Effects of Pressure on the Kinetics of Manganese Evaporation from the Ot4 Alloy / Wpływ Cisnienia Na Kinetyke Procesu Odparowania Manganu Ze Stopu Ot4

2013 ◽  
Vol 58 (1) ◽  
pp. 197-201 ◽  
Author(s):  
L. Blacha ◽  
R. Burdzik ◽  
A. Smalcerz ◽  
T. Matuła
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Gaseous Phase ◽  
Pressure Range ◽  
Evaporation Rate ◽  
Evaporation Process ◽  
Pressure Reduction ◽  
Diffusion Controlled ◽  
Kinetics Of ◽  
Evaporation Kinetics

In the paper, results of the study on manganese evaporation from the OT4 alloy are presented. In the experiments, the effects of pressure on the manganese evaporation kinetics and the stages that limit the evaporation rate were investigated. It was demonstrated that the rate of manganese evaporation from the alloy increased with pressure reduction in the system. When the pressure decreases from 1000 Pa to 10 Pa, the value of overall mass transfer kMn increases from 3.9*10-6 ms-1 to 208.4*10-6 ms-1. At the same time, the manganese fraction in the alloy decreased from 1.49% mass to 0.045% mass. Within the whole pressure range, the analysed evaporation process is diffusion-controlled. For pressures above 50 Pa, the determining stage is transfer in the gaseous phase, while for pressures below 50 Pa, it is transfer in the liquid phase.

Effects of Surface Topography and Colloid Particles on the Evaporation Kinetics of Sessile Droplets on Superhydrophobic Surfaces

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Wei Xu ◽  
Chang-Hwan Choi
Keyword(s):  
Rate Constants ◽  
Water Droplet ◽  
Evaporation Rate ◽  
Pure Water ◽  
Hydrophobic Surface ◽  
Superhydrophobic Surfaces ◽  
Clear Correlation ◽  
Planar Surface ◽  
Kinetics Of ◽  
Evaporation Kinetics

In this paper, the evaporation kinetics of microliter-sized sessile droplets of gold colloids (∼250 nm in particle diameters) was experimentally studied on micropatterned superhydrophobic surfaces, compared with those of pure water on a planar hydrophobic surface. The structural microtopography of superhydrophobic surfaces was designed to have a constant air fraction (∼0.8) but varying array patterns including pillars, lines, and wells. During evaporation in a room condition, the superhydrophobic surfaces exhibited a stronger pinning effect than a planar surface, especially in the initial evaporation stage, with significant variations by the surface topographies. Compared to a pure water droplet, colloids exhibited further promoted pinning effects, mainly in the later stage of evaporation. While the well-known evaporative mass transport law of sessile droplets (i.e., linear law of “V2/3∝t”) was generally applicable to the superhydrophobic surfaces, much smaller evaporation rate constants were measured on the patterned superhydrophobic surfaces than on a planar hydrophobic surface. A colloidal droplet further showed lower evaporation rate constants than a pure water droplet as the concentration of particles in the droplets increased over the evaporation. Such transition was more dramatic on a planar surface than on the micropatterned surfaces. Whereas there was no clear correlation between evaporation mode and the evaporation rate observed on the superhydrophobic surfaces, the prominent decrease of the evaporation rate on the planar hydrophobic surface was accompanied with the onset of a second pinning mode.

Elimination of Aluminum During the Process of Ti-6Al-4V Alloy, Smelting in a Vacuum Induction Furnace / Eliminacja Aluminium W Procesie Wytopu Stopu Ti-6Al-4V W Indukcyjnym Piecu Próżniowym

2012 ◽  
Vol 57 (4) ◽  
pp. 951-956 ◽  
Author(s):  
G. Siwiec
Keyword(s):  
Mass Transfer ◽  
Liquid Alloy ◽  
Pressure Range ◽  
Induction Furnace ◽  
Aluminum Concentration ◽  
Vacuum Induction Furnace ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Kinetics Of

In the paper, results of the study on kinetics of aluminum evaporation from a liquid Ti-6Al-4V alloy during its smelting in a vacuum induction furnace are presented. The experiments were performed with the use of a VIM 20-50 furnace (manufactured by SECO-WARWICK) at 1973 K and 5-1000 Pa. Based on the values of changes in aluminum concentration in a liquid alloy, overall mass transfer coefficients were estimated. Within the analysed pressure range, the coefficient values changed from 0.97·10-5 ms-1 to 1.93·10-5 ms-1 for 1000 Pa and 5 Pa, respectively

scholarly journals Modelling Droplet Heat and Mass Transfer in Aero-Engine Bearing Chambers

2019 ◽  
Author(s):  
Dafne Gaviria Arcila ◽  
Hervé Morvan ◽  
Kathy Simmons ◽  
Stephen Ambrose ◽  
Michael Walsh ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Evaporation Rate ◽  
Numerical Study ◽  
Droplet Diameter ◽  
Air Flow ◽  
Core Region ◽  
Evaporation Process ◽  
Data Set ◽  
The Core

