Heating Element Research Articles

Numerical Analysis Of Natural Convection In A Closed Circular Cavity With A Elliptical Heater

The natural convection heat transfer in a closed circular cavity containing a constant temperature elliptic heating body was studied by finite volume method. The influences of Rayleigh number Ra, relative size of heating element and rotation Angle on flow and heat transfer in the cavity are discussed. The variation range of Rayleigh number is 103 ~ 106, the variation range of length-diameter ratio of elliptic long axis to cavity diameter is 0.1 ~ 0.4, and the variation range of rotation angle is 0° ~ 90°.The results show that the changes of the above three parameters can affect the structure of temperature field and flow field in the cavity. Increasing the Rayleigh number, decreasing the size of the heating element and increasing the rotation Angle of the heating element will be more conducive to the heat transfer in the cavity. The research results can provide theoretical basis for the heat dissipation and management of electronic equipment.

Experimental evaluation on the power characteristic of direct-photovoltaic charging for thermal storage equipment

Thermal storage is an essential equipment for storing excessive heat, especially for water heating systems. The present work proposes a preliminary study to maximize the operation of thermal storage using photovoltaics as the primary source for charging the heat storage material. The assessment indicates the concept is feasible, where the output power from photovoltaics can be directly converted to heat using a heating element. The power ratio is considerably high (up to 38.6%), resulting in the maximum temperature of the heat absorber material (water) increasing to 43.2 °C. The final assessment using suitable phase transition material shows that steady phase behavior is essential to maximizing the temperature profile of the material. It is achieved using stabilized-hexadecanoic acid, which shows a transient phase transition at a temperature of 54.2 °C, reducing the possibility of heat loss with an average temperature rate of 0.54 °C/min in the discharge stage. This finding proves the proposed concept is applicable, while further improvement can be done to adjust the suitable power output from photovoltaic and storage tank arrangement for the actual system. Despite that, the result is expected to accelerate the utilization of photovoltaics as reliable solar renewable technology.

Process improvement in Zamak injection machines for automotive component fabrication

Die casting processes are nowadays widely used in the industry and differentiate from metal casting from the high-speed and pressure applied to inject the metal into the cavity. Due to this procedure, the produced parts manage to acquire better mechanical characteristics, dimensional precision, and smaller roughness. Due to the automation possibility, and mould coating possibilities, the process becomes cost competitive at significant production rates. However, to assure proper functioning and extended life of die casting equipment, it is necessary to continuously control the process variables, undertake maintenance, and implement process improvement actions to the production lines. The objective of the present work is to improve the efficiency of a Zamak die cast injection line for cable terminals used in Bowden or control cables for the automotive industry. By reducing wear and number of failures of standard components in this production line, and thus by diminishing the stoppage and replacement costs, it becomes possible to improve the current process. By applying specific improvements to the injection subset, heating element, and pump, including geometry modifications to the injection elements and respective interactions, heat treatments, higher power resistor, and groove/ring system in the pumps’ piston, a significant process improvement was accomplished by the proposed and tested modifications, leading to reduction of failures and operational costs, and consequently higher competitiveness of the process.

A unique warm–water oasis in the Siberian Arctic’s Chaun Bay sustained by hydrothermal groundwater discharge

Chaun Bay, located on the fringe of the East Siberian Sea, has been described since the mid-20th century to support a unique marine ecosystem that is atypical for the local Siberian Arctic. Here we use ship-board physical, biogeochemical and geological measurements taken in October 2020, along with hydrographic observations taken from land-fast ice in April 2023, to demonstrate that these warm-water biological communities are supported by hydrothermal submarine groundwater discharge that delivers heat, salinity, nutrients, and trace elements to the bay. We identify a cyclonic eddy that mixes the warm nutrient-rich groundwater with oxygen-rich surface water, resulting in a water mass within Chaun Bay that has similar physical and chemical properties to the highly productive waters of the North Pacific and Southern Chukchi Sea. The bay showed elevated concentrations of chlorophyll-a and zooplankton, and the abundance and species diversity of epibenthos significantly exceeded values observed elsewhere in the East Siberian Sea. The benthic communities contained a number of boreal species that are not typically found in the Arctic Ocean. We also observed Thysanoessa krill populations, a pelagic species generally considered an expatriate in Arctic waters.

