scholarly journals Density Measurements of an Air-Like Binary Mixture over the Temperature Range from 100 K to 298.15 K at Pressures up to 8.0 MPa

2021 ◽  
Vol 42 (9) ◽  
Author(s):  
Nils von Preetzmann ◽  
Reiner Kleinrahm ◽  
Philipp Eckmann ◽  
Giuseppe Cavuoto ◽  
Markus Richter
Keyword(s):  
Binary Mixture ◽  
Saturated Vapor ◽  
Saturation Pressure ◽  
Transmission Error ◽  
Magnetic Suspension ◽  
Mixture Component ◽  
Liquid Region ◽  
Force Transmission ◽  
Temperature Range ◽  
Combined Uncertainty

AbstractDensities of an air-like binary mixture (0.2094 oxygen + 0.7906 nitrogen, mole fractions) were measured along six isotherms over the temperature range from 100 K to 298.15 K at pressures up to 8.0 MPa, using a low-temperature single-sinker magnetic suspension densimeter. The measurements were carried out at T = (100, 115, and 130) K in the homogeneous gas and liquid region, and at T = (145, 220, and 298.15) K in the supercritical region (critical temperature TC = 132.35 K); in total, we present results for 52 (T, p) state points. The relative expanded combined uncertainty (k = 2) of the experimental densities was estimated to be between 0.03 % and 0.13 %, except for four values near the critical point. The largest error is caused by the magnetic suspension coupling in combination with the mixture component oxygen, which is strongly paramagnetic; the resulting force transmission error is up to 1.1 %. However, this error can be corrected with a proven correction model to an uncertainty contribution in density of less than 0.044 %. Due to a supercritical liquefaction procedure and the integration of a special VLE-cell, it was possible to measure densities in the homogeneous liquid phase without changing the composition of the liquefied mixture. Moreover, saturated liquid and saturated vapor densities were determined at T = (100, 115, and 130) K by extrapolation of the experimental single-phase densities to the saturation pressure. The new experimental results were compared with the mixture model of Lemmon et al. for the system (nitrogen + argon + oxygen) and the GERG-2008 equation of state.

Force Transmission Error Analysis for a High-Pressure Single-Sinker Magnetic Suspension Densimeter

2010 ◽  
Vol 31 (4-5) ◽  
pp. 698-709 ◽  
Author(s):  
Diego E. Cristancho ◽  
Ivan D. Mantilla ◽  
Saquib Ejaz ◽  
Kenneth R. Hall ◽  
Gustavo A. Iglesias-Silva ◽  
...  
Keyword(s):  
High Pressure ◽  
Error Analysis ◽  
Transmission Error ◽  
Magnetic Suspension ◽  
Force Transmission

Influence of Nano-Refrigeration-Oil on Saturated Vapor Pressure of R22

2011 ◽  
Vol 694 ◽  
pp. 309-314 ◽  
Author(s):  
Jiang Feng Lou ◽  
Rui Xiang Wang ◽  
Min Zhang
Keyword(s):  
Experimental Data ◽  
Vapor Pressure ◽  
Mass Fraction ◽  
Saturated Vapor Pressure ◽  
Saturated Vapor ◽  
Experimental Results ◽  
Vapor Pressures ◽  
Temperature Range ◽  
Mass Fractions

The saturated vapor pressures of R22 uniformly mixed with refrigeration oil and nano- refrigeration-oil were measured experimentally at a temperature range from 263 to 333K and mass fractions from 1 to 5%. The experimental results showed that the saturated vapor pressure of R22/KT56 mixture was lower than that of pure R22; the pressure deviation between them increased with a raising mass fraction of refrigeration oil and temperature. After adding nano-NiFe2O4 and nano-fullerene into KT56, the pressure deviation increased at the same mass fraction and temperature. A saturated vapor pressure correlation for R22 and refrigeration oil/nano-refrigeration-oil mixture was proposed, and the calculated values agreed with the experimental data within the deviation of ± 0.77%.

A New Approach in Approximating Thermodynamics Properties in Compressed Liquid Region

2008 ◽  
Author(s):  
Amir Karimi ◽  
Isa Tan
Keyword(s):  
Thermodynamic Properties ◽  
Internal Energy ◽  
Saturation Pressure ◽  
Approximation Formula ◽  
Liquid Region ◽  
Saturated Liquid ◽  
Thermodynamics Properties ◽  
Compressed Liquid ◽  
The Right ◽  
Current Approximation

