An experimental investigation of the saturated vapor pressure of solutions proL pane in compressor oils in the presence of fullerene C60 in oil

An investigation of the saturated vapor pressure for the solutions of propane in the two type of industrial compressor oils ProEco®RF22S and RENISO SP46, also as in oil ProEco®RF22S containing fullerene C60 6.837·10-4kg·kg-1is presented in this paper. The measurement of the saturated vapor pressure was conducted using a static method in a temperature range (273…333) K and thepropanemass fraction (0.11…0.595) kg·kg-1. An analysis revealed that the expanded uncertainties of the measured saturated vapor pressure do not exceed 0.0419·105Pafor solutionpropane/ProEco®RF22S,0.0716·105Pa for solution propane /RENISO SP46, and 0.0095·105Pa for solution propane/ProEco®RF22 Scontaining C60.The temperature and concentration dependences of the saturated vapor pressure for the object of study have been discussed. The excess of saturated vapor pressure for the solution of propane in oil ProEco®RF22S over the pressure of the solution of propane in oil RENISO SP46 reaches 1.5 105 Pa at a temperature of 330 K and propane fractionof 0.1 kg·kg-1. This effect decreases with temperature decreasing and propane fraction increasing.It was proven that the additive of the fullerene C60 increase the saturated vapor pressure of the solution propane/ProEco® RF22S up to 0.4·105Pa at low temperature and low propane mass fraction insolution. The results obtained proved the expediency of the introduction in the industry the solution of propane/compressor oil ProEco® RF22Scontaining the fullerene C60 as working fluid of vapor compression refrigeration system. The ability of C60additive in oil to increase the saturated vapor pressure of considered working fluid will contribute to increasing the energy efficiency of refrigeration systems.

Phase vapor–liquid equilibrium for the solutions of diethyl selenide and diethylzinc

Using a semi-empirical Wilson’s model, the vapor-liquid equilibrium in the “diethylzinc - diethyl selenide” system is described: the activity coefficients of the solution components, the separation coefficient, the excess functions of the solution (HE, GE, TSE) are calculated, and isothermal P-X diagrams are obtained. The parameters of the Wilson’s model were calculated on the basis of our data on measuring the temperature dependence for saturated vapor pressure of high-purity samples of diethylzinc, diethyl selenide and their equimolecular solution using iterations from the mathematical software package Mathsad 14. Peculiarities of intermolecular interaction in the “diethylzinc – diethyl selenide” system and the presence of a negative deviation from Raoul's law have been found. The studied system is homogeneous in the whole concentration range. The concentration dependence of the enthalpy of mixing is alternating for the researched temperature range (280-340 K).

Experimental Investigation on Cavity Pressure Inside Sheet Cavitation

The gas content is one of the important factors in cavitation, which may increase the pressure inside the cavity through the diffusive mass transfer of the dissolved gas into the cavity. In the present study, we try to directly measure the cavity pressure inside the sheet cavity at the throat of a converging-diverging nozzle. Then the influences of the flow velocity and the gas content (amount of dissolved oxygen) on the gas partial pressure are investigated. It is found that, even in low gas content level, the cavity pressure is slightly but apparently higher than the saturated vapor pressure, indicating the presence of gas partial pressure. It is observed that the gas partial pressure in significantly developed cavitation is almost constant regardless of the flow velocity but slightly increases against the increase of the saturation level of dissolved gas. It is also found that the gas partial pressure inside cavity depends on the degree of cavitation development; the gas partial pressure decreases with the development of cavitation.

High Fluorescence Efficiency of Intrinsic Ligand-Free Zero-Dimensional Cs4PbBr6 Particles and Microcrystals

Ligand-free Cs4PbBr6 particles of sub-micron dimensions were fabricated by a simple tip-sonication method showing 85.1% photoluminescence quantum yield (PLQY). Cs4PbBr6 microcrystals can be grown under saturated vapor pressure with the...

Investigation of applicability of Peng–Robinson and GERG-2008 equations of state of real gas for calculating properties of Freons for refrigeration machines and compressors

A study of real gas state equations Peng–Robinson and GERG-2008 with respect to calculation of Freons R404A, R408A and R410A has been carried out. Four Freon parameters are calculated during the study: saturated vapor pressure at the saturation line at some Freon temperature, Freon density at saturation pressure and some temperature, enthalpy and entropy at the same pressures and temperature. The data obtained from the calculation of Freon by the above equations are compared with the experimental data for each of the above Freons. As a result of this work, data have been obtained to evaluate the accuracy of the Peng–Robinson and GERG-2008 equations of state for each of the three CFCs, to evaluate the effectiveness of these equations, and to provide recommendations for the calculation and application of these equations in the design and mathematical modelling of refrigeration machines

Glycerin-containing Working Fluids for Hydraulic Drives for Special Purposes

The cavitation properties of a liquid must be taken into account in the engineering design of hydraulic machines and devices for hydraulic automation in cases when in their working process the absolute pressure in the liquid may drop below atmospheric, and the liquid is in a rarefied state for a certain time. Cold boiling, which occurs at a relatively low temperature and reduced absolute pressure inside or on the surface of the liquid, is considered as hydrostatic cavitation, if the liquid is stationary, or as hydrodynamic cavitation, if the liquid enters conditions under which the velocity head sharply increases in the flow section and the absolute pressure.In accordance with the theory of cavitation, the first phase of cavitation occurs when the absolute pressure in the degassed liquid drops to the value of the saturated vapor pressure and the air dissolved in the liquid, leaving the intermolecular space, turns into microbubbles of undissolved air and becomes a generator of cavitation "nuclei". Of practical interest is a quantitative assessment of the value of the minimum permissible absolute pressure in a real, partially or completely degassed liquid, at which hydrostatic cavitation occurs.Since the pressure of saturated vapor of a liquid is, to a certain extent, associated with the forces of intermolecular interaction, it is necessary to have information on the cavitation properties of technical solutions, including the solution of air in a liquid, since a solute can weaken intermolecular bonds and affect the value of the pressure of saturated vapors of the solvent. The article describes an experiment carried out by the authors to evacuate liquids. During the experiment, evacuation of various liquids was carried out using a developed hydraulic vacuum pump with a pneumatic drive.The article presents the technologies of hydrostatic and hydrodynamic degassing of liquids used in the experiment.As a result of experimental studies of the cavitation properties of pure glycerin and glycerin in the form of a 49/51% solution in water, mineral oil and aviation kerosene, quantitative estimates of the permissible absolute pressure in the considered technical fluids and solutions were obtained, its dependence on the saturated vapor pressure, the influence of the degree of hydrodynamic degassing the liquid, and the amount of dissolved substance in it on the strength of the liquid to rupture.In the process of studying the cavitation properties of solutions, it was found that the level of permissible absolute pressure in the solution is greater than that of the solvent. It has been suggested that dissolved solid, liquid or gaseous substances weaken the intermolecular bonds of the solvent and increase the pressure of its saturated vapor.On the basis of the experimental studies, a method for determining the highest rarefaction in solvents and in glycerol solutions has been developed. In addition, a comparative assessment of the cavitation properties of the considered technical fluids is given.