Vapor condensation in the presence of a noncondensable gas

1986 ◽  
Vol 29 (6) ◽  
pp. 1796 ◽  
Author(s):  
Lichung Pong ◽  
Gregory A. Moses
Keyword(s):  
Vapor Condensation ◽  
Noncondensable Gas

Diffusion Layer Theory for Turbulent Vapor Condensation With Noncondensable Gases

1993 ◽  
Vol 115 (4) ◽  
pp. 998-1003 ◽  
Author(s):  
P. F. Peterson ◽  
V. E. Schrock ◽  
T. Kageyama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mass Transfer ◽  
Vapor Condensation ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Noncondensable Gas ◽  
Noncondensable Gases ◽  
Vertical Tubes

In turbulent condensation with noncondensable gas, a thin noncondensable layer accumulates and generates a diffusional resistance to condensation and sensible heat transfer. By expressing the driving potential for mass transfer as a difference in saturation temperatures and using appropriate thermodynamic relationships, here an effective “condensation” thermal conductivity is derived. With this formulation, experimental results for vertical tubes and plates demonstrate that condensation obeys the heat and mass transfer analogy, when condensation and sensible heat transfer are considered simultaneously. The sum of the condensation and sensible heat transfer coefficients becomes infinite at small gas concentrations, and approaches the sensible heat transfer coefficient at large concentrations. The “condensation” thermal conductivity is easily applied to engineering analysis, and the theory further demonstrates that condensation on large vertical surfaces is independent of the surface height.

A Study of Shellside Condensation of a Hydrocarbon in the Presence of Noncondensable Gas on Twisted Elliptical Tubes

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
H. F. Gu ◽  
Q. Chen ◽  
H. J. Wang ◽  
Z. Zhang
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Tube Bundle ◽  
Vapor Condensation ◽  
Condensation Heat Transfer ◽  
Process Conditions ◽  
Diffusion Resistance ◽  
Condensation Temperature ◽  
Noncondensable Gas ◽  
Twisted Tubes

Experimental data were collected for one smooth round tube bundle and three twisted elliptical tube bundles using a kerosene mixture as a condensing vapor and air as a noncondensable gas. Experimental results showed that heat transfer for the twisted tubes was enhanced by a factor of 1.5–3 as compared to the plain tubes, depending on the specific tube geometry and process conditions. Heat transfer enhancement was found to increase with decreasing twist pitch, increasing tube ellipticity, and increasing mass flow rate. The presence of noncondensable gas was observed to significantly decrease condensation heat transfer performance due to the increase in mass diffusion resistance and lowering of the vapor condensation temperature at the vapor–liquid interface. Using the heat and mass transfer analogy method, a correlation for the condensation heat transfer coefficient of the mixture has been developed from the experimental data. Comparisons show that the predicative accuracy of the new correlation is within ±25% for the majority of experimental data.

Theoretical Modeling of Vapor Condensation in the Presence of Noncondensable Gas on a Horizontal Tube

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Junhui Lu ◽  
Haishan Cao ◽  
JunMing Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Film ◽  
Mass Flux ◽  
Horizontal Tube ◽  
Vapor Condensation ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Noncondensable Gas ◽  
Mass Fluxes

Abstract Double-boundary layer theory was adopted to investigate the distributions of the liquid film, gas film, heat transfer coefficient, and condensate mass fluxes around a horizontal tube for vapor condensation with noncondensable gases like steam–air and steam–CO2 mixtures under free convection. The investigation considered the effects of the noncondensable gas concentration, surface subcooling temperature, and pressure. The thicknesses of the liquid and gas films increase gradually along the wall from top to bottom, whereas the local heat transfer coefficient and the condensate mass flux decrease. The film thicknesses do not change significantly around the upper part of the tube but increase sharply around the lower part. The liquid film thicknesses, gas film thicknesses, condensate mass fluxes, and heat transfer coefficients of steam–air systems are compared with those of steam–CO2 systems. The condensate mass flux in the steam–air system is smaller than that of steam–CO2 system under the condition of the same surface subcooling and gas mass fraction because air has more moles of molecules in the mixture than CO2 and the steam more easily diffuses through CO2 than through air. The predicted average condensation heat transfer coefficients agree well with the available experimental data.

scholarly journals Numerical Investigation of Influence of Nanoparticles Presence on Water Vapor Condensation Process inside a Vertical Channel

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Mustapha Ait Hssain ◽  
Sara Armou ◽  
Kaoutar Zine-Dine ◽  
Rachid Mir ◽  
Youness El Hammami
Keyword(s):  
Water Vapor ◽  
Volume Fraction ◽  
Vertical Channel ◽  
Vapor Condensation ◽  
Film Condensation ◽  
Condensation Process ◽  
Cu Nanoparticles ◽  
Humid Air ◽  
Noncondensable Gas ◽  
Maximum Improvement

This paper is aimed at investigating the nanofluid film condensation by mixed convection in the presence of water vapor, Cu nanoparticles, and air treated as a noncondensable gas (NCG) on the inner walls of a vertical channel. In this simulation, the flow is laminar, stationary, two dimensional, and axisymmetric. The coupled governing equations for the liquid film with the nanoparticles and the mixture air-humid-nanoparticles are solved together using the finite volume method. Since the application of humid air condensation is one of the most applicable methods of phase change processes that is observed in different industrial fields such as heating, ventilation, and air conditioning (HVAC) or cooling systems, for this purpose, the influence of injecting a uniform volume fraction of nanoparticles on improving heat and mass transfer is determined as a function of the variation in relative humidity, velocity, temperature, pressure, and volume fraction of Cu nanoparticles at the channel inlet. The numerical results indicate that under the best conditions in the range of variation studied RH in = 100 % , Re in = 2000 , T in = 50 ° C , P in = 0.5     atm , and φ in = 0.1 % , the use of nanoparticles has a greater impact, and the maximum improvement in the condensation film thickness, the local Nusselt number, and the accumulated condensation rate has an effective ratio strictly greater than one compared with the case of pure humid air.

TEM study of amorphization of Cu and Ti foils by cold-rolling

1990 ◽  
Vol 48 (4) ◽  
pp. 146-147
Author(s):  
W. A. Chiou ◽  
N. L. Jeon ◽  
Genbao Xu ◽  
M. Meshii
Keyword(s):  
Solid State ◽  
Cold Rolling ◽  
High Energy ◽  
Rapid Quenching ◽  
Vapor Condensation ◽  
Metallic Alloys ◽  
Solid State Reactions ◽  
High Energy Particle ◽  
Amorphous Metallic Alloys ◽  
Thin Foils

For many years amorphous metallic alloys have been prepared by rapid quenching techniques such as vapor condensation or melt quenching. Recently, solid-state reactions have shown to be an alternative for synthesizing amorphous metallic alloys. While solid-state amorphization by ball milling and high energy particle irradiation have been investigated extensively, the growth of amorphous phase by cold-rolling has been limited. This paper presents a morphological and structural study of amorphization of Cu and Ti foils by rolling.Samples of high purity Cu (99.999%) and Ti (99.99%) foils with a thickness of 0.025 mm were used as starting materials. These thin foils were cut to 5 cm (w) × 10 cm (1), and the surface was cleaned with acetone. A total of twenty alternatively stacked Cu and Ti foils were then rolled. Composite layers following each rolling pass were cleaned with acetone, cut into half and stacked together, and then rolled again.

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