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 System Built for Both Deterministic Transfer Processes and Contact Photolithography

A home‐built compact system that functions as both a transfer stage for deterministic transfer processes and a mask aligner for contact photolithography, is constructed. The precision translation sample stage and optical microscope are shared between the two modes. In the transfer mode, assisted by either an adhesive or a heating element, the setup has been used to deterministically transfer freestanding semiconductors, 2D materials, and van der Waals electrodes. When configured in photolithography mode, the proposed instrument has been employed to fabricate various microscale patterns and devices, with minimum feature sizes of 1–2 μm achieved. The prototype instrument provides a feasible solution for performing high‐quality deterministic transfer and photolithography processes on one single tool in‐house.

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.

Shape memory polymer composite hinges for solar sails

Smart hinges for self-deployable solar sails have been prototyped by using shape memory polymer composites (SMPCs). During hinge lamination, a shape memory (SM) epoxy resin is deposited between carbon fiber reinforced (CFR) plies, and consolidation is obtained by an out-of-autoclave (OOA) process. The smart hinges have been assembled with CFR booms to prototype a small self-deployable square sail. Polymeric supports, made by fused deposition modelling (FDM), have been added for correct assembly and to drive the recovery of the SMPC hinges. Flexible heaters have been used as heating elements for SMPC hinge activation. The sail consisted of a polyimide membrane which was connected with the composite booms by flexible joints. The solar sail prototype size has been limited to 260 × 260 mm2 for on-Earth testing, with 4 hinges at the middle length of the composite booms. Recovery tests have shown the ability of the smart hinges to overcome the sail weight and additional friction forces, and the small sail has been successfully deployed in laboratory. Full recovery has been achieved in less than 3 min under different configurations.

MECHANICAL PROPERTIES OF POROUS SILICON CARBIDE CERAMICS: A REVIEW

Porous silicon carbide (SiC)-based ceramics exhibit exceptional structural and functional properties, such as excellent mechanical, chemical, and thermal stability, and controlled electrical resistivity. Owing to their superior properties, porous SiC ceramics are suitable for various industrial applications, including heatable filters, heating elements, thermoelectric energy converters, fusion reactors, thermal insulators, water purifiers, molten metal and hot gas filters, diesel particulate filters, membrane supports, and catalyst supports. A deeper understanding of the mechanical properties of porous SiC ceramics, coupled with the development of new strategies for tuning these properties, will enable the realization of numerous new applications. In this review, important factors known to determine the mechanical strength of porous SiC ceramics, such as microstructures (necking area) and pore characteristics (porosity, pore size), have been analyzed. With increasing porosity and pore size of porous SiC ceramics, the flexural strength tends to decrease. The flexural strength increases with decreasing pore size at a constant porosity, whereas the flexural strength decreases with increasing porosity at a constant pore size. In addition, the flexural strength of porous SiC ceramics is primarily influenced by the developed necking area between SiC grains, which can be obtained through the doping of soluble atoms into the SiC lattice. Based on these critical factors affecting the mechanical properties, a novel strategy for tuning the flexural strength of porous SiC ceramics is proposed.

Акустика кипения с недогревом на лазерном нагревательном элементе

We study acoustic signals arising during cavitation initiated by laser heating of water in the vicinity of the end of an optical fiber immersed in water. It is shown that the growth and collapse of the vapor phase in the vicinity of the end of the optical fiber (laser heating element), along which laser radiation propagates, generate acoustic signals characteristic of the elementary act of boiling, which precede the appearance of large-amplitude signals. It has been established that large amplitude signals are caused by shock waves that arise during the collapse of the main bubble and secondary bubbles - “rebounds”.

Enhanced comprehension of the cross-scale forming mechanism in CF/PEEK resistance welding: Analysis of temperature gradients and meso–microscopic phase transitions

