Electric Heating Research Articles

Modelling and performance evaluation of a parabolic trough solar water heating system in various weather conditions in South Africa

In recent years, various energy sources and methods have been used to heat water in domestic and commercial buildings. Water heating methods for large households or commercial buildings include electrical heating elements, gas heaters, and solar energy (solar concentrators, flat plate collectors, evacuated tube collectors, etc.). In recent decades, the focus of water heating has shifted to solar energy, which is abundantly available in most African countries. The weather condition of a region has a huge impact on the system's performance. South Africa is characterised by four different weather seasons (winter, spring, summer, and autumn), unlike most African countries. Therefore, this study focuses on the impact of weather seasons on the system's performance for water heating through the combined use of solar energy and solar concentrator techniques. The system performance was modelled by using Matlab Simulink®, where historical weather data for Pretoria, South Africa, was fed into the model. Based on the weather data input, the system behaviour varied per season due to the change in solar intensity. The average outlet temperatures of the absorber, in the order of magnitude, were 333, 332, 328, and 325 K during the autumn, summer, spring, and winter seasons, respectively. Similarly, the average storage tank temperatures, in the order of magnitude, were 366, 364, 363, and 360 K in spring, summer, autumn, and winter, respectively. From this study, it is concluded that the different weather seasons in South Africa, have a direct impact on the performance of the system. Irrespective of the season, the system produced the required volume of hot water required throughout the year.

A novel hybrid enhanced oil recovery technique to enhance oil production from oil-wet carbonate reservoirs by combining electrical heating with nanofluid flooding

Enhanced Oil Recovery provides a promising technique to maximise fossil fuel recovery from existing resources, and when used in conjunction with Carbon Capture and Storage/Utilisation provides a way to support a transition to alternative cleaner fuels. A hybrid Enhanced Oil Recovery method by a combination of electrical heating and nanofluid flooding was applied to oil-wet carbonate reservoirs and assessed in terms of the oil production, zeta potential, contact angle, pellet compaction, interfacial tension, and pH values. The hybrid technique consisted of a combination of direct current (up to 30 V) and iron oxide (Fe2O3) or magnesium oxide (MgO) nanofluids. Both nanofluids were injected into oil-wet Austin chalk – our laboratory model of an oil-wet carbonate reservoir – and then electrical heating was started, or vice versa. Introducing electrical heating first increased oil recovery by up to 27% in seawater compared to 16% in deionised water. When Fe2O3 nanofluid was injected, oil recovery further increased to 32% in seawater and 24% in deionised water. The contact angle and zeta potential decreased from 124° to 36° and from −24.4 to −23.7 mV, respectively, when nanofluid was injected in seawater, leading to better nanofluid stability and penetration into the carbonate rock as shown by increased pellet porosity from 6.6% to 14.8%. Moreover, it was found that the interfacial tension was reduced from 72 to 32.7 mN/m in the pre-magnetised samples with Fe2O3 NPs injection compared to 33.2 mN/m in the samples with MgO injection. It was found from our experiments that the effect of the generated electricity on the surface charge was of a temporary nature as the zeta potential of the rock returned to its original value as soon as the power was disconnected. The mechanism underlying the hybrid Enhanced Oil Recovery EOR technique from the laboratory findings was found to be based on electrowetting and nanofluid adsorption. Results indicate that the technique is promising for further improving oil recovery and securing energy supply during the transition to net zero.

Investigation of the Temperature Distribution and Energy Consumption of an Integrated Carbon Fiber Paper-Embedded Electric-Heated Floor

This study examined spatial and temporal thermal performance and energy consumption. The temperature distribution in the running period was monitored in test rooms with integrated electric- and hot water-heated floors. The short- and long-term energy consumption of the two heating systems were recorded and compared. The results indicated that the integrated electric heating system generated higher temperatures for indoor air and on the exterior surface of the wooden floor than the hot water heating system; meanwhile, the difference in the mean temperatures of the exterior and rear surfaces of the electric-heated floor was 2.44 °C, while that of the hot water-heated test room was 13.25 °C. The efficient structure of the integrated electric heating system saved 22.97% energy compared to the hot water system after short-term (7 h) charging and reaching a dynamic balance, and it efficiently increased the energy utilization rate to 11.81%. After long-term charging, the daily energy consumption of the integrated electric heating system consumed much less energy than the hot water system every month. The integrated electric heating system saved 62.55% and 34.30% of energy in May and January, respectively, and consumed less than half of the energy the hot water system consumed in the less cold months. Therefore, a high-efficiency and energy-saving integrated electric-heated floor could be a potential indoor heating solution.

