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1.
Compressed liquid densities of 1-pentanol and 2-pentanol have been measured from 313 to 363 K at pressures to 25 MPa. Measurements
have been achieved using a vibrating tube densimeter. Water and nitrogen are the reference fluids to calibrate the densimeter.
Measurements uncertainties are estimated to be ±0.03 K for temperatures, ±0.008 MPa for pressures and ±0.20 kg·m−3 for densities. Two volume-explicit equations with five and six parameters and the 11-parameter BWRS equation of state are
used to correlate the experimental densities of 1-pentanol and 2-pentanol reported in this work. Statistical values for the
evaluation of the correlations are reported. Comparisons with literature data are performed for the temperature and pressure
ranges of the measurements. 相似文献
2.
K. H. Kang H. S. Moon K. C. Song M. S. Yang S. H. Lee S. W. Kim 《International Journal of Thermophysics》2007,28(5):1595-1606
The thermal diffusivity of a simulated fuel with fission products forming a solid solution was measured using the laser-flash
method in the temperature range from room temperature to 1673 K. The density and the grain size of the simulated fuel with
the solid solutions used in the measurement were 10.49 g · cm−3 (96.9% of theoretical density) at room temperature and 9.5 μm, respectively. The diameter and thickness of the specimens were 10 and 1 mm, respectively. The thermal diffusivity decreased
from 2.108 m2 · s−1 at room temperature to 0.626 m2 · s−1 at 1673 K. The thermal conductivity was calculated by combining the thermal diffusivity with the specific heat and density.
The thermal conductivity of the simulated fuel with the dissolved fission products decreased from 4.973 W · m−1 · K−1 at 300 K to 2.02 W · m−1 · K−1 at 1673 K. The thermal conductivity of the simulated fuel was lower than that of UO2 by 34.36% at 300 K and by 15.05% at 1673 K. The difference in the thermal conductivity between the simulated fuel and UO2 was large at room temperature, and decreased with an increase in temperature.
Paper presented at the Seventeenth European Conference on Thermophysical Properties, September 5–8, 2005, Bratislava, Slovak
Republic. 相似文献
3.
Frank Hemberger Sebastian Weis Gudrun Reichenauer Hans-Peter Ebert 《International Journal of Thermophysics》2009,30(4):1357-1371
Novel graded carbon aerogels were synthesized to study the impact of different synthesis parameters on the material properties
on a single sample and to test a new, locally resolved thermal-conductivity measurement technique. Two identical cylindrical
aerogels with a graded structure along the main cylindrical axis were synthesized. Along the gradient with an extension of
about 20 mm the densities range from 240 kg·m−3 to 370 kg·m−3 and the effective pore diameter determined via small angle X-ray scattering and SEM increase systematically from 70 nm up
to 11,000 nm. One specimen was cut perpendicular to the cylinder axis into disc-shaped samples; their thermal conductivities
in an argon atmosphere, as determined via a standard laser-flash technique, range from 0.06W·m−1·K−1 to 0.12W·m−1·K−1 at 600 °C. The second specimen, cut to obtain a sample with the gradient in-plane, was investigated with a spatially resolved
laser-flash technique at ambient conditions. The results of the two different techniques are compared and discussed in detail. 相似文献
4.
Koji Takahashi Norsyazwan Hilmi Yohei Ito Tatsuya Ikuta Xing Zhang 《International Journal of Thermophysics》2009,30(6):1864-1874
The small size of nanomaterials deposited by either focused ions or electron beams has prevented the determination of reliable
thermal property data by existing methods. A new method is described that uses a suspended platinum hot film to measure the
thermal conductivity of a nanoscale deposition. The cross section of the Pt film needs to be as small as 50 nm × 500 nm to
have sufficient sensitivity to detect the effect of the beam-induced nanodeposition. A direct current heating method is used
before and after the deposition, and the change in the average temperature increase of the Pt hot film gives the thermal conductivity
of the additional deposited material. In order to estimate the error introduced by the one-dimensional analytical model employed,
a two-dimensional numerical simulation was conducted. It confirmed the reliability of this method for situations where the
deposit extends onto the terminals by (1 μm or more. Measurements of amorphous carbon (a-C) films fabricated by electron beam
induced deposition (EBID) produced thermal conductivities of 0.61 W · m−1 · K−1 to 0.73 W · m−1 · K−1 at 100 K to 340 K, values in good agreement with those of a-C thin films reported in the past. 相似文献
5.