Currently it is a common practice to use saturated liquid properties to approximate thermodynamics properties of fluids in the compressed liquid region. In this practice it is assumed that specific volume, internal energy, and entropy of fluids in the compressed liquid region are functions of temperature only and pressure practically has very little or no effect on these properties. Therefore, these properties at a given temperature and pressure are approximated by the saturated liquid properties at the given temperature. In the current literature the approximation formula given for enthalpy in the compressed liquid region is expressed as h(T, p) = hf (T) + vf (T) [p – psat (T)], where the aim of the second term on the right hand side of the equation is to improve the accuracy of the approximation, when pressure is much greater than the saturation pressure. However, in a recent study of thermodynamic properties of water, Kostic has shown that the second term in the equation improves the accuracy of the approximation of the enthalpy only at temperatures below 100 °C. In fact, he has shown that the second term increases the error when the formula is used to approximate the enthalpy of water in the compressed liquid region at intermediate and high temperatures. Kostic’s investigation is expanded in this paper to include substances other than water. The study shows that in many situations pressure has a bigger influence on the internal energy than it does on enthalpy of fluids in the compressed liquids. This paper demonstrates that the current practice of approximating properties of fluids in the compressed liquid region is not accurate at all range of temperatures and pressures. It establishes the range of pressures and temperatures for which the current approximation method could be used with reasonable accuracies. It also proposes a new scheme for the approximation of thermodynamic properties in the compressed liquid region.

Gaseous PvTx measurements of HFO-1234yf + HFC-32 binary mixture by single-sinker magnetic suspension densimeter

2018 ◽  
Vol 460 ◽  
pp. 119-125 ◽  
Author(s):  
Xu-Dong Cai ◽  
Nan Zhang ◽  
Long-Xiang Chen ◽  
Peng Hu ◽  
Gang Zhao ◽  
...  
Keyword(s):  
Binary Mixture ◽  
Magnetic Suspension

Broad temperature range of cubic blue phase present in simple binary mixture systems containing rodlike Schiff base mesogens with tolane moiety

Soft Matter ◽  
2016 ◽  
Vol 12 (12) ◽  
pp. 3110-3120 ◽  
Author(s):  
Chiung-Cheng Huang ◽  
Yu-Hao Chen ◽  
Sheng-Yen Chen ◽  
Yi-Zeng Sun ◽  
Zong-Ye Wu ◽  
...  
Keyword(s):  
Schiff Base ◽  
Binary Mixture ◽  
Broad Temperature Range ◽  
Temperature Range ◽  
Blue Phase

Analysis of Energetic, Design and Operational Criteria When Choosing an Adequate Working Fluid for Small ORC Systems

2009 ◽  
Author(s):  
Jorge Faca˜o ◽  
Armando C. Oliveira
Keyword(s):  
Thermal Stability ◽  
Low Temperature ◽  
Heat Source ◽  
Specific Volume ◽  
Saturated Vapor ◽  
Saturation Pressure ◽  
Working Fluid ◽  
Inlet Temperature ◽  
Turbine Inlet ◽  
Cycle Efficiency

Small cogeneration (CHP) systems may lead to a significant reduction of primary energy consumption and harmful emissions. Low temperature Rankine cycles, that can be assisted by solar energy, are a possible solution for producing combined electricity and useful heat. These cycles usually use an organic working fluid. This study presents an analysis of the energetic, design and operational features, that have to be taken into account when choosing an adequate working fluid for these Organic Rankine Cycles (ORC). When using renewable energies as a heat source, like solar or geothermal, the cycles may operate at temperatures between 120°C and 230°C. A system producing 5 kW of electricity was considered as a basis of comparison. Several fluids were analysed: n-dodecane, water, toluene, cyclohexane, n-pentane, HFE7100, R123, isobutane and R245fa. The organic dry fluids, with a positive slope of the saturated vapor curve in a T-s diagram, are in principle desirable for low temperature applications, simplifying turbine design. The degree to which the fluids are drying, is generally related to their molecular weight or molecular complexity. Practical issues, like thermal stability, toxicity, flammability and cost are considered. The thermodynamic cycle efficiency is also important. The saturated vapor specific volume gives an indication of condenser size, which is related to system initial cost. A super-atmospheric (>100 kPa) saturation pressure eliminates infiltration gases, which is important for operational reasons, because infiltration reduces system efficiency. The degree of superheating was optimized for maximum cycle efficiency, with a quadratic approximation method. This optimization makes it possible to decide if it is better to have saturated vapor or superheated vapor at turbine inlet, for a fixed turbine inlet temperature. For a heat source temperature of 120°C, only toluene and isobutane present a small advantage in superheating. It is difficult to find the best fluid, which has simultaneously: high cycle efficiency, low vapor specific volume at turbine outlet, super-atmospheric saturation pressure, good thermal stability, small environmental impact, small toxicity and no flame propagation. From the point of view of cycle efficiency, n-dodecane presents the best performance. However, this fluid presents the highest saturated vapor specific volume (resulting in a larger condenser) and the smallest condenser saturation pressure (resulting in infiltration of gases). The best candidates for the cycle regarding all the aspects are: toluene, cyclohexane and n-pentane. Comparing the three fluids, toluene presents the highest efficiency, the highest impact in environment and the biggest vapor specific volume. N-pentane presents the smallest cycle efficiency and smallest vapor specific volume, but is the unique fluid with super-atmospheric saturation pressure. Cyclohexane is the fluid with lowest impact in environment.

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