Induction Heating: An Enabling Technology for the Heat Management in Catalytic Processes

Electrical heating rods are state of the art heating systems to keep railway turnouts clear from ice and snow. Installation, maintenance and procurement is easy. Operational experience of several decades show good efficacy up to moderate wintry weather conditions. However, the energy efficiency is low. A significant amount of heat does not contribute to snow and ice removal but is transferred directly to the environment. Anthropogenic climate change will most likely lead to less days with snowfall but increased short-term snowfall intensity. Future turnout heating systems therefore would need increased capabilities of snow and ice removal. In contrast, overall energy efficiency must be increased to reduce greenhouse gas emissions, explicitly required by the EU energy efficiency directive. Inductive heating of railway turnouts is considered a potential heating method to achieve higher energy efficiency in railway infrastructure. To obtain a well-founded overview of the current scientific knowledge and for future decision-making, this paper presents a scoping review of scientific publications of the last 14 years about inductive turnout heating systems. Technical design approaches and operating parameters of several inductive heating systems are compared. Expressed drawbacks of inductive heating used in railroad infrastructure and so far unanswered topics regarding electromagnetic exposition and health safety as well as electromagnetic interference are pointed out. Additional investigations need to be carried out before inductive heating can be considered as a preferred future heating method for railway turnouts.

In this study, electromagnetic induction heating is developed to achieve a rapid mold surface heating. Both a single turn of circular coil and a spiral coil were properly designed for induction heating experiments on a flat steel mold plate. Mold surface temperature distribution during induction heating process was measured using infrared thermal image system. Simulation tool was also developed by integration of both thermal and electromagnetic analysis modules of ANSYS. The capability and accuracy of simulations on the induction heating were verified via experiments. To evaluate the practical purpose of induction heating on the real injection molding, a mold plate, roughly about an inset size of cellular phone housing, designed with four cooling channel design and running 12deg coolant were utilized for the demo experiment. After 3 seconds' induction heating, mold surface temperature increases from 110degC to 180degC. It takes another 24 seconds for mold surface to cool down to 110degC. The rapid heating and cooling of mold surface temperatures using induction technology was successfully illustrated via both experiments and simulations.

The rapid development of wearable electronics requires a revolution of power accessories regarding flexibility and energy density. The Li-CO2 battery was recently proposed as a novel and promising candidate for next-generation energy-storage systems. However, the current Li-CO2 batteries usually suffer from the difficulties of poor stability, low energy efficiency, and leakage of liquid electrolyte, and few flexible Li-CO2 batteries for wearable electronics have been reported so far. Herein, a quasi-solid-state flexible fiber-shaped Li-CO2 battery with low overpotential and high energy efficiency, by employing ultrafine Mo2 C nanoparticles anchored on a carbon nanotube (CNT) cloth freestanding hybrid film as the cathode, is demonstrated. Due to the synergistic effects of the CNT substrate and Mo2 C catalyst, it achieves a low charge potential below 3.4 V, a high energy efficiency of ≈80%, and can be reversibly discharged and charged for 40 cycles. Experimental results and theoretical simulation show that the intermediate discharge product Li2 C2 O4 stabilized by Mo2 C via coordinative electrons transfer should be responsible for the reduction of overpotential. The as-fabricated quasi-solid-state flexible fiber-shaped Li-CO2 battery can also keep working normally even under various deformation conditions, giving it great potential of becoming an advanced energy accessory for wearable electronics.

