Liquid Saturation Density from Simple Equations of State

Several simple equations of state, requiring only two input properties, have been studied in order to determine the liquid saturation density of 144 fluids of different kinds. This study includes old and new simple modifications of the van der Waals equation of state, and the Carnahan–Starling–Yelash–Kraska and Carnahan–Starling–Dieterici equations. The new simple modifications of the van der Waals equation give better overall results than some other more complex proposed equations, especially near the critical point. The recent equation proposed by Eslami including the boiling temperature and density as input parameters was also checked, and was found not to reproduce the critical point, but to give excellent results at intermediate or low temperatures. As a reference, the behavior of the well-known Soave– Redlich–Kwong and Peng–Robinson equations, and the more recent expression proposed by Mohsen-Nia et al. that requires three input parameters were also checked. The latter does not improve the accuracy of the Peng–Robinson equation, and very simple van-der-Waals type equations give better overall results.     

混合制冷剂饱和气体密度的推算

在对比态原则下,作者发现混合工质饱和气体密度与其纯组分饱和气体密度的无量纲对比关系有同一化规律;同时,还寻找到利用纯组分的临界点密度与临界压力拟合混合工质临界点密度与临界压力的关系式,确立了混合工质的这两个特征参数。进而给出了计算混合制冷剂饱和气体密度的通用方程,该方程是隐式的。比较了文献中5种二元和三元混合工质的推算值与文献值,误差基本在±2%内。     

湿空气饱和水蒸气压与温度关系式的选用

本文比较了-30℃至65℃湿空气饱和水蒸气压与温度的各个关系式以及露点温度与水蒸气分压力各关系式的精度,供空调有关工作者选用.     

湿空气饱和水蒸气压力与温度关系式的改进与应用

比较了-30～65℃湿空气饱和水蒸气压力与温度的各个关系式,以及露点温度与水蒸气分压力各关系式的精度,举例说明了这些关系式的应用.     

Density of Liquid Ni-Cr Alloy

The density of liquid Ni-Cr alloy was measured by a modified sessile drop methold.The density of liquid Ni-Cr alloy was found to decrease with increasing temperature and Cr concentration in the alloy,The molar volume of liquid Ni-Cr alloy increases with increasing the Cr concentration in the alloy ,The molar volume of Ni-Cr alloy determined in the present work shows a positive deviation from the linear molar volume.     

除湿溶液蒸汽压的研究

除湿溶液表面蒸汽压的大小直接影响液体除湿空调系统的性能,在常用的除湿剂中由于氯化钙的价格低廉,是一种比较经济的除湿剂,但它的缺点是蒸气压比较高,除湿效果不稳定,而氯化锂的价格高,水蒸气压较低且稳定,是一种性能非常优良的除湿剂.为了提高除湿溶液的除湿性能和降低其价格,可以把两种除湿剂按不同的比例进行混合,就可以得到性价比比较好的除湿溶液.文中应用经典热力学理论研究了常用除湿溶液表面蒸汽压的形成机理.对氯化钙、氯化锂及其混合溶液表面蒸汽压进行了计算,计算结果和实验结果非常接近,认为该方法可以用来较准确的估算各类除湿溶液的蒸汽压,为液体除湿空调系统中除湿剂的选择提供理论依据.     

A Float-Type Liquid Density and Viscosity Sensor

A primary transducer is described for the density and viscosity of a liquid, which employs a ferromagnetic float and oscillates vertically in response to an alternating magnetic force. The viscosity and density are determined from the times taken for the float to rise and fall a set distance.     

Density and Thermal Expansion of Liquid Au-Cu Alloys

The density of liquid Cu-Au alloys is measured using the technique of electromagnetic levitation, which entails producing a shadow image of the sample. The shadow is recorded by a digital CCD-camera, and the volume of the sample is calculated by an image processing algorithm. The density and thermal expansion of several alloys and the pure elements copper and gold are investigated at various temperatures above their melting points. In addition, the densities are also investigated as a function of the gold concentration at constant temperature. The measured values agree with literature data and with predictions obtained by molecular dynamics. It was found from data analysis that the ideal solution model applies.     

Viscosity and Liquid Density of Asymmetric Hydrocarbon Mixtures

Although a large body of viscosity data exists for simple mixtures of lighter n-alkanes, available information for heavy or asymmetric systems is scarce. Experimental measurements of viscosity and liquid densities were performed, at atmospheric pressure, in pure and mixed n-heptane, n-hexadecane, n-eicosane, n-docosane, and n-tetracosane from 293.15 K, or above the melting point, up to 343.15 K. The measured densities were correlated using the Peng–Robinson equation of state, and viscosities were modelled using the friction theory.     

