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1.
O.I. Verba 《Thermophysics and Aeromechanics》2007,14(2):165-168
Thermal conductivity of gaseous refrigerant R 404A was studied by the method of coaxial cylinders within the ranges of thermodynamic
parameters 309÷422 K and 0.13÷0.184 MPa. The estimated measurement errors for the temperature, pressure, and thermal conductivity
are ± 0.05 K, ± 3.75 kPa, and ± 1.5–2.5%, correspondingly. The approximation dependence for thermal conductivity was obtained
for the whole studied range of temperatures and pressures. The results obtained were compared with available published data.
The work was financially supported by the Russian Foundation for Basic Research (grant No. 04-02-16355). 相似文献
2.
O. I. Verba 《Thermophysics and Aeromechanics》2011,18(1):151-154
Thermal conductivity of refrigerant 507A in gaseous state has been measured with a stationary method of coaxial cylinders
in the temperatures range of 315–425 K and pressures 0.105–1.855 MPa. Estimated values of temperature, pressure, and thermal
conductivity measurement errors are, respectively, ± 0.05 K, ± 3.75 kPa and ± 1.5–2.5 %. Approximation dependence for thermal
conductivity in the whole studied temperature and pressure range has been obtained. Results have been compared with available
literature data. 相似文献
3.
Thermal conductivity of liquid ozone-safe refrigerant R404A was studied for the first time in the range of temperatures of
297.9–332.6 K and pressures from the saturation line to 3.7 MPa. The uncertainties of temperature, pressure, and thermal conductivity
measurements were estimated to be within ±0.1 K, ±3 kPa, and ±0.15%, correspondingly. Values of thermal conductivity were
calculated for liquid R404A at the boiling line. Approximating dependences for thermal conductivity were obtained for the
whole range of studied temperatures and pressures, and at the boiling line.
The work was financially supported by the Russian Foundation for Basic Research (grant No. 04-02-16355). 相似文献
4.
Thermal conductivity and thermal diffusivity of “ozone-safe” refrigerant R134a in liquid state within the range of temperatures
295.9–354.9 K and pressures from the liquid — vapor equilibrium line up to 4.08 MPa have been studied by high-frequency thermal-wave
method. The experimental uncertainties of the temperature, pressure, thermal conductivity and thermal diffusivity measurement
errors were estimated to be 0.1 K, 3 kPa, 1.5 and 2.5 %, respectively. Values of thermal conductivity and thermal diffusivity
of liquid R134a on saturated line have been calculated. Approximation dependences for thermal conductivity and thermal diffusivity
within the whole studied range of temperatures and pressures as well as on the saturated line have been obtained.
The work was financially supported by the Russian Foundation for Basic Research (grant No. 07-08-00295-a). 相似文献
5.
The saturation pressure, pressure and density of superheated vapor of 1,1,1,2,3,3-hexafluoropropane (HFC-236ea, R-236ea) were
studied by an isochoric piezometer within the temperature range of 294–423 K up to the pressure of 4.0 MPa. The uncertainties
of temperature, pressure, and density measurements were estimated as ±20 mK, ±1.5 kPa, ±(0.1–0.2) %, and ±(0.1–0.2) %, correspondingly.
The purity of studied samples was 99.68 mass %. The obtained experimental data are shown as tables and analytical equations.
Coefficients of the virial state equation were calculated for R-236ea on the basis of these data.
The work was financially supported by the Russian Foundation for Basic Research (Grant No. 04-02-16355). 相似文献
6.
Thermal conductivity of ozone-safe liquid refrigerant R507 was studied by the method of high-frequency thermal waves within
the temperature range of 297.95 … 332.55 K and pressures from the saturation line up to 3.7 MPa. The estimated errors of temperature,
pressure, and thermal conductivity measurements are 0.1 K, 3 kPa, and 1.5 %, correspondingly. Thermal conductivity of liquid
R507 was calculated on the saturation line. Approximation dependences for thermal conductivity were derived for the whole
range of studied temperatures and pressures and on the saturation line.
The work was financially supported by the Russian Foundation for Basic Research (Grant No. 07-08-00295-a). 相似文献
7.
Thermal conductivity of refrigerant R-409A in vapor phase was studied in the range of temperatures 306–425 K and pressures
0.12–1.33 MPa. Measurements were performed with the stationary method of coaxial cylinders. Uncertainty of experimental data
on thermal conductivity was 1.5–2.5 %, and errors of temperature and pressure measurements did not exceed 0.05 K and 4 kPa,
respectively. Approximating dependence of thermal conductivity on pressure and temperature was obtained. Thermal conductivity
on dew line and in ideal gas state was calculated. 相似文献
8.
