scholarly journals Closure conditions for a one temperature non-equilibrium multi-component model of baer-nunziato type

2019 ◽  
Vol 66 ◽  
pp. 42-60 ◽  
Author(s):  
M. Hantke ◽  
S. Müller
Keyword(s):  
Water Vapor ◽  
Physical Properties ◽  
Sufficient Conditions ◽  
Component Model ◽  
Interfacial Velocity ◽  
Mathematical Properties ◽  
Chemical Potentials ◽  
Closure Conditions ◽  
Velocity Pressure ◽  
Non Equilibrium

A class of non-equilibrium models for compressible multi-component uids is investigated. These models are subject to the choice of interfacial pressures and interfacial velocity as well as relaxation terms for velocity, pressure and chemical potentials. Sufficient conditions are derived for these quantities that ensure meaningful physical properties such as a non-negative entropy production and thermodynamical stability as well as mathematical properties such as hyperbolicity. For the relaxation of chemical potentials a three-component model gas-water-vapor is considered.

scholarly journals Effect of hot calendering on physical properties and water vapor transfer resistance of bacterial cellulose films

2016 ◽  
Vol 51 (21) ◽  
pp. 9562-9572 ◽  
Author(s):  
V. L. D. Costa ◽  
A. P. Costa ◽  
M. E. Amaral ◽  
C. Oliveira ◽  
M. Gama ◽  
...  
Keyword(s):  
Water Vapor ◽  
Physical Properties ◽  
Bacterial Cellulose ◽  
Transfer Resistance ◽  
Cellulose Films ◽  
Vapor Transfer ◽  
Water Vapor Transfer

Kinetic effects during ocean evaporation: observed relationship with wind speed 

2021 ◽  
Author(s):  
Daniele Zannoni ◽  
Hans Christian Steen-Larsen ◽  
Andrew Peters ◽  
Árný Erla Sveinbjörnsdóttir
Keyword(s):  
Water Vapor ◽  
Wind Speed ◽  
Water Interface ◽  
Fractionation Factor ◽  
Wind Speeds ◽  
Air Water Interface ◽  
Kinetic Fractionation ◽  
Speed Effect ◽  
Equilibrium Fractionation ◽  
Non Equilibrium

<p>Water vapor has a fundamental role in weather and climate, being the strongest natural greenhouse gas in the Earth’s atmosphere. The main source of water vapor in the atmosphere is ocean evaporation, which transfers a large amount of energy via latent heat fluxes. In the past, evaporation was intensively studied using stable isotopes because of the large fractionation effects involved during water phase changes, providing insights on processes occurring at the air-water interface. Current theories describe evaporation near the air-water interface as a combination of molecular and turbulent diffusion processes into separated sublayers. The importance of those two sublayers, in terms of total resistance to vapor transport in air, is expected to be dependent on parameters such as moisture deficit, temperature and wind speed. Non-equilibrium fractionation effects in isotopic evaporation models are then expected to be related to these physical parameters. In the last 10 years, several water vapor observations from oceanic expeditions were focused on the impact of temperature and wind speed effect, assuming the influence of those parameters on non-equilibrium fractionation in the marine boundary layer. Wind speed effect is expected to be small on total kinetic fractionation and was discussed at length but was not completely ruled out. With a gradient-diffusion approach (2 heights above the ocean surface) and Cavity Ring-Down Spectroscopy we have estimated non-equilibrium fractionation factors for <sup>18</sup>O/<sup>16</sup>O during evaporation, showing that the wind speed effect can be detected and has no significant impact on kinetic fractionation. Results obtained for wind speeds between 0 and 10 m s<sup>-1</sup> in the North Atlantic Ocean are consistent with the Merlivat and Jouzel (1979) parametrization for smooth surfaces (mean ε<sub>18</sub>=6.1‰). A small monotonic decrease of the fractionation parameter is observed as a function of 10 m wind speed (slope  ≅ 0.15 ‰ m<sup>-1</sup> s), without any evident discontinuity. However, depending on the data filtering approach it is possible to highlight a rapid decrease of the kinetic fractionation factor at low wind speed (≤ 2.5 m s<sup>-1</sup>). An evident decrease of fractionation factor is also observed for wind speeds above 10 m s<sup>-1</sup>, allowing to hypothesize the possible effect of sea spray in net evaporation flux. Considering the average wind speed over the oceans, we conclude that a constant kinetic fractionation factor for evaporation is a more simple and reasonable solution than a wind-speed dependent parametrization. </p><p> </p><p>Merlivat, L., & Jouzel, J. (1979). Global climatic interpretation of the deuterium‐oxygen 18 relationship for precipitation. Journal of Geophysical Research: Oceans, 84(C8), 5029-5033.</p>

