共查询到20条相似文献,搜索用时 15 毫秒
1.
The viscosity of liquid carbon dioxide 总被引:1,自引:0,他引:1
The viscosity coellicient of carbon dioxide in the liquid phase has been measured by means of a vibrating-wire viscometer at temperatures of 220, 230, 240, 2411, 260, and 380 K. The measurements extended beyond both phase transition lines into the coexistence region (superheated liquid) and into the solid range (undercooled liquid). At 3811 K. the measurements extended only to 3511 MPa since no density data are available for high pressures. The accuracy of the measurements is estimated to be I % The agreement with the data of Ulybin and Makarushkin is rather good, but our values are in general a few percent lower than those of Diller and Ball. The results show, for the most part, a linear pressure dependence for the various isotherms, with a common intersection with the negative pressure axis of 113.7 MPa. The fluidity, the reciprocal of the viscosity, shows a linear dependence of the molar volume in adjacent density ranges. After reduction of the molar volume with the volumes of close packing, two sets of linear functions result, with common intersections of the axis forV/V
0=1.31 andV/V
0=1.40.Paper presented at file Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A. 相似文献
2.
The shear viscosity coefficients of compressed gaseous and liquid carbon dioxide hav been measured with the torsional piezoelectric crystal method at temperatures between 220 and 320 K and at pressures to 30 MPa. The dependencies of the viscosity on pressure, density, and temperature and the dependencies of the fluidity (inverse viscosity) on molar volume and temperature have been examined. The measurements on the compressed liquid were correlated with a modified Hildebrand equation.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A. 相似文献
3.
The paper reports new masurements of the viscosity of liquid carbon dioxide along three isotherms at 260, 280, and 300 K for pressures up to 100 MPa. The measurements have been carried out in a vibrating-wire viscometer and have an estimated accuracy of ±0.5%. The results are employed to distinguish between conflicting data sets that already exist in the literature and that have inhibited accurate representations of the viscosity of this important fluid. It is shown that the experimental results can be represented with a high precision by means of procedures founded on the hard-sphere theory of liquids, although the observed density dependence of the viscosity is different from that characteristic of hydrocarbons. 相似文献
4.
The shear viscosity coefficients of saturated and compressed liquid normal butane and isobutane have been measured with the torsional piezoelectric crystal method at temperatures beween 115 and 300 K and at pressures to 30 MPa. The measurements have been correlated with a modified Hildebrand equation. The experimental error is estimated to be smaller than 3%. The measurements of normal butane and isobutane have been compared with a global extended corresponding states model and with each other. Differences between measured and calculated viscosities are discussed. 相似文献
5.
A new automated adiabatic flow calorimeter was developed which enables one to measure the isobaric heat capacity, C
p, of pure fluids and their mixtures in the liquid phase. The calorimeter has been carefully designed to keep the heat loss from the sample fluid as small as possible being regarded as negligible. The experimental apparatus constitutes a closed circuit of the sample circulation using a combination of two mounted metallic bellows and a metering pump. The present apparatus is designed to measure C
p at temperatures to 500 K and pressures to 15 MPa and is also applicable to measurements in the critical region as well as the region near the saturated liquid state because of its excellent mass flow rate control stability and the high adiabatic efficiency of the calorimeter. The C
p of liquid refrigerant 114 (R114) has been measured at temperatures from 275 to 415 K and pressures up to 3.2 MPa including the critical region with experimental uncertainty of less than ±0.4%. The heat capacity of saturated liquid R114 has also been derived from the data measured in the single phase.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A. 相似文献
6.
Measurement methods and instruments for the saturated vapor pressure (SVP) in the standards described are analyzed. Results
are given for work on metrological provisions in the field of SVP measurement including creation of a standard device and
standard specimens for the absolute pressure of saturated vapors in oil products.
__________
Translated from Izmeritel’naya Tekhnika, No. 3, pp. 42–45, March, 2006. 相似文献
7.
