Thermal diffusivity of solids by photoacoustic cell rotation and phase lag measurement

1995 ◽  
Vol 66 (7) ◽  
pp. 3907-3908 ◽  
Author(s):  
Sheenu Thomas ◽  
Johney Isaac ◽  
J. Philip
Keyword(s):  
Thermal Diffusivity ◽  
Phase Lag ◽  
Photoacoustic Cell ◽  
Cell Rotation

scholarly journals Some aspects of thermal diffusivity for various soil layers in different harmonics

MAUSAM ◽  
2021 ◽  
Vol 49 (2) ◽  
pp. 255-258
Author(s):  
B. S. LAMBA ◽  
SUNITA BHANDARI
Keyword(s):  
Thermal Diffusivity ◽  
Amplitude Ratio ◽  
Phase Lag ◽  
Soil Medium ◽  
Soil Layers ◽  
Annual Cycles ◽  
Third Harmonic ◽  
The Third ◽  
Experimental Values ◽  
Dry Farming

Values of thermal diffusivity (K) in different soil layers for the first three harmonics have been computed for six stations in the dry farming tract of India by using amplitude ratio and phase lag. In general, the combined effect of all these harmonics gives the values of K close to the order of the experimental values. It is found that the theory of simple heat conduction is not applicable to soil medium. While the lowest values of K in all the harmonics are found at Rajahmundry, the highest values are observed at either Hissar or Bhubaneshwar for the first two harmonics and at Pantnagar for the third harmonic. Strong annual and bi-annual cycles dominate at Hissar. Pantnagar and Bhubaneshwar while quarterly cycle is significant only at Pantnagar.  

Human nail thermal diffusivity obtained using the open photoacoustic cell technique

2005 ◽  
Vol 125 ◽  
pp. 657-660 ◽  
Author(s):  
D. T. Dias ◽  
L. E.R. Nuglish ◽  
E. Sehn ◽  
M. L. Baesso ◽  
A. N. Medina ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Photoacoustic Cell ◽  
Open Photoacoustic Cell ◽  
Human Nail

scholarly journals Improvement of the photoacoustic response in thermal diffusivity measurements

2020 ◽  
Vol 3 (4) ◽  
pp. 196-205
Author(s):  
David Gasca-Figueroa ◽  
Micael Gerardo Bravo-Sánchez ◽  
Adriana Guzmán-López ◽  
José Guadalupe Zavala-Villalpando ◽  
Francisco Javier García-Rodríguez
Keyword(s):  
Mathematical Model ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Room Temperature ◽  
Heat Energy ◽  
Photoacoustic Cell ◽  
Solid Materials ◽  
Diffusivity Measurements ◽  
Materials Used

An alternative photoacoustic cell configuration for the determination of the thermal diffusivity (α), at room temperature, for solid materials is presented. The method is based on the use of two identical photoacoustic chambers, inside both of them, a metallic foil thermally thin is used to transform the light energy to heat energy.  A Reference material placed parallel to a study material allows to relate the thermal properties of the materials used as support in the photoacoustic chambers of the experimental arrangement presented here. The ratio between experimental and theoretical photoacoustic amplitudes is realized to validate a proposed mathematical model.

Thermal Properties Measurement Photoacoustic Technique for Hardmetals

2006 ◽  
Vol 530-531 ◽  
pp. 41-47 ◽  
Author(s):  
F.A.L. Machado ◽  
Roberto da Trindade Faria Jr. ◽  
Marcello Filgueira ◽  
M.F. Rodrigues ◽  
Guerold Sergueevitch Bobrovinitchii ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Cutting Tool ◽  
Thermal Capacity ◽  
Liquid Phase Sintering ◽  
Point Of View ◽  
Photoacoustic Technique ◽  
Photoacoustic Cell ◽  
Open Photoacoustic Cell ◽  
High Pressure High Temperature