Effects of liquid-fuel temperature on rotating-detonation-wave propagation

The utilization of liquid fuel will greatly expand the application scope of rotating detonation engines, and there are still great challenges to achieve high-performance liquid-fuel rotating detonation operation. In this paper, aviation kerosene was used as the liquid fuel to investigate the effects of fuel temperature on the propagation characteristics of rotating detonation waves in two combustor structures: annular and cavity. An electric heating tape was employed to heat the kerosene up to 390 K. The results demonstrate that increasing the temperature of kerosene enhances its atomization efficiency, leading to a marked enhancement in the peak pressure and propagation stability of detonation waves. Moreover, the duration required to establish a detonation wave is notably reduced, as low as 11.2 ms. Furthermore, the detonation wave velocity increases with fuel temperature, with significantly higher velocities observed in the cavity combustor structure compared to the annular combustor structure. In the cavity combustor, the detonation wave velocity can reach up to 74 % of the theoretical CJ value. The results verify the feasibility of improving the rotating-detonation performance via increasing liquid-fuel temperature, which can provide reference for the engineering application of rotating detonation.

Исследование существующих методов сушки увлажненной изоляции тяговых электродвигателей локомотива

Objective: consider the issue of increasing the reliability of electric locomotive traction motors, which depends on various factors. This article examines the factor of the impact of climate conditions on the operation of a locomotive. All attention is paid to the relevance of research into methods for drying the insulation of traction motors at the present time. It has been proven over many years of work that the most vulnerable part of the engine is insulation. All methods that are aimed at solving the assigned problems are listed. The article describes the principle of operation and technology of processes in each of these methods. From the proposed methods, efficiency indicators are derived from the perspective of technical and economic results, and some of their advantages and disadvantages are also noted. The article is based on a comparison of various methods that are aimed at solving current problems associated with increasing the reliability of traction rolling stock. Statistics on traction motor failures over the past three years are presented, and the reasons for moisture in the insulation of electric locomotive power equipment are described. The main methods and methods for drying moistened insulation used in VSZhD locomotive depots are listed, and the characteristics of each method are given. Methods: the method of statistical data and analytical review of the current state of the process of drying the insulation of traction rolling stock was applied. Results: the article lists the studies, experiments and results that evaluate the existing methods and methods of insulation drying processes on rolling stock. An updated method of three-cycle drying of moistened insulation of electrical machines has been developed, which is based on the use of electric heating units and provides for oscillatory energy supply. The task has been set to solve the optimal methods for removing moisture from the insulation of traction motors of electric locomotives based on the use of the convective method. Practical importance: based on the conducted research, the possibility of using the proposed three-cycle method for drying moistened insulation of electrical machines has been confirmed, which allows reducing energy costs for repairs and the time of the insulation drying process.

Role of power-to-heat and thermal energy storage in decarbonization of district heating

The sector integration of the heat and electricity sectors promotes the flexibility of the energy system. This, together with the already almost carbon dioxide-free electricity supply in Finland, facilitates the environmental transition to a carbon-neutral heating system. In this study, pathways to decarbonize the district heating system in Åland (an autonomous region of Finland) are explored. Especially, the roles of different power-to-heat technologies, e.g., heat pumps and direct electric heating, and thermal energy storage are investigated in the decarbonization of the district heating system. The focus is on studying the impact of varying prices in electricity markets on the operation of climate-neutral district heating systems. For this, three scenarios were modeled over the five years of 2018–2022 with varying demand and electricity market prices by using the modeling software PLEXOS. The study showed that electricity prices, but also reserve market prices, have a very significant impact on the operation cost and profit of a district heating system. Overall, electrification has the strong potential to reduce emissions cost-effectively in a district heating system, but it also makes the system vulnerable to electricity price volatility. It can be concluded that thermal energy storage and reserve market participation are crucial for protecting against cost increases and reducing investment risk.