T. J. Bruno 《International Journal of Thermophysics》1987,8(2):205-216
The fugacity coefficients of hydrogen in binary mixtures with carbon dioxide were measured isothermally using a physical equilibrium technique. This technique involves the use of an experimental chamber which is divided into two regions by a semipermeable membrane. Hydrogen can penetrate and pass through the membrane, while carbon dioxide cannot. During the approach to equilibrium, the pressure of pure hydrogen on one side of the membrane approaches the partial pressure of hydrogen in the mixture on the other side of the membrane. This allows a direct measurement of the hydrogen component fugacity at a given mixture mole fraction. In this study, results are reported for measurements made on the hydrogen + carbon dioxide binary at 130°C (403 K), with total mixture pressure of 3.45, 5.17, 8.62, 10.34, and 13.79 MPa. General trends in the experimental results are discussed, and comparisons are made with predictions from the Redlich-Kwong, Peng-Robinson, and extended corresponding-states models. 相似文献
8.
Presented here is an investigation into the solvent properties of liquid carbon dioxide by means of FT-IR spectroscopy. A high-pressure, circulation-type apparatus was designed and built specifically for this study. The spectra for the combination bands for carbon dioxide show that there are interactions between methanol and carbon dioxide. However, the spectra of the fundamental O-D vibration of deuterated methanol in liquid carbon dioxide indicate that there is no hydrogen bonding. Therefore. we conclude that the interactions between carbon dioxide and methanol are Lewis acid-base interactions rather than hydrogen bonding. This conclusion is supported by experiments where acetone is introduced into the CO2/methanol-d binary system. FT-IR measurements show that acetone hydrogen bonds with deuterated methanol.Paper presented at the Twelfth Symposium on Thermophysical Properties, June 19–24, 1994, Boulder, Colorado, U.S.A. 相似文献
9.
Comprehensive isochoric (p, v, T) measurements have been obtained for (0.98 CO2+0.02 CH4) at densities from 1 to 26mol·dm–3. Supplemental isochoric (p, v, T) measurements have been obtained for high-purity CO2 at densities from 12 to 24 mol·dm–3. Measurements of p(T) cover a broad range of temperature, 225 to 400 K, at pressures to 35 MPa. Comparisons have been made with independent sources and with a predictive method based on corresponding states. 相似文献
10.
M. M. Aliev J. W. Magee I. M. Abdulagatov 《International Journal of Thermophysics》2003,24(6):1527-1549
Volumetric (PVT) and calorimetric (C
V
VT) properties of pure methanol were measured in the liquid phase with a twin-cell adiabatic calorimeter. Temperatures were measured in a range from 314 to 411 K, densities between 699.3 and 775.6 kgm–3, and pressures to 20 MPa. The calorimetric cell (70 cm3 capacity) was surrounded by adiabatic thermal shielding (high vacuum). The sample pressures were measured by means of a quartz crystal transducer to within an uncertainty of about ±7 kPa. The relative uncertainty of C
V
was estimated to be 2%, with a coverage factor k = 2, by combining the various sources of experimental uncertainty using a root-sum-of-squares formula. The results for pure methanol were compared with other recent measurements performed with a second high-temperature, high-pressure adiabatic calorimeter. Deviations of less than 3% were found between the earlier C
V
data and the present results for pure methanol. The uncertainty of the density measurements was estimated to be 0.2% (k = 2). The measured densities and isochoric heat capacities were compared with values calculated with an IUPAC equation of state. Agreement of density was within 0.088% and that for isochoric heat capacity was within 0.95%. Values of vapor pressure were determined by extrapolating experimental P–T data to the saturated temperature along a fixed isochore. In the temperature range of this study, decomposition of methanol was not observed. 相似文献
11.
The calculations of gas solubilities in supercritical solvents require equations of state remaining accurate in the critical range, which are difficult to obtain with classical models. In this work, the Helmholtz energy of a mixture is considered as the sum of the Helmholtz energies of pure components taken at a constant packing fraction and of a residual term which may have the form of a RedlichKister, Van Laar, NRTL, UNIQUAC, or UNIFAC function. Thus it is possible to assign to a given component an equation of state whose form is different from that of the others. This model has been applied to binary systems containing supercritical carbon dioxide. The results are improved with respect to those obtained with the classical model for vapor-liquid equilibria and for volumetric properties. 相似文献
12.
