Proposal of novel measurement method for thermal diffusivity from infrared thermal movie

Abstract

A brand new thermal diffusivity measurement method was developed. In this new noncontact and absolute measurement method, thermal diffusivity was measured from infrared movie data. The model of one-dimensional thermal conduction was constructed by taking into account the thermal flow other than one-dimensional thermal conduction in the sample. On the basis of this thermal conduction model, the analytical equation for calculating thermal diffusivity was derived. A single-crystal sapphire plate was used as a test specimen for the new method. The test specimen was arranged to cause one-dimensional heat conduction. Infrared movies were taken by using an infrared camera at room temperature. Then, thermal diffusivity was numerically calculated from the acquired movie data using the analytical equation. It was experimentally demonstrated that thermal diffusivity was measured with an accuracy of around 10% error, from an infrared movie of a single-crystal sapphire sample.

Temperature Diffusivity Measurement and Nondestructive Testing Requiring No Extensive Sample Preparation and Using Stepwise Point Heating and IR Thermography

“…They use various temporal profiles of incoming heat flow such as Dirac delta function, step or periodic ones [18,23,27,28,38]. The latter mode is used by thermal wave interferometry (TWI) technique, which opens additional possibilities related to synchronous signal detection referred to as lock-in technique like accuracy improvement, reduction of drift impact, and gathering information from two independent channels, namely signal amplitude and phase [38][39][40]. However, due to the necessity for oscillations to be close to asymptotic, this method exhibits some of the abovementioned drawbacks of stationary methods.…”

Improvements of measurement method for thermal diffusivity from infrared thermal movie

“…As described in the previous paper, 1) our final objective is to establish a simultaneous and absolute measurement system for thermal conductivity κ and specific heat C. This paper is one of the intermediate stages leading to the final objective. Needless to say, κ and C are very important parameters of thermophysical properties.…”

“…As noted in the previous paper, 1) one of the authors, around two decades before, had come up with the idea that α could be measured from IR movie data. But the performance of the IR movie camera (NEC INFRAVISION IRV2010, 1996 model) was unsatisfactory, so the calculated α values were quite unreliable.…”

“…Then, quantitative evaluation of α value was reported in the previous paper. 1) The quantitative evaluation method used both information on the time dependence of temperature and information on the spatial distribution of temperature from the IR movie data. Unfortunately, one problem remained.…”

In-plane thermal diffusivity measurement of thin plates by the transient fin method

“…The thermal conductivity can be deduced from the measurement of the thermal diffusivity coupled with the measurement of the mass heat capacity by differential calorimetry. Many measurement methods [8][9][10][11][12][13][14][15][16][17] derived from flash method and using infrared thermography were previously proposed to estimate in-plane thermal diffusivity of thin plates but they were applied to medium to high thermal diffusivity materials. The transient fin method 18 has already been used to measure the in-plane diffusivity of thin plates but only for highly conductive materials.…”