scholarly journals The Effects of Absorbing Materials on the Homogeneity of Composite Heating by Microwave Radiation

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7362
Author(s):  
Betime Nuhiji ◽  
Matthew P. Bower ◽  
William A. E. Proud ◽  
Steven J. Burpo ◽  
Richard J. Day ◽  
...  
Keyword(s):  
Electromagnetic Field ◽  
Temperature Distribution ◽  
Electromagnetic Radiation ◽  
Heat Distribution ◽  
Temperature Uniformity ◽  
Geometric Complexity ◽  
Uniform Temperature ◽  
Better Regulation ◽  
Absorbing Materials ◽  
Complexity Increase

When cured in a microwave, flat thin composite panels can experience even heat distribution throughout the laminate. However, as load and geometric complexity increase, the electromagnetic field and resulting heat distribution is altered, making it difficult to cure the composite homogeneously. Materials that absorb and/or reflect incident electromagnetic radiation have the potential to influence how the field behaves, and therefore to tailor and improve the uniformity of heat distribution. In this study, an absorber was applied to a composite with non-uniform geometry to increase heating in the location which had previously been the coldest position, transforming it into the hottest. Although this result overshot the desired outcome of temperature uniformity, it shows the potential of absorbing materials to radically change the temperature distribution, demonstrating that with better regulation of the absorbing effect, a uniform temperature distribution is possible even in non-uniform composite geometries.

Investigation of the Effect of Different Materials on Uniform Heat Distribution Over a Solar Collector Pipe

2020 ◽  
Vol 17 (5) ◽  
pp. 2021-2023
Author(s):  
V. Sriram ◽  
B. Kanimozhi
Keyword(s):  
Temperature Distribution ◽  
Power Plant ◽  
Solar Collector ◽  
Nuclear Power ◽  
Turbine Blades ◽  
Heat Distribution ◽  
Uniform Temperature ◽  
Uniform Heat ◽  
Solar Radiation Incident ◽  
Copper Aluminum

Collector pipe used in solar power plant is a device for converting water from ambient temperature to the raised temperature which in turn used to rotate turbine blades. The raise in temperature is not that much when compared to thermal or nuclear power plant, so researches are going on for improving the heat carrying capacity of collector pipes. The productivity in pipe directly depends on the factors such as solar radiation incident on it, temperature distribution over the pipe, surrounding temperature, material of the pipeline used, and thickness of the pipe. When comparing to all of such parameters, the temperature distribution over the pipe is the main parameter which determines the performance of the collector pipe. For a particular type of solar collector pipe, the temperature distribution is function of length with day variation of solar incidence over it. In this work a collector pipe of length 2.2 m and 7 cm diameter is fabricated and tested under standard laboratory conditions for the uniform heat dissemination over the pipe. For keeping up the uniform temperature over the collector pipe, it is necessary to wound the pipe with metals like copper, aluminum. The results show that the heat distribution over the pipe is increased in case of copper when compared with aluminium.

scholarly journals A Design Method to Improve Temperature Uniformity on Wafer for Rapid Thermal Processing

Electronics ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 213
Author(s):  
Peng Huang ◽  
Hongguan Yang
Keyword(s):  
Temperature Distribution ◽  
Thermal Processing ◽  
Design Method ◽  
Rapid Thermal Processing ◽  
Design Parameters ◽  
Temperature Uniformity ◽  
Uniform Temperature ◽  
Simple Method ◽  
Uniform Temperature Distribution ◽  
Proposed Model

Single-wafer rapid thermal processing (RTP) is widely used in semiconductor manufacturing. Achieving temperature uniformity on silicon wafer is a major challenge in RTP control. In this work, a lamp configuration including five concentric lamp zones is designed to obtain uniform temperature distribution on the wafer. An optics-based model is developed to determine the optimal lamp design parameters, and a uniformity criterion is proposed to evaluate the effective irradiance distribution of the tungsten–halogen lamps on the wafer. This method can be used to determine geometric parameters of the lamp array in order to achieve uniform temperature distribution on the wafer. A realistic simulation of a cold wall RTP system with five lamp rings and a 200-mm wafer is performed. The proposed model makes way for a simple method for determining the optimal lamp design parameters in RTP systems.