In recent years, deep neural networks (DNNs) have brought revolutionary progress in various fields with the advent of technology. It is widely used in image pre-processing, image enhancement technology, face recognition, voice recognition, and other applications, gradually replacing traditional algorithms. It shows that the rise of neural networks has led to the reform of artificial intelligence. Since neural network algorithms are computationally intensive, they require GPUs or accelerated hardware for real-time computation. However, the high cost and high power consumption of GPUs result in low energy efficiency. It recently led to much research on accelerated digital circuit hardware design for deep neural networks. In this paper, we propose an efficient and flexible neural network training processor for fully connected layers. Our proposed training processor features low power consumption, high throughput, and high energy efficiency. It uses the sparsity of neuron activations to reduce the number of memory accesses and memory space to achieve an efficient training accelerator. The proposed processor uses a novel reconfigurable computing architecture to maintain high performance when operating Forward Propagation and Backward Propagation. The processor is implemented in Xilinx Zynq UltraSacle+MPSoC ZCU104 FPGA, with an operating frequency of 200MHz and power consumption of 6.444W, and can achieve 102.43 GOPS.

The electromagnetic induction heating technology has the advantages of fast heating speed and cleanness, and can realize the rapid temperature curing of carbon fiber reinforced polymer (CFRP). In order to improve production efficiency and curing quality, a finite element model of induction heating CFRP was established, and the temperature field distribution and heating mechanism during induction heating of CFRP were analyzed. The correctness of the model and conclusion is verified by experiments. On this basis, the influence of current, diameter, frequency and distance on the heating rate is analyzed, and it is found that frequency has the greatest influence on the heating rate. In addition, the mathematical relationship between temperature field uniformity and entropy value is established, which provides a quantitative analysis method for the temperature field uniformity of induction heating CFRP. Through optimization analysis, it is obtained that for the CFRP mentioned in the article, the coil size is selected between 65 mm and 95 mm, and the spacing is between 3.5 mm and 6.5 mm, so that the temperature field has the best uniformity.

Catalytic cracking of polystyrene pyrolysis oil: Effect of Nb2O5 and NiO/Nb2O5 catalyst on the liquid product composition

Designing sustainable products is an important element of the low carbon economy that is emerging around the globe. Low carbon materials utilization and energy efficiency in manufacturing and in the consumption phase of a product’s life cycle are key components of sustainable product design. However, integrating these factors into the design of consumer products needs further development. The technical, economic and policy aspects of sustainable manufacturing are vital drivers for integrated low carbon and energy efficient products. In this paper, we present some of our work on the technical and policy aspects of sustainable product design. We present a view of the energy efficiency of select appliances in the market and also show an example of integrating low carbon and energy efficiency in various stages of a product life cycle. This work is being extended further to be able to develop an integrated platform for the design of sustainable products.

Thermoelectric (TE) generation is becoming a valuable and promising research direction. Many researchers have carried out system analysis and performance optimization of thermoelectric technologies based on the generalized thermoelectric energy balance equations. However, it is assumed that TE legs have no heat exchange with the ambient except at the junctions of the hot and cold ends where heat flows in and out. Based on basic thermoelectric effects and fundamental theories of heat transfer, a detailed derivation of the revised generalized thermoelectric energy equations considering convective heat transfer between TE legs and the ambient has been carried out. Irreversible heat transfer processes have been analyzed by employing energy analysis based on the first law of thermodynamics and exergy analysis based on the second law of thermodynamics. The results show that convective heat transfer leads to a decrease in both energy and exergy efficiencies: the rate and magnitude of the decrease in exergy efficiency are greater than those of the decrease in energy efficiency. The exergy efficiency is relatively high despite the low energy efficiency in operation, revealing the features and advantages of thermoelectric generators (TEGs) in low‐grade energy utilization. For TEG efficient operation, the load resistance value should match the system's internal resistance, or at least be greater than that, to avoid a sharp drop in power output and efficiencies. In an attempt at theoretical analysis, the concept of entransy was first introduced into thermoelectric analysis, yielding two concise relational equations which reflect the intrinsic link between Carnot cycle efficiency, energy efficiency, exergy efficiency, and entransy flow transfer efficiency. The entransy analysis based on the index of entransy flow transfer efficiency, together with energy analysis and exergy analysis, may be a novel and valuable guideline for the operation and optimization of TEGs, which needs to be further investigated.

