scholarly journals Influence of Vibration on Diffusion in Liquid Mixtures On-Board the International Space Station

2021 ◽  
Author(s):  
Aram Parsa

Experiments on-board the International Space Station experience a convective flow due to the oscillatory g-jitters induced by several sources such as crew activities, mechanical systems, thrusters firing, spacecraft docking, etc. Although g-jitter seems to have a major impact on diffusion-related experiments in Space, very few experimental studies have addressed this topic. This study examined the effect of oscillatory g-jitters on transport processes (fluid flow, heat transfer and mass transfer). Cubic rigid cells filled with water and isopropanol at different concentrations were subjected to thermal gradients and forced vibrations. The cells were exposed to different levels of vibration in terms of frequency and amplitude, which were applied perpendicular to the temperature gradient. The full transient Navier Stokes equations coupled with the mass and heat transfer formulas were solved numerically using the control volume technique. The physical properties of the fluid mixture such as the density were determined using two different models. The effect of different levels of vibration on the flow was analysed and the results were compared in a benchmark study with other scientific groups. The effect of the diffusion coefficients variation and other physical properties on the temperature and concentration distribution was compared to those results obtained with constant diffusion coefficients. Results show that use of variable physical properties in the modelling produces different flow patterns and component concentration. By examining different flow patterns, it was found that the effect of using variable coefficients is much more significant in the cases with high Rayleigh vibration that result in strong flow when compared with numerical analysis using constant variables. The numerical analysis was also performed for the actual experiment on board the International Space Station. The same trend was seen for both the numerical and experimental results. However, the separation of components was higher in the experiment in comparison with the numerical analysis. This was discussed in detail for various scenarios in terms of the applied frequency and amplitude. Recommendations are made according to the findings from this study for the improvement of accuracy in the numerical and experimental analyses of future diffusion experiments in Space.

2021 ◽  
Author(s):  
Aram Parsa

Experiments on-board the International Space Station experience a convective flow due to the oscillatory g-jitters induced by several sources such as crew activities, mechanical systems, thrusters firing, spacecraft docking, etc. Although g-jitter seems to have a major impact on diffusion-related experiments in Space, very few experimental studies have addressed this topic. This study examined the effect of oscillatory g-jitters on transport processes (fluid flow, heat transfer and mass transfer). Cubic rigid cells filled with water and isopropanol at different concentrations were subjected to thermal gradients and forced vibrations. The cells were exposed to different levels of vibration in terms of frequency and amplitude, which were applied perpendicular to the temperature gradient. The full transient Navier Stokes equations coupled with the mass and heat transfer formulas were solved numerically using the control volume technique. The physical properties of the fluid mixture such as the density were determined using two different models. The effect of different levels of vibration on the flow was analysed and the results were compared in a benchmark study with other scientific groups. The effect of the diffusion coefficients variation and other physical properties on the temperature and concentration distribution was compared to those results obtained with constant diffusion coefficients. Results show that use of variable physical properties in the modelling produces different flow patterns and component concentration. By examining different flow patterns, it was found that the effect of using variable coefficients is much more significant in the cases with high Rayleigh vibration that result in strong flow when compared with numerical analysis using constant variables. The numerical analysis was also performed for the actual experiment on board the International Space Station. The same trend was seen for both the numerical and experimental results. However, the separation of components was higher in the experiment in comparison with the numerical analysis. This was discussed in detail for various scenarios in terms of the applied frequency and amplitude. Recommendations are made according to the findings from this study for the improvement of accuracy in the numerical and experimental analyses of future diffusion experiments in Space.