The Assessment of the Temperature Uniformity in Processing Small Food Objects

2005 ◽  
Vol 1 (3) ◽  
Author(s):  
Xiao Dong Chen
Keyword(s):  
Temperature Distribution ◽  
Biot Number ◽  
Evaporative Cooling ◽  
The Other ◽  
Temperature Uniformity ◽  
Uniform Temperature ◽  
Cooling Process ◽  
Surface Evaporation ◽  
Uniform Temperature Distribution ◽  
Internal Generation

Conventionally, a small Biot number must be ensured to proceed with the assumption of the uniform temperature distribution within the material (being heated or cooled, or dried) of interest. In this communication, several situations are analysed, i.e. internal generation or dissipation and surface evaporation while the material being heated illustrating the above rule can be relaxed. On the other hand, when considering the surface evaporative cooling process, derivations made have shown that the criterion is in fact too generous. The study provides useful formula for justifying the assumption of uniform temperature within the small objects being processed.

The Study on the Uniform Drying of Microwave Heating System with Multiple Waveguides

2013 ◽  
Vol 329 ◽  
pp. 219-223 ◽  
Author(s):  
Woo Seong Che ◽  
Jun Ma
Keyword(s):  
Electromagnetic Field ◽  
Objective Function ◽  
Microwave Heating ◽  
Heating System ◽  
Temperature Uniformity ◽  
Uniform Temperature ◽  
Heating Method ◽  
Uniform Electromagnetic Field ◽  
Parallel Type

Microwave heating is an important heating method that is widely used in industries. Developing a uniform electromagnetic field inside the cavities might be a crucial challenge to avoid localized overheating. The uniformity of the electromagnetic field is governed by the configurations of the waveguides. To better understand the design of cavities, the simulations are carried out. This paper discussed the comparison in result between two configurations of waveguides and introduced the use of uniformity objective function in order to evaluate the temperature uniformity. As conclusion, it was found out that using the perpendicular type of waveguides had better uniform temperature than using the parallel type.

scholarly journals Shape Effect on the Temperature Field during Microwave Heating Process

2018 ◽  
Vol 2018 ◽  
pp. 1-24 ◽  
Author(s):  
Zhijun Zhang ◽  
Tianyi Su ◽  
Shiwei Zhang
Keyword(s):  
Electromagnetic Field ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Microwave Cavity ◽  
Heating Process ◽  
Shape Effect ◽  
Power Absorption ◽  
Sample Shape ◽  
Distribution Uniformity ◽  
Microwave Process

Aiming at improving the food quality during microwave process, this article mainly focused on the numerical simulation of shape effect, which was evaluated by microwave power absorption capability and temperature distribution uniformity in a single sample heated in a domestic microwave oven. This article only took the electromagnetic field and heat conduction in solid into consideration. The Maxwell equations were used to calculate the distribution of microwave electromagnetic field distribution in the microwave cavity and samples; then the electromagnetic energy was coupled as the heat source in the heat conduction process in samples. Quantitatively, the power absorption capability and temperature distribution uniformity were, respectively, described by power absorption efficiency (PAE) and the statistical variation of coefficient (COV). In addition, we defined the comprehensive evaluation coefficient (CEC) to describe the usability of a specific sample. In accordance with volume or the wave numbers and penetration numbers in the radial and axial directions of samples, they can be classified into different groups. And according to the PAE, COV, and CEC value and the specific need of microwave process, an optimal sample shape and orientation could be decided.

Temperaturverteilung beim Wälzschälen/Temperature distribution during power skiving

2021 ◽  
Vol 111 (11-12) ◽  
pp. 786-791
Author(s):  
Florian Sauer ◽  
Michael Gerstenmeyer ◽  
Volker Schulze
Keyword(s):  
Temperature Distribution ◽  
Wear Mechanisms ◽  
Experimental Temperature ◽  
Heat Distribution ◽  
Temperature Analysis ◽  
Power Skiving ◽  
Underlying Mechanisms

Innenverzahnungen, die aufgrund der Elektromobilität zunehmend im Fokus stehen, lassen sich mithilfe des Wälzschälens produktiv herstellen. Um diese Produktivität weiter zu steigern, müssen die wirkenden Verschleißmechanismen untersucht und verstanden werden. Der Beitrag behandelt die experimentelle Temperaturuntersuchung des Wälzschälens mit anschließender Modellierung der Wärmeverteilung, welche als erster Schritt zum Mechanismenverständnis angesehen werden kann.   Internal gears, which are increasingly in focus due to electromobility, can be manufactured productively with the help of power skiving. In order to further increase the productivity, the wear mechanisms have to be investigated and understood. This paper discusses the experimental temperature analysis of power skiving by subsequently modelling the heat distribution. This process can be seen as a first step towards understanding the underlying mechanisms.

