European Space Agency experiments on thermodiffusion of fluid mixtures in space (original) (raw)
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The numerical simulations of a thermodiffusion experiment in atmospheric pressure binary mixtures of water and isopropanol subject to micro-vibrations at reduced gravity are presented. The vibrations are induced on board ISS and FOTON-M3 due to many different reasons like crew activity, spacecraft docking or operating other experiments, etc. The effects of micro-gravity vibration were investigated in detail on all of the mixture properties. The influences of different cavity sizes as well as different signs of Soret coefficients in the solvent were considered. In this paper, the thermodiffusion experiment was subjected to two different g-jitter vibrations on board ISS and FOTON-M3 as a cavity with a lateral thermal gradient, filled with a mixture of water and isopropanol, is numerically simulated. The full steady-state Navier-Stokes equations, as well as the energy, mass transport and continuity equations were solved numerically using the finite element method. It must be noted that two different methods to present micro gravity vibrational acceleration on ISS and FOTON-M3 were performed and programmed in MATLAB to find proper value of acceleration at any step time. All physical properties including density, mass diffusion and thermodiffusion coefficients were assumed variable as function of temperature and concentration using PC-SAFT equation of state. Assuming all physical properties to be variable made the results more practical in comparison with the constant model, particularly in the ISS cases. The separation behavior of isopropanol and water in terms of the concentration profiles as well as the thermodiffusion coefficients was in agreement with the experimental trends with a small discrepancy for FOTON cases; however, the ISS results show a strong single convection cell that disturbed the pure diffusion process.
Microgravity Science and Technology, 2013
The numerical simulations of a thermodiffusion experiment in atmospheric pressure binary mixtures of water and isopropanol subject to micro-vibrations at reduced gravity are presented. The vibrations are induced on board ISS and FOTON-M3 due to many different reasons like crew activity, spacecraft docking or operating other experiments, etc. The effects of micro-gravity vibration were investigated in detail on all of the mixture properties. The influences of different cavity sizes as well as different signs of Soret coefficients in the solvent were considered. In this paper, the thermodiffusion experiment was subjected to two different g-jitter vibrations on board ISS and FOTON-M3 as a cavity with a lateral thermal gradient, filled with a mixture of water and isopropanol, is numerically simulated. The full steady-state Navier-Stokes equations, as well as the energy, mass transport and continuity equations were solved numerically using the finite element method. It must be noted that two different methods to present micro gravity vibrational acceleration on ISS and FOTON-M3 were performed and programmed in MATLAB to find proper value of acceleration at any step time. All physical properties including density, mass diffusion and thermodiffusion coefficients were assumed variable as function of temperature and concentration using PC-SAFT equation of state. Assuming all physical properties to be variable made the results more practical in comparison with the constant model, particularly in the ISS cases. The separation behavior of isopropanol and water in terms of the concentration profiles as well as the thermodiffusion coefficients was in agreement with the experimental trends with a small discrepancy for FOTON cases; however, the ISS results show a strong single convection cell that disturbed the pure diffusion process.
Non-intrusive techniques for thermal measurements in microgravity fluid science experiments
Advances in Space Research, 1986
Non intrusive techniques for thermal measurements in Microgravity Fluid~namics are considered in the paper: Liquid Crystals Tracers, Thermographic System, and Thin Foil Fluxmeter. Liquid crystals have been employed both as tracers (for the evaluation of the flow field organization) and as point thermometers (for the temperature distribution). Liquid surface measurements are performed in closed and open cells. Heat fluxes measurements have been performed by Thin Foil Fluxmeters and temperature by Thermographic Method. The Laboratory experimentation substantiate the applicability of these techniques in fluidynamics experimentation on Space Platforms.
Space experiments of thermocapillary convection in two-liquid layers
Science China-technological Sciences, 2002
In 1999, the space experiments on the Marangoni convection and thermocapillary convection in a system of two immiscible liquid layers in microgravity environment were conducted on board the Chinese scientific satellite SJ-5. A new system of two-layer liquids such as FC-70 liquid and paraffin was used successfully, with the paraffin melted in the space. Two different test-cells are subjected to
A new process for the determination of the Soret coefficient of a binary mixture under microgravity
International Journal of Thermal Sciences
In the presence of a gravity field or under microgravity, pure thermo-diffusion leads to very weak species separation in binary mixtures. To increase the species separation in the presence of gravity, many authors use thermo-gravitational diffusion in vertical columns (TGC). For a given binary mixture, the species separation between the top and the bottom of these columns depends on the temperature difference, ΔT, imposed between the two vertical walls facing each other, and the thickness, H, between these two walls (annular or parallelepipedic column). These studies show that, for a fixed temperature difference, the species separation is optimal for a thickness, H opt , much smaller than one millimetre. The species separation decreases sharply when the thickness H decreases with respect to this optimum value. It decreases progressively as H increases with respect to H opt. In addition, for mixtures with a negative thermo-diffusion coefficient, the heaviest component migrates towards the upper part of the column and the lightest one towards the lower part. The loss of stability of the configuration thus obtained leads to a brutal homogeneity of the binary solution. The objective of this study in microgravity was to increase the optimum of species separation. For this purpose, the binary fluid motion was provided by uniform velocities imposed on the two walls of the cavity facing each other. This forced flow led to species separation between the two motionless walls of the cavity. In this case, the fluid motion generated in the cavity was not dependent on the imposed temperature difference, ΔT contrarily to the case of thermogravitational column. Under these conditions and for a given column of thickness H, there are three independent control parameters: ΔT and the two velocities of the walls facing each other. Using the parallel flow approximation for a cell of large aspect ratio, the velocity, temperature and mass fraction fields within the cavity were determined analytically. Thus the parameters leading to optimal species separation were calculated. The analytical results were corroborated by direct numerical simulations. The present paper thus proposes a new process for the determination of the Soret coefficient, the thermodiffusion coefficient and mass-diffusion coefficient.
