CSH gels, thus enhancing the mechanical performance of CFFGC. In addition, when the carbon fiber dosage reaches 0.4 wt%, a substantial conductive network is formed inside CFFGC, which shortens the conductive path and greatly improves the charge transfer capability in CFFGC. Once the carbon fiber dosage exceeds 0.4 wt%, the agglomerated carbon fibers within CFFGC can intensify the phonon scattering, thus reducing its thermal conductivity.

Small-Sized Immersible Water Heaters for Domestic Induction Heating Technology

Induction cooktops are a key element in home electrification. This paper presents a new use of induction cooktops, which allows the preparation of infusions directly in a ceramic mug. It is proposed the design of a water heater with an immersible metallic load. The dimensions of the load allow its embedding in small ceramic vessels. Despite being smaller than conventional inductors, the immersible load has a specific shape that allows it to efficiently receive the energy from the induction cooktops and quickly heat the liquid inside the mug. Its geometry consists of a flat disk with sidewalls on its edge, which provides low reluctance paths for the magnetic field, resulting in improved transmitted power and efficiency. The load is arranged in a multilayer structure consisting of a ferromagnetic alloy with low Curie temperature at the bottom and aluminum on the top, which confers self-detection capabilities against dangerous overheating. The study of the proposal has been carried out with a finite element analysis model, and the feasibility of this proposal has been demonstrated through experimental results of its performance. Finally, the immersible water heater, powered by an induction cooktop, has been compared to other liquid heating systems, such as the microwave and the kettle, with promising results.

Research on an SVM Prediction of Welding Deformation Rectification for High-Strength Steel Fillet-Welded Joints after Traveling Induction Heating

_ To effectively realize the welding deformation rectification of high-strength steel fillet-welded joints in hull construction, a traveling induction coil was used to research the rectification effect of the welding deformation, and the support vector machine (SVM) method was applied to study the ability to predict the rectification amount. Welding and induction heating experiments were carried out on the fillet-welded joints, and finite element models, which were used to expand the prediction sample library of the SVM model, were established according to the experimental process. Then, the induction current, frequency, moving rate of the induction coil, weld deformation amount, and sheet thickness were selected as the input characteristic parameters of the SVM model to predict the rectification results achieved by traveling induction heating. It can be concluded that the established finite element model can accurately simulate the continuous machining process of welding-induction heating in reality, the induction heating method can actively eliminate welding deformation, and the SVM algorithm based on the radial basis function can predict the rectification result of weld deformation with high precision. Introduction The welding process of fillet-welded joints is one of the most common basic construction process units in shipbuilding, and the welding deformation caused by thermal elastoplastic deformation directly threatens the structural strength of hull construction (Liang et al. 2015; Yi et al. 2020). Extensive results indicate that welding deformation and welding residual stress are the main causes of hull structure deformation and stress corrosion; therefore, how to effectively realize the welding deformation rectification of fillet-welded joints has become a research topic of interest (Zhou & Wang 2019). At present, the flame heating method is the preferred method used to rectify a welding deformation; however, some disadvantages in the flame heating method, which include temperature control difficulties, poor automation, harsh construction environments, and ease of material property damage, can seriously affect the quality and strength of a hull structure (Kotani et al. 2016; Kalyankar & Shah 2018). In contrast, electromagnetic induction heating technology, which has a high degree of controllability, environmental friendliness, high heating efficiency, and low dependence on worker experience, has attracted the attention of researchers (Barclay et al. 2013; Haglund & Kristoffersen 2014).

Characteristic Analysis of Irregular Workpiece Based on Electromagnetic Induction Heating Technology

Simulation of coil electromagnetic heating provides an effective model basis for a temperature control system. However, due to the irregularity of industrial heating molds, they cannot meet the model requirements. In this paper, based on the research of electromagnetic heating of thin plates, hypothesis research is carried out. Bony plates and cylinders in fixed positions on thin plates are defined as irregular workpieces. Taking the influence of cylinder height on temperature as the research direction, the temperature distribution on the surface of workpieces is explored, and the influence of different parameters on the simulation results is analyzed, which provides a simulation analysis method and data support for the electromagnetic heating system of irregular workpieces under this model and follow-up researchers.