Study on cold start of fuel cell stack combined with liquid heating and fuel cell self-starting

Fuel cell vehicles have been paid more and more attention, while the low temperature cold start capability has become the main reason that hinders their large-scale commercialization, especially for the fuel cell bus. Generally, liquid heating (positive temperature coefficient thermistor (PTC) as the heat source) and fuel cell self-starting heating are the common cold start methods. However, these methods can bring about low start speed and high energy consumption. Therefore, a new cold start method combined with liquid heating and fuel cell self-starting is proposed to solve the problems. Besides, phase change material (PCM) is introduced to reduce energy consumption further. The PCM can absorb the waste heat of the fuel cell stack. Then the heat can be used for stack cold start by circulating liquid. In this study, a fuel cell bus cold start system simulating model is built. Based on this model, the fuel cell temperature and energy consumption during the cold start are analyzed. The results show that the method combined with liquid heating and fuel cell self-starting is superior to the liquid heating method. The cold start time and PTC consumption of the PTC-PCM-self-starting heating mode are 19.0 % and 19.2 % less than that of PTC-PCM heating mode. As for the combined heating method, dropping the self-starting temperature can not only increase the cold start speed but also reduce the proportion of electric heating. For every 1 °C decrease, the start-up time is shortened by 1 % on average, and the waste heat utilization rate is increased by 0.5 %. Although increasing the self-starting current can increase energy consumption, it will save more cold start time and reduce the proportion of electric heating. For every 1 A increase, the start-up time is shortened by 0.3 % on average, and the waste heat utilization rate is increased by 0.1 %. The PTC-PCM-self-starting heating method provides a way for fuel cell stack to start quickly and energy-efficiently in low temperature environment.

Modelling and optimising of MED-TVC seawater desalination plants assisted with electric heaters

One major issue with MED-TVC systems, a widely used thermal-based desalination technology, is their high energy consumption and carbon emissions. This underscores the importance of optimising and integrating these thermal-based desalination technologies with sustainable energy systems to utilize their waste heat and enhance the performance of these plants effectively. This research aimed to optimize and address the environmental challenges of MED-TVC desalination plants in areas with insufficient sunlight, unstable weather conditions, and limited economic resources. To this end, a model of an electric heater for generating thermal energy coupled with an optimized MED-TVC desalination plant was proposed. The MED-TVC section was optimized by incorporating an additional ejector in the final stage of MED-TVC demonstrating an increase of over 11 % in evacuating non-condensable gases from the last effect and increasing the product water by up to 14.89 %. Regarding the design of the electric heating elements used in electric heaters, the use of one-plus-two U-tubes with helical baffles was more efficient than multi-layer U-tubes with segmental baffles as improved the pressure loss of the thermal fluid by 25 % and increased the heat transfer coefficient of the heating elements to 18 %. The power section was also equipped with an off-grid system to provide the necessary power for the equipment of the proposed model. In the economic analysis of employing a parabolic trough solar collector and electric heaters, not only were the direct costs of the electric heaters almost equal to just 40 % of the direct costs of the parabolic trough solar collector approach but also the required thermal fluid was 50 % of the solar case.