2021 ◽  
Author(s):  
Amirhossein Ahadi

Thermodiffusion or Soret effect is a heat and mass transfer phenomenon in a non-isothermal liquid and gas mixtures. This phenomenon is more pronounced in oil fields, usually due to the porous environment. A precise and better understanding of the thermodiffusion phenomena in multi-component mixtures results in a more accurate modeling of oil reservoirs. Accordingly, the main objective of this study is to investigate the thermodiffusion phenomenon in the multicomponent mixtures. In order to achieve this objective, two series of thermodiffusion experiments conducted on board the International Space Station (ISS) using the SODI (Selectable Optical Diagnostics Instrument) facility were analyzed. The first series of experiments aimed to study the effects of the forced vibration on the Soret phenomena. The experimental mixture was water and isopropanol with different compositions subjected to various temperature gradients normal to the vibrations. Results revealed maximum separation for the case with the minimum vibration and the lower temperature gradient; however, a linear relationship between Gershuni number and maximum separation was not found. On the other hand, the second series of experiment was aimed to the measurement of the diffusion coefficients of selected ternary mixtures. Mixtures of tetrahydronaphthalene-isobutylbenzene-dodecane at five different compositions were hosted in the DSC (Diffusion and Soret Coefficient) cell array. Thus, the Soret diffusion coefficients and the molecular diffusion coefficients of the mentioned hydrocarbon mixture at five different compositions have been reported. To process the results of these experiments an advance image processing technique was developed and implemented in an application with GUI (Graphical User Interface) for the Mach-Zehnder interferometer (MZI). Then, the application of the windowed Fourier transformation (WFT) to analyze the heat and mass transfer problem using the MZI setup is proposed. Results show that the WFT noticeably improves the measurement of concentration. This improvement is more evident for the ternary. It was shown that about 10% underestimation of the Soret coefficient would be resulted; if an accurate determination of the thermal time for the MZI is not used. The reliability and the repeatability of the MZI apparatus on board ISS to study thermodiffusion for binary and ternary mixtures were shown.


2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Rishi Raj ◽  
Jungho Kim ◽  
John McQuillen

The relatively poor understanding of gravity effects on pool boiling heat transfer can be attributed to the lack of long duration high-quality microgravity data, g-jitter associated with ground-based low gravity facilities, little data at intermediate gravity levels, and a poor understanding of the effect of important parameters even at earth gravity conditions. The results of over 200 pool boiling experiments with n-perfluorohexane as the test fluid performed aboard the International Space Station (ISS) are presented in this paper. A flat, transparent, constant temperature microheater array was used to perform experiments over a wide range of temperatures (55 °C < Tw < 107.5 °C), pressures (0.58 atm < P < 1.86 atm), subcoolings (1 °C ≤ ΔTsub ≤ 26 °C), and heater sizes (4.2 mm ≤ Lh ≤ 7.0 mm). The boiling process was visualized from the side and bottom. Based on this high quality microgravity data (a/g<10−6), the recently reported gravity scaling parameter for heat flux, which was primarily based on parabolic flight experiments, was modified to account for these new results. The updated model accurately predicts the experimental microgravity data to within ±20%. The robustness of this framework in predicting low gravity heat transfer is further demonstrated by predicting many of the trends in the pool boiling literature that cannot be explained by any single model.


2011 ◽  
Vol 24 (3) ◽  
pp. 189-194 ◽  
Author(s):  
Balázs Tóth ◽  
ESA’s Science Management, Payload Development and Operations teams ◽  
Science Teams ◽  
Space Industry

2021 ◽  
Author(s):  
Amirhossein Ahadi

Thermodiffusion or Soret effect is a heat and mass transfer phenomenon in a non-isothermal liquid and gas mixtures. This phenomenon is more pronounced in oil fields, usually due to the porous environment. A precise and better understanding of the thermodiffusion phenomena in multi-component mixtures results in a more accurate modeling of oil reservoirs. Accordingly, the main objective of this study is to investigate the thermodiffusion phenomenon in the multicomponent mixtures. In order to achieve this objective, two series of thermodiffusion experiments conducted on board the International Space Station (ISS) using the SODI (Selectable Optical Diagnostics Instrument) facility were analyzed. The first series of experiments aimed to study the effects of the forced vibration on the Soret phenomena. The experimental mixture was water and isopropanol with different compositions subjected to various temperature gradients normal to the vibrations. Results revealed maximum separation for the case with the minimum vibration and the lower temperature gradient; however, a linear relationship between Gershuni number and maximum separation was not found. On the other hand, the second series of experiment was aimed to the measurement of the diffusion coefficients of selected ternary mixtures. Mixtures of tetrahydronaphthalene-isobutylbenzene-dodecane at five different compositions were hosted in the DSC (Diffusion and Soret Coefficient) cell array. Thus, the Soret diffusion coefficients and the molecular diffusion coefficients of the mentioned hydrocarbon mixture at five different compositions have been reported. To process the results of these experiments an advance image processing technique was developed and implemented in an application with GUI (Graphical User Interface) for the Mach-Zehnder interferometer (MZI). Then, the application of the windowed Fourier transformation (WFT) to analyze the heat and mass transfer problem using the MZI setup is proposed. Results show that the WFT noticeably improves the measurement of concentration. This improvement is more evident for the ternary. It was shown that about 10% underestimation of the Soret coefficient would be resulted; if an accurate determination of the thermal time for the MZI is not used. The reliability and the repeatability of the MZI apparatus on board ISS to study thermodiffusion for binary and ternary mixtures were shown.


