A dynamic simulation of a large scale existing refrigerator has been performed using the software Aspen Hysys(R). The model comprises the typical equipments of a cryogenic system: heat exchangers, ...expanders, helium phase separators and cold compressors. It represents the 400 W @ 1.8 K Test Facility located at CEA-Grenoble. This paper describes the model development and shows the possibilities and limitations of the dynamic module of Aspen Hysys(R). Then, comparison between simulation results and experimental data are presented; the simulation of cooldown process was also performed.
Helium refrigeration system for the KSTAR Choi, C.H.; Chang, H.-S.; Park, D.S. ...
Fusion engineering and design,
11/2006, Letnik:
81, Številka:
23
Journal Article, Conference Proceeding
Recenzirano
The KSTAR, a tokamak with fully superconducting (SC) magnets, is under construction in the National Fusion Research Center (NFRC). For the proper operation of the KSTAR, the superconducting magnets ...have to be maintained below the critical temperature of the SC components while charged at their corresponding operation current values. In this paper, a large scale helium refrigeration system (HRS) which has been designed and developed to fulfill such a mission is presented.
The cold components of the KSTAR are kept at their operating temperatures thanks to various kinds of cryogenic helium which are produced in the cold box (C/B) of the HRS in combination with the supercritical helium (SHe) cryogenic circulators and a liquid helium (LHe) thermal damper (TD) located in the primary helium distribution box (D/B #1). The relative distribution of the cryogenic helium among the cooling channels of each cold component of the KSTAR is performed by the secondary helium distribution system which consists of the secondary distribution box (D/B #2) and the cryogenic transfer lines (CTL’s).
•Supersonic panel flutter analysis of aeroelastic systems incorporating viscoelastic materials.•The iterative reduction method is a powerful tool in the flutter prediction of aeroviscoelastic ...systems.•An efficient iterative scheme to predict the flutter of full and reduced aeroviscoelastic systems.•Verification of the proposed reduction method with those available in the open literature.
The flutter boundary prediction of complex aeroelastic systems is not an easy task. In some cases, these analyses may become prohibitive due to the high computational cost and time associated with the large number of degrees of freedom of the aeroelastic models, particularly when the aeroelastic model incorporates a control strategy with the aim of suppressing the flutter phenomenon, such as the use of viscoelastic treatments. In this situation, the use of a model reduction method is essential. However, the construction of a modal reduction basis for aeroviscoelastic systems is still a challenge, owing to the inherent frequency- and temperature-dependent behavior of the viscoelastic materials. Thus, the main contribution intended for the present study is to propose an efficient and accurate iterative enriched Ritz basis to deal with aeroviscoelastic systems. The main features and capabilities of the proposed model reduction method are illustrated in the prediction of flutter boundary for a thin three-layer sandwich flat panel and a typical aeronautical stiffened panel, both under supersonic flow.
The KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting (SC) magnets operated at 4.4 K. The cold components of KSTAR require a forced flow of ...supercritical helium for magnets and structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. A helium refrigeration system has been custom-designed for this project. The purpose of this paper is to give a brief overview of the proposed cryogenic system. The specified thermal loads for the different operating modes are presented. This specification results in the definition of a design mode for the refrigerator. The design and construction of the resulting 9 kW at 4.5-K Helium Refrigeration System (HSR) are presented.
Gravity assisted recovery of liquid xenon at large mass flow rates Virone, L.; Acounis, S.; Beaupère, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2018, Letnik:
893
Journal Article
Recenzirano
Odprti dostop
We report on a liquid xenon gravity assisted recovery method for nuclear medical imaging applications. The experimental setup consists of an elevated detector enclosed in a cryostat connected to a ...storage tank called ReStoX. Both elements are part of XEMIS2 (XEnon Medical Imaging System): an innovative medical imaging facility for pre-clinical research that uses pure liquid xenon as detection medium. Tests based on liquid xenon transfer from the detector to ReStoX have been successfully performed showing that an unprecedented mass flow rate close to 1 ton per hour can be reached. This promising achievement as well as future areas of improvement will be discussed in this paper.
XEMIS: A liquid xenon detector for medical imaging Gallego Manzano, L.; Bassetto, S.; Beaupere, N. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2015, Letnik:
787
Journal Article
Recenzirano
A new medical imaging technique based on the precise 3D location of a radioactive source by the simultaneous detection of 3 gamma rays has been proposed by Subatech laboratory. To take advantage of ...this novel technique a detection device based on a liquid xenon Compton telescope and a specific (beta(+), gamma) emitter radionuclide, Sc-44, are required. A first prototype of a liquid xenon time projection chamber called XEMIS1 has been successfully developed showing very promising results for the energy and spatial resolutions for the ionization signal in liquid xenon, thanks to an advanced cryogenics system, which has contributed to a high liquid xenon purity with a very good stability and an ultra-low noise front-end electronics (below 100 electrons) operating at liquid xenon temperature. The very positive results obtained with XEMIS1 have led to the development of a second prototype for small animal imaging. XEMIS2, which is now under development. To study the feasibility of the 3 gamma imaging technique and optimize the characteristics of the device, a complete Monte Carlo simulation has been also carried out. A preliminary study shows very positive results for the sensitivity, energy and spatial resolutions of XEMIS2. (C) 2014 Elsevier B.V. All rights reserved.
The Large Hadron Collider (LHC) is the largest particle accelerator in the world. It is a superconducting machine over 27 km in circumference. Its magnets and cavities require helium refrigeration ...and liquefaction over the temperature range of 1.8 K to 300 K. This is the largest cryogenic system in the world with respect to the needed cryogenic power: 144-kW equivalent power at 4.5 K. The LHC cryogenic system is composed of 8X18 kW at 4.5 K refrigerators, 8X2.4 kW at 1.8 K systems, 5 main valve boxes, more than 27 km of helium transfer lines and around 300 service modules connecting the transfer line to the magnet and cavity strings. More than half of these components have been designed, manufactured, installed and commissioned by Air Liquide. Due to the huge size of the project, the engineering, construction and commissioning of the equipment has lasted for 8 years, from the first order of equipment in 1998 to final commissioning in 2006. Specifications, architecture and the Air Liquide design of major components of the LHC Refrigeration System are presented in this paper.
The main cryogenic users of ITER are the superconducting magnet system and the cryogenic vacuum pumps. The magnet system consists of 18 toroidal field and six poloidal field coils and the central ...solenoid coils. The cryogenic vacuum pumps contain eight pumps for the vacuum vessel, up to four pumps for the neutral beam injectors and two for the tokamak cryostat.The paper presents the current design status of the ITER cryoplant and its operating features that allow stable and flexible operation for different plasma pulsing scenarios and transient operating modes including cool-down and coil quench. The LHe plant operates in a combined liquefaction / refrigeration mode. Liquefied helium is used for the coil current leads and for cool-down of the cryopumps after their regeneration at 80 K. The operating temperature of the LHe plant can vary in the range of 4.3 K to 4.5 K to satisfy different cooling demands of various plasma scenarios. The LHe plant is designed for a large variation ratio of refrigeration to liquefaction in order to facilitate filling of the coils with a large amount of supercritical helium after a standard cool-down or specific cool-down mode following a fast energy discharge.
PDF