Induction heating is a common non-contact and isolation heating heat treatment process. Medium frequency electromagnetic induction heating equipment is used to heat steel pipe, which is beneficial to the improvement of steel pipe characteristics. The circuit structure design and control of induction heating power supply is the key step of high efficiency and stable operation of induction heating equipment. This paper designs the structure of the electromagnetic induction heating power supply system, selects the dc side power regulation method as the output power control method, and uses the visual simulation tool to model and simulate the system. According to the simulation results, the load can reach the parallel resonance state, output stable sinusoidal voltage waveform and square wave current waveform, achieve stable power output, meet the design requirements.

Hot embossing and injection molding are popular methods to duplicate micro features formed during polymer micro-fabrication of MEMS devices. However, both methods face challenges in filling the polymer melt completely into a micro-featured geometry of a high aspect ratio. In this study, electromagnetic induction heating combined with water cooling is used to achieve rapid mold surface temperature control during the micro-feature injection molding process. A CAE simulation was also developed through integration of both thermal and electromagnetic analysis modules of ANSYS, and its capability and accuracy were verified experimentally. Efficiency evaluations of induction heating and the uniformity of mold temperature control were conducted on a micro-featured mold. This mold was designed with a micro channel array of 30–50 µm in width and 120 and 600 µm in depth, corresponding to aspect ratios ranging from about 2.4 to 12. The accuracies of the micro channels in molded PMMA parts can be used to evaluate the effect of mold temperature on replication accuracy. It was found that rapid mold surface heating with temperature rising from 60 °C to between 100 °C and 140 °C by induction heating requires 2–3.5 s, while the mold temperature returns to 60 °C in about 70–110 s. The simulated mold surface temperature results are consistent with measured results. Achieving the same temperature variation by switching circulation coolants of different temperatures requires at least 7 min. The simulation also reveals that the electromagnetic wave can penetrate into the bottom of the micro channel and results in only about a 2 °C difference in temperature uniformity. For mold temperatures of 100 °C, 120 °C and 140 °C, the molded channel depths were 94.9 µm, 105.4 µm and 116.0 µm, respectively, when the ideal channel depth was 120 µm. When the channel depth is 600 µm, the mold temperature must exceed 120 °C, so that reasonable accuracy in micro-feature replication can be achieved. Our results to date indicate that the aspect ratio for molded PMMA micro channels can be as high as 12. Efficient mold temperature variation by induction heating to improve the replication accuracy in molding micro features is successfully illustrated.

It is theoretical and practical to investigate the causes and effects of energy efficiency. However, few empirical studies have been conducted to examine the potential underlying drivers of energy efficiency from a spatial perspective. In light of this, we combined the data envelopment analysis and spatial econometric analysis to explore the driving factors of energy efficiency. The results show that China's energy efficiency shows significant characteristics of regional disparity and spatial agglomeration; that is, high energy efficiency has presented a benefit agglomeration, while low energy efficiency has presented a disadvantage agglomeration. The empirical results indicate that technological progress, trade openness, and foreign direct investment have effectively improved energy efficiency, while energy structure and industrial structure adversely affect energy efficiency. Furthermore, technological progress, trade openness, energy structure, foreign direct investment, and industrial structure exert different influences on energy efficiency, but their potential underlying mechanisms vary essentially across regions. Thus, using a spatial econometric model allowing for spatial dependence in analyzing drivers of energy efficiency is urgent and necessary for promulgating energy policies.