РЕПРОФИЛИРОВАНИЕ ЖЕЛЕЗНОДОРОЖНЫХ РЕЛЬСОВ НА РЕЛЬСОФРЕЗЕРНЫХ СТАНКАХ

The study objective is to increase the productivity of restoring rail profiles. The paper is devoted to the solution of the problem to determine thermal force, vibro-acoustic and energy parameters of milling machining of rail steel in various conditions. The computational and analytical method of research, express diagnostics are used. The novelty is in the proposed improved technology of rail reprofiling. The following results are obtained: it is found that the most productive and effective method of rail reprofiling in stationary conditions is milling on special rail milling machines; the main directions of increasing the machinability of rail steel are determined, which allows the development of induction heating technology for softening the surface defective metal layer of the rail head. Conclusion: the range of rational cutting modes of rail steel with thermal annealing are found.

유도가열 기술을 활용한 에너지 저감형 분기기 히팅시스템의 유효성 검증

Recently, when railways are opened in winter, the number of railway accidents tends to increase. Conventional rail heaters in railway switches consist of bus wires. Although it has the advantage of being simple and convenient, it consumes a lot of power, but the disadvantage is that it takes a long time to melt. In this paper, a commonly used Induction Heating(IH) technology is applied to the heating system of a railway switch to improve this. The electric power of the induction heater was targeted to be reduced compared to the conventional one. At the same time, induction heaters are designed in a similar size to replace rail heaters. The inverter is designed to meet the operating frequency and output required by the induction heater. Based on this, multi-physics analysis and experiments using the prototypes were performed. In addition, it was confirmed that there is an energy-saving effect through frequency control compared to the conventional system.

Calculative method of effective induction heating depth and its influences on induction healing of dense-graded asphalt pavement

Induction heating technology has been widely used in the induction healing of dense-graded asphalt pavement (DGAP). It’s realized by heating the inductive materials under the electromagnetic field. The induced healing efficiency is related to the effective induction heating depth (EIHD) of inductive materials. Nevertheless, In the existing studies, the EIHD was defined by the temperature method, which is inaccurate and sensitive. Also, the relationship between EIHD and the induced healing efficiency of DGAP has not been investigated. Therefore, in this study, the heat generation and heat conduction processes of DGAP internal material were analyzed, and the EIHD was defined as the main heat generation area of inductive materials. After establishing the 2-D induction heating model of DGAP, to determine EIHD, the thermal energy of different materials in DGAP was calculated in layers by temperature measurements based on meshing. Additionally, induction heating experiments were conducted to verify the correctness of the method. At last, the relationship between EIHD and the induced healing efficiency of DGAP was found by induction healing tests. The results show that the energy-based calculative method is more accurate than the traditional temperature method. Besides, the relationship between EIHD and the overall average healing ratios of DGAP is accorded with a positive linear correlation, and the gradient healing alleviates with the increase of EIHD. This paper proposes a calculative method of EIHD in DGAP and reveals the relationship between EIHD and induced healing behaviors, which can promote the development of pavement maintenance technology.

Improving catalyst performance of Ni-CaO-C to enhance H2 production from biomass steam gasification through induction heating technology

Catalyst performance plays a key role in biomass gasification for H2 production. In this study, induction heating technology was proposed to in-situ heat Ni-based catalyst via Joule heating effect to improve the catalyst performance during steam gasification of biomass for enhancing H2 production. Scanning electron microscope, Brunauer-Emmett-Teller, Thermogravimetric analysis and X-ray diffraction analysis confirmed that less coke deposition, larger specific surface area and more active sites of Ni particles with better crystallinity degree were observed for the used Ni-CaO-C catalysts in induction heating reactor compared to conventional heating reactor (Electric resistance heating). Thus, Ni-CaO-C catalyst in induction heating reactor showed significantly higher catalyst performance, and the H2 production was greatly enhanced from 591–692 mL/g-biomass to 1097–1325 mL/g-biomass (increase rate up to 101.1 %). Furthermore, adding metallic particles into catalyst bed in induction heating reactor can also promote the catalyst performance and then enhanced H2 production. By using induction heating catalytic technology coupled with metallic particles addition, all the H2 yields from steam gasification of four typical biomass (reed straw, wheat straw, corn cob and rice husk) were increased (increase rates reached 106.6–133.5 %) compared to conventional heating reactor. And the ranking of the positive effects of Ni and metallic particles via induction heating on enhancing H2 production was as follows: Ni + Metallic particles coupling effect > Ni effect > Metallic particles effect. Under the optimal conditions, the H2 yields from these four biomass were as high as 1803, 1805, 1722 and 1740 mL/g-biomass, respectively.

