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1.
低温下导热系数测定对生物器官的低温保存、低温外科医学及数值模拟计算至关重要.在分析探针法测量原理的基础上,用探针法对低温下猪主动脉的导热系数进行了测量研究.实验表明探针在用甘油和蒸馏水进行标定后,可以方便准确地测量-90~-35℃温区下猪主动脉的导热系数. 相似文献
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The thermal conductivity of AISI 304L stainless steel 总被引:1,自引:0,他引:1
R. S. Graves T. G. Kollie D. L. McElroy K. E. Gilchrist 《International Journal of Thermophysics》1991,12(2):409-415
A compilation and critical analysis of the thermal conductivity () of AISI 304 stainless steel (SS) between 100 and 1707 K has been given in the literature. The author represented his recommended values of by an inflection in the A versus temperature relationship between 300 and 500 K. Because a physical mechanism had not been identified that would produce such a temperature dependence in of 304 SS, interest was generated in the possible existence of an as yet undiscovered phenomenon that might cause such an inflection. Consequently, experimental verification of the inflection was sought. The present paper presents recent measurements of , the electrical resistivity, and the absolute Seebeck coefficient of 304L SS from 300 to 1000 K and of the thermal diffusivity () from 297 to 423 K. The values computed from the a measurements were within ± 1.6% of the directly measured An inflection was not observed in the temperature dependence of between 300 and 500 K. After careful evaluation and because a physical mechanism still has not been identified which would produce such an inflection, the authors conclude that the inflection in the vs T relationship reported in the literature was caused by the data analysis technique. 相似文献
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M. J. Assael M. Dix I. Drummond L. Karagiannidis M. J. Lourenco C. Nieto de Castro M. Papadaki M. L. Ramiers H. van den Berg W. A. Wakeham 《International Journal of Thermophysics》1997,18(2):439-446
The paper describes the progress made in the development of an instrument for the measurement of the thermal conductivity
of molten materials at high temperatures. The instrument is designed to provide experimental data of unique accuracy at temperatures
up to 1500 K on a wide range of materials, some of which will be suitable as standard reference substances. In particular,
the paper concentrates upon the method of analysis of the experimental data and upon those critical aspects of the experimental
technique which will enable a high accuracy to be achieved. Demonstrations of the validity of the method of treating one correction
and of its behavior under typical conditions are included.
Paper presented at the Fourth Asian Thermophysical Properties Conference, September 5–8, 1995, Tokyo, Japan. 相似文献
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The thermal conductivity of tin single crystals with zinc admixtures has been measured in the temperature range 3.5–25 K for concentrations up to 0.1 wt%. The anisotropy of thermal conductivity for two orientations, [001] and [010], has been determined. It was found that the influence of zinc admixture on the thermal conductivity anisotropy is of a complex, temperature-dependent character.Nomenclature
T
1
T
2
Temperature differences in the specimen
-
Thermal conductivity coefficient
-
W
Thermal resistivity
-
A, B, C
Constants in Eq. (1)
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T
Temperature
-
th
Residual electrical resistivity calculated from W-F law
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0
Residual electrical resistivity from measurements
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L
0
Lorenz constant
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th
Anisotropy coefficient of thermal conductivity
-
el
Anisotropy coefficient of electrical conductivity
-
c
Admixture concentration 相似文献
7.
Chubin Yang Xianhua Chen Ning Luo Baojun Han Tianyong Zhou 《Materials Science & Technology》2018,34(2):138-144
This study investigated the effect of Sm additions on the microstructure, thermal conductivity, and mechanical properties of Mg-Zn-Zr alloy. The results indicate that the addition of Sm led to the formation of a rare-earth phase at the grain boundaries, and the grain size was significantly refined in the extruded state. The thermal conductivity of Mg alloy increased with the increase in Sm content because of the formation of a rare-earth phase that helps to dissolve the Zn atoms in the α-Mg matrix. Moreover, the as-extruded Mg alloy exhibited a higher thermal conductivity (up to124?W?(m?K)?1) than its as-cast counterparts. The Sm-containing as-extruded Mg alloy showed excellent yield strength of up to 254?MPa, and also a good plastic deformation ability. 相似文献
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B. J. Monaghan 《International Journal of Thermophysics》1999,20(2):677-690
A four-probe dc technique for measuring liquid-metal electrical resistivities has been developed, and liquid-resistivity measurements on gallium, tin, lead, copper, a lead tin alloy, a copper tin alloy, and a zinc alloy have been presented. The Lorenz relation has been used to calculate thermal conductivities from these resistivity measurements. The thermal conductivities calculated from these resistivity measurements are (where data are available) in good agreement with recommended liquid-metal thermal conductivities. 相似文献
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B. M. Suleiman S. E. Gustafsson A. Lundén 《International Journal of Thermophysics》1997,18(6):1527-1537
The electrical resistance and its temperature coefficient have been measured for a platinum foil as a function of uniaxial
pressure over the pressure range 0 to 60 MPa. The measurements were performed at room temperature using the transient hot-strip
method. The data are analyzed using the electrical resistivity formula within the Block-Grüneisen approximation. The pressure
dependence of the Debye temperature was directly obtained from an expansion of this formula and using the basic definition
of the temperature resistivity coefficient. The reliability of the experimental data was then verified using the basic definition
of Grüneisen constant. Within the investigated pressure range, the analysis supports the interpretation that the change in
resistance of platinum under pressure is mainly due to the change in the amplitude of the atomic vibrations that are directly
related to the change in Debye temperature. The pressure dependence of resistance and the Debye temperature of the platinum
were reasonably good in spite of the approximations involved. 相似文献
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K. Hisano 《International Journal of Thermophysics》1997,18(2):535-545
Thermal radiation calorimetry was applied to measure the thermal conductivity of insulating solid specimens. We consider the
system in which a disk-shaped specimen and a flat heater are mounted in a vacuum chamber with the specimen heated on one face
by irradiation. A temperature difference between two faces was observed at elevated temperatures under steady-state conditions.