Resistance welding technology is an effective solution for connecting thermoplastic composites. However, limited research on non-uniform distribution of interfacial temperature and complex evolution mechanism of phase-change molding hinders its application. This reliance on traditional experimental and trial-and-error methods severely impedes its development. Therefore, this study employed a novel cross-scale numerical simulation method, being applied for the first time in the field of resistance welding for elucidating the underlying mechanism of joint formation through multi-component phase transformation. The constructed model accurately represented the transient heat transfer of a realistic wire mesh structure in three dimensions, while incorporating complex gradient effects arising from both spatial and temporal variations in heating element temperature due to air interference. Further, melting, flow, and consolidation behavior of the resin matrix in resistance welding of carbon fiber/polyetheretherketone (CF/PEEK) thermoplastic composite was investigated herein at a mesoscopic scale. To accomplish this objective, a three-phase flow spatial forming and evolution model for resistance welding was developed at the mesoscopic scale by integrating principles from fluid dynamics. Interestingly, introduction of an air phase reinstated the spatial voids formation and flow in resistance welding, providing robust evidence for the initiation mechanism of internal defects. Moreover, this study revealed variations in the melting mode of PEEK resin across different regions within the weld and highlighted distinct distributions of voids resulting from uneven heat transfer. The interfacial phenomenon and flow diffusion mechanism between components in resistance welding tests were further verified and discussed through analyzing scanning electron microscopy and energy dispersive spectroscopy results. Temporal and spatial correlation in void distribution within the welding zone was observed, which was found to be consistent with simulation results. Specifically, with the progress of the welding process, air near the wire mesh gradually dispersed into the laminate, with significantly more voids at weld seam edges than in central regions. This research methodology based on stepwise scale reduction offers a promising avenue for investigating resistance welding and other connection forming applications, in particular, within the context of engineering underlying logical behavior.

Multifunctional Polymer Composites for Automatable Induction Heating with Subsequent Temperature Verification

Manipulating ferromagnetic particles using an alternating current (AC) magnetic field is a versatile method for quick, local, and on‐demand heat generation. These particles can be incorporated into various matrices as heating elements. Their heat release can be controlled by adjusting process or material parameters. Herein, a proof‐of‐concept for a flexible polymer composite with customizable magnetically triggered heat release due to prior object identification via fluorescence readout is presented. The maximum temperature resulting from this process can be determined through a second fluorescence readout ex post. This novel combination of functionalities results from the synergistic interaction of inductively heatable magnetic supraparticles (SPs) and luminescent communicating SPs in one polydimethylsiloxane composite. The surface of the composite can be heated to the maximum temperatures of choice in a range between 125 and 200 °C within 2 s. Heat release and temperature verification provide spatial resolution of millimeters. The identification signature and the working range of the temperature indication functionality of the composite are customizable by exploiting its modular material design. The temperature indication functionality of the composite offers spatial resolution and ex‐post readout at any point of interest, making it a versatile alternative to established optical thermometry methods.

Design and evaluation of an efficient mosquito trap.

Vector mosquito control is important for preventing and controlling mosquito-borne infectious diseases. This study designed and developed a mosquito killer (MK) with a specific light wavelength, simulated human body temperature, human odor, and a photocatalyst to stimulate CO2 based on the physiological characteristics and ecological habits of mosquitoes. We tested the trapping effect of individual and multiple mosquito-trapping elements of the MK through two-way selection experiments and compared them with several commercial mosquito traps. The 365 nm wavelength MK was significantly more effective than the 395 nm (Cx. quinquefasciatus: 62.00% vs. 34.25%; Ae. albopictus: 50.75% vs 45.00%, An. sinensis: 49.75% vs 39.00%). Mosquitoes captured by the MK with heaters at 365 nm were significantly more than those captured by the MK without heaters at 365 nm. A trap with a 365 nm wavelength, heating element, and lure showed significantly better capture effectiveness than MK with a 365 nm wavelength, heating element, but without lure (Cx. quinquefasciatus: 67.00% vs. 29.75%, Ae. albopictus: 60.25% vs 36.25%, An. sinensis: 49.75% vs 39.75%). The coated photocatalyst trap with a 365 nm wavelength, heating element, and lure showed significantly better capture effectiveness than the trap without coating (Cx. quinquefasciatus: 54.25% vs. 42.50%; Ae. albopictus: 53.50% vs 44.00%, An. sinensis: 50.00% vs 41.25%). This trap demonstrated a significantly better capture advantage for Cx. quinquefasciatus and Ae. albopictus compared to the three commercial products. The developed mosquito trap with multiple attractant factors significantly enhanced the capture effectiveness of common mosquitoes. © 2024 Society of Chemical Industry.

