A study of the Sherwood–Rayleigh relation for water undergoing natural convection-driven evaporation

Bower, S.M.; Saylor, J. R.

doi:10.1016/j.ijheatmasstransfer.2009.01.034

Cited by 56 publications

(48 citation statements)

References 24 publications

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“…1, relates the Sherwood number (Sh), which is a dimensionless mass transfer coefficient for evaporation, to the Rayleigh number (Ra), which generally represents the relative effects of buoyancy and viscosity. A comprehensive review of published Sh-Ra correlations was conducted by Bower and Saylor [4]. The second popular correlation form is the Dalton model.…”

Section: Introductionmentioning

confidence: 99%

“…1, all three of the terms have the same order of dependency, n, since they are contained within the Rayleigh number. The definition of the Ra commonly includes the Prandtl number (ν/α), which is appropriate for thermallyinduced natural convection, and that is the form used in the correlations reviewed by Bower and Saylor [4]. Since our study pertains to natural convection induced by a non-uniform mass distribution resulting from the vapor distribution, we replaced the Prandtl number with the Schmidt number (ν/D), essentially replacing thermal diffusivity with mass diffusivity in the expression for the Rayleigh number.…”

Section: Introductionmentioning

confidence: 99%

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Correlation for sessile drop evaporation over a wide range of drop volatilities, ambient gases and pressures

Kelly-Zion

Pursell

Wassom

et al. 2018

International Journal of Heat and Mass Transfer

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A correlation for the evaporation of sessile drops over a very broad range of conditions was developed based on measured evaporation rate data obtained for drops of acetone, methanol, and six hydrocarbons ranging from hexane to isooctane, evaporating in air, helium, argon, and krypton, over a range of ambient pressures from 96 kPa to 615 kPa. The experiments were designed to produce a large variation in the rates of diffusion and buoyancy-induced (natural) convection of the vapor phase amongst the experimental conditions. The correlation, which fits the measurements with an RMS relative error of 5.2%, is a simple equation involving conventional parameters for diffusive and convective transport and is applicable to conditions for which vapor transport limits the rate of evaporation. Application of the correlation requires knowledge of eight basic properties: the ambient pressure and temperature, the equilibrium vapor pressure of the evaporating component, the diffusion coefficient for the evaporating component in the ambient gas, the viscosity of the ambient gas, the radius of the sessile drop, and the molecular weights of the evaporating component and the ambient gas. The correlation is much easier to implement than a computational model based on the coupled conservation equations of mass, energy, and momentum for the two phases, and it offers a single mathematical expression that provides valuable insight into how the roles of diffusive and convective transport change with physical and geometrical parameters. The correlation can be a valuable tool to aid in the analyses of applications involving sessile drop evaporation and to support the validation of complex computational models.The range of experimental conditions resulted in a large variation in the rates of diffusive and naturally convective transport of the vapor. Over the range of experimental conditions, the liquid volatility, as indicated by the equilibrium vapor pressure, was varied by a factor of 16.7, the mass diffusivity by a factor of 52.2, the density difference ratio (the impetus for natural convection) by a factor of 3,557, and the drop radius by a factor of 22. In terms of the Rayleigh number, the experimental data covers a range from 5 to 361,000. Consequently, the correlation is applicable to a very broad range of conditions. To our knowledge these evaporation rate measurements of sessile drops in gases other than air and at pressures above one atmosphere are the first to be reported in the literature.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Correlation for sessile drop evaporation over a wide range of drop volatilities, ambient gases and pressures

Kelly-Zion

Pursell

Wassom

et al. 2018

International Journal of Heat and Mass Transfer

View full text Add to dashboard Cite

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“…This set of correlations is dominated by those developed specifically for water evaporation [8][9][10][11][12][13][14][15]. For the evaporation of liquids other than water, the heat and mass transfer analogy may be used but, to our knowledge, no simple, non-computational models have been developed for evaporation of sessile drops under conditions for which natural convection may be significant.…”