Quantitative Study on the Electrothermal Properties of Carbon Nanotube Film and its Out-of-Autoclave-Manufactured Glass Fiber-Reinforced Epoxy-Resin Composites

Abstract: Carbon nanotube films are utilized in various fields, particularly electric heating, owing to their exceptional thermal and electrical properties. However, quantitative research on the electrothermal characteristics of carbon nanotube film is insufficient, and glass fiberreinforced epoxy-resin composites prepared through the electrothermal method of carbon nanotube films (i.e., the out-of-autoclave technique) have not yet been reported. Herein, according to a mathematical model and experimental demonstration, a quantitative relationship, T = T0 + (t/L2)·(V2σ)·(1/αw), was proposed to explain the electrothermal properties of carbon nanotube films. Glass fiber-reinforced composites with an outstanding tensile strength of 535.6 MPa and an elongation-at-break of 1.6% were prepared through the out-of-autoclave technique using the designed carbon nanotube film. The composites outperformed previous mechanical composites in terms of energy consumption. Experimental investigations and molecular simulations revealed the mechanical mechanisms of the composites. These findings quantitatively revealed the electrothermal properties of carbon nanotube films, advancing their application in the out-ofautoclave manufacturing of high-performance resin-matrix composites.

Evolution of electrical resistance of graphite foils during spark plasma sintering

The progression of the electrical resistance of graphite foils during spark plasma sintering process (SPS) was investigated at constant temperature and pressure. The study applied various set-ups of the SPS device, and the electrical data used for the evaluation of electrical resistance (heating power and current) was obtained from the SPS apparatus in real-time. The contact resistance and resistance due to graphite foil/s was evaluated by subtracting the resistance of the single punch set-up from the set-up of two punches in direct contact and the set-ups with various graphite foils. The results showed that during the initial stages of sintering, set-up resistance increases with time and that, overall, set-up resistance increases with number of graphite foils. Both contact resistance and resistance due to graphite foils was found to decrease with sintering time. In contrast to previous conceptions, the electrical resistance of graphite foils changes in response to sintering conditions during the SPS process.

A comparative investigation of eco-friendly fly ash-based geopolymer mortar produced by using electrical and heat curing: Mechanical properties, energy consumption and cost

This study investigates the eco-friendly fly ash-based geopolymer mortar (GM) production using electrical curing (EC) and heat curing. Within the scope of the study, GM produced using the EC method was compared with GM produced using the heat curing (HC) method in terms of mechanical properties, energy consumption, and cost. The study consists of a preliminary experiment to determine the parameters to be used, mortar experiments using the limited parameters defined in preliminary experiments, and an energy consumption and cost analysis. In the preliminary experiments, different mix designs produced according to different MS modulus and Na2O concentrations were studied to decide an applicable range for temperatures of HC and an applicable range for voltages of EC. In the second stage, EC and HC were compared according to temperature changes in GMs, current changes in GMs, and compressive strength (CS). As a final stage, an energy consumption and cost analysis were performed to compare two curing methods according to the updated dollar-based unit prices for electricity per kWh for industrial uses in various countries in February 2024. Results showed that the MS modulus should be at least 1.2 and the Na2O concentration should be 10 % on average to obtain a workable mortar. The compressive strength of all mortars with any MS modulus increased up to 100 °C and then decreased HC applied samples. Stress values of 20, 25, 30, and 35 volts are applicable and the highest compressive strength values could be obtained with 25 volts, and 6 h of application is sufficient at 25 volts EC. MS module is a key parameter in current and temperature change. In EC application, 30 volts is the threshold value, and when an electrical voltage above 30 volts is applied, the mortar's internal temperature suddenly reaches the peak value and the desired compressive strength results cannot be achieved. According to the cost analysis, it is seen that the HC electricity cost is 6.78 times more than the EC cost. A comprehensive efficiency calculation is strongly recommended for future studies. It has also been concluded that geopolymers could gain strength at much lower voltage values, so they have the potential to consume less electrical energy in comparison to conventional concrete.

Performance optimization and evaluation of integrating thermochemical energy storage with low-temperature driven absorption heat pump for building heating: 4E analyses

A heating system achieved by combining thermochemical energy storage and absorption heat pump is proposed and verified. Based on the experimental data, a mathematical model of the zeolite/water reactor is established and verified. By setting up a micro-compressor between the evaporator and absorber, the AHP is driven by low temperature source. Based on typical days in winter, the stable operation of the system is explored, and the influence of main parameters on the charging/discharging and heating processes are analyzed. The results show that the charging and heating efficiency reached 55.11% and 73.52% during the daytime. The discharging efficiency at night reaches 88.27%. The AHP can be driven by a heat source at a minimum of 75 °C, and hot water at 48.3 °C is provided. Parameters influence analysis shows that temperature is an important factor affecting the charging process, and the initial air temperature is recommended to increase. Humidity is the biggest influencing factor in the discharging process and easily changed and controlled. By replacing electric heating, the system can allow the investment to be recovered within 6.23 years. Environmental analysis shows that the proposed system has significant benefits in terms of primary energy savings and pollutant emission reduction

