An investigation of condensation from steam–gas mixtures flowing downward inside a vertical tube

Kuhn, S.Z.; Schrock, V.E.; Peterson, Per F.

doi:10.1016/s0029-5493(97)00185-4

Cited by 120 publications

(53 citation statements)

References 11 publications

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“…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. Various resistance network models have been developed to provide accurate ways to correlate experimental data on in-tube condensation with steam-air, steamhelium, and other mixtures [16][17][18].…”

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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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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“…In this section, an estimate of this thermal resistance using wealth of experimental data in literature is made [10,11]. In particular, researchers from BARC (Bhabha Atmoic Research Center) in India [12] reviewed various experimental correlations that give the condensation heat transfer performance of steam in the presence of non-condensables (including air and helium) for simple geometries (e.g., a vertical tube).…”

Section: Estimate Of Gas Side Heat Transfer Coefficient In the Dehumimentioning

confidence: 99%

Helium as a Carrier Gas in Humidification Dehumidification Desalination Systems

Narayan

McGovern

Lienhard

et al. 2011

Volume 1: Advances in Aerospace Technology; Energy Water Nexus; Globalization of Engineering; Posters

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A promising technology for small scale seawater desalination is the humidification dehumidification (HDH) system. This technology has been widely investigated in recent years. Since existing HDH systems have very high specific energy consumption, the authors have previously invented several ways to increase the energy efficiency of these systems. Even for these relatively higher efficiency systems the dehumidifier is expected to be large, owing to the large thermal resistance associated with the presence of non-condensable carrier gas (air) in the system. In this manuscript, we demonstrate that changing the carrier gas from air to helium a potential solution to this problem. In addition, the energy performance of a brine heated HDH system using helium relative to those using air is analysed in detail through well established on-design models for the components in the system. Symbols c p specific heat capacity at constant pressure (J/kg·K) D h hydraulic diameter (m) h specific enthalpy (J/kg) h cgm specific enthalpy of moist carrier gas (J/kg of dry carrier gas) h fg specific enthalpy of vaporization (J/kg) HCR modified heat capacity rate ratio (-) Ja Jakob number (-) k thermal conductivity (W/m.K) M molar mass (kg/kmol) m r mass flow rate ratio (-) m mass flow rate (kg/s) Nu Nusselt number (-) p partial pressure (Pa) P absolute pressure (Pa) ∆P pressure drop (Pa) Q heat transfer rate (W) Re Reynolds number (-) RR recovery ratio (%) s specific entropy (J/kg·K) NOMENCLATURE Acronyms GOR Gained Output

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“…Kuhn et al [2] investigated experimentally local heat transfer from condensation in the presence of non-condensable gases inside a vertical tube. The condenser tube has an inner diameter of 47.5 mm and is 3.37 m long.…”

Section: Validation Of the Nrg Condensation Model With The Kuhn Condementioning

confidence: 99%

“…Unfortunately, the local heat fluxes are not presented in the article of Kuhn et al [2]. Therefore, the NRG condensation model is compared to the physically based correlations in the Kuhn article.…”

Section: Validation Of the Nrg Condensation Model With The Kuhn Condementioning

confidence: 99%

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Validation of the CFX4 CFD code for containment thermal-hydraulics

Houkema

Siccama

Nijeholt

et al. 2008

Nuclear Engineering and Design

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An investigation of condensation from steam–gas mixtures flowing downward inside a vertical tube

Cited by 120 publications

References 11 publications

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

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

Helium as a Carrier Gas in Humidification Dehumidification Desalination Systems

Validation of the CFX4 CFD code for containment thermal-hydraulics

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