scholarly journals A Non-Equilibrium Thermodynamics-Based View of the Kinetics of Autocatalytic Reactions – a Simple Illustrative Example

2020 ◽  
Author(s):  
Miloslav Pekař
Keyword(s):  
Second Law Of Thermodynamics ◽  
Rate Equations ◽  
Second Law ◽  
Equilibrium Thermodynamics ◽  
Autocatalytic Reactions ◽  
Chemical Potentials ◽  
Entropic Inequality ◽  
Reaction Stoichiometry ◽  
Kinetics Of ◽  
Non Equilibrium

Autocatalytic reactions are in a certain contrast with the linear algebra of reaction stoichiometry, on whose basis rate equations respecting the permanence of atoms are constructed. These mathematical models of chemical reactions are termed conservative.Using a non-equilibrium thermodynamics-based theory of chemical kinetics, this paper demonstrates how to properly introduce an autocatalytic step into a (conservative) rate equation. Further, rate equations based on chemical potentials or affinities are derived, and conditions for the consistency of rate equations with entropic inequality (the second law of thermodynamics) are illustrated.<br><div><br></div>

scholarly journals Physical Properties of Edible Films from Pangasius catfish Bone Gelatin-Breadfruits Strach with Different Formulations

2020 ◽  
Vol 3 (2) ◽  
pp. 42-47
Author(s):  
Rian Adhi Santoso ◽  
Yoni Atma
Keyword(s):  
Tensile Strength ◽  
Water Vapor ◽  
Moisture Content ◽  
Physical Properties ◽  
Food Packaging ◽  
Edible Films ◽  
Fish Bone ◽  
Edible Film ◽  
Japanese Industrial Standard ◽  
Water Vapor Transmission

Abstract— This research aims to provide edible film made from fish bone gelatin of Pangasius catfish mixed breadfruit starch with different formulations. The study was carried out through three stages including breadfruit starch isolation, edible films fabrication and analysis of physical properties of resulted edible film such as thickness, water vapor transmission, tensile strength and percent of elongation as well as moisture content. Edible films which were formulated from fish bone gelatin of Pangasius catfish by breadfruit starch addition have thickness values ranged of ​​0.084-0.123 mm, 6.08 - 16.77% of moisture content, water vapor transmission of 1.07 - 1.60 g/ m²/hour, tensile strength of 0.245 - 1.186 MPa, and percent of elongation around 70 - 87.14%. The edible films from gelatin of Pangasius catfish bone with breadfruit starch addition have physical characteristic which fulfill the standard requirements issued by Japanese Industrial Standard (JIS) Keywords— edible film; biodegradable materials; fish gelatin;breadfruit starch; food packaging    

Tensorielle chemische Potentiale — eine notwendige Erweiterung der Gibbs'schen Thermodynamik / Tensorial Chemical Potentials — a Necessary Extension of Gibbs' Thermodynamics