Evaluation of Life Cycle CO2 Emissions for the LDR-50 Nuclear District Heating Reactor

The LDR-50 low-temperature nuclear reactor is designed for the Finnish and European district heating markets, as an environmentally sustainable heating option for the 2030s. While the carbon footprint of conventional electricity-producing reactors is known to be small, there have been no comprehensive studies on the emission reduction potential when the technology is applied to the heating sector. This paper aims to fill this knowledge gap by means of life cycle assessment (LCA) analysis. The carbon footprint of the LDR-50 heating plant is evaluated, and compared to conventional heating fuels, direct electric heating, and heat pumps. The results of the analysis show that the life cycle CO2 emissions are low, although there are still significant uncertainties related to the construction phase, due to missing data. In addition to carbon footprint, the analysis is also extended to other adverse environmental impacts. It is concluded that significant reductions in CO2 emissions can be achieved by replacing fossil heating fuels with nuclear energy. The technology is considered a viable option alongside biofuels and heat pumps. The overall environmental impacts are low, and the production does not compete for low-carbon electricity or scarce natural resources.

Model coupling and comparison on optimal load shifting of battery electric vehicles and heat pumps focusing on generation adequacy

The energy transition fosters a dynamic landscape marked by renewable energy, electrification, and complex interactions among actors and technologies. Employing model experiments and comparisons shows promise for exploring these connections and enhancing model clarity and precision. This study adopts a multi-model approach, integrating a model comparison to probe how the electrification of demand-side sectors and strategic load shifts of battery electric vehicles and heat pumps might impact Germany's generation adequacy by 2030. Specific demand models from the transport and heating sectors and a future load structure projection model are interlinked with three electricity system models. The comparative analysis of the three electricity system models unveils discrepancies in dispatch decisions for power plants, flexibility options' load shifts, and their effects on generation adequacy, directly tied to model attributes.The comparison underscores methodological variations (linear optimization versus agent-based simulation, myopic foresight versus perfect foresight) as pivotal, emphasizing the significance of considering load change and start-up costs for power plants. The results show that with optimized load shifting by electric vehicles and heat pumps, the adequacy of power generation is less strained despite increased electricity demand. Moreover, load shifts mitigate curtailment of renewables and consumers, reducing carbon emissions by lowering conventional power generation.

Modeling Granule Consolidation During Electrical Heating

Modeling Granule Consolidation During Electrical Heating

Glass frit and method of forming electrical insulating coatings on steel substrates of film heaters

Electric film heaters (EFHs) applied on flat steel substrates show promising potential in the production of heating devices. The basis for manufacturing EHFs is heat-resistant steel, the surface of which is coated with a heat-resistant electrical insulation coating. These coatings are glass crystalline and are applied mainly by screen printing. Compared to screen printing, the electrophoretic method of coating is more productive. In this work, glass in the MgO–CaO–B2O3–SiO2 oxide system was chosen for obtaining glass crystalline coatings. The paper provides a description of the material composition and the method used to prepare a suspension for еру electrophoretic deposition of coating. The main technological parameters for forming electrophoretic coatings with a specific thickness are determined based on experimental results. Utilizing calculated data on the properties of the selected glass, the study substantiates the most rational temperature and time regime for coating firing. These conditions promote crystallization and result in the production of heat-resistant coatings with sufficient electrical insulating properties for steel substrates of EFHs.

