Passive wine macromixing from 3D natural convection for different winery tank shapes: application to lees resuspension

2020 ◽  
Vol 21 (2) ◽  
pp. 207
Author(s):  
Fabien Bogard ◽  
Fabien Beaumont ◽  
Yann Vasserot ◽  
Sébastien Murer ◽  
Florica Simescu-Lazar ◽  
...  
Keyword(s):  
Natural Convection ◽  
Fluid Mixing ◽  
Thermal Gradients ◽  
Laboratory Studies ◽  
Literature Study ◽  
Temperature Variations ◽  
Laser Tomography ◽  
Internal Mixing ◽  
Internal Fluid

The works presented in this paper aim at investigating the problems related to the clarification of wines when random passive resuspension of lees occurs. More precisely, resuspension is addressed when temperature variations occur between the wine stored in tanks and the external surroundings of the tanks. From in situ laboratory studies involving laser tomography techniques, it is shown that low temperature gradients between a wine containing light lees and its external environment induce mass transfer by natural convection, generating enough fluid energy to resuspend the light lees in the liquid phase. The experiments are then complemented by numerical, CFD-based simulations focused on the role played by the geometry of different commercial tanks in the intensity of internal mixing. Finally, the groundwork for a study on a new internal design of the tanks by helical grooving is presented. To the best of the authors' knowledge, no literature study mentions the influence of thermal gradients on the resuspension of light lees and the influence of winery tank shapes on the internal fluid mixing intensity.

scholarly journals Combined Experimental and CFD Approach of Two-Phase Flow Driven by Low Thermal Gradients in Wine Tanks: Application to Light Lees Resuspension

Foods ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 865
Author(s):  
Fabien Bogard ◽  
Fabien Beaumont ◽  
Yann Vasserot ◽  
Florica Simescu-Lazar ◽  
Blaise Nsom ◽  
...  
Keyword(s):  
Two Phase Flow ◽  
Flow Behavior ◽  
Full Scale ◽  
Thermal Gradients ◽  
Phase Flow ◽  
Two Phase ◽  
Temperature Variations ◽  
Laser Tomography ◽  
Dependent Flow

In winemaking, clarification and stabilization are the processes by which insoluble matter suspended in the wine (called lees) is removed before bottling. The light lees represent 2–4% of the total wine volume. Under certain circumstances, resuspension of lees may occur. The resuspension of lees has been attributed to temperature variations between the wine stored in tanks and the environment of the cellar. From in situ, laboratory-scale studies involving laser tomography techniques, it was shown that low (positive or negative) thermal gradients between a wine tank containing light lees and its external environment induce mass transfer by natural convection. To extrapolate these findings to full-scale tanks, an Eulerian-Eulerian multiphase CFD model was applied to simulate the two-phase flow behavior as a function of temperature variations on a 24–h cycle. Numerical temperature and time-dependent flow patterns of both wine and lees confirm that low thermal gradients induce sufficient fluid energy to resuspend the lees, thus showing that the laboratory results can be extrapolated to full-scale tanks.

Studies on radionuclide transport behaviour–The next generation of in-situ experiments at the Grimsel Test Site

2009 ◽  
Vol 1193 ◽  
Author(s):  
Andrew James Martin ◽  
Ingo Blechschmidt
Keyword(s):  
Shear Zone ◽  
Diffusion Processes ◽  
Test Site ◽  
Core Material ◽  
Laboratory Studies ◽  
Grimsel Test Site ◽  
And Migration ◽  
Colloid Formation