The Relationship between Covering Power at Saturation Density and Undeveloped Grain Size

Experimental values of covering power at diffuse saturation density of a range of commercial emulsions an energetic chemical development are compared with those expected on the basis of the Nutting expression for density. employing in the latter the grain-size characteristics of the undeveloped emulsions. For the size range investigated (0.07 to 2µ²) there is reasonable prediction of the variation of covering power with grain size, but the predicted values are too small. Apparently the average ratio of effective developed mean grain projective area to undeveloped mean area is about 2-6, this factor decreasing at a significant rate with increasing grain size. This ratio represents the product of two factors: the increase in geometric area of grains as a result of the development process, and the effective increase in size owing to light-scatter effects within the layer. Experimental observations indicate that the factorial increase of projective area on energetic chemical development is about 1-3 times. In turn this means that the factorial increase in effective size owing to light-scatter effects within the layer must be about 2-6/1-3, or twice.     

浅谈液体密度检测技术

文章介绍了液体密度检测中的误差及解决办法.     

Simultaneous Measurement of the Density and Viscosity of Compressed Liquid Toluene

A vibrating-wire densimeter described previously has been used to perform simultaneous measurements of the density and viscosity of toluene at temperatures from 222 to 348 K and pressures up to 80 MPa. The density measurements are essentially based on the hydrostatic weighing principle, using a vibrating-wire device operated in forced mode of oscillation, as a sensor of the apparent weight of a cylindrical sinker immersed in the test fluid. The resonance characteristics for the transverse oscillations of the wire, which is also immersed in the fluid, are described by a rigorous theoretical model, which includes both the buoyancy and the hydrodynamic effects, owing to the presence of the fluid, on the wire motion. It is thus possible, from the working equations, to determine simultaneously, both the density and the viscosity of the fluid from the analysis of the resonance curve of the wire oscillation, the density being related essentially to the position of the maximum and the viscosity to its width. New results of measurements of the density and viscosity of toluene in the compressed liquid region are presented, and compared with literature data. The density results extend over a temperature range 222 KT348 K, and pressures up to 80 MPa. The viscosity results cover a temperature range of 248 KT348 K and pressures up to 80 MPa. The uncertainty of the present density data is estimated to be within ±0.1% at temperatures 298 KT350 K, and ±0.15% at 222 KT273 K. The corresponding overall uncertainty of the viscosity measurements is estimated to be ±2% for temperatures 298 KT350 K, and ±3% for 248 KT273 K.     

Density Measurement of Liquid Metals Using Dilatometer

The dilatometer method for density measurement of liquid metals was improved to give a high measurement accuracy with simple operation. The density of liquid tin was measured and the results are in agreement with values in literature. The melting point density of liquid Sn was measured to be 6.966×103 Kg·m-3 and the temperature (T) dependence of the density (ρ) for liquid Sn can be well described by a polynomial equation ρ(T)=7.406 - 9.94 × 10-4T 2.12 × 10-7T2.     

Vortex Line Density Fluctuations of Quantum Turbulence

We investigate vortex line density fluctuations of quantum turbulence generated by an oscillating grid in superfluid ³He-B. The scenario of quantum turbulence experimentally suggested by the Lancaster group is confirmed in the numerical simulation. The spectrum of the vortex line density fluctuations with respect to frequency obeyed a ?5/3 power law, which is consistent with the experiment of the Lancaster group. Based on the argument of time scales experienced by vortex rings with different sizes and on the power spectrum, the connection between the self-similar structure of the vortex tangle and the power spectrum is discussed.     

输电线路电晕放电液体的荷电情况

导线电晕放电会引起能量损失、无线电干扰、可听噪声等危害。本文实验研究了气液两相体放电中液体的荷电情况。测量表明在气液混合两相体直流电晕放电中液滴的荷电极性随水雾位置的不同而不同,水雾靠近正电极的时候,液滴荷正电荷,水雾靠近负电极的时候,液滴荷负电荷。     

支撑共振法测量液体密度的研究

采用支撑共振法测量材料杨氏模量的实验装置,由分离变量法近似求解内部含液体管状材料横振动Housner方程,得到管状材料内部液体密度计算公式。通过实验测量并计算了蒸馏水及不同浓度蔗糖溶液的密度值,得到的实验值与理论值之间的相对误差在正常误差范围3%以内。     

密度补偿式液位检测系统的调试

描述了核电及核化工中密闭容器内介质密度变化时的液位测量原理、安装要求、仪表组态、调试数据和方法。使该项难度较大的调试工作有了切实可行的操作性。