Influence of coil shapes on temperature distribution in induction heating process

Induction heating technology has been widely applied in industrial applications like preheating, brazing, and melting furnaces. In induction heating, eddy currents are induced internally in the workpiece, restriction in these eddy currents due to resistance of material dissipates energy and generates heat into the workpiece. In these processes, obtaining desired temperature profile for homogenized processing of the workpiece can be a very challenging task, here coil geometry can play a significant role in the resulting temperature distribution obtained on the workpiece. This paper provides an improved knowledge of the induction heating process through numerical simulation as well as helps in understanding the relationship between magnetic flux density distribution and resulting heating patterns. Four different shapes of the helical coil including classical, conical, square, and oval are analyzed. Their resulting magnetic fields and temperature control profiles are computed using the finite element method. Results obtained show that different shapes of coil produce different heat patterns. These results can be further applied to predict the heating zones and assist in designing induction heating coils for the induction heating applications like thixoforming, in order to achieve desired temperature profiles.

Non-contact heating efficiency of flowing liquid effected by different susceptors in high-frequency induction heating system

Abstract The skin effect causes about 86% of the energy to be concentrated in the narrow surface layer during the induction heating process, which leads to the uneven temperature distribution during the treatment of flowing liquid by induction heating technology. The concentration of heat caused by the skin effect can be avoided by dispersing the induced heating metal structure in the treated fluid, but in most cases, this will lead to a decrease in heating efficiency. Therefore, the purpose of this study is to compare and design the susceptor structures that can avoid the heating concentration problem caused by the skin effect and have higher efficiency. Hence, in this research four kinds of susceptor structures that are the metal sphere, sheet metal, static mixer, and metal pipe were studied. The results show that the combination of metal sphere susceptor and sheet metal susceptor can result in higher heating efficiency than the metal sphere susceptor alone. Ferromagnetic stainless steel with lower relative permeability is more suitable for making sheet metal susceptor than paramagnetic stainless steel. Adding internal components to the metal pipe susceptor will not change its heating efficiency. The heating efficiency of metal sphere type susceptor, sheet metal susceptor, and static mixer susceptor can be up to 58%, 64%, and 67%, respectively. When 430 metal pipe heater is used, the highest heating efficiency can be obtained, and the highest heating efficiency is 80%.

Cooking and pasteurizing evaluation of barramundi (Lates calcarifer) meats subjected to an emerging microwave-assisted induction heating (MAIH) technology

Microwave-assisted induction heating (MAIH) is a complex heating process characterized by rapid and uniform heating based on a combination of microwave heating (power: 1000 W; frequency: 2450 MHz) applied from above and electromagnetic induction heating (power: 1500 W) applied from below. In this study, we assessed the utility of MAIH in processing the flesh of barramundi (Lates calcarifer), an important aquaculture species in Asian countries. To determine the effects of different heating conditions on the microbial contamination and physicochemical qualities of barramundi meat, fresh barramundi meats (100 g) were sealed in heat-resistant crystallized polyethylene terephthalate containers containing 150 mL of saline solution, and were subsequently heated in MAIH to 90 °C or 70 °C and held to different time. The results revealed that in response to an increase in the duration of heating, there were reductions in the aerobic plate count, psychrotrophic bacteria count, hydrogen sulphide-producing bacteria count, and coliform count, along with lower contents of total volatile basic nitrogen, in treated samples. Conversely, with a prolongation of the time exposed to heat, we detected increases in the L* (lightness),W (whiteness), ΔE(colour difference), and texture (hardness and chewiness) of fish meat, whereas there was a reduction of a* (redness). When the samples were heated for at least 110 s to 90 °C or for at least 130 s to 70 °C, the barramundi meats obtained appeared to be fully cooked with microbial counts below the limits of detection. In addition, under both heating conditions, thermal imaging revealed a uniform distribution of temperature within treated samples. Furthermore, monitoring of temperature profiles at central points in fish samples revealed that maximum temperatures of 97 °C and 79 °C were reached in response to MAIH processing at 90 °C for 110 s and 70 °C for 130 s, respectively. Thus, on the basis of the quality considerations of appearance, microbial count, and texture, the recommended optimal heating conditions for barramundi meats produced using MAIH are 90 °C for 110 s and 70 °C for 130 s. Industrial relevanceThe MAIH equipment is a novel thermal processing technology and allows food to be heated and pasteurized simultaneously after the package is sealed, eliminates issues of secondary contamination due to the need for subsequent packaging, and extends the shelf life. MAIH technology, therefore, serves as a viable future alternative for thermal processing of manufacturing refrigerated ready-to-eat seafood.