L’udovít Kubičár Viliam Vretenár Vladimír Štofanik Vlastimil Boháč 《International Journal of Thermophysics》2010,31(10):1904-1918
This article deals with the theory and performance of a sensor for measuring thermal conductivity. The sensor, in the form
of a small ball, generates heat and simultaneously measures its temperature response. An ideal model of the hollow sphere
in an infinite medium furnishes a working equation of the hot-ball method. A constant heat flux through the surface of the
ball generates the temperature field. The thermal conductivity of the surrounding medium is to be determined by the stabilized
value of the temperature response, i.e., when the steady-state regime is attained. Error components of the sensor are discussed
due to analysis of the deviations of the real hot-ball construction from the ideal model. The functionality of a set of hot
balls has been tested, and the calibration for a limited range of thermal conductivities was performed. A working range of
thermal conductivities of tested materials has been estimated to be from 0.06 W· m−1 · K−1 up to 1 W· m−1 · K−1. 相似文献
6.
S. P. Andersson O. Andersson G. Bäckström 《International Journal of Thermophysics》1997,18(1):209-219
The thermal conductivity, λ of amorphous Teflon AF 1600 [poly(1,3-dioxole-4,5-difluoro-2,2-bis(trifluoromethyl)-co-tetrafluoroethylene)]
has been measured at pressures up to 2 GPa in the temperature range 93–392 K. At 295 K and atmospheric pressure, we obtained
λ=0.116, W·m−1·K−1. The bulk modulus was measured up to 1.0 GPa in the temperature range 150–296 K and the combined data yielded the following
values ofg=(∂ln λ ∂lnp)
r
:2.8±0.2 at 296 K, 3.0±0.2 at 258 K, 3.0±0.2 at 236 K. 3.4±0.2 at 200 K. and 3.4±0.2 at 150 K. 相似文献
7.
M. Wiener G. Reichenauer S. Braxmeier F. Hemberger H.-P. Ebert 《International Journal of Thermophysics》2009,30(4):1372-1385
Carbon aerogels, monolithic porous carbons derived via pyrolysis of porous organic precursors synthesized via the sol–gel
route, are excellent materials for high-temperature thermal insulation applications both in vacuum and inert gas atmospheres.
Measurements at 1773K reveal for the aerogels investigated thermal conductivities of 0.09W · m−1 · K−1 in vacuum and 0.12W · m−1 · K−1 in 0.1MPa argon atmosphere. Analysis of the different contributions to the overall thermal transport in the carbon aerogels
shows that the heat transfer via the solid phase dominates the thermal conductivity even at high temperatures. This is due
to the fact that the radiative heat transfer is strongly suppressed as a consequence of a high infrared extinction coefficient
and the gaseous contribution is reduced since the average pore diameter of about 600nm is limiting the mean free path of the
gas molecules in the pores at high temperatures. Based on the thermal conductivity data detected up to 1773K as well as specific
extinction coefficients determined via infrared-optical measurements, the thermal conductivity can be extrapolated to 2773K
yielding a value of only 0.14W· m−1 · K−1 in vacuum. 相似文献
8.
