Equivalent Thermal Conductivity Estimation for Compact Electromagnetic Windings

Currently, there are few studies on the influence of microscale thermal radiation on the equivalent thermal conductivity of microscale porous metal. Therefore, this paper calculated the equivalent thermal conductivity of high-porosity periodic cubic silver frame structures with cell size from 100 nm to 100 µm by using the microscale radiation method. Then, the media radiation characteristics, absorptivity, reflectivity and transmissivity were discussed to explain the phenomenon of the radiative thermal conductivity changes. Furthermore, combined with spectral radiation properties at the different cross-sections and wavelength, the radiative transmission mechanism inside high-porosity periodic cubic frame silver structures was obtained. The results showed that the smaller the cell size, the greater radiative contribution in total equivalent thermal conductivity. Periodic cubic silver frames fluctuate more in the visible band and have better thermal radiation modulation properties in the near infrared band, which is formed by the Surface Plasmon Polariton and Magnetic Polaritons resonance jointly. This work provides design guidance for the application of this kind of periodic microporous metal in the field of thermal utilization and management.

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Effective Thermal Conductivity of Open Cell Polyurethane Foam Based on the Fractal Theory

Advances in Materials Science and Engineering ◽

10.1155/2013/125267 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 4

Author(s):

Kan Ankang ◽

Han Houde

Keyword(s):

Thermal Conductivity ◽

Fractal Dimension ◽

Effective Thermal Conductivity ◽

Polyurethane Foam ◽

Solid Phase ◽

Fractal Theory ◽

Heat Radiation ◽

Total Thermal Conductivity ◽

Equivalent Thermal Conductivity ◽

Open Cell

Based on the fractal theory, the geometric structure inside an open cell polyurethane foam, which is widely used as adiabatic material, is illustrated. A simplified cell fractal model is created. In the model, the method of calculating the equivalent thermal conductivity of the porous foam is described and the fractal dimension is calculated. The mathematical formulas for the fractal equivalent thermal conductivity combined with gas and solid phase, for heat radiation equivalent thermal conductivity and for the total thermal conductivity, are deduced. However, the total effective heat flux is the summation of the heat conduction by the solid phase and the gas in pores, the radiation, and the convection between gas and solid phase. Fractal mathematical equation of effective thermal conductivity is derived with fractal dimension and vacancy porosity in the cell body. The calculated results have good agreement with the experimental data, and the difference is less than 5%. The main influencing factors are summarized. The research work is useful for the enhancement of adiabatic performance of foam materials and development of new materials.

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Equivalent Thermal Conductivity Model Based Full Scale Numerical Simulation for Thermal Management in Fan-Out Packages

2017 IEEE 67th Electronic Components and Technology Conference (ECTC) ◽

10.1109/ectc.2017.82 ◽

2017 ◽

Cited By ~ 1

Author(s):

Ningyu Wang ◽

Yudan Pi ◽

Wei Wang ◽

Yufeng Jin

Keyword(s):

Thermal Conductivity ◽

Numerical Simulation ◽

Thermal Management ◽

Full Scale ◽

Equivalent Thermal Conductivity ◽

Conductivity Model ◽

Model Based ◽

Thermal Conductivity Model

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Finite-Element Determination of the Equivalent Thermal Conductivity of Hollow Blocks Masonry Wall

Lecture Notes in Mechanical Engineering - Design and Modeling of Mechanical Systems - IV ◽

10.1007/978-3-030-27146-6_89 ◽

2020 ◽

pp. 815-822

Author(s):

Houda Friaa ◽

Myriam Laroussi Hellara ◽

Abdelwaheb Dogui

Keyword(s):

Thermal Conductivity ◽

Finite Element ◽

Masonry Wall ◽

Equivalent Thermal Conductivity ◽

Element Determination

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Optimization of LD’s Temperature Control System Using Finned Tubular Radiator

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.546-547.800 ◽

2012 ◽

Vol 546-547 ◽

pp. 800-805 ◽

Cited By ~ 1

Author(s):

Fei Guo ◽

Wen Dong Zou ◽

Hai He Xie ◽

Qiang Du

Keyword(s):