A Study on the Thermal Distribution of the Thermoforming Process for Polyphenylene Sulfite (Polyphenylene Sulfide) PPS Composites Towards Out of Autoclave Activity

The thermoforming process is a widely utilized manufacturing technique for shaping thermoplastic materials into various products. Achieving uniform and controlled thermal distribution within the material during thermoforming is crucial to ensure high-quality products and minimize defects. This study investigates and enhances the understanding of thermal distribution in thermoforming processes through simulation analysis before it is done via experiment. This research investigates the thermal distribution in the thermoforming process of Polyphenylene Sulfide composites. The heating element distances were varied during the simulations of the thermoforming process of Polyphenylene Sulfide (PPS) composites, focusing on understanding how different distances affect the material’s deformability, dimensional accuracy, and overall quality. Three heater temperatures with three heater distances are tested. The distance between two heated surfaces is 200, 300 and 500 mm for 320oC, 360oC and 400oC heated surfaces. The desired PPS temperature (320oC) and maximum heater temperature (400oC) are parameters. The test result shows that to achieve 320oC thermoplastic temperature, we can use 385oC IR heater temperature with a heater distance of 200 mm. However, this 200 mm distance might be too close for the operation, and a larger distance might be needed. Using 300 mm or 500 mm can achieve close to 320oC if the heater temperature is set to 400oC. In conclusion, this value is a reference for the distance of the material between the heater during the fabrication process.

Uniformizing the temperature of turbine blades during the heat treatment process from the perspective of radiation energy distribution

Nickel-based single-crystal turbine blades are critical components of jet engines. Due to element segregation and microstructural defects in as-cast blades, vacuum heat treatment is essential. Controlling the blades’ heat treatment temperature is crucial for improving mechanical performance. However, when treating multiple blades simultaneously, large temperature differences often occur, making it challenging to ensure consistent and uniform temperatures. This paper establishes a numerical algorithm that links blade temperature with radiant energy, optimizing blade arrangement to achieve uniform energy distribution and temperature field homogenization. The improved view factor finite element algorithm is more suitable for blade structures. The Particle Swarm Optimization (PSO) and Coordinate Descent (CD) methods were used to solve the optimization function, aiming to minimize the temperature difference among blades. Finite element simulation was utilized to model the temperature field of the blades during radiative heat transfer from heating elements. The PSO and CD optimization methods were employed to find the local optimal solution that minimizes the view factor variance, reducing it from 2.24 before optimization to about 1. Simultaneously, the optimized maximum average temperature difference of the blades was 71.1 °C, approximately 50 % lower than the 138.8 °C before optimization. By comparing the view factor values with the simulated temperature fields, the strong correlation between the view factor and blade temperature was verified. This paper innovatively proposes a numerical method for optimizing blade arrangement to homogenize the temperature field, effectively enhancing temperature consistency during the heat treatment process.

Hot Fingers: Individually Addressable Graphene-Heater Actuated Liquid Crystal Grippers.

Liquid crystal-based actuators are receiving increased attention for their applications in wearables and biomedical or surgical devices, with selective actuation of individual parts/fingers still being in its infancy. This work presents the design and realization of two gripper devices with four individually addressable liquid-crystal network (LCN) actuators thermally driven via printed graphene-based heating elements. The resistive heat causes the all-organic actuator to bend due to anisotropic volume expansions of the splay-aligned sample. A heat transfer model that includes all relevant interfaces is presented and verified via thermal imaging, which provides good estimates of dimensions, power production, and resistance required to reach the desired temperature for actuation while maintaining safe electrical potentials. The LCN films displace up to 11 mm with a bending force of 1.10 mN upon application of 0-15 V potentials. The robustness of the LCN finger is confirmed by repetitive on/off switching for 500 cycles. Actuators are assembled into two prototypes able to grip and lift objects of small weights (70-100 mg) and perform complex actions by individually controlling one of the device's fingers to grip an additional object. Selective actuation of parts in soft robotic devices will enable more complex motions and actions to be performed.

Design, Fabrication, and Performance Evaluation of a Varying Temperature Dehydrator for Food Preservation

This study focuses on creating and evaluating a dehydrator that can operate at different temperatures for preserving food. The dehydrator includes a drying chamber, an axial fan, a heating element, trays, vents, and a thermostat. Various experiments were carried out on the food dehydrator for performance evaluation. The first experiment was carried out on plantain, and it was observed that the drying time decreased as the drying temperature increased. The shortest drying time for plantain drying was obtained at 75℃, which is 210 minutes, followed by 70℃, with a total drying time of 240 minutes, and 65℃, with a total drying time of 270 minutes. Equilibrium moisture content was reached when no more change in weight was observed. These results explained that temperature significantly affected the selected product during dehydration. For the second experiment, it was observed that the higher the proximity of trays to the heating element, the faster the drying time. The shortest drying time for tomato was obtained at the tray closest to the heat source, with a total drying time of 90 minutes. The second tray in the middle had a total drying time of 120 minutes, whereas the third tray at the top took 150 minutes for the tomatoes to completely dry. This boldly explains that the dehydrator’s efficiency depends on the tray position. The food dehydrator increases its utility for drying a wide range of foodstuffs, including fruits, vegetables, meats, and fish, which have different moisture content and drying requirements.

