共查询到20条相似文献,搜索用时 140 毫秒
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1-羟乙基-3-甲基咪唑氯盐([HOEtMIM][Cl])是一种亲水性极强的离子液体,与水可以组成吸收式制冷工质对,具有良好的工业应用前景.在制冷工程应用中,离子液体水溶液的低温特性研究非常重要,包括低温段的水溶液蒸汽压数据和凝固特性,而[HOEtMIM][Cl]的相关研究缺乏.本文对水的质量分数分别为17.10%、24.29%、38.03%、49.89%、69.94%,温度范围(278.15K~408.15K)的[HOEtMIM][Cl]水溶液的汽液相平衡进行了测定;并对水的质量分数范围为1.3%~90.0%,温度范围为150K~360K的离子液体水溶液的凝固特性进行了测定,揭示其在低温应用时可能出现的固化问题.获得的蒸汽压及凝固特性数据对该离子液体水溶液应用于制冷系统设计具有重要意义. 相似文献
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本文选择含离子液体体系TFE-[BMIm][Br]作为吸收式制冷循环的工质体系,基于文献数据给出了计算TFE-[BMIm][Br]热物性模型,建立并联双效吸收式制冷循环的模拟程序,分别考察了四种双效并联制冷流程中溶液换热器的热交换效率、蒸发温度、吸收温度以及发生温度对系统性能、溶液循环倍率以及系统操作压力的影响.探索新工质对TFE-[BMIm][Br]的可行性,确定了TFE-[BMIm][Br]双效并联吸收式制冷循环的适宜的运行操作范围以及适宜的流程方案. 相似文献
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本文通过实验研究,测定在一定温度范围内,离子液体[EMIm]Ac及摩尔分数分别为0.8、0.6、0.4和0.2的[EMIm]Ac水溶液的比热容、导热系数及黏度。实验结果表明:比热容和黏度受温度影响较大,比热容随温度升高而增大;黏度随温度升高而急剧减小;导热系数受温度影响较小;添加水后,随着水含量的增加即水溶液摩尔分数的减小,比热容增大,相比于纯离子液体,比热容最高增加70%;导热系数最高增加35%;其黏度急剧减小,最高减小82%。本文的研究结果为[EMIm]Ac及其水溶液在吸收式制冷方面的应用研究提供了可靠的数据。 相似文献
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V. V. Cheverda I. V. Marchuk A. L. Karchevsky E. V. Orlik O. A. Kabov 《Thermophysics and Aeromechanics》2016,23(3):415-420
Heat transfer at rivulet water flow over the constantan foil with the length of 80 mm, width of 35 mm, and thickness of 25 mm was studied experimentally. The foil surface temperature was measured by an IR-scanner. Distributions of heat flux density on the surface of the foil, where the liquid flowed, were obtained. To determine the heat flux density from the foil to liquid near the contact line, the Cauchy problem was solved for the stationary heat equation using the thermographic data. Calculation results showed that the maximal heat flux occurs in the area of the contact line and exceeds the average heat flux from the entire foil surface by several times. This is explained by the influx of heat from the periphery of foil to the rivulet due to the relatively high value of heat conductivity coefficient of the foil material and high evaporation rate in the region of the contact line. 相似文献
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V. V. Cheverda A. L. Karchevsky I. V. Marchuk O. A. Kabov 《Thermophysics and Aeromechanics》2017,24(5):803-806
The evaporating water droplets on a horizontal heated substrate were experimentally studied. The constantan foil 25 μm thick with a size of 42×35 mm2 was used as a substrate. The experiments were carried out with a single droplet or with an ensemble of two or three droplets on the foil. The temperature of the lower surface of foil was measured by an IR scanner. To determine the heat flux density at evaporation of liquid near the contact line, the Cauchy problem for the heat conduction equation was solved using the thermographic data. The results of calculations showed that the maximal heat flux density takes place in the region of the contact line and exceeds the average heat flux density from the entire surface of foil. This is explained by the heat inflow from the foil periphery to the droplet due to relatively high value of the coefficient of heat conductivity of the foil material and high evaporation intensity in the contact line region. 相似文献
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A. N. Pavlenko V. P. Koverda A. V. Reshetnikov A. S. Surtaev A. N. Tsoi N. A. Mazheiko K. A. Busov V. N. Skokov 《Journal of Engineering Thermophysics》2013,22(3):174-193
This paper represents results on investigating the dynamics of boiling and disintegration of superheated liquid films and jets. The first part deals with experimental study of boiling liquid outflow through short cylindrical and slit channels. Evolution of disintegration of a hot water jet flow is observed both at low and moderate superheating and at high and limit superheating, and also for vaporization mechanisms corresponding to these superheatings. Peculiarities of disintegration of jets through slit and cylindrical channels are noticed. Results on measuring the reactive thrust of the jet through a slit channel under different geometrical conditions behind the channel outlet are represented. The 1/f fluctuations in transient regimes of superheated liquid boiling and in transient regimes of behavior of the jet shape are found. The second part of this article represents results on experimental investigation of nonsteady heat transfer and dynamics of the development of crisis phenomena at boiling of a falling subcooled liquid film in the conditions of stepwise heat release. The experimental data were obtained using synchronized high-speed infrared thermography and video. It is shown that with growth and condensation of vapor bubbles, on the liquid film interface appear large-amplitude waves that lead to considerably increasing local intensity of heat transfer. New data on the boiling incipience temperature in a subcooled liquid film, depending on the heat flux density, are obtained. It is found that the development of boiling crisis is a result of appearance of local dry patches and their subsequent growth by the mechanism of longitudinal thermal conductivity in the heat transfer wall as the equilibrium heat flux density is exceeded. 相似文献