Gradient structures of Ni – Zn ferrites for electromagnetic radiation protection devices

2021 ◽  
Vol 5 ◽  
pp. 39-46
Author(s):  
V. V. Karanskij ◽  
◽  
S. V. Smirnov ◽  
A. S. Klimov ◽  
E. V. Savruk ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electromagnetic Radiation ◽  
Radiation Protection ◽  
Electromagnetic Compatibility ◽  
Protective Coatings ◽  
Frequency Range ◽  
Near Surface ◽  
Zn Ferrite ◽  
Absorbing Materials ◽  
Plasma Electronic

Increasing the reliability requirements for electromagnetic compatibility of electronic equipment requires the creation of protective coatings that absorb electromagnetic radiation or the development of new radio-absorbing materials. In the frequency range up to 1 GHz, radio-absorbing materials based on Ni – Zn ferrites are of the greatest interest. The absorption of electromagnetic radiation by ferrites occurs due to resonant phenomena at the level of domains and atoms. Improving the performance of ferrites is possible by modifying their surface properties. In this paper, gradient structures for electromagnetic radiation protection products are obtained by treating the surface of Ni – Zn ferrite samples with a low-energy electron beam. To generate the electron beam, a unique development was used — a forevacuum plasma electronic source that allows forming and transporting a beam with a power density of up to 105 W/cm2 under conditions of high pressure and high gas release. As a result of processing, gradient structures were found on the surface of ferrites. A theoretical analysis and experimental study of the obtained structures “non – magnetic conductor – ferrite”, characterized by an increased attenuation coefficient and a reduced reflection coefficient of electromagnetic radiation in the frequency range from 0.5 to 2.5 GHz. The possibility of obtaining near-surface layers depleted in zinc with increased electrical conductivity and reduced magnetic permeability is shown.

Non-uniform temperature distribution of the main reflector of a large radio telescope under solar radiation

2021 ◽  
Vol 21 (11) ◽  
pp. 293
Author(s):  
Shan-Xiang Wei ◽  
De-Qing Kong ◽  
Qi-Ming Wang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Radio Telescope ◽  
Thermal Imaging ◽  
Uniform Temperature ◽  
Large Radio Telescope ◽  
Uniform Temperature Distribution ◽  
Uniform Temperature Field ◽  
Main Reflector

Abstract The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector, which will dramatically reduce the aperture efficiency of a radio telescope. To study the non-uniform temperature field of the main reflector of a large radio telescope, numerical calculations including thermal environment factors, the coefficients on convection and radiation, and the shadow boundary of the main reflector are first discussed. In addition, the shadow coverage and the non-uniform temperature field of the main reflector of a 70-m radio telescope under solar radiation are simulated by finite element analysis. The simulation results show that the temperature distribution of the main reflector under solar radiation is very uneven, and the maximum of the root mean square temperature is 12.3°C. To verify the simulation results, an optical camera and a thermal imaging camera are used to measure the shadow coverage and the non-uniform temperature distribution of the main reflector on a clear day. At the same time, some temperature sensors are used to measure the temperature at some points close to the main reflector on the backup structure. It has been verified that the simulation and measurement results of the shadow coverage on the main reflector are in good agreement, and the cosine similarity between the simulation and the measurement is above 90%. Despite the inevitable thermal imaging errors caused by large viewing angles, the simulated temperature field is similar to the measured temperature distribution of the main reflector to a large extent. The temperature trend measured at the test points on the backup structure close to the main reflector without direct solar radiation is consistent with the simulated temperature trend of the corresponding points on the main reflector with the solar radiation. It is credible to calculate the temperature field of the main reflector through the finite element method. This work can provide valuable references for studying the thermal deformation and the surface accuracy of the main reflector of a large radio telescope.

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