L. Miettinen P. Kekäläinen J. Merikoski J. Timonen 《International Journal of Thermophysics》2009,30(6):1902-1917
The transient fin model introduced recently for determination of the in-plane thermal diffusivity of planar samples with the
help of infrared thermography was modified so as to be applicable to poor heat conductors. The new model now includes a temperature-dependent
heat loss by convective heat transfer, suitable for an experimental setup in which the sample is aligned parallel to a weak,
forced air flow stabilizing otherwise the convective heat transfer. The temperature field in the sample was measured with
an infrared camera while the sample was heated at one edge. The symmetric temperature field created was averaged over the
central fifth of the sample to obtain one-dimensional temperature profiles, both transient and stationary, which were fitted
by a numerical solution of the fin model. One of the fitting parameters was the thermal diffusivity, and with a known density
and specific heat capacity, the thermal conductivity was thus determined. The test measurements with tantalum samples gave
the result (57.5 ± 0.2) W · m−1 · K−1 in excellent agreement with the known value. The other fitting parameter was a temperature-dependent heat loss coefficient
from which the lower limit for the temperature-dependent convection coefficient was determined. For the stationary state the
result was (1.0 ± 0.2) W · m−2 · K−1 at the temperature of the flowing air, and its temperature dependence was found to be (0.22 ± 0.01) W ·m−2 · K−2. 相似文献
9.
The thermal conductivities, thermal diffusivity, thermal anisotropy ratio, and thermal boundary resistance for the multilayered
microstructure of a carbon nanotube (CNT) array are reconstructed experimentally using the 3ω method with two different width
metal heaters. The thermal impedance in the frequency domain and sensitivity coefficients are introduced to simultaneously
determine the multiple thermal parameters. The thermal conductivity at 295 K is 38 W · m−1 · K−1 along the nanotube growth direction, and two orders of magnitude lower in the direction perpendicular to the tubes with the
anisotropy ratio as large as 86. Separation of the contact and CNT array resistances is realized through circuit modeling.
The measured thermal boundary resistances of the CNT array/Si substrate and insulating diamond film interfaces are 3.1 m2 · K · MW−1 and 18.4 m2 · K · MW−1, respectively. The measured thermal boundary resistance between the heater and diamond film is 0.085 m2 · K · MW−1 using a reference sample without a CNT array. The thermal conductivity for a CNT array already exceeds those of phase-changing
thermal interface materials used in microelectronics. 相似文献
10.
T. Ishikawa J. T. Okada P.-F. Paradis Y. Watanabe 《International Journal of Thermophysics》2010,31(2):388-398
Thermophysical properties of liquid gadolinium were measured using non-contact diagnostic techniques with an electrostatic
levitator. Over the 1585 K to 1920 K temperature range, the density can be expressed as ρ(T) = 7.41 × 103 − 0.46 (T − T
m) (kg · m−3) where T
m = 1585 K, yielding a volume expansion coefficient of 6.2 × 10−5 K−1. In addition, the surface tension data can be fitted as γ(T) = 8.22 × 102 − 0.097(T − T
m)(10−3 N · m−1) over the 1613 K to 1803 K span and the viscosity as η(T) = 1.7exp[1.4 × 104/(RT)](10−3 Pa · s) over the same temperature range. 相似文献
11.
Jerzy Bodzenta Anna Kaźmierczak-Bałata Maciej Lorenc Justyna Juszczyk 《International Journal of Thermophysics》2010,31(1):150-162
A steady-state thermal model of the nanofabricated thermal probe was proposed. The resistive type probe working in the active
mode was considered. The model is based on finite element analysis of the temperature field in the probe-sample system. Determination
of the temperature distribution in this system allows calculations of relative changes in the probe electrical resistance.
It is shown that the modeled probe can be used for measurements of the local thermal conductivity with the spatial resolution
determined by the probe apex dimensions. The probe exhibits the maximum sensitivity to the changes in the thermal conductivity
of the sample between 2 W·m−1 ·K−1 and 200 W·m−1 ·K−1. The influence of the thermal conductivity of the probe substrate on metrological characteristics of the probe as well as
the thermal resistance of the probe-sample contact on the determination of the sample thermal conductivity were also analyzed.
The selected results of numerical analysis were compared with data of preliminary experiments. 相似文献
12.