An apparatus was developed using a thin graphite sheet as the heater element. Disk-shaped Pyrex glass and Pyroceram specimens,
whose surfaces were blackened with colloidal graphite, were used in the measurements. Noncontact temperature measurement was
performed using pyrometers and a thermocouple set in the gap between the heater and the specimen. Deviations of the estimated
thermal conductivities from the recommended values were about 5% in the temperature range 250 to 800°C.
Paper presented at the Fourth Asian Thermophysical Properties Conference, September 5–8, 1995, Tokyo, Japan. 相似文献
11.
Results on electrical resistivity and thermal conductivity measured in the temperature range 4.2–40 K are presented for single-crystal and polycrystalline samples of Cd3As2. Hall effect has been studied at temperatures of 4.2, 77, and 300 K. The calculated value of the conduction electron concentration was in the range 1.87–1.95 1024m–3. Electrical resistivity of all investigated samples was independent of temperature up to about 10K and increased slowsly at higher temperatures. The thermal conductivity shows a maximum in the region in which the lattice component of thermal conductivity dominates. The strong anisotropy of the lattice component determines the anisotropy of the total thermal conductivity. The electronic component of thermal conductivity does not exhibit any anisotropy and shows a maximum at a temperature of about 300 K.Paper submitted to the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A. 相似文献
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Electrical Resistivity and Thermal Conductivity of Pure Aluminum and Aluminum Alloys up to and above the Melting Temperature 总被引:1,自引:0,他引:1
Experimental improvements of a four-probe technique to measure the electrical resistivity of molten metals led to an improvement
of the measurement uncertainty to less than 6%. Measurements of pure Al and AlSi-, AlSiMg-, and AlSiCu-alloys with a systematic
variation of individual components are described. The problem of the calculation of the thermal conductivity has been investigated,
and the resulting values of the binary system have been discussed in terms of behavior during melting and solidification.
There is a remarkable difference of the thermal conductivity before melting and after resolidification.
Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak
Republic. 相似文献
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A submicrosecond ohmic pulse heating technique is described for measurements of thermal properties of cylindrical metallic samples at high temperatures. Electrical and optical measurements for determination of thermophysical data such as enthalpy, specific heat, and electrical resistivity are presented. Effects that can falsify the results are discussed.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A. 相似文献
14.
A discussion is presented regarding the significance of the spatial temperature gradient approximation normally used in thermal conductivity measurement. Examples are presented illustrating the magnitude of temperature differences allowed for conductivity integral (TCI) method of analysis is presented as an alternative method which totally eliminates the need to impose temperature difference restrictions on the measurement process, so long as other errors, such as radiative heat losses, do not become excessive. 相似文献
15.
P. G. Klemens 《International Journal of Thermophysics》1996,17(4):979-981
Previous approximations for the effective conductivity of a matrix with inclusions of low conductivity, and for the effective resistivity of a matrix with inclusions of high conductivity, are combined to give the effective conductivity when both types of inclusions are present. This applies, for example, to a ceramic which contains both pores and metallic inclusions. 相似文献
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We measured the thermal conductivity of a Kevlar 49 in the temperature range. The data were fitted with a power-law: . Kevlar 49 is a candidate material for the supports of CUORE experiment. 相似文献
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《Materials Science & Technology》2013,29(6):581-587
In the present work, the effects of Sn, Ca additions on thermal conductivity were investigated in as cast Mg–Sn–Ca alloys. The measured values of thermal conductivity of Mg–3Sn–xCa alloys obviously increased from 85.6 to 126.3?W?m??1?K??1 with the increasing Ca from 0 to 1.5?wt-%, and then decreased to 98.3?W?m??1?K??1 with the 2.5?wt-% Ca. In addition, the thermal conductivity of the Mg–Sn–Ca (Sn/Ca atomic ratio of 1) alloys decreased slightly from 154.2 to 132.1?W?m??1?K??1 with the increasing Sn, Ca. Meanwhile, the microstructures of the selected alloys were discussed in detail, suggesting that the solute atoms that caused lattice distortion had greater effect on thermal conductivity compared with the second phases formed in as cast Mg–Sn–Ca alloys. 相似文献
19.
The mathematical model that describes a dynamic thermal conductivity experiment is reconsidered by taking into account the role of thermal expansion. Two differential equations are presented that take into account the various physical phenomena occurring in a long thin rod directly heated by a current pulse. One of the two equations keeps variables space and time completely separate and is particularly useful for computer simulations.Paper presented at the Second Workshop on Subsecond Thermophysics, September 20–21, 1990, Torino, Italy. 相似文献
20.
V. M. Anisimov N. I. Sidorov E. L. Studnikov Yu. V. Tarlakov V. S. Yargin 《International Journal of Thermophysics》1990,11(5):875-888
Values calculated for the dynamic viscosity and thermal conductivity are presented for vapors of binary eutectics of the alkali metals at temperatures from 800 to 1500 K and at pressures from 100 to 8×105 Pa. Data are presented for the vapors of the systems Li + Na, Na + Rb, Na + Cs, K + Rb, K + Cs, Na + K, and Rb + Cs. The values of the concentrations of the five components in the vapor phase of each binary eutectic are also presented. The accuracy of the calculated viscosities is estimated to be within 4–5% and the accuracy of the calculated thermal conductivities is estimated to be within 8–10%. 相似文献