Abstract The oil inside aeroengine bearing chambers can be found in many forms, including droplets which interact with the core airflow. The ability to model such bearing chambers computationally is desirable and thus a better understanding of the evaporation process of oil droplets is of great interest. Previous studies have analyzed the flow of isothermal droplets in bearing chambers. However, further investigation is needed into the heating of droplets in the highly rotating core region. This will enable designers to evaluate the behavior of droplets in a chamber and the likelihood that they will evaporate. The aim of this research is to analyze the oil droplet evaporation process under aeroengine bearing chamber representative conditions. An ultimate goal is the ability to predict the oil-air heat and mass transfer in the core flow region, as well as to develop an understanding of the flow inside a droplet, and how this affects evaporation. This latter is important as it has not been studied before. This paper presents the results of a numerical study of the evaporation process of a single droplet under bearing chamber temperature and air flow conditions. The two-phase flow is simulated using ANSYS Fluent with the volume of fluid approach and the evaporation process with the “D−square law”. First, the modelling approach is validated against previous experimental and numerical analysis of fuel droplets in an air flow with heat transfer. The simulation results were in excellent agreement with a benchmarking data set. The validated approach is then applied for investigation to smaller, bearing chamber representative droplets of an oil base stock used in jet engines. The oil evaporation rate was quantified as well as the evolution of droplet diameter, which revealed the effect of different air velocities and temperatures on the droplet. The extent to which evaporation rate increased with air velocity and temperature is quantified. It is concluded that droplets of initial diameters less than 200μm that remain in the chamber core region for more than 0.3s are likely to evaporate completely. This study allows us to estimate droplet heat and mass transfer and the associated phase change in a bearing chamber. It also provides best practice to predict the performance of small droplets under the effects of high temperature and velocity convective air flows. In future work this methodology will be applied in simulations in a representative bearing chamber to predict how the cooling process is affected by oil evaporation.

Factors controlling the kinetics of crystallization: supersaturation evolution in a porous medium. Application to barite crystallization

1990 ◽  
Vol 127 (6) ◽  
pp. 485-495 ◽  
Author(s):  
Manuel Prieto ◽  
Andrew Putnis ◽  
Lurdes Fernandez-Diaz
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Porous Silica ◽  
Experimental System ◽  
Concentration Profiles ◽  
Effect Of Additives ◽  
Diffusion Controlled ◽  
Porous Silica Gel ◽  
Resultant Increase ◽  
Kinetics Of

AbstractThe nucleation of barite has been studied in a system involving the doublediffusion of Ba2+and SO42-in an Na-rich aqueoussolution, through a porous medium. The evolution of the concentration profiles in the medium, which is a column of porous silica gel, has been determined as a function of time by direct chemical analysis of the diffusion-controlled mass transfer. By measuring the pH evolution, a Debye–Huckel treatment of ionic complexing has enabled the supersaturation evolution to be determined. The location of barite precipitation in the column is controlled both by the need to exceed a threshold supersaturation, as well as achieve an ‘equality range’ in which [Ba2+]/[SO42−] is close to unity. The value of the threshold supersaturation is a kinetic parameter and depends on the rate at which supersaturation increases. The experimental system described here has wide application to the study of crystallization phenomena in rocks. Experiments on the effect of additives designed to inhibit nucleation of barite in North Sea oil wells are used to quantify the resultant increase in supersaturation threshold.

Aluminium Evaporation from Titanium Alloys in the VIM Process

2013 ◽  
Vol 211 ◽  
pp. 117-128 ◽  
Author(s):  
Beata Oleksiak ◽  
Leszek Blacha ◽  
Lubomir Pikna ◽  
Rafał Burdzik
Keyword(s):  
Mass Transfer ◽  
Titanium Alloy ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Evaporation Rate ◽  
Induction Furnace ◽  
Vacuum Induction Furnace ◽  
Al Alloy ◽  
Overall Mass Transfer Coefficient ◽  
Kinetics Of

In the paper, results of the study on aluminium evaporation from the Ti-Al alloy (6.5%mass) during smelting in a vacuum induction furnace (VIM) are presented as well as the kinetics of the process is discussed. The experiments were performed at 51000 Pa for 1972 K and 2023 K. Based on the determined values of aluminium overall mass transfer coefficient, the mass transfer coefficient in the liquid phase and the evaporation rate constant, the stages that determined the investigated process were defined. It was demonstrated that Al evaporation from the aluminium-titanium alloy is kinetically controlled.

Effect of the Concentration of Viscosifier on Desorption Kinetics of Methane From Synthetic Based Fluids

2020 ◽  
Author(s):  
Damilola Ojedeji ◽  
Yuanhang Chen
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Drilling Fluid ◽  
Desorption Kinetics ◽  
Drilling Mud ◽  
Well Control ◽  
Kinetics Of Formation ◽  
Control Decision ◽  
Internal Olefin ◽  
Kinetics Of

Abstract Synthetic-oil based drilling mud is currently the most commonly used type of drilling fluid for offshore drilling in the Gulf of Mexico, due to the environmental regulation in the area, as well as the numerous operational benefits they provide. However, early kick detection and well control decision-making are more challenging due to the solubility of formation gas in synthetic-based fluids. This partially contributes to the poor understanding of the mass transfer kinetics of formation gas in and out of synthetic fluids during these well control events. The objective of this work was to better understand the mass transfer of gas from a solution by evaluating the influence of viscosifier concentration on the desorption kinetics of methane from pure internal olefin and internal olefin-viscosifier mixture. The desorption coefficients were determined from a custom-built mass transfer apparatus. Different suspentone concentrations ranging from 0 to 5wt% by volume of liquid were used to investigate the influence of viscosifier concentration on the desorption coefficient. It was observed that the presence of suspension agents in the liquid phase decreased the mass transfer coefficient. This decrease could be due to an increase in the resistance to the flow of gas bubbles evolving from the liquid phase.

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