13.
The use of a general correlation, proposed for organic liquid thermal conductivity λ prediction and checked in the case of organic refrigerant fluids, is extended to inorganic refrigerant fluids whose λ decreases when the reduced temperature, Tr, increases. Suggestions are given for the refrigerants fluids whose λ increases with the reduced temperature. 相似文献
14.
The shear viscosities of saturated and compressed fluid 1-chloro-l,2,2,2-tetrafluoroethane (R124) and pentafluoroethane (R125) have been measured with two torsional crystal viscometers at temperatures between 120 and 420 K and at pressures up to 50 MPa. At small molar volumes, the fluidity (reciprocal viscosity) increases linearly with molar volume at fixed temperature and weakly with temperature at fixed volume. We have described this behavior with simple empirical equations and have compared the data of Shankland and of Ripple with them. The data of Ripple are in good agreement with our data for both fluids. 相似文献
15.
J. Steinbeck G. Dresselhaus M. S. Dresselhaus 《International Journal of Thermophysics》1990,11(4):789-796
A model for the transport properties of liquid carbon based on Ziman liquid metal theory with refinements for polyvalent liquid metals and Fermi surface blurring is applied to calculate the electrical resistivity of liquid carbon at the melting temperature. The thermal and electrical properties predicted by the model are compared to experimental results using numerical heat flow calculations and found to be in good agreement with pulsed-current heating experiments on the resistivity of carbon fibers.Paper presented at the First Workshop on Subsecond Thermophysics, June 20–21, 1988, Gaithersburg, Maryland, U.S.A. 相似文献
16.
Thermal radiation calorimetry has been applied to measure the thermal conductivity and the specific heat capacity of an isolated solid specimen simultaneously. 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, is presented. A theoretical formulation of the simultaneous measurement at quasi-steady state is described in detail. Noncontact temperature measurement of both specimen surfaces has been performed using pyrometers and a thermocouple set in the gap between the heater and the specimen. Pyroceram 9609 specimens, whose surfaces were blackened with colloidal graphite, were used in the measurement. The largest error involved in the noncontact temperature measurement is ±2°C in the range from 450 to 650°C. The resultant values of the specific heat capacity and the thermal conductivity deviate by about 10% from the recommended values for the Pyroceram specimen. 相似文献
17.
家用二氧化碳热泵热水器跨临界系统压力安全设计概要 总被引:1,自引:0,他引:1
黄逊青 《制冷与空调(北京)》2009,9(4):48-52,44
讨论采用跨临界二氧化碳家用热泵热水器制冷系统的压力安全特性,根据ISO/CD5149.2:2007的规定,简要归纳压力安全设计要求,包括设计压力确定、结构要求、强度试验、安全措施以及保护装置设置等。 相似文献
18.
19.
在负载双金属PBM型催化剂下,以二氧化碳(CO2),环氧丙烷(PO)和马来酸酐(MA)为原料,三元共聚反应合成了聚碳酸亚丙酯马来酸酐(PPCMA).采用FTIR、1H-NMR、13C-NMR、DSC等对PPCMA进行了表征.结果表明,产物中引入了马来酸酐单元且共聚过程中不发生双键交联和构型转化;同时,马来酸酐单元的引入有效地提高了聚合物的特性粘数[η],玻璃化转变温度T g以及热稳定性;且增强了材料的降解性;不同的聚合反应时间对PPCMA的特性粘数和粘均分子量有着明显的影响. 相似文献
20.
建立了跨临界二氧化碳热泵热水系统中的气体冷却器模型,对管内二氧化碳和水侧的流动和传热进行了数值仿真;并运用该模型分析了系统运行时各有关参数对换热器性能的影响,并结合最优排气压力,研究使系统高效运行的方法,为气冷器的优化设计提供了基础。 相似文献