scholarly journals Investigation of Production of Nanofiber Nonwoven Fabric and its Thermal Properties

2020 ◽  
Vol 14 (2) ◽  
pp. 264-273
Author(s):  
Wei Wu ◽  
Kenichi Urabe ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama ◽  
Hiroyoshi Sota ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Dissipation ◽  
Thermal Characteristics ◽  
Nonwoven Fabric ◽  
Melt Blowing ◽  
One Dimensional ◽  
Manufacturing Method ◽  
Apparent Thermal Conductivity ◽  
Computational Fluid Dynamics Cfd ◽  
Lateral Heat

Nanofibers of polypropylene were produced by a modified melt-blowing method. The manufacturing method and thermal characteristics of fabricated nonwoven-fabric nanofibers were studied. Apparent thermal conductivity was measured as an evaluation of adiabatic properties, and a prediction model was developed with computational fluid dynamics (CFD) based on a one-dimensional computer-aided engineering method. In addition, we attempted to evaluate true thermal conductivity in consideration of lateral heat dissipation during measurement by thickness. Consequently, we determined the influence of the fiber diameter and thickness of the nonwoven fabric on the thermal conductivity and demonstrated that the proposed CFD model was effective for estimating the characteristics of the thermal conductivity of the nonwoven fabric.

Efficient Heat Dissipation Design of High-Power Multi-Chip Cob Package Led Modules

2012 ◽  
Vol 463-464 ◽  
pp. 1332-1340 ◽  
Author(s):  
Lei Wu ◽  
Xiao Yun Xiong ◽  
De Xing Wang
Keyword(s):  
Thermal Conductivity ◽  
Forced Convection ◽  
High Power ◽  
Heat Dissipation ◽  
Heat Sinks ◽  
Junction Temperature ◽  
Ir Camera ◽  
Chip Size ◽  
Computational Fluid Dynamics Cfd ◽  
Convection Cooling

In this study, the junction temperature (Tj) and thermal resistance (Rth) of five high-power multi-chip COB (chip-on-board) LED packages with different chip spacings were compared. The actual Tjwas measured by an IR camera and compared with the simulation results from a computational fluid dynamics (CFD) software. In addition, the effects of heat slugs with different thermal conductivity, heat sinks of various thicknesses, chip size, and forced convection cooling on the Tjand Rthof high-powered LED components were investigated. The experimental results show that smaller chip spacing resulted in higher Tjand Rth. The heat dissipation performance can be improved by using a heat slug with a high thermal conductivity; and increasing the thickness of the heat sink, or employing forced convection cooling.

scholarly journals Heat Dissipation and Ripple Current Rating in Electrolytic Capacitors

1975 ◽  
Vol 2 (2) ◽  
pp. 109-114 ◽  
Author(s):  
F. G. Hayatee
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Temperature Rise ◽  
Mathematical Analysis ◽  
Heat Dissipation ◽  
Thermal Characteristics ◽  
Electrolytic Capacitors ◽  
Allowable Temperature

The ripple current rating in electrolytic capacitors is limited by the maximum allowable temperature rise inside the capacitor. The temperature rise is determined by the I2R losses inside the capacitor and the efficiency of heat flow from the interior to the surrounding. The ripple current rating can be extended by either reducing the tanδof the capacitor or by increasing the efficiency of heat flow to ambient.The heat flow is determined by the thermal characteristics of the capacitor surface and thermal conductivity of the medium separating the capacitor winding from the surrounding.In this article a mathematical analysis for the heat flow in capacitors is given. The effects of various parameters are examined and methods of extending the ripple current rating are discussed.

A Study on the Thermal Conductivity of Thermal Grease According to Cu-Ni Content

2021 ◽  
Vol 880 ◽  
pp. 71-76
Author(s):  
Haneul Kang ◽  
Hyunji Kim ◽  
Sunghoon Im ◽  
Jinho Yang ◽  
Sunchul Huh
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Electronic Device ◽  
Thermal Contact ◽  
Thermal Characteristics ◽  
Internal Heat ◽  
Thermal Interface Material ◽  
Thermal Grease

An increase in power consumption density is related to the internal thermal characteristics of an electronic device, and the heat dissipation of the device is directly related to the high performance and miniaturization of the device. TIM (thermal interface material) with excellent internal heat dissipation performance are mainly used to improve the heat dissipation performance of electronic devices. Recently, the need for a high-efficiency TIM with high-performance thermal conductivity and low thermal contact resistance has increased. In this study, thermal grease was prepared by mixing Cu-Ni nanopowders with silicon oil, the thermal grease was then used as a heat transfer material. Compared to silicone thermal grease, the thermal conductivity of all prepared samples was excellent. In particularly, thermal conductivity was improved by about maximum 212% compared to that of thermal silicone of thermal grease mixed with Cu-Ni powder.