The density of solid and liquid indium antimonide was studied by irradiating the samples with a narrow beam of monochromatic
gamma-radiation in the temperature range of 293–1950 K, including the range of melting — crystallization. The measurement
errors for the density and thermal expansion coefficients were ±(0.25–0.40) % and ± 4 %, correspondingly. The approximating
equations and tables of reference data were obtained for the temperature dependence of thermal properties. Measurement results
were compared with the known published data.
The work was financially supported by the Russian Foundation for Basic Research (Grant No. 06-08-00040). 相似文献
9.
Thermal conductivity and thermal diffusivity coefficients of liquid indium have been determined in the range of temperatures
from 470 to 1275 K by the laser flash method. Errors of heat transfer coefficients are ±(3.5–5) %. Approximating equations
and tables of reference data have been developed for temperature dependence of properties. Measurement results have been compared
with the data available in the literature. Temperature dependence of Lorentz number has been calculated up to 1000 K. 相似文献
10.
L. S. Parfen’eva T. S. Orlova N. F. Kartenko N. V. Sharenkova B. I. Smirnov I. A. Smirnov H. Misiorek A. Jezowski T. E. Wilkes K. T. Faber 《Physics of the Solid State》2010,52(6):1115-1122
This paper reports on measurements performed in the temperature range 5–300 K for the thermal conductivity κ and electrical
resistivity ρ of high-porosity (cellular pores) biocarbon preforms prepared by pyrolysis (carbonization) of beech wood in
an argon flow at carbonization temperatures of 1000 and 2400°C. X-ray structure analysis of the samples has been performed
at 300 K. The samples have revealed the presence of nanocrystallites making up the carbon matrices of these biocarbon preforms.
Their size has been determined. For samples prepared at T
carb = 1000 and 2400°C, the nanocrystallite sizes are found to be in the ranges 12–25 and 28–60 κ(T) are determined for the samples cut along and across the tree growth direction. The thermal conductivity κ increases with
increasing carbonization temperature and nanocrystallite size in the carbon matrix of the sample. Thermal conductivity measurements
conducted on samples of both types have revealed an unusual temperature dependence of the phonon thermal conductivity for
amorphous materials. As the temperature increases from 5 to 300 K, it first increases in proportion to T, to transfer subsequently to ∼T
1.5 scaling. The results obtained are analyzed. 相似文献
11.
In the present work, a novel blend polymer electrolyte membrane using poly(vinyl acetate) (PVAc), poly(methyl methacrylate)
(PMMA), and lithium per chlorate (LiClO4) in different compositions has been prepared by the solution-casting technique. Their chemical, structural characters, thermal
behavior, surface morphology, and ionic conductivity were studied using Fourier transform infrared spectroscopy, X-ray diffraction,
thermogravimetric/differential thermal analyzer, scanning electron microscopy, and AC impedance analyzer, respectively. A
maximum ionic conductivity value of 1.67 × 10−4 S/cm at 303 K is obtained for PVAc–PMMA–LiClO4 complexes in the ratio of 25 × 75, keeping LiClO4 constant as 10 wt.% among all the compositions studied. 相似文献
12.
New generalized formulas for calculation of thermal conductivity of aqueous solutions of binary and multicomponent inorganic
substances under high values of state parameters were derived. New values of thermal conductivity were calculated for aqueous
solutions of salts within the ranges of temperatures of 293–473 K. concentrations of 0–25 mass % and pressures P
s of 100 MPa. 相似文献
13.
A. E. Ramazanova S. N. Emirov 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(1):125-127
The effective thermal conductivity of rocks (siltstone and dolomite) at high pressures of up to 250 MPa and temperatures of
275–523 K is investigated. It is established that the degree of crystallization of rock-forming substances affects the temperature
dependence of thermal conductivity. The thermal conductivity of amorphous and crystalline components in the structure of rock
is calculated. 相似文献
14.
Popov P. A. Solomennik V. D. Lomonova E. E. Borik M. A. Myzina V. A. 《Physics of the Solid State》2012,54(3):658-661
The thermal conductivity of ZrO2−x
Y2O3 single crystals (x = 0.5, 1.5, 2.0, 2.5, 3.0, 8.0 mol %) has been studied experimentally in the temperature range 50–300 K. The influence of
high-temperature annealings on the thermal conductivity has been analyzed. 相似文献
15.