Thermal Conductivity ◽

Temperature Control ◽

Optimization Method ◽

System Structure ◽

Experimental Result ◽

Temperature Control System ◽

Air Cooling ◽

Equivalent Thermal Conductivity ◽

Temperature Controller ◽

Control Efficiency

By analyzing of thermoelectric cooler(TEC) working characteristics and using one-dimensional heat transfer equation, mathematical relationship between TEC working power and radiator equivalent thermal conductivity is derived. Temperature control efficiency could be improved by increasing equivalent thermal conductivity was proved. So that an optimization method using finned tubular radiator in LD temperature controller was presented, including theoretical foundation of radiator selection and system structure. Compared with normal radiator, the stable-time of the LD temperature controller using finned tubular reduces 50%, and stable-error reduces 60%, which was proved by mathematical calculation and experimental result of 2W LD system. Compared with forced air cooling and forced water cooling, the system has property of low vibration disturbance and simple structure. It followed that the finned tubular radiator was suitable for temperature control of medium and small power LD, which can improve temperature control efficiency and optimize the system.

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Thermal Performance of 3D IC Integration with Through-Silicon Via (TSV)

International Symposium on Microelectronics ◽

10.4071/isom-2011-ta1-paper4 ◽

2011 ◽

Vol 2011 (1) ◽

pp. 000025-000032 ◽

Cited By ~ 1

Author(s):

Heng-Chieh Chien ◽

John H. Lau ◽

Yu-Lin Chao ◽

Ra-Min Tain ◽

Ming-Ji Dai ◽

...

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Thermal Behavior ◽

Thermal Performance ◽

Equivalent Thermal Conductivity ◽

3D Ic ◽

Through Silicon Via

Thermal performance of 3D IC integration is investigated in this study. Emphasis is placed on the determination of a set of equivalent thermal conductivity equations for Cu-filled TSVs with various TSV diameters, TSV pitches, TSV thicknesses, passivation thicknesses, and microbump pads. Also, the thermal behavior of a TSV cell is examined. Furthermore, 3D heat transfer simulations are adopted to verify the accuracy of the equivalent equations. Finally, the feasibility of these equivalent equations is demonstrated through a simple 3D IC integration structure.

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Detection of grouting defects in prestressed tendon ducts using distributed fiber optic sensors

Structural Health Monitoring ◽

10.1177/1475921719880318 ◽

2019 ◽

Vol 19 (4) ◽

pp. 1273-1286

Author(s):

Shilin Gong ◽

Xin Feng

Keyword(s):

Thermal Conductivity ◽

Temperature Rise ◽

Fiber Optic ◽

Detection Efficiency ◽

Fiber Optic Sensors ◽

Detection Methods ◽

Experimental Program ◽

Accurate Identification ◽

Equivalent Thermal Conductivity ◽

Abnormal Temperature

To compensate for the shortcomings of the existing point detection methods for grouting defects in prestressed tendon ducts, such as low detection efficiency, stringent detection environment, and easy omission of grouting defects, this article presents a distributed detection approach to detect the grouting defects in tendon ducts. The main objective of the research pertained to the development of a method for accurate identification and location of grouting defects and qualitative evaluation of the size of grouting defects using distributed fiber optic sensors with active heating. Using the thermal analysis of grouting defects in the tendon duct and the research on distributed fiber optic sensors measurement characteristics, our work proposed a method for identifying and locating grouting defects and explored the effect of the grouting defect length and the grouting compactness on the temperature rise of distributed fiber optic sensors. The feasibility of the proposed approach is evaluated through an experimental program. The experimental program involved use of heating distributed fiber optic sensors for the distributed measurement of temperature after the heating and detection of grouting defects in tendon ducts in a concrete beam. The results indicate that distributed fiber optic sensors can monitor the temperature distribution of the tendon duct during a temperature rise in real time. Grouting defects in the tendon duct can be quickly detected and located by identifying temperature anomalies in the temperature contour of the distributed fiber optic sensors. Furthermore, there is a linear relationship between the defect length and the abnormal temperature length on the distributed fiber optic sensors, and the defect length can be identified based on the abnormal temperature length obtained by the measurement. Plane-equivalent thermal conductivity can be used to evaluate the grouting compactness of the tendon duct. When the grouting compactness is greater than 70%, the smaller the plane-equivalent thermal conductivity is, the lower the grouting compactness is. The plane-equivalent thermal conductivity is basically the same when the grouting compactness is less than 70%.

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