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New laser flash technique for the measurement of heat transfer coefficients of liquid metals is presented. The thermal diffusivity
of the liquid mercury has been studied experimentally over the room temperature range. The thermal conductivity coefficient
has been calculated with the use of the reference data on density and heat capacity. Analysis of systematic errors of the
measurements has shown that the data error is about 3%. Comparison of the obtained results with data available in publications
has proved their reliability. 相似文献
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Chunyi Zhi Yoshio Bando Chengchun Tang Dmitri Golberg 《Solid State Communications》2011,151(2):183-186
We report on the basic physical quantities of boron nitride nanotubes (BNNTs), namely specific heat capacity and density, which have not been measured to date. A series of differential scanning calorimetry experiments were performed, and specific heat capacity was calculated for multi-walled BNNTs synthesized by chemical vapor deposition using boron and metal oxide as precursor. Very close specific heat capacity values were revealed for BNNTs and a BN powder of hexagonal (h-BN) phase. Densities of BNNTs were measured through density analyses of their epoxy composites. Our work is important as far as bulk properties of large amounts of BNNTs are crucial, for example, thermal property and density prediction for composite materials with BNNTs embedded. 相似文献
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D.J. Adams 《Molecular physics》2013,111(3):647-657
A combination of canonical and grand-canonical ensemble Monte Carlo calculations, together with the virial expansion, have been used to calculate the thermodynamic properties of the liquid/vapour co-existence curve of the (6 : 12) Lennard-Jones fluid for reduced temperatures, [Ttilde] ? 1·1. The results for the liquid density and energy and the latent heat of vaporization are believed to be precise, with the exception of the point at [Ttilde]=1·1 which may lie outside the range of the function fitting the liquid phase Monte Carlo data. The liquid density and the saturated vapour pressure are in very good agreement with the results of perturbation theory. The latent heat of vaporization does not agree well with the experimental data for argon though the fit to liquid density and internal energy is good. 相似文献
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J.T. Schriempf 《Solid State Communications》1973,13(6):651-653
The thermal diffusivity of liquid gallium was measured by the laser flash technique at temperatures from 45 to 512° C. By using values from the literature for the specific heat, density, and electrical conductivity, the present measurements were found to be in reasonable agreement with a temperature-independent Lorenz ratio equal to the Sommerfeld value. 相似文献
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A. N. Pavlenko E. A. Tairov V. E. Zhukov A. A. Levin A. N. Tsoi 《Journal of Engineering Thermophysics》2011,20(4):380-406
The paper presents results on experimentally investigated dynamics of boiling development and formation of film boiling zones
under stepwise heat generation on a horizontally and vertically oriented cylindrical surface in a large volume of Freon-21.
Experimental data on the expectation time and boiling temperature, the propagation velocity and structure of evaporation and
boiling fronts for different heat flux density both in saturated liquid and in subcooling conditions are obtained. Results
of experiments on investigating the nucleation forms under development of nonstationary heat release crisis caused by heat
loading on the vertical heater immersed into the volume of liquid (water, ethanol) subcooled to saturation temperature are
presented. A calculation ratio for determining the expectation time to the beginning of intense vaporization in water is proposed
and compared with experimental data obtained on surfaces with different-size roughness. Peculiarities of evolution of evaporation
fronts from incipient bubbles are investigated in the experiments with ethanol. Data on the evaporation front velocity as
a function of wall overheating are obtained. The obtained experimental data on the propagation velocity of self-sustained
evaporation fronts are compared with the known calculated data. 相似文献