DEvice for the study of Critical LIquids and Crystallization - High Temperature Insert (DECLIC-HTI) - 01.09.14
Science Objectives for Everyone
DEvice for the study of Critical LIquids and Crystallization (DECLIC) is a multi-user facility utilized to study transparent media and their phase transitions in microgravity onboard the International Space Station (ISS). The High Temperature Insert (HTI) portion of DECLIC studies water (H20) near its critical point, and this insert will be installed for the first run of the DECLIC series of experiments.
Science Results for Everyone Information Pending
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:
October 2009 - May 2012
Previous ISS Missions
DECLIC is a continuation of an experiment conducted aboard the Mir Space Station and the Space Shuttle.
- DEvice for the study of Critical LIquids and Crystallization (DECLIC) is an apparatus developed by CNES for a NASA Express rack to support the study of material growth and the behavior of liquids near their critical point. It provides all subsystems required to operate an experiment dedicated insert installed on an optical bench. HTI (High Temperature Insert) is one of the modules that have been developed for DECLIC. The science of HTI is based on the analysis of optical and thermal properties of H20 near the critical points.
- HTI is the first insert that will be installed into DECLIC. HTI will be installed into DECLIC for initial run #1. HTI is a thermostat for critical fluid experiments involving water between 350
On a technical point of view, the DECLIC hardware uses two ISS program-provided lockers comprised of the lower locker called the ELectronic Locker (ELL), which houses power supplies, data handling and central regulation electronics for operation and control. It contains all necessary electrical and electronic systems that permit the facility to operate in an autonomous mode or with telescience interactions from the scientific team at the dedicated user center. The upper locker is the EXperiment Locker (EXL). It contains the DECLIC optical bench that receives the experiment insert in which specific scientific material is conditioned. This optical bench contains all optical and opto-electronic sensors that are necessary to perform measurements at low or high rate of acquisition.
High Temperature Insert (HTI) is operated by the Central Regulation Electronics (CRE), located in the EXL of the DECLIC instrument, which performs several functions such as: running thermal control algorithms (step-by-step procedures for solving a problem); making a precision acquisition of temperature sensors used by the thermal control algorithm; supplying accurate electrical voltages to be width modulated by insert electronics for heating elements and TEC (Thermal Electric Coolers); piloting power of heating elements; and managing the safe status of the insert (overheating).
HTI studies the transfer of heat and mass in near-critical water and measurement of its physical properties. The HTI design is intended to be later compatible with the use of possible toxic samples. The main functions of HTI are: to isolate sample from the Shuttle atmosphere; to provide an adequate thermal environment to the sample material; to enable optical observation of the sample; and to enable temperature measurements for the control and safety of the experiment.
Several experimental sequences are planned to explore pure water near its critical point (Tc = 374 dedrees Celsius and pc = 22 MPa), taking benefit from the high-level performances of the DECLIC facility, in particular high accuracy temperature control. The cell design satisfies several scientific and safety requirements. Since the cell is intended to study water in the vicinity of its critical point using the optical diagnoses of the DECLIC instrument, its optical design permits the observation by (incoherent) light transmission and grid shadowscopy of the complete cell volume, the turbidity measurements by laser light attenuation and static diffusion measurements by small angle and 90 degrees laser light scattering. Since this optical cell will be operated at high temperature and high pressure under the safety requirements of NASA on board the ISS, the cell design is conform to a maximum operating temperature of 405°C and pressure of 35 MPa, and to leak before burst safety constraint. Moreover, both the cell body and the transparent materials are resistant to corrosion at high temperature, especially corrosion within supercritical water and aqueous media.
Indeed, the following step concerns studies of supercritical fluids as media for chemical analysis and chemical processing, especially for the aqueous solutions which are involved in many promising applications and natural processes. For example, in the emerging environmental technology of supercritical water oxidation, or in material processing in hydrothermal batches, the temperature and the pressure are typically above the corresponding ones of the critical point of water and it is important to be able to predict the precipitation of various salts species from the complex mixture of water, salts, oxidant gases or liquids, organic solutes. Such high temperatures and pressures, added to the insufficiency of the fundamental knowledge on dissolved compounds in water might produce drastic modifications of the expected chemical behavior of the aqueous media. One of the important issues is the nature of the vapor-liquid criticality of aqueous solutions. Other issues, especially those connected with the large thermal expansion and compressibility of supercritical water, are of crucial importance for understanding the impact of the high fluid compressibility, for example the so-called piston effect which can lead to the interaction of the heat transfer with the chemical processes. DECLIC facility was designed to support the technical evolution of a new insert dedicated to this scientific challenge, in the frame of an international cooperative program.
The DECLIC facility provides power, communications, command/control, data storage, and multiple, flexible optical capabilities in support of the HTI experiment. 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 and the HTI insert. The results obtained with the HTI-DECLIC scientific program should benefit to the fluid management in space, and potentially the organic waste treatment considering the combustion in supercritical water processes, for future interplanetary manned missions.
DECLIC will enable the development of supercritical water reactors to be developed to treat waste as part of applications on Earth (treatment of household waste; nuclear waste; and extraction of oil fuels). This research will lead to spin-offs in the field of clean technologies for producing energy and treating waste.
After the HTI insert installation by the crew, the DECLIC runs automatically following the timeline sequences operated by the payload control center (CADMOS in Toulouse, France). During the first increment of DECLIC utilization on board the ISS, scientific modules are planned to complete the HTI scientific program. Each sequence duration is typically from 10 days up to 20 days, and the total program duration using the HTI insert is about 40 days. Data produced are stored on two DECLIC hard disks, and transmitted to ground in differed time by telemetry. Few information is transmitted to ground by real time telemetry, allowing the investigator to monitor the experiments. The data sent to ground are stored at the CADMOS operational center, and transmitted to the scientific User Home Base (UHB) at ICMCB in Bordeaux.
The ISS crew will install the DECLIC hardware into an EXPRESS Rack in the U.S. Laboratory. The HTI insert will be installed into DECLIC for 90 days. Crew participation is not required during the run(s). Tape change-out will be required by the crew at some stage during the run(s). Typical timeline of an experiment with HTI inside DECLIC consists in thermal cycling of the fluid cell above and below the critical temperature (around 374°C). A first experiment is dedicated to the precise determination of the critical temperature of the fluid cell observed in transmission. This procedure uses the automatic method implemented in DECLIC software, based on the analysis of the turbidity of the fluid cell when approaching the gas-liquid transition. Due to the very high compressibility of near critical fluids close to the critical point, long time duration are necessary to approach the critical temperature Tc. A logarithmic scale is used for temperature distance to Tc (e.g. : 1K, 0.3K; 100mK, 30mk, etc?). The high performance of the HTI thermostat inside DECLIC allows to perform calibrated temperature steps of amplitude better than 1 mK at high temperature around Tc. Duration of each temperature step is then calculated adequately with the temperature distance to Tc.
Ground Based Results Publications
Image of the optical fluid cell for the study of water properties inside DECLIC-HTI. Image courtesy of CNES.
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Pure water above the critical point observed in wide field transmission during ground tests of DECLIC-HTI. Image courtesy of CNES.
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The deformation of the shadow of a grid evidences some density gradients inside the cell. Image courtesy of CNES.
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