Effect of vapor phase pressure in synthesis of polyamide-6 on its indexes

Two-phase pressure drop is experimentally examined in a flow boiling condition in a tube of diameter 1.45 mm using water in ranges of pressure from 10 to 100 kPa, mass flux from 18 to 152 kg/m2s, heat flux from 13 to 646 kW/m2, and exit quality from 0.02 to 0.77. Also, pressure drop in an adiabatic air-water two-phase flow is measured at atmospheric pressure using the same test section and mass flux ranges of liquid and gas as those in the flow boiling. Decreasing system pressure the pressure drop significantly increases at a given mass flux. Influence of vapor phase on the pressure drop is found to be large both in the adiabatic and the diabatic conditions. The frictional pressure drop correlation for the adiabatic two-phase flow is developed and applied to predict pressure drop in the flow boiling. But it cannot give satisfactory predictions. The Chisholm correlation calculating a two-phase pressure drop multiplier is modified to account the influence of vapor phase in a capillary tube and the modified correlation can predict the pressure drop in the flow boiling within an error of 20%.

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Investigation of Local Evaporation Flux and Vapor-Phase Pressure at an Evaporative Droplet Interface

Langmuir ◽

10.1021/la900337j ◽

2009 ◽

Vol 25 (13) ◽

pp. 7424-7431 ◽

Cited By ~ 32

Author(s):

Fei Duan ◽

C. A. Ward

Keyword(s):

Vapor Phase ◽

Evaporation Flux ◽

Phase Pressure

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Pressure Drop Study and Correlation Development for Two-Phase Flow of R134a in Annular Helicoidal Pipe

Heat Transfer, Volume 2 ◽

10.1115/imece2004-61729 ◽

2004 ◽

Author(s):

H. L. Mo ◽

R. Prattipati ◽

C. X. Lin

Keyword(s):

Experimental Data ◽

Liquid Phase ◽

Pressure Drop ◽

Vapor Phase ◽

Test Section ◽

Circular Tube ◽

Phase Flow ◽

Two Phase ◽

Annular Section ◽

Phase Pressure

Pressure drop characteristics of R134a in annular helicoidal pipe was investigated experimentally with R134a flowing in the annular section. The experimental results revealed that when more R134a vapor was condensed, the liquid phase pressure drop increased largely while the vapor phase pressure drop decreased slightly. By comparing with the experimental data obtained from the same test section with R134a flowing in the inner circular tube of the helicoidal pipe, it was observed that the pressure drop for refrigerant in the annular section was always larger. It was also observed that the helicoidal pipe orientation showed little effect on the pressure drop variations. A pressure drop correlation was developed from the experimental data in terms of pressure drop multiplier with respect to Lockhart-Martinelli parameter.

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Crystal Surface Stoichiometry and the Fermi Level Effects on Outdiffusion of Si in GaAs

MRS Proceedings ◽

10.1557/proc-282-151 ◽

1992 ◽

Vol 282 ◽

Author(s):

Horng-Ming You ◽

Ulrich M. GöSele ◽

Teh Yu Tan

Keyword(s):

Fermi Level ◽

Vapor Phase ◽

Electron Concentration ◽

Crystal Surface ◽

Capacitance Voltage ◽

Phase Pressure

ABSTRACTGaAs samples doped with Si to a concentration of ∼2.7×10 18cm−3 were annealed at temperatures between 800 and 1000°C for 3 to 20 hours under As-rich and As-poor conditions for Si outdiffusion which were then measured using the capacitance-voltage method employing an electrochemical profiler. The deduced Si diffusivity showed strong dependencies on the As4 vapor phase pressure, PAs4 and on the electron concentration, n. When reduced to that under intrinsic conditions, activation enthalpies of 3.91 eV and 4.19 eV were obtained for As-rich and As-poor annealing cases, respectively. From these results, it is concluded that Si outdiffusion in GaAs is governed by the triply-negatively-charged Ga vacancies, .

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Prediction of the Saturation Pressure of Water From Non-Equilibrium Measurements

ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference, Volume 3 ◽

10.1115/ht2007-32347 ◽

2007 ◽

Author(s):

Fei Duan ◽

C. A. Ward

Keyword(s):

Vapor Phase ◽

Saturation Pressure ◽

Rate Theory ◽

Statistical Rate Theory ◽

Equilibrium Evaporation ◽

Phase Temperature ◽

Evaporation Flux ◽

Saturation Vapor ◽

Phase Pressure ◽

Non Equilibrium

Statistical rate theory (SRT) was applied to predict the saturation pressure of H2O based on the measurements of interfacial liquid-phase temperature, interfacial vapor-phase temperature, vapor-phase pressure, and average evaporation flux in non-equilibrium evaporation experiments. It is found that the predicted saturation pressure agrees with the Smithsonian Tables and Table given in the Handbook of Chemistry and Physics for water, H2O. SRT provides a new efficient method to determine the saturation-vapor pressure from a non-equilibrium precess.

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Planar defects in ordered (Ga,In)P

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106570 ◽

1988 ◽

Vol 46 ◽

pp. 902-903

Author(s):

S. McKernan ◽

C. B. Carter ◽

D. Bour ◽

J. R. Shealy

Keyword(s):

Electron Diffraction ◽

Vapor Phase ◽

Growth Direction ◽

High Density ◽

Ordered Structure ◽

Planar Defects ◽

Diffraction Patterns ◽

Ternary Semiconductors ◽

Anion Species ◽

Metallic Vapor

The growth of ternary III-V semiconductors by organo-metallic vapor phase epitaxy (OMVPE) is widely practiced. It has been generally assumed that the resulting structure is the same as that of the corresponding binary semiconductors, but with the two different cation or anion species randomly distributed on their appropriate sublattice sites. Recently several different ternary semiconductors including AlxGa1-xAs, Gaxln-1-xAs and Gaxln1-xP1-6 have been observed in ordered states. A common feature of these ordered compounds is that they contain a relatively high density of defects. This is evident in electron diffraction patterns from these materials where streaks, which are typically parallel to the growth direction, are associated with the extra reflections arising from the ordering. However, where the (Ga,ln)P epilayer is reasonably well ordered the streaking is extremely faint, and the intensity of the ordered spot at 1/2(111) is much greater than that at 1/2(111). In these cases it is possible to image relatively clearly many of the defects found in the ordered structure.

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