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Position-dependent velocity of an effective temperature point for the estimation of the thermal diffusivity of solids

Balachandar, Settu and Shivaprakash, NC and Rao, Kameswara L (2016) Position-dependent velocity of an effective temperature point for the estimation of the thermal diffusivity of solids. In: MEASUREMENT SCIENCE AND TECHNOLOGY, 27 (1).

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Official URL: http://dx.doi.org/10.1088/0957-0233/27/1/015201

Abstract

A new approach is proposed to estimate the thermal diffusivity of optically transparent solids at ambient temperature based on the velocity of an effective temperature point (ETP), and by using a two-beam interferometer the proposed concept is corroborated. 1D unsteady heat flow via step-temperature excitation is interpreted as a `micro-scale rectilinear translatory motion' of an ETP. The velocity dependent function is extracted by revisiting the Fourier heat diffusion equation. The relationship between the velocity of the ETP with thermal diffusivity is modeled using a standard solution. Under optimized thermal excitation, the product of the `velocity of the ETP' and the distance is a new constitutive equation for the thermal diffusivity of the solid. The experimental approach involves the establishment of a 1D unsteady heat flow inside the sample through step-temperature excitation. In the moving isothermal surfaces, the ETP is identified using a two-beam interferometer. The arrival-time of the ETP to reach a fixed distance away from heat source is measured, and its velocity is calculated. The velocity of the ETP and a given distance is sufficient to estimate the thermal diffusivity of a solid. The proposed method is experimentally verified for BK7 glass samples and the measured results are found to match closely with the reported value.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Keywords: thermal diffusivity; interferometer; isothermal surface; unsteady heat flow; step-temperature excitation; velocity; effective temperature point
Department/Centre: Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Depositing User: Id for Latest eprints
Date Deposited: 23 Apr 2016 07:36
Last Modified: 23 Apr 2016 07:36
URI: http://eprints.iisc.ac.in/id/eprint/53701

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