The open photoacoustic cell technique (OPC) was carried out in order to measure the thermal diffusivity of hardmetal. Hardmetal is usually processed by the conventional powder technology techniques: mix of WC + Co powders, compacting, and liquid phase sintering A new method to process hardmetal parts is hereby described. Parts of WC-15%wt Co were processed by using high pressure – high temperature sintering. It was used the pressure of 5GPa, temperature of 1350 oC, and time of 2 minutes of sintering. In addition to the thermal diffusivity, heat capacity was considered and the thermal conductivity achieved. Results matched with the values of the literatures where others photoacoustic techniques have been employed. It was achieved a thermal capacity of 3.34J/cm3K, thermal diffusivity of 0.35cm2/s, and thermal conductivity of 116.9W/mK. It reveals that the HPHT processed WC- 15%wtCo hardmetal is able to work as a cutting tool, in the thermal point of view.

scholarly journals Soil thermal diffusivity estimated from data of soil temperature and single soil component properties

2013 ◽  
Vol 37 (1) ◽  
pp. 106-112 ◽  
Author(s):  
Quirijn de Jong van Lier ◽  
Angelica Durigon
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Soil Temperature ◽  
Spatial Organization ◽  
Amplitude Ratio ◽  
Subsurface Layer ◽  
Phase Lag ◽  
Soil Thermal Diffusivity ◽  
Soil Component ◽  
Soil Components

Under field conditions, thermal diffusivity can be estimated from soil temperature data but also from the properties of soil components together with their spatial organization. We aimed to determine soil thermal diffusivity from half-hourly temperature measurements in a Rhodic Kanhapludalf, using three calculation procedures (the amplitude ratio, phase lag and Seemann procedures), as well as from soil component properties, for a comparison of procedures and methods. To determine thermal conductivity for short wave periods (one day), the phase lag method was more reliable than the amplitude ratio or the Seemann method, especially in deeper layers, where temperature variations are small. The phase lag method resulted in coherent values of thermal diffusivity. The method using properties of single soil components with the values of thermal conductivity for sandstone and kaolinite resulted in thermal diffusivity values of the same order. In the observed water content range (0.26-0.34 m³ m-3), the average thermal diffusivity was 0.034 m² d-1 in the top layer (0.05-0.15 m) and 0.027 m² d-1 in the subsurface layer (0.15-0.30 m).

Measurement of thermal diffusivity at high pressures and temperatures using synchrotron radiography

2008 ◽  
Vol 72 (2) ◽  
pp. 653-658 ◽  
Author(s):  
D. P. Dobson ◽  
S. A. Hunt ◽  
L. Li ◽  
D. Weidner
Keyword(s):  
Thermal Diffusivity ◽  
High Pressures ◽  
Temperature Cycle ◽  
Phase Lag ◽  
Radiographic Imaging ◽  
Amplitude Variation ◽  
Temperature Variations ◽  
Synchrotron Radiography ◽  
High Pressures And Temperatures ◽  
Best Fit

AbstractA new method to measure thermal diffusivity in samples at simultaneous high pressure and high temperature is presented. The sample is placed inside a cylindrical heater and subjected to a heater power that varies sinusoidally with time. The diffusion of the temperature variations into the sample is monitored using radiographic imaging of marker foils. This provides measurements of the phase lag and amplitude variation of the temperature cycle at a range of radii from the sample axis without the need for multiple thermocouples. The technique is tested using a NaCl sample at 4 GPa; the best-fit thermal diffusivity for NaCl at 4 GPa and 673 K is 2.4±0.5x10-6 m2/s.

scholarly journals Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring

2012 ◽  
Vol 111 (1) ◽  
pp. 014701 ◽  
Author(s):  
F. B. G. Astrath ◽  
N. G. C. Astrath ◽  
M. L. Baesso ◽  
A. C. Bento ◽  
J. C. S. Moraes ◽  
...  
Keyword(s):  
Thermal Diffusivity ◽  
Photoacoustic Cell ◽  
Open Photoacoustic Cell ◽  
Diffusivity Measurements
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