scholarly journals Thermal Diffusivity of Linear Alkanes and its Behaviour with the Size of the Chain: Study with a Photopyroelectric Technique

2020 ◽  
Vol 27 (5) ◽  
Author(s):  
Joel Díaz Reyes
Keyword(s):  
Thermal Diffusivity ◽  
Photopyroelectric Technique ◽  
Linear Alkanes

scholarly journals Thermal Diffusivity of Linear Alkanes and its Behaviour with the Size of the Chain: Study with a Photopyroelectric Technique

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Thermal Diffusivity ◽  
Thermal Property ◽  
Heat Transport ◽  
Spatial Configuration ◽  
Molecular Size ◽  
Photopyroelectric Technique ◽  
Molecular Configuration ◽  
Science And Engineering ◽  
Linear Alkanes ◽  
Nonstationary Conditions

Thermal transport properties of substances are fundamental for science and engineering. Among these properties, thermal diffusivity characterizes the way materials transport heat under nonstationary conditions. The manner in which this thermal property behaves with the size or molecular configuration is very important to understand the mechanisms involved in heat transport. It is a complicated work to study variations on this thermal property taking these two variables (size and configuration) together. Linear alkanes have essentially the same spatial configuration, varying only the molecular size (the number of involved carbon atoms in the molecule), so they are ideal substances to study the behaviour of thermal properties with the molecular size alone. In this work photopyroelectric technique, taking the sample´s thickness as variable (the so-called TWRC method), is used for thermal diffusivity measurements of linear alkanes, from 1-heptane to 1-heptadecane. It is shown that this thermal property increases with the molecular size. This behaviour can be explained in a very simple way if it is considered that the increase in molecular size increases “routes” of heat transport.

Heat transport in epoxy and polyester carbonyl iron microcomposites: The effect of concentration and temperature

2017 ◽  
Vol 52 (10) ◽  
pp. 1331-1338
Author(s):  
NW Pech-May ◽  
C Vales-Pinzon ◽  
A Vega-Flick ◽  
A Oleaga ◽  
A Salazar ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Carbonyl Iron ◽  
Numerical Differentiation ◽  
Photopyroelectric Technique ◽  
Iron Particles ◽  
High Concentration ◽  
Polyester Resins ◽  
Wide Range ◽  
Study Heat Transfer

Temperature dependence of the thermal diffusivity in composites of epoxy and polyester resins, loaded with carbonyl iron particles, has been studied using the photopyroelectric technique. Increments of eight and 2.5 times the thermal conductivity of the polymers are obtained, as the volume concentration of microparticles is increased from 0% to 40% for epoxy and from 0% to 20% for polyester matrices, respectively. Additionally, the thermal diffusivity falls systematically as the temperature is increased from 270 to 400 K; the effect is more pronounced for high concentration of microparticles in epoxy composites. The glass transition of the composites is explored by implementing a numerical differentiation algorithm. In order to explain the consequences of the loading of the composites on the thermal conductivity, a modified Lewis-Nielsen model, which includes the presence of crowded regions in the samples, is used to study heat transfer in a wide range of particle concentrations.

Theoretical description of the photopyroelectric technique in the slanted detector configuration for thermal diffusivity measurements in fluids

2014 ◽  
Vol 582 ◽  
pp. 101-105 ◽  
Author(s):  
J.B. Rojas-Trigos ◽  
E. Marín ◽  
A.M. Mansanares ◽  
E. Cedeño ◽  
G. Juárez-Gracia ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Theoretical Description ◽  
Photopyroelectric Technique ◽  
Diffusivity Measurements

scholarly journals Influence of Sonication on the Stability and Thermal Properties of Al2O3Nanofluids

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Monir Noroozi ◽  
Shahidan Radiman ◽  
Azmi Zakaria
Keyword(s):  
Thermal Diffusivity ◽  
Particle Concentration ◽  
Correlation Spectroscopy ◽  
Photopyroelectric Technique ◽  
Absorption Properties ◽  
Transmission Electron ◽  
Low Concentrations ◽  
Higher Power ◽  
Ultrasonic Devices ◽  
The Stability

Nanofluids containing Al2O3nanoparticles (either 11 or 30 nm in size) dispersed in distilled water at low concentrations (0.125–0.5 wt%) were prepared using two different ultrasonic devices (a probe and a bath sonicator) as the dispersant. The effect of the ultrasonic system on the stability and thermal diffusivity of the nanofluids was investigated. Thermal diffusivity measurements were conducted using a photopyroelectric technique. The dispersion characteristics and morphology of the nanoparticles, as well as the optical absorption properties of the nanofluids, were studied using photon cross correlation spectroscopy with a Nanophox analyzer, transmission electron microscopy, and ultraviolet-visible spectroscopy. At higher particle concentration, there was greater enhancement of the thermal diffusivity of the nanofluids resulting from sonication. Moreover, greater stability and enhancement of thermal diffusivity were obtained by sonicating the nanofluids with the higher power probe sonicator prior to measurement.

Photopyroelectric Measurement of the Thermal Diffusivity of Recrystallized High Purity Aluminum

1991 ◽  
Vol 3 (1) ◽  
pp. 69-80
Author(s):  
S. B. Peralta ◽  
S. C. Ellis ◽  
C. Christofides ◽  
A. Mandeiis ◽  
H. Sang ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
High Purity ◽  
High Purity Aluminum
Sign in / Sign up

Export Citation Format

Share Document