Recent advances of preparing structure-enhanced conductive yarns to control their performance in potential applications

There has been a recent transition from conventional textiles to smart and electronic textiles, mostly due to the rise of wearable technology. Functional yarns have been created to fulfil the varied application needs in various environments. Conductive yarns have attracted considerable interest because of their exceptional softness, comfort, and diverse capabilities, such as electromagnetic shielding and soft sensors. This paper presents a comprehensive examination of spinning techniques utilized for the production of conductive yarns, incorporating a range of conductive additives, conductive fabrics, and conventional electrical elements. The text emphasizes that the performance of conductive yarns is significantly affected by their structure, which is dictated by the geometrical configurations of their elements, and the spinning geometry, commonly known as the twisted triangle. The performance of conductive yarns is primarily determined by the concentration of conductive components in their structure. Moreover, this paper examines the possible uses of conductive fabrics in several technical domains. The mentioned applications encompass antistatic packaging, heating elements, wearable electronics, smart membrane technology, data storage and transmission, sensors, actuators, and protection against electromagnetic interference and electrostatic discharge. Conductive textiles possess a versatile character that presents a wide range of opportunities for progress in multiple industries. To summarize, this review thoroughly examines the spinning methods used to create conductive yarns, with a particular focus on the significance of yarn structure in influencing their performance. Furthermore, it emphasizes the wide range of technological applications in which conductive textiles can be utilized.

Resistive Heating Catalytic Micro-Reactor for Process Intensified Fuel Reforming to Hydrogen

Abstract Process intensification of fuel reforming using micro-reactors has become crucial for feed flexibility in H2 production for fuel cells. In the literature on microreactors, energy supply for these endothermic reactions has faced limitations, relying on external heating, or autothermal operation. This paper explores a novel approach using a thin-film catalytic heater to develop micro-reactors. The study focuses on dry methane reforming in a simplified micro-reactor where thermal energy is supplied through electric resistive heating of a thin carbon sheet with a catalyst applied to its surface. The thin catalytic heated layer inside the reactor minimizes energy losses and the reactor footprint. Power input was varied from 90-225 W to understand its impact on the reactor temperature, CH4 conversion, H2 and CO yields. Fast thermal response times were achieved using the carbon paper as thin film for heating. Ni/MgO impregnated onto carbon paper was utilized as the catalytic heating element which resulted in CH4 conversions greater than 60% at temperature above750 K. Influence of operating conditions such as the input molar ratio of CO2/CH4, and gas hourly space velocity (GHSV) were also investigated to understand the scope of the catalyst in this setup. High GHSVs (592,885 and 948,617 mL/(hr.gcatalyst)) were tested to understand the throughput achievable using this setup. This approach demonstrates improved scope and feasibility for further intensification compared to conventionally heated microreactors. The research paves the way for efficient and compact micro-reactors for fuel reforming processes.

Numerical study of thermal comfort and energy efficiency about electrically heated footwear under a cold environment

PurposeThe paper aims to reveal the relationship among energy efficiency, thermal comfort and thermal regulation of electrically heated footwear and to investigate influencing factors on the energy efficiency and thermal comfort.Design/methodology/approachA finite volume model was proposed to simulate the two-dimensional heat transfer in electrically heated footwear (EHF) under an extremely cold condition. The model domain consists of three-layer footwear materials, a heating pad, a sock material, an air gap and skin tissues. Model predictions were verified by experimental data from cold-contact exposure. Then the influencing factors on the energy efficiency and thermal comfort were investigated through parametric analysis.FindingsThe paper demonstrated that the skin temperature control (STC) mode provided superior thermal comfort compared to the heating pad temperature control (HPTC) mode. However, the energy efficiency for the HPTC mode with a heating temperature of 38 °C was 18% higher than the STC mode. The energy efficiency of EHF while reaching the state of thermal comfort was strongly determined by the arrangement and connection of heating elements, heating temperature, thickness and thermal conductivity of footwear materials.Originality/valueThe findings obtained in this paper can be used to engineer the EHF that provides optimal thermal comfort and energy efficiency in cold environments.