Dependence of the water vapor diffusion coefficient of aspen (Populus spec.) on moisture content

1991 ◽  
Vol 26 (1) ◽  
Author(s):  
W.T. Simpson ◽  
J.Y. Liu
Keyword(s):  
Diffusion Coefficient ◽  
Water Vapor ◽  
Moisture Content ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion

scholarly journals Macroscopic water vapor diffusion is not enhanced in snow

2020 ◽  
Author(s):  
Kévin Fourteau ◽  
Florent Domine ◽  
Pascal Hagenmuller
Keyword(s):  
Diffusion Coefficient ◽  
Water Vapor ◽  
Effective Diffusion Coefficient ◽  
Molecular Diffusion ◽  
Pore Space ◽  
Effective Diffusion ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion

Abstract. Water vapor transport in dry snowpacks plays a significant role for snow metamorphism and the mass and energy balance of snowpacks. The molecular diffusion of water vapor in the interstitial pores is usually considered as the main or only transport mechanism, and current detailed snow physics models therefore rely on the knowledge of the effective diffusion coefficient of water vapor in snow. Numerous previous studies have concluded that water vapor diffusion in snow is enhanced relative to that in air. Various field observations also indicate that for vapor transport in snow to be explained by diffusion alone, the effective diffusion coefficient should be larger than that in air. Here we show using theory and numerical simulations on idealized and measured snow microstructures that, although sublimation and condensation of water vapor onto snow crystal surfaces do enhance microscopic diffusion in the pore space, this effect is more than countered by the restriction of diffusion space due to ice. The interaction of water vapor with the ice results in water vapor diffusing more than inert molecules in snow, but still less than in free air, regardless of the value of the accommodation coefficient of water on ice. Our results imply that processes other than diffusion, probably convection, play a preponderant role in water vapor transport in dry snowpacks.

scholarly journals Photothermal Techniques Applied to the Determination of the Water Vapor Diffusion Coefficient and Thermal Diffusivity of Edible Films

2007 ◽  
Vol 23 (4) ◽  
pp. 457-461 ◽  
Author(s):  
M. A. AGUILAR-MENDEZ ◽  
E. San MARTIN-MARTINEZ ◽  
J. E. MORALES ◽  
A. CRUZ-OREA ◽  
M. R. JAIME-FONSECA
Keyword(s):  
Diffusion Coefficient ◽  
Water Vapor ◽  
Thermal Diffusivity ◽  
Edible Films ◽  
Photothermal Techniques ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion

The Influence of Vapor Attachment Kinetics on Snow Effective Properties

2021 ◽  
Author(s):  
Kevin Fourteau ◽  
Florent Domine ◽  
Pascal Hagenmuller
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Water Vapor ◽  
Heat And Mass Transfer ◽  
Surface Kinetics ◽  
Fast Kinetics ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion ◽  
Effective Coefficients ◽  
The Impact

<p>Proper modelling of heat and mass transfer in snow is a prerequisite for understanding snow metamorphism and simulating the mass and energy budget of a snowpack and the underlying ground. The transfer of heat and water vapor in snow can be described with macroscopic conservation equations, which include effective coefficients such as the snow thermal conductivity or the snow water vapor diffusion coefficient. Here, we investigate the impact of the surface kinetics of water vapor sublimation and deposition at the microscopic scale on these macroscopic equations, restraining ourselves to the limiting cases of slow and fast kinetics. In particular, we show that under the assumption of fast kinetics the thermal behavior of snow is similar to that of a regular inert medium, but with an enhanced conduction in the pores, due to latent heat transported with water vapor. Besides, faster kinetics increases the effective water vapor diffusion coefficient, which nonetheless remains less than that in free air. M<span>ost (but not all) available experimental investigations suggest that in snow, fast surface kinetics prevails, so that our results have numerous implications for the proper simulation of heat and mass transfer in snow.</span></p>

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