Improving the Load Flexibility of Stratified Electric Water Heaters: Design and Experimental Validation of MPC Strategies

Improving the Load Flexibility of Stratified Electric Water Heaters: Design and Experimental Validation of MPC Strategies

Flexible thin-layer plasma sterilizer based on polyimide and efficacy evaluation under bending deformation

Cold atmospheric pressure plasma is receiving attention in biomedical treatment for its non-thermal, dry-type, and high-efficiency disinfection effects on bacteria, fungi, and viruses, compared to typical sterilization methods, such as pasteurization, chemical solutions, and ultraviolet radiation. There are great demands of plasma decontamination on the surface of complex 3D objects, with the request of large coverage, convenience, and uniformity, which still remains a challenge for the current plasma devices. In this work, a flexible thin-layer plasma source for sterilization is developed based on a polyimide substrate, and its plasma generation process is characterized by experiment and simulation. The influences of bending deformation are studied and evaluated by electrical waveforms, heat radiation, and ozone production, of which the mechanisms are further explained. Results illustrate that the variation in electron impact ionization induced by different curvatures is the main cause leading to the change in microparticle production, thus affecting the macroscopic properties of plasmas. Activations of the plasma sterilizer for 30 and 120 s reduce both S. aureus and P. aeruginosa on the flat surface by around 2.5 and 5 log colony forming units (CFU). However, the plasma sterilization effect decreases with an extent of about 1 log CFU when treating the curved surface, while being regained after conforming the plasma sterilizer to the curved surface. This kind of plasma generator offers significant flexibility and efficacy, being promising for the treatment of objects with irregular surfaces in future plasma biomedicine and material processing.

Noise coupling reduction using temperature enhanced device for future integrated circuit integration applications

<p>Information technology-to-internet of things may have succeeded because of fast silicon chip capability expansion. Moore's law, which reduces device size, boosted integrated circuit (IC) performance. Delay rises with highdensity connection parasitic capacitance. Interconnect delays have surpassed transistor delays and slowed progress. An alternative is required now to reduce connection latency. The third dimension is used in popular 3D IC technology IC technology requires through silicon via (TSV) for signal integrity and heat mitigation. Noise coupling hinders electrical communication between signal-carrying TSVs (aggressive TSVs) and ground TSVs (victim TSVs), a 3D IC bottleneck. TSVs must be dielectrically insulated from Si substrates to avoid electrical signal interference. Additionally, first-order modelling will confirm the suggestions. This article proposes using the nanosheet field effect transistor (NSFET) to overcome 3D IC noise coupling and complementary metal oxide semiconductor (CMOS) technology nodes. After discussing the electronic industry and sub nm, several basic metrics and criteria for developing electronic components are presented. The first technique uses Perylene-N's exceptional noise-cancelling characteristics. Second technique uses electrical TSV (ETSV), thermal TSV (TTSV), and heat source models to measure noise coupling on numerous ICs. The third proposes many noise-reducing materials. The suggested structures outperform traditional approaches.</p>

System Optimization and Operating Strategy of Single-Stage Air Source Heat Pump with Thermal Storage to Reduce Wind Power Curtailment

Wind power generation has increased in China to achieve the target of decreasing CO2 emissions by 2050, but there are high levels of wind curtailment due to the mismatch between electricity supply and demand. This paper proposes a single-stage air source heat pump coupled with thermal storage for building heating purposes. The main objective is to find the proper system designs and operating strategy, which can help to avoid peak demand periods while obtaining minimized running costs and reduced wind energy curtailment. Dynamic simulations were performed using TRNSYS to investigate its use in a typical office building based on an actual electricity tariff, wind power, and meteorological data. The proper system designs, including the tank size and thermal storage temperature, were determined to maximize the system’s performance. It was found that a proper combination of the two parameters exists for a specific application. Further, results showed that the use of auxiliary electric heating is necessary for single-stage air source heat pumps to participate in a wind curtailment reduction. The operating strategy of the system was also studied. Results indicate that by implementing a proper operating strategy, non-renewable power consumption can be reduced by 11% for the studied building, with a total wind power utilization of 3348 kWh during the heating season while still satisfying the heating demands of users. These findings can contribute to the green and low-carbon development of the building industry and further enhance the grid’s accommodation capacity for renewable energy sources.