Numerical simulation of a magnetic induction coil for heat treatment of an AISI 4340 gear

In manufacturing industry, heat treatment is a fundamental requirement for improving the material quality of readily manufactured products. Induction heating technology is repeatable and easily controlled by the advantage of having an electronical control unit. Nowadays, numerical methods have gained so much importance that it become as a reference for the induction heating industry. Experimental methods are costly and time demanding procedures. However, making use of finite element method software, induction heating simulations of a steel gear can be performed relatively cost effective and in a short time. In this paper, induction heating simulation of an AISI 4340 steel gear using FEA software is performed. The effect of variation of inductor frequency and gear workpiece-inductor coil distance on the hardening depth of the gear surface is investigated. The temperature profile of the workpiece is obtained. From the temperature distribution on the steel gear workpiece, the regions of the gear at which the austenitizing temperature (Ac3) - responsible for martensite phase formation- are observed. From the numerical results, hardening profile and hardening depth of the gear is interpreted.

Road Performance and Ice‐Melting Characteristics of Steel Wool Asphalt Mixture

Elastic pavements, low‐freezing point pavements, and energy exchange pavements meet the function of road ice and snow melting but may damage the pavement performance. To solve the above problems, this study intends to develop a noncontact snow‐melting pavement by using induction heating technology. The steel wool asphalt mixture was prepared, and the effects of steel wool on road performances including the high‐temperature performance, low‐temperature performance, water stability, and fatigue performance were studied. The influence of the asphalt mixture’s factors, environmental factors, and human factors on the ice‐melting characteristics of steel wool asphalt mixture was analyzed. A prediction model of the ice‐melting rate of steel wool asphalt mixture based on a double‐hidden layer backpropagation (BP) neural network was established. The results show that the road performance of the asphalt mixture mixed with steel wool mostly meets the requirements of the specification. The increase in steel wool content and length can improve the road performance to a certain extent. In terms of ice‐melting performance, the content and length of steel wool have a beneficial effect on the ice‐melting rate. The lower the ambient temperature or the thicker the ice layer, the slower the ice‐melting rate. The greater the heating intensity, the faster the ice‐melting rate. The average absolute error of the melting ice prediction model is 0.016, so the melting ice effect can be well predicted by this model.

Quasi Resonant Inverter Load Recognition Method

Induction heating (IH) technology is very popular in domestic applications because of its efficiency and safe operating properties. Resonant inverter circuits are widely used in IH systems owing to their high efficiency and soft-switching capability. Among the resonant inverters used in IH systems, the single-switch quasi-resonant inverter topology is generally preferred for low-cost and low-output-power applications. Despite the low-cost advantage of the quasi-resonant inverter, the soft-switching range is quite narrow, and it is not stable depending on the electrical parameters of the load that is desired to be heated. In other words, there is a critical relationship between the electrical characteristics of the pan, turn-on, and turn-off times, which are the control parameters of the semiconductor switch, and the safe working conditions. In addition, when the importance of closed-loop control methods is evaluated together with the selection of resonant circuit elements, it is essential to determine whether the load is suitable for heating, and to determine the electrical properties of the load to provide both reliable and efficient operating conditions. This study focuses on a new load-detection method based on circuit analysis for quasi-resonant induction hobs. After determining the load parameters, the turn-on and turn-off times of the semiconductor switch were determined to obtain the lowest possible switching loss. Therefore, the boundary conditions of the semiconductor switch are maintained within these limits. The proposed method and its advantages for the switch safe operating area were theoretically examined and proved through simulations and prototype circuits.

Design of an electromagnetic induction steam generator device based on air source heat pump

Aiming at the current problems of coal-fired boilers and electromagnetic induction steam generators for environmental pollution and high energy consumption, this article combines air source heat pumps and electromagnetic induction heating technology, and at the same time carries out the structure of the condensate tank and electromagnetic induction steam generator. Redesign. Through trial production and experimentation of the prototype, the results show that compared with traditional coal-fired boilers and separate electromagnetic induction heating technology to generate steam, this device not only achieves energy saving and environmental protection, but also the stability of the steam outlet temperature and the amount of steam generated. Compared with the use of electromagnetic induction heating alone, it has increased by 20%. It can be seen that the use of air source heat pump’ electromagnetic induction heating technology to generate steam saves energy and increases the amount of steam generated.