Since the European Energy Efficiency Directive, a lot of attention has been paid to energy saving measures, including how to overcome the barriers for implementation. This paper addresses the dilemmas of the Dutch dairy sector, where farms are getting bigger and mechanization is increasing, while at the same time the sector is aiming for improved energy efficiency and sustainability. With an online tool which systematically recorded the energy performance of dairy farmers, a unique dataset on farm energy use with more than 25,000 observations over the years 2015–2018 was obtained. This allows for a robust analysis of the determinants of energy efficiency in the sector, using panel data analyses. The results of this study reveal three major trends. First, the on-farm use of solar panels proves to be the most significant determinant for reducing non-renewable energy use. Second, gains in energy efficiency triggered by government policies are countervailed by the continuous trend of mechanization, with especially automatic milking systems causing lower energy efficiency. Third, the increasing economies of scale in milk production substantially improve per-unit energy efficiency. However, the increased need for mechanization related to higher on-farm production can cancel out this economies-of-scale effect. These findings add important new insights to the literature on cleaner production in farms and have important policy implications. Strategies for more energy-efficient farming should entail two directions for innovation: first, the stimulation of more energy efficient automatic milking systems, and second, the stimulation of solar energy production on farms including a better on-farm utilization of solar electricity.

Due to growing challenges regarding crash-performance, CO 2 emission as well as increasing demand for lightweight construction, hot forming of car body parts has risen to one of the most important technologies for saving weight of a car body. During hot forming shaped blanks of steel are heated and austenitized at around 950 °C and subsequently quenched for martensitic formation. Currently the heating is realized in roller hearth furnaces which allow only a slow heating and, therefore, limited production. Additionally, due to the indirect heating principle of roller hearth furnaces the energy efficiency is low. Induction heating for hot metal forming offers a big potential to increase the production rate dramatically and also to improve the energy efficiency. Only due to the fact, that the heated parts typically are already pre-shaped and mostly have already holes and cut-outs induction heating becomes a very complex task. The paper describes the numerical and experimental investigation and the optimization of a single-stage induction heating process for hot forming of pre-shaped blanks and gives design rules for an optimized induction heating system.

The production of fired bricks in traditional wood-fired kilns is a common practice, particularly in developing countries, where it holds cultural and economic significance. However, this method raises environmental and health concerns because of its often low energy efficiency and high fuel consumption. This study aims to model the thermal transition in these traditional kilns to optimize the firing process, reduce wood consumption, and improve energy efficiency. The brick firing process, which includes a critical transitional phase of temperature rise, is frequently poorly managed, leading to significant thermal losses and incomplete combustion. A systematic approach is needed to analyze and improve thermal management, considering factors such as brick stacking, kiln geometry, and combustion parameters. We develop a thermodynamic model that simulates heat transfer, incorporating equations of conduction, convection, and radiation. This model relies on simplifying assumptions that facilitate resolution while maintaining sufficient accuracy. The results revealed a rapid temperature increase followed by stabilization, revealing a dynamic balance between energy input and thermal loss. Our simulations indicate that wood consumption initially increases to reach a plateau when the temperature stabilizes. However, energy efficiency gradually declines, highlighting the importance of optimizing heating and combustion conditions to minimize losses. This research is crucial for small producers, as it could yield significant economic and environmental benefits by enhancing the energy efficiency of brick production. The findings of this study underscore the complex interactions among temperature increase, wood consumption, thermal loss, and energy efficiency. Optimizing thermal parameters, such as heating duration and heat distribution, is essential to reduce reliance on forest resources and improve the sustainability of traditional production methods. These findings pave the way for innovations in brick kiln technology, promoting more environmentally friendly construction practices.

The continuous increase in the energy consumption of wireless networks has led to extensive research and development into energy-efficient communications. Towards this objective, this paper employs a novel technique for maximizing the energy efficiency (EE) of wireless networks, using weighted average EE contours with multiple decoding policies (DPs), where users are prioritized based on different criteria such as channel condition. Moreover, our EE based resource allocation method is extended such that other system targets such as rate-fairness and quality of service (QoS) are satisfied. Results indicate that our EE-based resource allocation scheme achieves the highest EE when DP 2 is employed, i.e. the user with the best channel gain achieves its single user bound, whilst other users experience residual interference. Moreover, both the fairness and QoS constraints increase user satisfaction, in terms of achievable data rate, which comes at the cost of a higher transmit power, and therefore lower EE.