A computational fluid dynamics (CFD) coupled multi-objective optimization framework for thermal system design for Li-ion batteries with metal separators

2021 ◽  
pp. 1-19
Author(s):  
Xujian Cui ◽  
Siqi Chen ◽  
Mi Xiao ◽  
Wei Li
Keyword(s):  
Fluid Dynamics ◽  
Thermal Conductivity ◽  
Air Temperature ◽  
Heat Dissipation ◽  
Battery Pack ◽  
Cooling Efficiency ◽  
Multi Objective Optimization ◽  
Optimization Framework ◽  
Computational Fluid Dynamics Cfd ◽  
Temperature Standard

Abstract Battery thermal management system (BTMS) has significant impacts on the performance of electric vehicles (EVs). In this research, a computational fluid dynamics (CFD) coupled multi-objective optimization framework is proposed to improve the thermal performance of the battery pack having metal separators. CFD is utilized to study the thermal and fluid dynamics performance of the designed battery pack. Input parameters include inlet air temperature, thermal conductivity of coolant, thermal conductivity of metal separator, and diameter of heat dissipation hole. Five vital output parameters are maximum temperature, average temperature, temperature standard deviation, maximum pressure, and volume of the pack. The support vector machine (SVM) model is used to replace the real output parameters of the battery pack. Sensitivity analysis results indicate that the diameter of heat dissipation hole is the main factor affecting the volume of the structure and the pressure drop, while the inlet air temperature has significant influence on the battery pack thermal behavior. The cooling efficiency and the uniformity of temperature distribution are mainly determined by the inlet air temperature. The decrease of inlet air temperature could lead to a rise of temperature standard deviation. The non-dominated sorting genetic algorithm II (NSGAII) is taken to acquire the optimum set of input parameters. The obtained optimal scheme of battery pack can improve the cooling efficiency as well as reducing the volume cost and the energy consumption of the cooling system while such design may result in a higher level of non-uniformity of the temperature and pressure distribution.

Evaluation of compression-recovery and thermal characteristics of multilayer bedding textiles

2020 ◽  
Vol 32 (5) ◽  
pp. 631-643
Author(s):  
Sedat Özer ◽  
Yaşar Erayman Yüksel ◽  
Yasemin Korkmaz
Keyword(s):  
Thermal Conductivity ◽  
Sleep Quality ◽  
Thermal Comfort ◽  
Sleep Duration ◽  
Human Body ◽  
Design Methodology ◽  
Thermal Characteristics ◽  
Air Permeability ◽  
Content Type ◽  
Thermal Comfort Properties

PurposeDesign of bedding textiles that contact the human body affects the sleep quality. Bedding textiles contribute to comfort sense during the sleep duration, in addition to ambient and bed microclimate. The purpose of this study is to evaluate the effects of different layer properties on the compression recovery and thermal characteristics of multilayer bedding textiles.Design/methodology/approachIn this study, woven and knitted multilayer bedding textiles were manufactured from fabric, fiber, sponge and interlining, respectively. Different sponge thickness, fiber and interlining weight were used in the layers of samples. Later, the pilling resistance, compression and recovery, air permeability and thermal conductivity of multilayer bedding textiles were investigated.FindingsThe results indicated that samples with the higher layer weight and thickness provide better compression recovery and lower air permeability properties. It was also found that knitted surfaces show the higher air permeability than the woven surfaces depending on the fabric porosity. Layer properties have insignificant effect on the thermal conductivity values.Originality/valueWhile researchers mostly focus on thermal comfort properties of garments, there are limited studies about comfort properties of bedding textiles in the literature. Furthermore, compression recovery properties of bedding textiles have also a great importance in terms of comfort. Originality of this study is that these properties were analyzed together.

Measurement of apparent thermal conductivity of regenerator materials in 4-20 K temperature range

Cryogenics ◽  
2021 ◽  
pp. 103300
Author(s):  
Yang Biao ◽  
Xi Xiaotong ◽  
Liu Xuming ◽  
Xu Xiafan ◽  
Chen Liubiao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Temperature Range ◽  
Apparent Thermal Conductivity

Numerical investigation on a melt-blowing die with internal stabilizers

2019 ◽  
pp. 152808371986693 ◽  
Author(s):  
Changchun Ji ◽  
Yudong Wang ◽  
Yafeng Sun
Keyword(s):  
Average Velocity ◽  
Fiber Diameter ◽  
Measurement Data ◽  
Melt Blowing ◽  
One Dimensional ◽  
Temperature Decay ◽  
Slot Die ◽  
The Common ◽  
The One ◽  
Peak Value

In order to decrease the fiber diameter and reduce the energy consumption in the melt-blowing process, a new slot die with internal stabilizers was designed. Using computational fluid dynamics technology, the new slot die was investigated. In the numerical simulation, the calculation data were validated with the laboratory measurement data. This work shows that the new slot die could increase the average velocity on the centerline of the air-flow field by 6.9%, compared with the common slot die. Simultaneously, the new slot die could decrease the back-flow velocity and the rate of temperature decay in the region close to the die head. The new slot die could reduce the peak value of the turbulent kinetic energy and make the fiber movements more gradual. With the one-dimensional drawing model, it proves that the new slot die has more edge on the decrease of fiber diameter than the common slot die.

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