Modeling and Design of Cookware for Induction Heating Technology With Balanced Electromagnetic and Thermal Characteristics

Improving the cooking experience of induction-heating users involves, among other factors, an optimized power distribution at the bottom of the cooking vessel. Conventional ferromagnetic cookware presents high efficiency but unequal temperature distribution with flat inductors, which subsequently leads to uneven cooking results. In this work, we propose an alternative to the traditional cookware arrangement by inserting some aluminum pieces in the ferromagnetic bottom of cookware. This arrangement combines the optimal inductive performance of the ferromagnetic iron an the high thermal conductivity of aluminum. The performance of the proposed arrangement is analyzed by means of a multiphysics tool including electromagnetic and heat transfer sub-models which is applied to predict both the equivalent electrical circuit and the temperature distribution in cookware. As a result, a balanced trade-off between efficiency and temperature distribution is evidenced with the proposed solution. Experimental results also corroborates the predictions of the proposed solution.

Physicochemical and Microbial Quality of Prepackaged Shrimp Processed by a Scaled-Up Microwave-Assisted Induction Heating Technology

A second generation and scaled-up equipment, named Aligo-2TM (microwave-assisted induction heating, MAIH) with a sample capacity of approximately 1.0 L was designed and invented by Bottle Top Machinery Co., Ltd., Taiwan. Pre-packaged raw shrimps were heated in a scaled-up system using heating temperatures of 130 °C and 90 °C for 80 to 150 s, and the physicochemical and microbial qualities were evaluated. The total plate count, psychrotrophic bacteria count, and coliform levels decreased as heating time increased, whereas the cooking loss, color (L*, a*, and W) value, and texture increased. When shrimps were heated for the longest time of 120 s at 130 °C or 150 s at 90 °C, they displayed obvious overcooked, shrunken, and dry appearance. To obtain samples that showed a red color, cooked well, and had no microbial count, better heating conditions for the processing of pre-packaged shrimps via the MAIH scale-up system were 130 °C for 100 s or 90 °C for 130 s. This novel and scaled-up MAIH equipment provides shrimp to be cooked after being packed, thereof avoiding the post-contamination problem.

Effect of a Novel Microwave-Assisted Induction Heating (MAIH) Technology on the Quality of Prepackaged Asian Hard Clam (Meretrix lusoria).

The microwave-assisted induction heating (MAIH) method—an emerging thermal technique—was studied to heat the prepackaged raw hard clam (Meretrix lusoria). The cooking effects on microbial and physiochemical qualities of clam were investigated. After the heating of the clam meat samples, the aerobic plate count (APC), psychrotrophic bacteria count (PBC), and total volatile basic nitrogen (TVBN) levels decreased with increasing heating time, but the shucking ratio, area shrinkage, and texture (hardness, cohesiveness, and chewiness) increased. In addition, the L* (lightness) and W (whiteness) of the clam meat samples increased significantly at the beginning of the heating period, whereas they decreased significantly with extended heating time. However, a* (redness) had the opposite trend. This study found that when clams were heated for more than 120 s at 130 °C or 150 s at 90 °C, they displayed obvious shrinking and a yellow-brown appearance, indicating that they are overcooked. After heating by MAIH for at least 110 s at 130 °C or 130 s at 90 °C, the samples were cooked well and gains a completely shucking, along with no microbial count detected. Therefore, the results indicated that the optimum heating conditions for prepackaged hard clams subjected to an MAIH machine were 130 °C for 110 s or 90 °C for 130 s.

Insights into fracture mechanisms and strength behaviors of two-dimensional carbon fiber reinforced silicon carbide composites at elevated temperatures

Carbon fiber reinforced silicon carbide (C/SiC) composites are usually subjected to thermal-mechanical-oxidation-coupled loads during service. However, their mechanical properties at ultra-high temperatures in oxidizing environments have rarely been reported. In this paper, a method based on the induction heating technology is proposed for testing the ultra-high-temperature mechanical properties of materials in air. The flexural behaviors of a 2D plain-weave C/SiC material prepared via chemical vapor infiltration are investigated in air up to 1800 °C for the first time. Inverse temperature dependences of the flexural modulus and strength are observed. New fracture mechanisms that are responsible for the mechanical behaviors at elevated temperatures are elucidated. Fracture modes at different temperatures are proposed. A high-temperature fracture strength model for oxidizing environments is developed, which is in good agreement with the experimental results. The factors affecting the fracture strength behaviors of the C/SiC in air at elevated temperatures are characterized quantitatively.