AbstractTwo recent ongoing major projects at the Grimsel Test Site (GTS) (www.grimsel.com) that were initiated to simulate the long-term behaviour of radionuclides in the repository near-field and the surrounding host rock are presented: the Colloid Formation and Migration (CFM) project, which focuses on colloid generation and migration from a bentonite source doped with radionuclides and the Long-Term Diffusion (LTD) project, which aims at in-situ verification and understanding of the processes that control the long-term diffusion of repository-relevant radionuclides. So far, the CFM project has principally involved: development and implementation of a state-of-the-art sealing concept to control hydraulic gradients in a shear zone to imitate repository-relevant conditions; extensive laboratory studies to examine bentonite erosion and colloid formation in a shear zone; and, development of models to estimate colloid formation and migration. The next stage will be to assess the behavior of bentonite colloids generated from a radionuclide spiked bentonite source-term emplaced into the controlled flow field of the shear zone. This will be coupled with further extensive laboratory studies in order to refine and evaluate the colloid models currently used in performance assessments. The LTD project consists of: a monopole diffusion experiment where weakly sorbing and non-sorbing radionuclides (3H, 22Na, 131I, 134Cs) have been circulating and diffusing into undisturbed rock matrix since June 2007; experiments to characterise pore space geometry, including determination of in-situ porosity with 14C doped MMA resin for comparison with laboratory derived data; a study of natural tracers to elucidate evidence of long-term diffusion processes; and, an investigation of the in-situ matrix diffusion paths in core material from earlier GTS experiments. Future experiments will focus on diffusion processes starting from a water-conducting feature under realistic boundary conditions.

scholarly journals In situ S/TEM Heating Experiments to Study the Effects of Cyclic Thermal Gradients in Additive Manufacturing Build Processes

2019 ◽  
Vol 25 (S2) ◽  
pp. 1864-1865
Author(s):  
Joerg R. Jinschek ◽  
Sriram Vijayan ◽  
Meiyue Shao ◽  
Cheng-Han Li
Keyword(s):  
Additive Manufacturing ◽  
Thermal Gradients

Calibration of Constant-Temperature Hot-Wire Anemometers at Low Velocities in Water with Variable Fluid Temperature

1972 ◽  
Vol 94 (1) ◽  
pp. 17-22 ◽  
Author(s):  
K. Hollasch ◽  
B. Gebhart
Keyword(s):  
Experimental Study ◽  
Natural Convection ◽  
Constant Temperature ◽  
Fluid Temperature ◽  
Hot Wire ◽  
Temperature Variations ◽  
Wire Probe ◽  
Temperature Mode

Calibration of hot-wire probes operated in a constant-temperature mode in water at low velocities is discussed. Operation under circumstances where natural convection effects are important is considered. A method of calibrating a constant-temperature hot-wire probe for variations in fluid temperature is presented. The method consists of varying wire overheat during calibration at a constant fluid temperature. A relation is derived analytically relating anemometer output with a variable overheat resistance to anemometer output with fluid temperature variations. An experimental study to verify the analysis is presented.

Influence of natural convection during upward directional solidification: A comparison between in situ X-ray radiography and direct simulation of the grain structure

2013 ◽  
Vol 61 (13) ◽  
pp. 4765-4777 ◽  
Author(s):  
G. Reinhart ◽  
Ch.-A. Gandin ◽  
N. Mangelinck-Noël ◽  
H. Nguyen-Thi ◽  
J.-E. Spinelli ◽  
...  
Keyword(s):  
Natural Convection ◽  
Directional Solidification ◽  
Grain Structure ◽  
Direct Simulation ◽  
X Ray

scholarly journals In situ observation of pH change during water splitting in neutral pH conditions: impact of natural convection driven by buoyancy effects

2020 ◽  
Vol 13 (12) ◽  
pp. 5104-5116
Author(s):  
Keisuke Obata ◽  
Roel van de Krol ◽  
Michael Schwarze ◽  
Reinhard Schomäcker ◽  
Fatwa F. Abdi
Keyword(s):  
Natural Convection ◽  
Water Splitting ◽  
In Situ Observation ◽  
Ph Change ◽  
Neutral Ph ◽  
Ph Conditions

Buoyancy-driven natural convection stabilizes the pH and reduces overpotentials during water splitting, both in near-neutral pH unbuffered and buffered solutions.

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