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Through-plane and in-plane thermal diffusivity determination of graphene nanoplatelets by photothermal beam deflection spectrometry
Stefano Bellucci, Hanna Budasheva, Behnaz Abbasgholi N. Asbaghi, Humberto Cabrera, Dorota Korte, 2021, izvirni znanstveni članek

Opis: In this work, in-plane and through-plane thermal diffusivities and conductivities of a freestanding sheet of graphene nanoplatelets are determined using photothermal beam deflection spectrometry. Two experimental methods were employed in order to observe the effect of load pressures on the thermal diffusivity and conductivity of the materials. The in-plane thermal diffusivity was determined by the use of a slope method supported by a new theoretical model, whereas the through-plane thermal diffusivity was determined by a frequency scan method in which the obtained data were processed with a specifically developed least-squares data processing algorithm. On the basis of the determined values, the in-plane and through-plane thermal conductivities and their dependences on the values of thermal diffusivity were found. The results show a significant difference in the character of thermal parameter dependence between the two methods. In the case of the in-plane configuration of the experimental setup, the thermal conductivity decreases with the increase in thermal diffusivity, whereas with the through-plane variant, the thermal conductivity increases with an increase in thermal diffusivity for the whole range of the loading pressure used. This behavior is due to the dependence of heat propagation on changes introduced in the graphene nano-platelets structure by compression.
Najdeno v: ključnih besedah
Povzetek najdenega: ...of load pressures on the thermal diffusivity and conductivity of the materials. The in-plane thermal diffusivity...
Ključne besede: graphene nanoplatelets, thermal diffusivity, thermal conductivity, photothermal spectrometry
Objavljeno: 30.11.2021; Ogledov: 602; Prenosov: 26
URL Polno besedilo (0,00 KB)
Gradivo ima več datotek! Več...

Absolute Porosity Analysis in Carbon Allotropic Nanofluids: A Sankar–Swapna Model Approach

Opis: Porous materials have gained significant attention in recent years as a class of material exhibiting interesting chemical and physical properties. The existing methods of porosity analysis have limitations that prevent absolute porosity measurement. Hence, a technique independent of surface physical properties alone can give the absolute porosity of the material. The porosity greatly influences the thermal diffusivity of a material. The manuscript is the first report of employing the Sankar–Swapna model for analyzing the porosity variations in carbon allotropic nanofluids. The model helps not only in getting information about the absolute porosity variations among samples, but also suggests morphological modifications through the thermal diffusivity study using the sensitive single-beam thermal lens technique. The variations in thermal diffusivity and absolute porosity values are also correlated to morphological modifications based on the theoretical model and thereby proposing this as a surrogate method for absolute porosity analysis.
Najdeno v: ključnih besedah
Povzetek najdenega: ...the material. The porosity greatly influences the thermal diffusivity of a material. The manuscript is the...
Ključne besede: absolute porosity, Sankar–Swapna model, thermal diffusivity, thermal lens, thermal conductivity
Objavljeno: 04.07.2022; Ogledov: 76; Prenosov: 0
.pdf Polno besedilo (1,96 MB)

Generalized Theory of Thermal Conductivity for Different Media: Solids to Nanofluids

Opis: The advent of nanotechnology in the 21st century opened a new branch of nanoscience known as nanofluids, finding a wide range of industrial applications especially in heat transfer. Though the theory of thermal conductivity of solids is well established, there is no such conclusive model to explain the thermal conductivity of nanofluids. In the present work we propose a generalized theory for thermal conductivity applicable to materials ranging from heterogeneous solids, porous materials, nanofluids, and ferrofluids. The model could explain the effective thermal conductivity of not only the combination of solids but also solid−fluid mixtures. The proposed theory could successfully link the existing models for porous solid materials and nanofluids as its special cases. The proposed model is verified against experimental data by simulating the theoretical equations
Najdeno v: ključnih besedah
Ključne besede: thermal conductivity, generalised model, Sankar-Loeb model
Objavljeno: 05.07.2022; Ogledov: 103; Prenosov: 0
.pdf Polno besedilo (3,99 MB)

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