Effects of noncondensable gas and forced flow on laminar film condensation

Denny, V. E.; Jusionis, Vytautas J.

doi:10.1016/0017-9310(72)90077-4

Cited by 33 publications

(17 citation statements)

References 9 publications

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“…Therefore, we set the initial chamber pressure as high as 30 Pa (primarily composed of non-condensable gases, NCG) to avoid the evaporation of oil with steam pressures ranging from 2 to 3 kPa (1 < S < 1.6) in the experiments. This is consistent with actual condenser systems where NCG partial pressures are typically found in the range of 30 Pa and significantly affect the condensation heat transfer performance34353637. Accordingly, with these experimental conditions, we were able to emulate a more realistic condensation environment and demonstrate the practical significance of the immersion condensation mode.…”

Section: Resultssupporting

confidence: 86%

Immersion Condensation on Oil-Infused Heterogeneous Surfaces for Enhanced Heat Transfer

Xiao

Miljkovic

Enright

et al. 2013

Sci Rep

234

219

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Enhancing condensation heat transfer is important for broad applications from power generation to water harvesting systems. Significant efforts have focused on easy removal of the condensate, yet the other desired properties of low contact angles and high nucleation densities for high heat transfer performance have been typically neglected. In this work, we demonstrate immersion condensation on oil-infused micro and nanostructured surfaces with heterogeneous coatings, where water droplets nucleate immersed within the oil. The combination of surface energy heterogeneity, reduced oil-water interfacial energy, and surface structuring enabled drastically increased nucleation densities while maintaining easy condensate removal and low contact angles. Accordingly, on oil-infused heterogeneous nanostructured copper oxide surfaces, we demonstrated approximately 100% increase in heat transfer coefficient compared to state-of-the-art dropwise condensation surfaces in the presence of non-condensable gases. This work offers a distinct approach utilizing surface chemistry and structuring together with liquid-infusion for enhanced condensation heat transfer.

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Section: Resultssupporting

confidence: 86%

Immersion Condensation on Oil-Infused Heterogeneous Surfaces for Enhanced Heat Transfer

Xiao

Miljkovic

Enright

et al. 2013

Sci Rep

234

219

View full text Add to dashboard Cite

show abstract

“…Denny, Mills, and Jusionis [13,14] studied condensation of a number of species of vapor in forced, laminar flow using boundary layer equations. The work by Wang and Tu [15] is an early example of an analysis of falling film condensation in a vertical tube with noncondensable gas; the authors found that the effects of noncondensables are more pronounced in enclosures because the concentration of noncondensables increases as condensation proceeds.…”

Section: Condensation In the Presence Of Noncondensable Gasesmentioning

confidence: 99%

Entropy generation in condensation in the presence of high concentrations of noncondensable gases

Thiel

Lienhard

2012

International Journal of Heat and Mass Transfer

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The physical mechanisms of entropy generation in a condenser with high fractions of noncondensable gases are examined using scaling and boundary layer techniques, with the aim of defining a criterion for minimum entropy generation rate that is useful in engineering analyses. This process is particularly relevant in humidification-dehumidification desalination systems, where minimizing entropy generation per unit water produced is critical to maximizing system performance. The process is modeled by a consideration of the vapor/gas boundary layer alone, as it is the dominant thermal resistance and, consequently, the largest source of entropy production in many practical condensers with high fractions of noncondensable gases. Most previous studies of condensation have been restricted to a constant wall temperature, but it is shown here that for high concentrations of noncondensable gases, a varying wall temperature greatly reduces total entropy generation rate. Further, it is found that the diffusion of the condensing vapor through the vapor/noncondensable mixture boundary layer is the larger and often dominant mechanism of entropy production in such a condenser. As a result, when seeking to design a unit of desired heat transfer and condensation rates for minimum entropy generation, minimizing the variance in the driving force associated with diffusion yields a closer approximation to the minimum overall entropy generation rate than does equipartition of temperature difference.

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“…Figure 1 shows the physical picture of the model and the coordinates. (6) where d0 is the film thickness by Nusselt's model12) and X'c is the change of specific enthalpy accompanied by the condensation of unit mass of vapor. Equation (4) is identical with that obtained by Rohsenow et al.U) but differs in later treatment.…”

Section: Discussionmentioning

confidence: 99%

Forced convection film condensation of vapors in the presence of noncondensable gas on a small vertical flat plate.

Asano

Nakano

Inaba

1979

J. Chem. Eng. Japan

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Local measurements of vapor phase heat and mass fluxes and of heat fluxes through condensate liquid film were made for the forced convection film condensation of steam, methanol, benzene and carbon tetrachloride vapors on a small vertical flat plate in the presence of air with air mass fraction of 0.027-0.787.Measured vapor phase fluxes are compared with the theoretical value by laminar boundary layer theory over a flat plate with Blasius-type similarity transformation. A new method which enables one to evaluate the surface temperature of the condensate liquid film and the wall heat fluxes in the presence of noncondensable gas is proposed. The effect of vapor shear stress on the rate of heat transfer through condensate liquid film flowing cocurrently with vapor is also discussed.

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Effects of noncondensable gas and forced flow on laminar film condensation

Cited by 33 publications

References 9 publications

Immersion Condensation on Oil-Infused Heterogeneous Surfaces for Enhanced Heat Transfer

Immersion Condensation on Oil-Infused Heterogeneous Surfaces for Enhanced Heat Transfer

Entropy generation in condensation in the presence of high concentrations of noncondensable gases

Forced convection film condensation of vapors in the presence of noncondensable gas on a small vertical flat plate.

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