Modified Laser Flash Method for Thermal Property Measurements and the Influence of Heat Convection

2003 ◽  
Author(s):  
Bochuan Lin ◽  
Shen Zhu ◽  
Heng Ban ◽  
Chao Li ◽  
Rosalia N. Scripa ◽  
...  
Keyword(s):  
Heat Conduction ◽  
Natural Convection ◽  
Thermal Diffusivity ◽  
Laser Pulse ◽  
Rear Surface ◽  
Front Surface ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
Conduction Model

This study examined the effect of natural convection in the modified laser flash method for the measurement of thermo physical properties of semiconductor melts. Common laser flash method uses a laser pulse to heat the front surface of a thin circular sample and measures the temperature transient of the rear surface. Thermal diffusivity is calculated based on the analysis of the transient heat conduction process. For semiconductor melts, the sample is contained in a specially designed quartz cell with optical windows. When the laser pulse heats the melt front surface, the resulting natural convection can introduce errors in the calculation of thermal diffusivity based on the heat conduction model. The effect of natural convection was evaluated by Computational Fluid Dynamics (CFD) simulations in this study. The results indicated that natural convection can decrease the time needed for the rear surface to reach its peak temperature, and can also decrease the peak temperature slightly. Based on our experimental data for Tellurium, the calculation using only heat conduction model resulted in a thermal diffusivity about 3% greater than that using the heat transfer model with natural convection.

Laser Flash Measurement of Samples With a Transparent Reference Layer

2009 ◽  
Author(s):  
Heng Ban ◽  
Zilong Hua
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Temperature Response ◽  
Front Surface ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
Thermal Diffusivity Measurement ◽  
Reference Layer

The laser flash method is a standard method for thermal diffusivity measurement. This paper reports the development of a method and theory that extends the standard laser flash method to measure thermal conductivity and thermal diffusivity simultaneously. By attaching a transparent reference layer with known thermal properties on the back of a sample, the thermal conductivity and thermal diffusivity of the sample can be extracted from the temperature response of the interface between the sample and the reference layer to a heating pulse on the front surface. The theory can be applied for sample and reference layer with different thermal properties and thickness, and the original analysis of the laser flash method becomes a limiting case of the current theory with an infinitely small thickness of the reference layer. The uncertainty analysis was performed and results indicated that the laser flash method can be used to extract the thermal conductivity and diffusivity of the sample. The results can be applied to, for instance, opaque liquid in a quartz dish with silicon infrared detector measuring the temperature of liquid-quartz interface through the quartz.

Method for Obtaining Thermal Conductivity From Modified Laser Flash Measurement

2005 ◽  
Author(s):  
Bochuan Lin ◽  
Heng Ban ◽  
Chao Li ◽  
Rosalia N. Scripa ◽  
Ching-Hua Su ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Rear Surface ◽  
Temperature Response ◽  
Laser Flash ◽  
Fused Silica ◽  
Laser Flash Method ◽  
Flash Method ◽  
Silica Cell

Laser flash method is commonly used to measure the thermal diffusivity of solids. In the original thermal analysis, adiabatic boundary conditions were used and the time for sample rear surface temperature to reach 50% of maximum value was used to calculate the thermal diffusivity. Later other boundary conditions were included in the analysis to compensate for the heat loss. The laser flash method can be modified to determine the thermal conductivity by comparing the temperature rise of the sample with a standard sample, both of which are coated to ensure identical surface emissivity. In our previous studies of applying the laser flash method to semiconductor melts, we have shown that it is possible to obtain thermal conductivity, specific heat capacity and thermal diffusivity from the experimental data. In these studies, the melt sample was sealed in a specially-designed fused silica cell. The heat transfer between melt sample and the fused silica cell allows the thermal conductivity to be included in the analysis. Therefore, the temperature response of the melt sample was controlled not only by the thermal diffusivity and conductivity of sample, but also by the thermal properties of fused silica cell. Using a computational fitting process, we obtained both thermal diffusivity and thermal conductivity of the sample. In this paper, an analytic solution for the transient heat transfer inside the sample and fused silica cell was developed. The influence of fused silica cell was included and the heat transfer to fused silica cell had a significant effect on the time-temperature response of the sample. Therefore, the rear surface temperature of the sample, described by an analytical solution, could be used to obtain both thermal diffusivity and thermal conductivity of the sample with known properties of the fused silica cell. The results indicated that this method was applicable for a wide range of sample and cell properties. The original solution for laser flash method became an extreme case in the current theory

A high-temperature system based on the laser flash method to measure the thermal diffusivity of melts

1996 ◽  
Vol 17 (1) ◽  
pp. 253-261 ◽  
Author(s):  
Y. Maeda ◽  
H. Sagara ◽  
R. P. Tye ◽  
M. Masuda ◽  
H. Ohta ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Diffusivity ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
High Temperature System

scholarly journals Measurement of Thermal Diffusivity of Steels at Elevated Temperature by a Laser Flash Method.

2002 ◽  
Vol 42 (5) ◽  
pp. 498-503 ◽  
Author(s):  
Tsuyoshi Nishi ◽  
Hiroyuki Shibata ◽  
Koichi Tsutsumi ◽  
Hiromichi Ohta ◽  
Yoshio Waseda
Keyword(s):  
Elevated Temperature ◽  
Thermal Diffusivity ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method

Thermal Diffusivity of 16Kh12V2FTaR Steel in a Wide Temperature Range

2013 ◽  
Vol 8 (3) ◽  
pp. 163-167
Author(s):  
Alibek Agazhanov ◽  
Igor Savchenko ◽  
Dmitriy Samoshkin ◽  
Sergey Stankus ◽  
Olga Dutova
Keyword(s):  
Phase Transitions ◽  
Thermal Diffusivity ◽  
Wide Temperature Range ◽  
Curie Point ◽  
Martensitic Steel ◽  
Laser Flash ◽  
Austenite Phase ◽  
Laser Flash Method ◽  
Flash Method ◽  
Temperature Range

Thermal diffusivity of the ferritic-martensitic steel 16Kh12V2FTaR in the temperature range from 296 to 1274 K has been measured by the laser flash method with the error of 2–4 %. The approximating equations have been obtained, the Curie point of steel and the temperatures of martensitic-austenite phase transitions have been determined

Uncertainty of Thermal Diffusivity Measurements by Laser Flash Method

2005 ◽  
Vol 26 (6) ◽  
pp. 1883-1898 ◽  
Author(s):  
B. Hay ◽  
J. R. Filtz ◽  
J. Hameury ◽  
L. Rongione
Keyword(s):  
Thermal Diffusivity ◽  
Laser Flash ◽  
Laser Flash Method ◽  
Flash Method ◽  
Diffusivity Measurements
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