Mass transfer relations for transpiration evaporation experiments

Limpt, Hans Van; Beerkens, R.G.C.; Lankhorst, Adriaan; Habraken, Andries

doi:10.1016/j.ijheatmasstransfer.2005.04.009

Cited by 6 publications

(10 citation statements)

References 8 publications

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“…The local mass transfer boundary layer thickness or Nernst boundary layer thickness (δ) of the gas boundary layer at the glass melt surface can be determined from the gas velocities and the position of the nearest grid points and the Schmidt number (Sc). The local mass transfer coefficients were obtained from the calculated Nernst boundary layer and the relation: h g, i = D g, i /δ 9 . The thermodynamical‐associated species model can be used to calculate the local, temperature, and glass composition‐dependent chemical activities of volatile glass compounds on top of the glass melt.…”

Section: Resultsmentioning

confidence: 99%

“…This first principle evaporation model can be applied for industrial glass furnaces as well as for laboratory evaporation tests if the mass transport relation for gas phase (or Nernst boundary layer thickness) is known for the specific situation. From precisely controlled laboratory transpiration experiments, mass transport and Sherwood relations for the gas phase were obtained from CFD modeling and evaporation tests with water and acetone 9 …”

Section: Approachmentioning

confidence: 99%

“…For transpiration evaporation experiments (using a tube furnace), the value of the mass transfer coefficient, h g, i , depends on the gas velocity, the dimensions and geometry of the tube, and the position of the boat filled with the melt and the filling level of the boat 9 …”

Section: Evaporation Modelsmentioning

confidence: 99%

“…For the transpiration evaporation setup used here, Sherwood mass transfer relations have been derived from simple evaporation tests with water at room temperature and CFD calculations 9 . The Sherwood number depends on the Reynolds number (Re=ρvd/μ) in the tube and the Schmidt number (Sc=μ/[ρd]).…”

Section: Evaporation Modelsmentioning

confidence: 99%

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Models and Experiments for Sodium Evaporation From Sodium‐Containing Silicate Melts

Limpt¹,

Beerkens²,

Verheijen³

2006

Journal of the American Ceramic Society

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Universal simulation models based on (a) validated mass transfer relations and (b) thermodynamic modeling procedures for glass melts are developed to predict the evaporation rates of volatile species from a large range of glass melt compositions. Depending on the glass composition, temperature of the surface of the melt, local composition of the atmosphere, exposure time of a melt layer to the combustion atmosphere, and local gas velocities above the glass melt surface, the evaporation rates of volatile species can be estimated. Laboratory‐scale transpiration evaporation experiments have been used to study evaporation kinetics, to derive mass transfer relations, as well as to validate the sodium evaporation modeling results for sodium‐silicate melts as well as for soda‐lime‐silicate melts. In these investigations, the molten sodium‐silicate and soda‐lime‐silicate melts are exposed to atmospheres of flowing gases with controlled composition and gas flow rates. In a humid atmosphere for example, sodium mainly evaporates as NaOH. From the measured NaOH evaporation rates and the mass transfer relations, the NaOH vapor pressures in equilibrium with the molten glass at prevalent temperature and furnace atmosphere composition were derived. The NaOH vapor pressures are assumed to be in equilibrium with the glass melt composition at the surface of the melt. During the evaporation test, the Na2O surface composition will change due to depletion. This leads to equilibrium vapor pressures decreasing with time, reflecting the changing chemical activity at the glass melt surface. The results of evaporation tests for sodium‐disilicate and soda‐lime‐silicate glass melts are shown. Chemical activities derived from these measurements are compared with the results of thermodynamic modeling, using a method based on a glass melt from ideal mixtures of associate (stoichiometric) species of structural compounds with known thermodynamic properties.

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Section: Resultsmentioning

confidence: 99%

Section: Approachmentioning

confidence: 99%

Section: Evaporation Modelsmentioning

confidence: 99%

Section: Evaporation Modelsmentioning

confidence: 99%

See 2 more Smart Citations

Models and Experiments for Sodium Evaporation From Sodium‐Containing Silicate Melts

Limpt¹,

Beerkens²,

Verheijen³

2006

Journal of the American Ceramic Society

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“…The Sherwood number is a dimensionless number used in the mass transfer to represent the ratio of convective mass transport to diffusive mass transport. The average Sherwood number for the pulmonary region was estimated using equations given by Limpt et al (2005) number that represents the ratio of kinematic viscosity () of the fluid to the diffusion coefficient of the species (i.e., the ratio of momentum diffusion to mass diffusion).…”

Section: Modelmentioning

confidence: 99%

A transport model for nicotine in the tracheobronchial and pulmonary region of the lung

Gowadia

Dunn‐Rankin²

2009

Inhalation Toxicology

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Nicotine in mainstream cigarette smoke is predominantly present in the particulate phase. Interestingly, however, the deposition efficiency of smoke particles in the respiratory tract is less effective than is the nicotine retention. In the literature, four nicotine deposition mechanisms are identified: (a) direct gas deposition, (b) evaporative gas deposition, (c) particle deposition with evaporation, and (d) particle deposition with diffusion. In this article we present a physically motivated fundamental model to address nicotine deposition mechanisms (b) and (c) from the vapor phase. The model incorporates nicotine mass transport through estimates for the diffusion time across the epithelial layer and the time for nicotine vapor diffusion from the gas volume to the tissue surfaces in the tracheobronchial and pulmonary regions of the respiratory tract. The model comprises four mass transfer processes for nicotine at the surface of the respiratory tract epithelium: (1) conversion of free base nicotine from protonated nicotine; (2) free base nicotine transport across the epithelium; (3) free base nicotine evaporation; and (4) diffusion of free base nicotine vapor from the surface gas layer into the airway lumen. Results of the nicotine mass transport model suggest that the principal mechanism of nicotine delivery to the lung is by direct deposition of particles to the alveolar fluid lining, followed rapidly by evaporation into the lumen and then gas diffusion back to the surface as nicotine depletes in the surface layer through its transport across the epithelium.

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Dynamic flux chamber measurements of hydrogen sulfide emission rate from a quiescent surface – A computational evaluation

Prata¹,

Santos²,

Beghi³

et al. 2016

Chemosphere

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Mass transfer relations for transpiration evaporation experiments

Cited by 6 publications

References 8 publications

Models and Experiments for Sodium Evaporation From Sodium‐Containing Silicate Melts

Models and Experiments for Sodium Evaporation From Sodium‐Containing Silicate Melts

A transport model for nicotine in the tracheobronchial and pulmonary region of the lung

Dynamic flux chamber measurements of hydrogen sulfide emission rate from a quiescent surface – A computational evaluation

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