1975 ◽  
Vol 30 (11) ◽  
pp. 1433-1440 ◽  
Author(s):  
B. Stuke
Keyword(s):  
Chemical Potential ◽  
Spherically Symmetric ◽  
Relaxation Phenomena ◽  
Pressure Tensor ◽  
Equilibrium Thermodynamics ◽  
Equilibrium Conditions ◽  
Chemical Potentials ◽  
Thermodynamic Pressure ◽  
Fundamental Equations ◽  
Non Equilibrium

In a system with a non spherically symmetric pressure tensor, the chemical potential of at least one substance in the system has to be a tensor of the same character as the pressure. The necessary generalization of Gibbs' fundamental equations of thermodynamics is presented. Being already of consequence for equilibrium, this extension is more important for non-equilibrium thermodynamics, in particular for the proper thermodynamic formulation of general relaxation phenomena. Reasons are given why the distinction between dynamic and thermodynamic pressure, originating from the incomplete formulation of customary thermodynamics, is erroneous. Finally a tensorial temperature is introduced which can exist under extreme non-equilibrium conditions, e.g. shock waves

scholarly journals A non-equilibrium model for soil heating and moisture transport during extreme surface heating: the soil (heat–moisture–vapor) HMV-Model Version 1

2015 ◽  
Vol 8 (11) ◽  
pp. 3659-3680 ◽  
Author(s):  
W. J. Massman
Keyword(s):  
Soil Moisture ◽  
Water Vapor ◽  
Soil Temperature ◽  
Equilibrium Model ◽  
Laboratory Experiments ◽  
Source Term ◽  
Soil Water Potential ◽  
Residual Soil ◽  
Moisture Vapor ◽  
Non Equilibrium

Abstract. Increased use of prescribed fire by land managers and the increasing likelihood of wildfires due to climate change require an improved modeling capability of extreme heating of soils during fires. This issue is addressed here by developing and testing the soil (heat–moisture–vapor) HMV-model, a 1-D (one-dimensional) non-equilibrium (liquid–vapor phase change) model of soil evaporation that simulates the coupled simultaneous transport of heat, soil moisture, and water vapor. This model is intended for use with surface forcing ranging from daily solar cycles to extreme conditions encountered during fires. It employs a linearized Crank–Nicolson scheme for the conservation equations of energy and mass and its performance is evaluated against dynamic soil temperature and moisture observations, which were obtained during laboratory experiments on soil samples exposed to surface heat fluxes ranging between 10 000 and 50 000 W m−2. The Hertz–Knudsen equation is the basis for constructing the model's non-equilibrium evaporative source term. Some unusual aspects of the model that were found to be extremely important to the model's performance include (1) a dynamic (temperature and moisture potential dependent) condensation coefficient associated with the evaporative source term, (2) an infrared radiation component to the soil's thermal conductivity, and (3) a dynamic residual soil moisture. This last term, which is parameterized as a function of temperature and soil water potential, is incorporated into the water retention curve and hydraulic conductivity functions in order to improve the model's ability to capture the evaporative dynamics of the strongly bound soil moisture, which requires temperatures well beyond 150 °C to fully evaporate. The model also includes film flow, although this phenomenon did not contribute much to the model's overall performance. In general, the model simulates the laboratory-observed temperature dynamics quite well, but is less precise (but still good) at capturing the moisture dynamics. The model emulates the observed increase in soil moisture ahead of the drying front and the hiatus in the soil temperature rise during the strongly evaporative stage of drying. It also captures the observed rapid evaporation of soil moisture that occurs at relatively low temperatures (50–90 °C), and can provide quite accurate predictions of the total amount of soil moisture evaporated during the laboratory experiments. The model's solution for water vapor density (and vapor pressure), which can exceed 1 standard atmosphere, cannot be experimentally verified, but they are supported by results from (earlier and very different) models developed for somewhat different purposes and for different porous media. Overall, this non-equilibrium model provides a much more physically realistic simulation over a previous equilibrium model developed for the same purpose. Current model performance strongly suggests that it is now ready for testing under field conditions.

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