Jianli Wang Bai Song Xing Zhang Yang Song Gangping Wu 《International Journal of Thermophysics》2011,32(5):974-983
Combining the steady-state and quasi-steady-state T type probes, the longitudinal thermal conductivity and thermal effusivity
of individual mesophase pitch-based carbon fiber heat treated at 2800 °C and 1000 °C have been measured from 100 K to 300
K. The present method allows simultaneous measurements of thermal properties using the same instrument, by simply changing
the applied direct current to alternating current. The specific heat is found to decrease with increasing heat-treatment temperature
and to approach the value of graphite. The highly graphitized carbon fiber has a maximum thermal conductivity of 410 W · m−1 · K−1 at about 250 K, and its thermal diffusivity decreases with increasing temperature. Comparatively, the thermal conductivity
of the fiber heat treated at 1000 °C is much smaller, with the peak shifting to high temperature due to a large defect density,
and its thermal diffusivity is nearly temperature independent. 相似文献
13.
W. K. Rhim S. K. Chung A. J. Rulison R. E. Spjut 《International Journal of Thermophysics》1997,18(2):459-469
Several thermophysical properties of molten silicon measured by the high-temperature electrostatic levitator at JPL are presented.
They are density, constant-pressure specific heat capacity, hemispherical total emissivity, and surface tension. Over the
temperature range investigated (1350<T
m<1825 K), the measured liquid density (in g·cm−3) can be expressed by a quadratic function,p(T)=p
m−1.69×10−4(T−T
m)−1.75×10−7(T−T
m)2 withT
m andp
m being 1687 K and 2.56 g·cm−3, respectively. The hemispherical total emissivity of molten silicon at the melting temperature was determined to be 0.18,
and the constant-pressure specific heat was evaluated as a function of temperature. The surface tension (in 10−3 N·m−1) of molten silicon over a similar temperature range can be expressed by σ(T)=875–0.22(T−T
m).
Invited paper presented at the Fourth Asian Thermophysical Properties Conference, September 5–8, 1995, Tokyo, Japan. 相似文献
14.
The draining crucible (DC) technique was used for measurements on AZ91D under Ar and SF6. The DC technique is a new method developed to simultaneously measure the physical properties of fluids, the density, surface
tension, and viscosity. Based on the relationship between the height of a metal in a crucible and the outgoing flow rate,
a multi-variable regression is used to calculate the values of these fluid properties. Experiments performed with AZ91D at
temperatures from 923 K to 1173 K indicate that under argon, the surface tension (N · m−1) and density (kg · m−3) are [0.63 − 2.13 × 10−4 (T − T
L)] and [1656 − 0.158 (T − T
L)], respectively. The viscosity (Pa · s) has been determined to be [1.455 × 10−3 − 1.209 × 10−5 (T − T
L)] over the temperature range from 921 K to 967 K superheat. Above 967 K, the viscosity of the alloy under argon seems to
be constant at (2.66 × 10−4 ± 8.67 × 10−5) Pa · s. SF6 reduces the surface tension of AZ91D. 相似文献
15.
Lee Tin Sin W. A. W. A. Rahman A. R. Rahmat N. A. Morad M. S. N. Salleh 《International Journal of Thermophysics》2010,31(3):525-534
The specific heat capacity (C
sp) of polyvinyl alcohol (PVOH) blends with cassava starch (CSS) was studied by the differential scanning calorimetry method. Specimens of PVOH–CSS blends: PPV37 (70 mass% CSS)
and PPV46 (60 mass% CSS) were prepared by a melt blending method with glycerol added as a plasticizer. The results showed
that the specific heat capacity of PPV37 and PPV46 at temperatures from 330 K to 530 K increased from (2.963 to 14.995) J·
g−1 · K−1 and (2.517 to 14.727) J · g−1· K−1, respectively. The specific heat capacity of PVOH–CSS depends on the amount of starch. The specific heat capacity of the
specimens can be approximated by polynomial equations with a curve fitting regression > 0.992. For instance, the specific
heat capacity (in J · g−1 · K−1) of PPV37 can be expressed by C
sp = −17.824 + 0.063T and PPV46 by C
sp = −18.047 + 0.061T, where T is the temperature (in K). 相似文献
16.
Yu-Xia Kong You-Ying Di Ya-Qian Zhang Wei-Wei Yang Zhi-Cheng Tan 《International Journal of Thermophysics》2009,30(6):1960-1974
1-Dodecylamine hydrochloride was synthesized by the solvent-thermal method. The structure and composition of the compound
were characterized by chemical and elemental analyses, the X-ray powder diffraction technique, and X-ray crystallography.
