Thermal Conductivity
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Mayank Agarwal

Abstract: This work investigates the mechanical properties (Tensile Strength & Impact Strength) and thermal properties (Thermal conductivity & diffusivity) of a natural fiber composite that includes banana fiber as reinforcement in epoxy (LY 556) matrix as the base material with the addition of silicon carbide particles by 5% and 10% by weight. This Banana Fiber Reinforced Epoxy Composite (BFREC) prepared by hand lay-up technique. After curing for a sufficient period, samples taken out and tested. The results suggest that on increasing SiC wt% in the matrix, there is enhancement of its tensile strength, impact strength, and thermal conductivity. Bulk density also increases while thermal diffusivity decreases. Due to low density as compared to metals, improved tensile and impact strength and low elongation at break of banana fibers, BFREC composite with SiC have very good potential use in the various sectors. Keywords: Banana fiber, SiC, hand layup technique, mechanical characterization, thermal conductivity, thermal diffusivity

2021 ◽  
Vol 18 ◽  
pp. 100157
Denise das M. Camarano ◽  
Fábio A. Mansur ◽  
Ana Maria Matildes dos Santos

2021 ◽  
Vol 11 (1) ◽  
Varvara Apostolopoulou-Kalkavoura ◽  
Pierre Munier ◽  
Lukasz Dlugozima ◽  
Veit-Lorenz Heuthe ◽  
Lennart Bergström

AbstractAnisotropic cellulose nanocrystal (CNC) foams with densities between 25 and 130 kg m−3 (CNC25 –CNC130) were prepared by directional ice-templating of aqueous dispersions. Estimates of the solid and gas conduction contributions to the thermal conductivity of the foams using a parallel resistor model showed that the relatively small increase of the radial thermal conductivity with increasing foam density can be attributed to interfacial phonon scattering. The foam wall nanoporosity and, to a lesser extent, the orientation of the CNC particles and alignment of the columnar macropores, also influence the insulation performance of the foams. The insight on the importance of phonon scattering for the thermal insulation properties of nanocellulose foams provides useful guidelines for tailoring nanofibrillar foams for super-insulating applications.

2021 ◽  
Vol 324 ◽  
pp. 133-138
Jia Zhen Wang ◽  
Jing Du ◽  
Yun Bo Wang

Silica aerogels are the most widely studied type of aerogel. However, its application still suffers from low mechanical strength and high production cost. The paper studies the use of recyclable PVC as the backbone material of the aerogel and introduces an economically friendly fabrication process of flexible PVC aerogel using sol-gel technique and ambient drying instead of the CO2 critical drying. Three different types of PVC powder with the molecule weight of 43000, 48000, and 80000 respectively are chosen and dissolved in DMF in five different concentrations-0.2, 0.4, 0.6, 0.8, and 1.0 g (mL)-1. The lowest thermal conductivity of the aerogel is measured using hot-wire method as 0.0323W(m*K)-1, which is made of PVC with molecule weight of 80000 in a concentration of 0.4g (mL)-1. The analysis based on SEM pictures shows that PVC type and concentration would greatly influence aerogel’s structure thus affecting its thermal conductivity. The optimal solution for producing low thermal conductivity aerogel is to use PVC powder with low molecule weight with a concentration between 0.2 and 0.6 g (mL)-1.

Shafiq Ahmad ◽  
Zafar H Khan ◽  
Salman Zeb ◽  
Muhammad Hamid

This article examined the effects of boundary layer flow and heat transport of a two-dimensional incompressible magnetohydrodynamic tangent hyperbolic fluid under slip boundary conditions and variable thermal conductivity. The entropy generation model is also analysed for the said fluid. Non-similarity transformations transformed the governing equations of the fluid and entropy generation model into dimensionless form. Maple software is used to solve the transformed equations numerically. Effects of different dimensionless parameters on entropy generation rate, Bejan number, velocity and temperature fields are studied thoroughly through graphs. It is observed that for higher values of velocity slip parameter and power-law index, the entropy generation rate decreases while the Bejan number increases. Also, for the Hartmann number, Weissenberg number and Brinkman number, we found an increase in the entropy generation rate, and reverse behaviour is observed for the Bejan number. Nusselt number, temperature profile and Bejan’s number increase with an increase in variable thermal conductivity.

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