共查询到19条相似文献,搜索用时 62 毫秒
1.
异丁烷的饱和蒸汽压方程及饱和液体密度方程研究 总被引:4,自引:0,他引:4
1引言臭氧层正以惊人的速度被破坏,但在世界范围内CFC和HCFC用于制冷系统尤其是冰箱的量仍然很高,为了保护环境,迫切需要寻找新的更好的制冷剂。人们在寻找新的性能优良而又无公害制冷剂的过程中,意识到了碳氢化合物的价值。联合国环境规划署制冷技术评估小组称其为“长期的、经得起考验的制冷剂’巾]。本文对其中的异丁烷进行了研究,在分析比较的基础上,给出了异丁烷的新饱和蒸汽压方程和炮和液体密度方程,为进一步研究异丁烷的统一热物性方程提供了条件。2异丁烷的饱和蒸汽压方程2.1常用饱和蒸汽压方程的比较分析表1列出了常… 相似文献
2.
比较和分析了弯曲液面饱和蒸气压公式的两种推导方法,探讨了两种方法的区别和关联,指出它们在研究相平衡问题时原理上的一致性. 相似文献
3.
4.
5.
6.
发展了一种新型相位共轭干涉法可用于简单方面地测定介质三次非线性极化率的相位。文中用这种方法研究了二种染料掺杂高分子膜X^(3)的相位,发现由饱和吸收效应产生的X^(3)的相位,当波长远离吸收峰时,由-π/2趋于-π,而由光到漂白效应产生的X^(3)的相位都落在-17/18π附近。 相似文献
7.
8.
9.
10.
11.
碱金属气室是基于原子无自旋交换碰撞弛豫的超高灵敏惯性和磁场测量装置的核心敏感器件。碱金属气室内气体的含量会对原子的弛豫以及系统其他参数的选取产生很大的影响,因此精密测量气室内混合气体各自的压强具有重要的意义。当气室内存在气体时谱线会出现压力展宽和频移,且压力展宽远大于自然展宽和多普勒展宽,因此仅考虑压力展宽。利用压力展宽、频移的大小与气体压强存在的函数关系,提出一种基于原子吸收光谱的碱金属气室内多种混合气体压强测量方法。通过扫描碱金属原子的吸收光谱,得到光学深度曲线,并用洛伦兹函数对其拟合,测得多种混合气体引起的单种碱金属原子的混叠压力展宽和频移,再根据已知的单种、单位压强气体引起的单种碱金属原子的压力展宽和频移,联立计算得到多种气体各自的压强。当存在n种碱金属时,最多可以测量4n种混合气体的压强。仿真结果表明,该方法适用于入射激光未被原子完全吸收的情况;激光功率和频率的波动在1%~10%的数量级时,测量精度影响低于0.4%的数量级,而温度波动在1%~10%的数量级时,测量精度影响高达30%的数量级。 相似文献
12.
Liquids can be supercooled below their melting temperature Tm or pressurized above their melting pressure Pm. Many authors relate the maximum degree of supercooling—or overpressurization—to a value of the liquid–solid interfacial tension by using the standard theory of nucleation. The main goal of this review is to examine whether this relation is justified or not. We consider general arguments and two main examples: liquid helium which is simple and pure, consequently a model system, and liquid water which is complex but ubiquitous. To cite this article: S. Balibar, F. Caupin, C. R. Physique 7 (2006). 相似文献
13.
In this paper we extend the conventional theory of nucleation to take in the effects of excluded-volume interference between the precritical droplets present prior to phase transformation. It is shown that, close to the critical point, the effect of excluded volume is to cause a sizable increase in the surface free energy of the critical nucleus. A corresponding increase in the barrier to nucleation explains the large undercoolings achieveable experimentally in this region. Our results are compared with recent experimental measurements of Heady and Cahn and favorable agreement is found.Supported in part by National Science Foundation Grant NSF CHE 76-21297. 相似文献
14.
Tamara Basova Petr Semyannikov Vladimir Plyashkevich Aseel Hassan Igor Igumenov 《固体与材料科学评论》2009,34(3-4):180-189
The current review summarizes the data of saturated vapor pressure and thermodynamic parameters of the sublimation process of different phthalocyanines as reported in the literature as well as in our work. The volatility of phthalocyanines is analyzed from the standpoint of their molecular and crystal structure. The differences in the saturated vapor pressure value of the investigated phthalocyanines may reach some orders of magnitude and are determined by the Van der Waals and electrostatic interaction of the peripheral atoms of adjacent molecules, as well as to a specific interaction, the type and number of which depend on the type of molecules packing in the crystal. 相似文献
15.
Nucleation of liquid precipitates in semi-insulating GaAs is accompanied by deviatoric stresses resulting from the liquid/solid misfit. A competition of surface tension and stress deviators at the interface determines the nucleation barrier.The evolution of liquid precipitates in semi-insulating GaAs is due to diffusional processes in the vicinity of the droplet. The diffusion flux results from a competition of chemical and mechanical driving forces.The size distribution of the precipitates is determined by a Becker--Dö-ring system. The study of its properties in the presence of deviatoric stresses is the subject of this study. The main tasks of this study are: (i) We propose a new Becker/Döring model that takes thermomechanical coupling into account. (ii) We compare the current model with already existing models from the literature. Irrespective of the incorporation of mechanical stresses, the various models differ due to different environments where the evolution of precipitates takes place. (iii) We determine the structure of equilibrium solutions according to the Becker/Döring model, and we compare these solutions with those that result from equilibrium thermodynamics. 相似文献
16.
The formation of nuclei from a supersaturated vapor on a surface with active centers is treated within standard self-consistent classical model with exhaustion of active centers. Basic characteristics of nucleation process (total number of nuclei, nucleation rate, time lag and size distribution of nuclei) are determined by numerical solution of kinetic equations. It is shown that standard approach to nucleation on active centers based on Avrami model coincides with our approach in the values of time lag of nucleation process, but it differs in the total number of nuclei. 相似文献
17.
水汽多线光声光谱中压力线位移及加宽系数的分析 总被引:1,自引:1,他引:0
本工作从水汽的多线光声光谱中分析得到压力线位移和加宽系数。为了提高系数的精度和拟合效率,采用了Voigt线型和参数分组约束优化方法。 相似文献
18.