DEvice for the study of Critical LIquids and Crystallization - Alice Like Insert (DECLIC-ALI) - 07.15.14
ISS Science for Everyone
Science Objectives for Everyone DEvice for the study of Critical LIquids and Crystallization Alice Like Insert (DECLIC-ALI) studies liquids at the verge of boiling. The flow of heat during boiling events is different in microgravity than it is on Earth. Understanding how heat flows in fluids at the verge of boiling will help scientists develop cooling systems for use in microgravity.
Science Results for Everyone
Centre National d'Etudes Spatiales, Toulouse, , France
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
March 2010 - September 2012
Previous ISS Missions
DECLIC-ALI is a continuation of an experiment conducted aboard the Mir Space Station and the Space Shuttle.
- The temperature and pressure at which the distinction between the properties of the liquid and gas disappear (the two phases coexist in a critical phase) is called the critical point. DEvice for the study of Critical LIquids and Crystallization Alice Like Insert (DECLIC-ALI) DECLIC-ALI studies how heat flows in liquids which are just below the critical point in microgravity.
- This experiment uses a thermostat that will study certain liquids just below the critical point.
- This investigation is important for the development of cooling systems for use in space as well as systems which may be useful in waste disposal and recycling on earth.
Alice Like Insert (ALI) studies the transformation of fluids from the state of liquid/vapor coexistence to the supercritical single phase state. The objective of the ALI study is to use the DECLIC facility in the ISS to study a variety of equilibrium and non equilibrium phenomena using such near-critical fluids. These phenomena have in common the study of new, unexplored behavior of near critical fluids from which several breakthroughs can be expected.
ALI is intended to study near-ambient critical fluids (SF6 in first increments and possibly carbon dioxide (CO2) in future increments) and is installed in the Experiment Locker (EXL) of the DECLIC instrument. It provides the environment (set temperature in the range 30 degrees Celsius to 52 degrees Celsius) and stimuli for the 2 cells containing samples under study. One cell is used for direct observation, the other for interferometric (pertaining to the science of combining two or more waves) observation. The mechanical part accommodating the two fluid cells is called SCU (Sample Cell Unit).
These two experimental fluid cells housed in the SCU have a temperature that is monitored by a very accurate thermal regulation of the DECLIC facility. All the high-resolution and high-speed optical diagnostics are synchronized with in situ temperature and pressure measurements. The cells are adjusted to the selected monitoring rate of the thermal stimuli produced by the two heaters (thin resistive transparent layer or massive fluxmeter (instrument that measures the change of flow)).
Very compressible supercritical fluids such as SF6 in the vicinity of its critical point (45.5 degrees Celsius), can exhibit a very fast transport of heat through convective flows that are not caused by gravity. A hot boundary layer can expand and heat the bulk like a real "piston." Thermalization (the process of particles reaching thermal equilibrium through mutual interaction) has proved to be homogeneous in temperature (but not in density) following a dynamics which is intermediate between typical acoustic times and diffusive times. Many numerical simulations and experiments conducted onboard sounding rockets, Space Shuttle, and the orbital station MIR (ALICE I and ALICE II), have already demonstrated the existence of such a thermocompressible (related to the volume change of a fluid or solid as a response to a pressure change) transport of heat, and given explanation of its mechanisms. Taking into account this phenomenon is of major importance in order to understand the phenomena of critical behaviors.
The DECLIC facility provides power, communications, command/control, data storage, and multiple, flexible optical capabilities in support of each experiment. The knowledge gained will assist in the understanding of the behavior of cryogenic (of or relating to very low temperatures) rocket propellants for the study of dynamics regarding near-ambient temperature critical fluids. DECLIC is designed for telescience from the ground and will offer scientists the capability to remotely control experiment conditions onboard the ISS provided by DECLIC lockers.
The use of near-critical fluids allows important parameters (e.g., compressibility of supercritical fluids, density of gas and liquid phases, surface tension) to be easily varied in a scaled way by using small changes in temperature. The readily variable properties of near-critical fluids makes them appealing candidates for studying numerous interesting phenomena valid for all fluids, which will ultimately leads to the development of improved solvents for chemistry and the environment.
: The DECLIC-ALI Experiment is scheduled over a period of 74 days. DECLIC-ALI requires the collection of both temperature and pressure measurements. The DECLIC-ALI operation consists of a number of thermal cycles under various diagnostics. The first 2 cells, filled with SF6, will be studied simultaneously in the same insert during approximately a 2-month period of experiment running time. The status of the ongoing experiment will be reported to the ground via telemetry. The experiment survey by the crew is limited to occasionally checking the front panel LEDs. In case of alarm (red LED), the crew may report to ground and wait for instructions (either leave as is; ground will recover experiment; or it can be switched off for the end of the experiment).
The ISS crew will install the DECLIC hardware into an EXPRESS Rack in the U.S. Laboratory. After the first insert (ALI) is installed into DECLIC, the facility must be powered on to begin commissioning. The commissioning goes through a sequence of steps initiated from the ground to check the hardware integrity and software functions. Once commissioning is complete, the run is started. Crew participation is not required during the runs. The ALI insert will be installed into DECLIC for the first run of the DECLIC series of experiments (74 days). Tape change-out by the crew will be required at selected stages in the run(s).
Lecoutre C, Garrabos Y, Beysens D, Nikolayev V, Hahn I. Boiling phenomena in near-critical SF6 observed in weightlessness . Acta Astronautica. 2014 March; epub: 10 pp.
Ground Based Results Publications
DECLIC: French experiment on ISS reveals new insights