2021 ◽  
Author(s):  
Amirhossein Ahadi

Thermodiffusion or Soret effect is a heat and mass transfer phenomenon in a non-isothermal liquid and gas mixtures. This phenomenon is more pronounced in oil fields, usually due to the porous environment. A precise and better understanding of the thermodiffusion phenomena in multi-component mixtures results in a more accurate modeling of oil reservoirs. Accordingly, the main objective of this study is to investigate the thermodiffusion phenomenon in the multicomponent mixtures. In order to achieve this objective, two series of thermodiffusion experiments conducted on board the International Space Station (ISS) using the SODI (Selectable Optical Diagnostics Instrument) facility were analyzed. The first series of experiments aimed to study the effects of the forced vibration on the Soret phenomena. The experimental mixture was water and isopropanol with different compositions subjected to various temperature gradients normal to the vibrations. Results revealed maximum separation for the case with the minimum vibration and the lower temperature gradient; however, a linear relationship between Gershuni number and maximum separation was not found. On the other hand, the second series of experiment was aimed to the measurement of the diffusion coefficients of selected ternary mixtures. Mixtures of tetrahydronaphthalene-isobutylbenzene-dodecane at five different compositions were hosted in the DSC (Diffusion and Soret Coefficient) cell array. Thus, the Soret diffusion coefficients and the molecular diffusion coefficients of the mentioned hydrocarbon mixture at five different compositions have been reported. To process the results of these experiments an advance image processing technique was developed and implemented in an application with GUI (Graphical User Interface) for the Mach-Zehnder interferometer (MZI). Then, the application of the windowed Fourier transformation (WFT) to analyze the heat and mass transfer problem using the MZI setup is proposed. Results show that the WFT noticeably improves the measurement of concentration. This improvement is more evident for the ternary. It was shown that about 10% underestimation of the Soret coefficient would be resulted; if an accurate determination of the thermal time for the MZI is not used. The reliability and the repeatability of the MZI apparatus on board ISS to study thermodiffusion for binary and ternary mixtures were shown.


2021 ◽  
Author(s):  
Amirhossein Ahadi

Thermodiffusion or Soret effect is a heat and mass transfer phenomenon in a non-isothermal liquid and gas mixtures. This phenomenon is more pronounced in oil fields, usually due to the porous environment. A precise and better understanding of the thermodiffusion phenomena in multi-component mixtures results in a more accurate modeling of oil reservoirs. Accordingly, the main objective of this study is to investigate the thermodiffusion phenomenon in the multicomponent mixtures. In order to achieve this objective, two series of thermodiffusion experiments conducted on board the International Space Station (ISS) using the SODI (Selectable Optical Diagnostics Instrument) facility were analyzed. The first series of experiments aimed to study the effects of the forced vibration on the Soret phenomena. The experimental mixture was water and isopropanol with different compositions subjected to various temperature gradients normal to the vibrations. Results revealed maximum separation for the case with the minimum vibration and the lower temperature gradient; however, a linear relationship between Gershuni number and maximum separation was not found. On the other hand, the second series of experiment was aimed to the measurement of the diffusion coefficients of selected ternary mixtures. Mixtures of tetrahydronaphthalene-isobutylbenzene-dodecane at five different compositions were hosted in the DSC (Diffusion and Soret Coefficient) cell array. Thus, the Soret diffusion coefficients and the molecular diffusion coefficients of the mentioned hydrocarbon mixture at five different compositions have been reported. To process the results of these experiments an advance image processing technique was developed and implemented in an application with GUI (Graphical User Interface) for the Mach-Zehnder interferometer (MZI). Then, the application of the windowed Fourier transformation (WFT) to analyze the heat and mass transfer problem using the MZI setup is proposed. Results show that the WFT noticeably improves the measurement of concentration. This improvement is more evident for the ternary. It was shown that about 10% underestimation of the Soret coefficient would be resulted; if an accurate determination of the thermal time for the MZI is not used. The reliability and the repeatability of the MZI apparatus on board ISS to study thermodiffusion for binary and ternary mixtures were shown.


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