Section: Introductionmentioning

confidence: 99%

“…Bower and Saylor published an excellent review of correlations of this form and evaluated the ability of the correlations to fit their measurements, which were conducted with heated water in square tanks of widths between 15.2 and 60.9 cm [8,9]. After accounting for slight differences in the definitions of Sh and Ra and recomputing the correlations using uniform definitions, Bower and Saylor found significant differences in the prefactors, c, and the exponents, n, amongst four correlations for water evaporation under conditions of natural convection.…”

Section: Introductionmentioning

confidence: 99%

“…After accounting for slight differences in the definitions of Sh and Ra and recomputing the correlations using uniform definitions, Bower and Saylor found significant differences in the prefactors, c, and the exponents, n, amongst four correlations for water evaporation under conditions of natural convection. Three of the four correlations were developed for the case in which the water vapor is less dense than the surrounding air, which results in a buoyancy-induced upward flow of the vapor [8,9,11,12]. One correlation was developed for the case in which the water vapor was colder and denser than the surrounding air, resulting in a buoyancy-induced downward flow of the vapor [10].…”

Section: Introductionmentioning

confidence: 99%

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Correlation for the convective and diffusive evaporation of a sessile drop

Kelly-Zion

Batra

Pursell

2013

International Journal of Heat and Mass Transfer

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A simple correlation is developed to compute the evaporation rates of sessile drops and small puddles which are evaporating under the influences of both diffusion and natural convection of the vapor-air mixture surrounding the drop. The correlation is based on experiments conducted with eight hydrocarbons, which provide a factor of 16.6 variation in volatility as indicated by the equilibrium vapor pressures, a factor of 3.6 variation in molecular mass, and a factor of 2.2 variation in mass diffusivity, and thus the correlation is applicable for liquids having a broad range of properties. The correlation predicts the evaporation rates to within a root-mean-square (RMS) error of 6.5% over the broad range of conditions. Limitations of the correlation are investigated, and when one of the species is excluded, the RMS error is reduced to 4.9%.There are two main differences between this new correlation and the correlations that have been published previously. The first difference is the new correlation reduces to an expression for diffusion-limited evaporation as the density difference between the vapor-air mixture at the surface of the drop and the ambient air becomes negligible, or when the drop size becomes very small. The second difference is the form of the dependency on the density difference ratio, which in previous correlations is obtained solely through the Rayleigh number (Ra). This new correlation contains a term which represents the influence of natural convection on the evaporation rate and this term provides insight into the nature of the coupling of the diffusive and convective transport of the vapor.

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Sherwood–Rayleigh parameterization for evaporation in the presence of surfactant monolayers

Bower

Saylor

2012

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com).Presented here is an experimental investigation of the effects of several surfactant monolayers on evaporation driven by natural convection in the air above a water surface. Experiments were performed in a controlled laboratory setting with tanks of heated water for the following cases: (1) a clean water surface, and for surfaces covered with monolayers of (2) oleyl alcohol, (3) stearic acid, and (4) stearyl alcohol. Evaporation rates were measured using a laser-based method, and the Sherwood and Rayleigh numbers, Sh and Ra, were computed from the data. Power law scalings of the form Sh ¼ BÁRa m were developed for each case which yielded, essentially, m ¼ 1/3 for all four surface conditions. The oleyl alcohol and stearic acid conditions give essentially the same value for B as for the clean surface case. For stearyl alcohol, B is smaller than for all other surface conditions; this result is attributed to the ability of the stearyl alcohol monolayer to inhibit evaporation by blocking the passage of water molecules through the monolayer: the barrier effect. The surface temperature is measured in this work enabling a separation of the effect of surfactants on evaporation due to a reduction in surface temperature from their effect on evaporation due to a true barrier effect. This has not been accomplished heretofore. V V C 2012 American Institute of Chemical Engineers AIChE J, 59: [303][304][305][306][307][308][309][310][311][312][313][314][315] 2013

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A study of the Sherwood–Rayleigh relation for water undergoing natural convection-driven evaporation

Cited by 56 publications

References 24 publications

Correlation for sessile drop evaporation over a wide range of drop volatilities, ambient gases and pressures

Correlation for sessile drop evaporation over a wide range of drop volatilities, ambient gases and pressures

Correlation for the convective and diffusive evaporation of a sessile drop

Sherwood–Rayleigh parameterization for evaporation in the presence of surfactant monolayers

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