Experimental Investigation of Flow Condensation in Microgravity
Journal of Heat Transfer, 2013
Future manned space missions are expected to greatly increase the space vehicle's size, weight, and heat dissipation requirements. An effective means to reducing both size and weight is to replace single-phase thermal management systems with two-phase counterparts that capitalize upon both latent and sensible heat of the coolant rather than sensible heat alone. This shift is expected to yield orders of magnitude enhancements in flow boiling and condensation heat transfer coefficients. A major challenge to this shift is a lack of reliable tools for accurate prediction of two-phase pressure drop and heat transfer coefficient in reduced gravity. Developing such tools will require a sophisticated experimental facility to enable investigators to perform both flow boiling and condensation experiments in microgravity in pursuit of reliable databases. This study will discuss the development of the Flow Boiling and Condensation Experiment (FBCE) for the International Space Station (ISS),...
2021
In the present study, a two-dimensional numerical simulation was carried out for binary mixture. The influence of micro gravity vibration or acceleration on board Iinternational Space Station and FOTON-M3, influence of different cavities size as well as the effect of the sign of the Soret coefficient (fluid flow, heat and mass transfer and concentration) in the solvent were investigated in detail. It must be noted that based on previous experiences with this investigation using the same mixture and cavity by Saghir and Parsa [
Flow boiling CHF in microgravity
International Journal of Heat and Mass Transfer, 2005
Poor understanding of flow boiling in microgravity has recently emerged as a key obstacle to the development of many types of power generation and life support systems intended for space exploration. This study examines flow boiling CHF in microgravity that was achieved in parabolic flight experiments with FC-72 onboard NASAÕs KC-135 turbojet. At high heat fluxes, bubbles quickly coalesced into fairly large vapor patches along the heated wall. As CHF was approached, these patches grew in length and formed a wavy vapor layer that propagated along the wall, permitting liquid access only in the wave troughs. CHF was triggered by separation of the liquid-vapor interface from the wall due to intense vapor effusion in the troughs. This behavior is consistent with, and accurately predicted by the Interfacial Lift-off CHF Model. It is shown that at low velocities CHF in microgravity is significantly smaller than in horizontal flow on earth. CHF differences between the two environments decreased with increasing velocity, culminating in virtual convergence at about 1.5 m/s. This proves it is possible to design inertia-dominated systems by maintaining flow velocities above the convergence limit. Such systems allow data, correlations, and/or models developed on earth to be safely implemented in space systems.
Microgravity-Science and Technology , 2018
We report on thermodiffusion experiments conducted on the International Space Station ISS during fall 2016. These experiments are part of the DCMIX (Diffusion and thermodiffusion Coefficients Measurements in ternary Mixtures) project, which aims at establishing a reliable data base of non-isothermal transport coefficients for selected ternary liquid mixtures. The third campaign, DCMIX3, focuses on aqueous systems with water/ethanol/triethylene glycol as an example, where sign changes of the Soret coefficient have already been reported for certain binary subsystems. Investigations have been carried out with the SODI (Selectable Optical Diagnostics Instrument) instrument, a Mach-Zehnder interferometer set up inside the Microgravity Science Glovebox in the Destiny Module of the ISS. Concentration changes within the liquids have been monitored in response to an external temperature gradient using phase-stepping interferometry. The complete data set has been made available in spring 2017. Due to additionally available measurement time, it was possible to collect a complete data set at 30 • C and an almost complete data set at 25 • C, which significantly exceeds the originally envisaged measurements at a single temperature only. All samples could be measured successfully. The SODI instrument and the DCMIX experiments have proven reliable and robust, allowing to extract meaningful data even in case of unforeseen laser instabilities. First assessments of the data quality have revealed six out of 31 runs with some problems in image contrast and/or phase step stability that will require more sophisticated algorithms. This publication documents all relevant parameters of the conducted experiments and also events that might have an influence on the final results. The compiled information is intended to serve as a starting point for all following data evaluations.