ON MEASUREMENT OF THERMAL CONDUCTIVITY AT HIGH TEMPERATURES

1961 ◽  
Vol 39 (7) ◽  
pp. 1029-1039 ◽  
Author(s):  
M. J. Laubitz
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
High Temperatures ◽  
Mathematical Analysis ◽  
Temperature Range ◽  
Linear Heat ◽  
Flow Systems

A method is given for exact mathematical analysis of linear heat flow systems used in measuring thermal conductivity at high temperatures. It is shown that a popular version of such a system is very sensitive to the alignment of its components, which seriously limits the temperature range of its satisfactory use.

THERMAL CONDUCTIVITY OF METALS AT HIGH TEMPERATURES: I. DESCRIPTION OF THE APPARATUS AND MEASUREMENTS ON IRON

1947 ◽  
Vol 25a (6) ◽  
pp. 357-374 ◽  
Author(s):  
L. D. Armstrong ◽  
T. M. Dauphinee
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
High Temperatures ◽  
Armco Iron ◽  
Absolute Error ◽  
Cylindrical Sample ◽  
Comprehensive Analysis ◽  
Temperature Curve ◽  
Temperature Range ◽  
Thermal Conductivities

An apparatus for measuring the thermal conductivity of metals in the temperature range 0° to 800 °C. is described. The method utilizes unidirectional heat flow in a cylindrical sample in a vacuum. The advantages of the method are outlined and a comprehensive analysis of possible errors in the measurements is included. Measurements on Armco iron indicate that results with an absolute error of less than 2% may be obtained. The results of measurements on a sample of Armco iron gave thermal conductivities of 0.1819 c.g.s units at 0 °C. and 0.0698 c.g.s. units at 800 °C. A change in slope of the thermal conductivity–temperature curve was found at a temperature of approximately 375 °C., and is tentatively attributed to the presence of 0.03% nickel impurity.

Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

2009 ◽  
Vol 24 (2) ◽  
pp. 430-435 ◽  
Author(s):  
D. Li ◽  
H.H. Hng ◽  
J. Ma ◽  
X.Y. Qin
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperatures ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Temperature Range ◽  
A Value ◽  
Nb Doping ◽  
Thermal Conductivities

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1–xNbx)4Sb3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine β-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)4Sb3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)4Sb3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.

scholarly journals The variation with temperature of the thermal con­ductivity and the X-ray structure of some micas I—The thermal conductivity up to 600° C

1937 ◽  
Vol 163 (913) ◽  
pp. 189-198 ◽  
Keyword(s):  
Thermal Conductivity ◽  
High Temperatures ◽  
Temperature Curve ◽  
X Ray ◽  
Temperature Range ◽  
Conductivity Change ◽  
Initial Values ◽  
Thermal Conductivities

The authors recently had occasion to measure the thermal conductivities of several varieties of mica up to a temperature of 600° C. In the course of this work it has been observed that whereas the thermal conductivities of the muscovite varieties of mica alter but little over this temperature range, the thermal conductivities of certain phlogopite micas decrease to about one-third of their initial values when the micas are heated to about 200° C. In such cases there is incomplete reversibility in the thermal conductivity temperature curve on cooling. Subsequent examination of these micas by means of X-ray crystal analysis has revealed the fact that in those samples which suffered appre­ciable change in conductivity, the arrangement of the elementary crystals composing the mica laminae becomes displaced from their ordered setting at approximately the same temperature as the thermal conductivity change. The present paper describes the thermal conductivity experiments, which are believed to be the first determinations carried out on mica to high temperatures. In the paper which follows, Mr. W. A. Wood describes the X-ray experiments on some of these samples of mica.

Use of the linear heat flow for poor conductors and its application to the thermal conductivity of nylon

Cryogenics ◽  
1973 ◽  
Vol 13 (1) ◽  
pp. 34-40 ◽  
Author(s):  
T. Ashworth ◽  
L.R. Johnson ◽  
C.Y. Hsiung ◽  
M.M. Kreitman
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Linear Heat

Realization of the longitudinal heat flow method for measuring thermal conductivity of solids at high temperatures

2009 ◽  
Vol 52 (5) ◽  
pp. 743-746 ◽  
Author(s):  
E. A. Zhelobtsov ◽  
E. Kh. Isakaev ◽  
V. E. Peletskii ◽  
A. S. Tyuftyaev
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
High Temperatures ◽  
Flow Method

scholarly journals Heat Dissipation and Ripple Current Rating in Electrolytic Capacitors

1975 ◽  
Vol 2 (2) ◽  
pp. 109-114 ◽  
Author(s):  
F. G. Hayatee
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Temperature Rise ◽  
Mathematical Analysis ◽  
Heat Dissipation ◽  
Thermal Characteristics ◽  
Electrolytic Capacitors ◽  
Allowable Temperature

The ripple current rating in electrolytic capacitors is limited by the maximum allowable temperature rise inside the capacitor. The temperature rise is determined by the I2R losses inside the capacitor and the efficiency of heat flow from the interior to the surrounding. The ripple current rating can be extended by either reducing the tanδof the capacitor or by increasing the efficiency of heat flow to ambient.The heat flow is determined by the thermal characteristics of the capacitor surface and thermal conductivity of the medium separating the capacitor winding from the surrounding.In this article a mathematical analysis for the heat flow in capacitors is given. The effects of various parameters are examined and methods of extending the ripple current rating are discussed.

AN INSTRUMENT FOR MEASURING HEAT FLOW, TEMPERATURE, AND THERMAL CONDUCTIVITY IN THE LUNAR SURFACE LAYER

1970 ◽  
Author(s):  
A. E. Wechsler ◽  
E. M. Drake ◽  
F. E. Ruccia ◽  
J. E. McCullough ◽  
P. Felsenthal ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Layer ◽  
Heat Flow ◽  
Lunar Surface ◽  
Flow Temperature
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