New Measurements of the Thermal Conductivity of PMMA, BK7, and Pyrex 7740 up to 450K

Assael, Marc J.; Antoniadis, Konstantinos; Wu, Jiangtao

doi:10.1007/s10765-008-0504-z

Cited by 49 publications

(31 citation statements)

References 18 publications

(29 reference statements)

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“…In the literature (Sahin and Sumnu, 2006), the HW method is preferred, although with the appropriate arrangement of experimental apparatus, DPS method can also be used. The HW method is a transient dynamic technique based on the measurement of the temperature rise of a linear heat source (hot wire) embedded in the tested material (Assael et al, 2008;Kadjo et al, 2008). For an infinitely long metallic wire (length/ radius ratio >> 200) heated at the time span t > 0, with a constant heat flux per length unit q and immersed in an infinite homogeneous medium, thermal conductivity and diffusivity: λ and a, and with uniform initial temperature, the temperature rise ΔT (t) of the wire is given by Eq.…”

Section: Methodsmentioning

confidence: 99%

Selected physical properties of various diesel blends

Hlaváčová¹,

Božíková²,

Hlaváč³

et al. 2018

International Agrophysics

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A b s t r a c t. The quality determination of biofuels requires identifying the chemical and physical parameters. The key physical parameters are rheological, thermal and electrical properties. In our study, we investigated samples of diesel blends with rapeseed methyl esters content in the range from 3 to 100%. In these, we measured basic thermophysical properties, including thermal conductivity and thermal diffusivity, using two different transient methods -the hot-wire method and the dynamic plane source. Every thermophysical parameter was measured 100 times using both methods for all samples. Dynamic viscosity was measured during the heating process under the temperature range 20-80°C. A digital rotational viscometer (Brookfield DV 2T) was used for dynamic viscosity detection. Electrical conductivity was measured using digital conductivity meter (Model 1152) in a temperature range from -5 to 30°C. The highest values of thermal parameters were reached in the diesel sample with the highest biofuel content. The dynamic viscosity of samples increased with higher concentration of bio-component rapeseed methyl esters. The electrical conductivity of blends also increased with rapeseed methyl esters content.K e y w o r d s: diesel blends, rapeseed methyl ester, thermophysical, rheological and electrical properties INTRODUCTION

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Section: Methodsmentioning

confidence: 99%

Selected physical properties of various diesel blends

Hlaváčová¹,

Božíková²,

Hlaváč³

et al. 2018

International Agrophysics

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“…Less κ for the hybrid film can be attributed to two factors: low thermal conductivity of PMMA (κ = 0.25 W/m. K at room temperature [30]) and the phonon scattering from uniformly dispersed PMMA nanoparticles (as shown in Figure 3). These out-of-plane film thermal conductivity values κ(300K) measured at 300 K were further used in calculating the thermoelectric figure of merit ZT = σS 2 T/κ 0 (T) in the range of 300-600 K, where κ 0 (T) is the film in-plane thermal conductivity at a given temperature T. For elevated temperatures (T > 300 K), the replacement of κ 0 (T)b y κ(300K) can be validated by two facts: (i) in ZnO films, the in-plane thermal conductivity determined at different conditions was always higher than the out-of-plane one [31]; and (ii) the thermal conductivity of ZnO films was found to decrease with increasing temperature [32].…”

Section: Laser Ablation -From Fundamentals To Applicationsmentioning

confidence: 99%

Multi-Beam Multi-Target Pulsed Laser Deposition of AZO Films with Polymer Nanoparticles for Thermoelectric Energy Harvesters

Darwish¹,

Sarkisov²,

Mele³

et al. 2017

Laser Ablation - From Fundamentals to Applications

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In comparison with metallic thermoelectric films, oxide films with artificial nanodefects have been seldom studied. And there has been no report on the incorporation of islandshaped organic nanoparticles. We describe a new approach to introduce nanometer-sized phonon scatterers in aluminum-doped ZnO (AZO) thermoelectric thin films-concurrent multi-beam multi-target-pulsed laser deposition and the matrix-assisted pulsed laser evaporation (MBMT-PLD/MAPLE). The approach was used to make nanocomposite thin films of AZO matrix with evenly dispersed poly(methyl methacrylate) (PMMA) nanoparticles. The introduction of the nanoparticles enhanced phonon scattering with consequent decrease of thermal conductivity by 20%. The electrical conductivity did not decrease after the addition of the second phase, as it would be predicted by WiedemannFranz law, but improved by 350% over pure AZO film. The thermoelectric figure of merit of the nanocomposite film became twice that of the pure AZO film. Taking advantage of room-temperature deposition, optimized AZO nanocomposite films are expected to be used in real applications, such as thin film modules deposited on flexible polymeric substrates for ubiquitous harvesting of the waste heat.

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“…In this design, instead of changing the resistances of the upper right arm, the voltage of the lower right arm was changed to predetermined, by a computer, values. Hence, about 64 resistance measurements were obtained in 1 s. In design (c), employed after 2000 [64], voltages are registered continuously. Wire resistances are calculated from the known standard resistance (R Std ).…”

Section: Period From 1971 To Todaymentioning

confidence: 99%

Historical Evolution of the Transient Hot-Wire Technique

2010

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The paper attempts to describe the historical evolution of the transient hot-wire technique, employed today for the measurement of the thermal conductivity of fluids and solids over a wide range of conditions. Starting from the first experiments with heated wires in 1780 during the discussions of whether gases could conduct heat, it guides the reader through typical designs of cells and bridges, software employed and theory developed, to the modern applications. The paper is concluded with a discussion of the areas of application where problems still exist, and a glimpse of the technique's future.

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New Measurements of the Thermal Conductivity of PMMA, BK7, and Pyrex 7740 up to 450K

Cited by 49 publications

References 18 publications

Selected physical properties of various diesel blends

Selected physical properties of various diesel blends

Multi-Beam Multi-Target Pulsed Laser Deposition of AZO Films with Polymer Nanoparticles for Thermoelectric Energy Harvesters

Historical Evolution of the Transient Hot-Wire Technique

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