Kinetic regularities and mechanism of polymerization of perfluoromethylvinyl ether at high pressures
A. A. Zharov O. K. Nikolaeva 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(5):839-845
The kinetics of the thermal polymerization of perfluoromethylvinyl ether (PFMVE) is studied at pressures of 3–13 kbar (300–1300
MPa) and temperatures of 80–260°C. The activation energy (E
act = (76 ± 3) kJ/mol) and activation volume (ΔV0⪼ = −(27 ± 2) cm3/mol) for the overall polymerization rate are determined. The inhibition method is used to estimate the activation energy
of thermal initiation (E
in = (79.9 ± 3) kJ/mol). The quantity E
p
− (1/2)E
t
was calculated to be 36.6 ± 3 kJ/mol. The limiting polymerization temperature was evaluated: T
lim = (180 ± 3)°C. A mechanism of PFMVE polymerization is proposed on the assumption that the reaction is bimolecular. 相似文献
16.
A temperature-dependent hopping conduction was studied in lithium (Li)-doped zinc oxide (ZnO) in the temperature range 10–300 K.
Monodoping of Li in ZnO was made as suggested by the theory based on the first principle calculations. Li-doped ZnO films
were deposited both on glass and quartz substrates by pulsed laser deposition (PLD) in presence and absence of oxygen ambience.
The films were found to be p-type. It was found that whereas in the temperature range 10–40 K, variable range hopping resulted in Mott’s conductivity,
above 40 K, the conductivity was governed by the thermal assisted hopping. 相似文献
17.
A. M. Tereza V. G. Slutskii E. S. Severin 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(3):475-485
The delay time of ignition of various C2H4-O2-Ar mixtures behind reflected shock waves were measured at temperatures of 1090–1520 K and a pressure of 0.65 ± 0.05 MPa.
A kinetic scheme of the ignition of ethylene based on the known rate constants of the key elementary reactions was developed.
The scheme satisfactorily describes our own and published data on the ignition of ethylene in shock waves over wide ranges
of temperature (1100–2400 K), pressure (0.006–0.64 MPa) and ethylene (0.1–17.4 vol %) and oxygen (0.6–20.7 vol %) concentrations. 相似文献
18.
Awalendra K. Thakur 《Ionics》2011,17(2):109-120
We report substantial improvement in the mechanical stability, thermal stability, and conductivity of four series of ion-conducting
dispersed phase composite polymer electrolytes (CPEs). Tensile strength of filler-dispersed composite films was ≥2 MPa in
contrast to ~1 MPa for undispersed polymer–salt complex. Similarly, elongation at break has shown an increase by ~200–300%
in the composite films. Filler-induced enhancement in thermal and mechanical stability has clearly been noticed. The improvement
in the mechanical stability is also accompanied by a corresponding increase in electrical conductivity in the composite films
by 1–2 orders of magnitude at lower (2 wt.%) of the filler loading. A mechanism for the improvement in mechanical stability
has been proposed. The strength of the mechanism lies in evidenced polymer–filler interaction among the composite components.
Suppression of thermal degradation and increased mechanical strength of the CPEs on filler addition has been explained on
the basis of transient cross-linking of the polymeric segments and filler–polymer bridging effect. 相似文献
19.
F. F. Hatta M. Z. A. Yahya A. M. M. Ali R. H. Y. Subban M. K. Harun A. A. Mohamad 《Ionics》2005,11(5-6):418-422
A series of conducting thin-film solid electrolytes based on poly (vinyl alcohol)/ poly (vinyl pyrrolidone) (PVA/PVP) polymer
blend was prepared by the solution casting technique. PVA and PVP were mixed in various weight percent ratios and dissolved
in 20 ml of distilled water. The samples were analyzed by using impedance spectroscopy in the frequency range between 100
Hz and 1 MHz. The PVA/PVP system with a composition of 80% PVA and 20 wt.% PVP exhibits the highest conductivity of (2.2±1.4)
× 10−7 Scm−1. The highest conducting PVA/PVP blend was then further studied by adding different amounts of potassium hydroxide (KOH) ionic
dopant. Water has been used as solvent to prepare PVA/PVP-KOH based alkaline solid polymer blend electrolyte films. The conductivity
was enhanced to (1.5 ± 1.1) × 10−4 Scm−1 when 40 wt.% KOH was added.
Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 –
8, 2005. 相似文献
20.
Experimental data on the thermal conductivity K(T) of crystals of natural and highly enriched germanium (99.99%) 70Ge with lapped and polished surfaces are analyzed in the temperature range ∼1.5–8 K. In all the samples in the temperature
range ∼1.5–4 K the standard boundary mechanism of scattering dominates. As the temperature is raised, an isotopic scattering
mechanism is observed in the natural samples. In the highly enriched samples the theoretical values of K(T) turn out to be much smaller than the experimental ones. It is conjectured that a Poiseuille viscous flow regime of the phonon
gas emerges in this case.
Zh. éksp. Teor. Fiz. 114, 1757–1764 (November 1998) 相似文献