The main structure and performance of an improved automated adiabatic calorimeter are described. Low-temperature heat capacities
of the title compound are measured by the new adiabatic calorimeter over the temperature range from 78 K to 397 K. Two solid-to-solid
phase transitions have been observed at the peak temperatures of (330.78 ± 0.43) K and (345.09 ± 0.16) K. The molar enthalpies
of the two phase transitions of the substance were determined to be (25.718 ± 0.082) kJ · mol−1 and (5.049 ± 0.055) kJ · mol−1, and their corresponding molar entropies were calculated as (77.752 ± 0.250) J · mol−1 · K−1 and (14.632 ± 0.159) J · mol−1 · K−1, respectively, based on the analysis of heat–capacity curves. Experimental values of heat capacities for the title compound
have been fitted to two polynomial equations. In addition, two solid-to-solid phase transitions and a melting process of C12H25NH3Cl(s) have been verified by differential scanning calorimetry. 相似文献
17.
C. Glorieux J. De Groote J. Fivez W. Lauriks J. Thoen 《International Journal of Thermophysics》1993,14(6):1201-1214
Heat conduction in a free-standing chemical vapor-deposited polycristalline diamond film has been investigated by means of
combined front and rear photoacoustic signal detection techniques and also by means of a “mirage” photothermal beam deflection
technique. The results obtained with the different techniques are consistent with a value of α=(5.5±0.4)×10−4 m2 · s−1 for thermal diffusivity, resulting in a value ofκ=(9.8±0.7)×102 W·m−1·K−1 for thermal conductivity when literature values for the density and heat capacity for natural diamond are used. 相似文献
18.
The magnetocaloric effect of Gd5Si2Ge2 alloys under heat treatment conditions are investigated in low magnetic fields. The magnetocaloric effect (MCE) is studied
by measuring magnetic entropy change (ΔS
M) and adiabatic temperature change (ΔT
ad) in a magnetic field of 1·5 T using a vibrating sample magnetometer (VSM) and a home-made magnetocaloric effect measuring
apparatus, respectively. The maximum ΔS
M of the alloys increases by 200% from 4·38 to 13·32 J kg−1 K−1, the maximum ·T
ad increases by 105% from 1·9 to 3·9 K when compared to the as-cast due to the homogeneous composition distribution and microstructure,
while the magnetic ordering temperature is slightly reduced. These results indicate that the annealed Gd5Si2Ge2 compounds are promising as high-performance magnetic refrigerants working room temperature in relatively low magnetic fields. 相似文献
19.
M. Geisler J. Wachtel F. Hemberger T. Schultz S. Vidi H.-P. Ebert 《International Journal of Thermophysics》2008,29(4):1385-1394
Recent measurements have shown a record-breaking low thermal conductivity λtotal of less than 0.25 × 10−3 W·m−1·K−1 at temperatures of 120 K for an evacuated sample consisting of polyimide fibers with a trilobal fiber cross section. Existing
models for the heat transport in fiber insulations cannot sufficiently describe fiber insulations consisting of fibers with
non-cylindrical cross sections. In this article, a modification for the model for cylindrical fibers will be presented. The
modifications for the trilobal cross section of the fiber will be explained and compared to the original cylindrical model.
The results of the theoretical calculations will be discussed in comparison to experimental results of measurements performed
with a guarded hot-plate apparatus at temperatures in the range from 120 K to 420 K. 相似文献
20.
Thermoelectric power (TEP) of two YBa2Cu3O7−δ
compounds (with δ=0·17 and 0·21) was measured as a function of quasi-hydrostatic pressure up to 9GPa at 300K on samples with
low porosity. In both cases TEP decreases with increasing pressure, at a rate ∼ 0·8 μVK−1/GPa. The data obtained under hydrostatic pressure up to 3 GPa are in good agreement with those under quasi-hydrostatic pressure.
The TEP of both compositions is found to decrease linearly at a rate 0·8 μVK−1/GPa above 1·5 GPa. 相似文献