bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extended lattice Gelfand–Dickey hierarchy
Authors: Takasaki Kanehisa 
Published: June 2022

Abstract
The lattice Gelfand–Dickey (GD) hierarchy is a lattice version of the GD hierarchy. A special case is the lattice KdV hierarchy. Inspired by recent work of Buryak and Rossi, we propose an extension of the lattice GD hierarchy. The extended system has an infinite number of logarithmic flows alongside the usual flows. We present the Lax, Sato and Hirota equations and a factorization problem of difference operators that captures the whole set of solutions. The construction of this system resembles the extended 1D and bigraded Toda hierarchy, but exhibits several novel features as well.
Development of a thermal control coating optimized for cryogenic space applications
Authors: Krenn A , Youngquist R , Gibson T , Snyder S 
Published: June 2022

AbstractAs NASA endeavors to extend the human presence in space beyond low Earth orbit, methods to efficiently store cryogenic propellants in space are required. Current state of the art rigid thermal control coatings absorb approximate 6% of the total solar irradiance, while state of the art thermal control paints absorb approximately 10% of the total solar irradiance. Consequently, radiative heat transfer a lone makes passive storage of cryogens in space impossible. A new rigid thermal control coating is in development and has achieved solar absorption values as low as -0.6 % (compared to a NIST standard) while maintaining high emissivity. This negative value for a rigid tile of pure yttria has required a new testing method be developed. Rigid tiles are very high performance but have more mass than paints and paper-th in coatings. Tiles must have a metallic substrate and create application challenges. While some use cases may necessarily address the challenges associated with rigid tiles in order to achieve required performance, a similar paint-like coating was also developed. The spray-on version of the new thermal control coating is easily applied to large complex surfaces and is very low mass. This version is also primarily yttria but includes a potassium bromide binder. Application to various substrates shows solar absorption values consistently below 5%, with a minimum of 2.8% achieved. Details of each version of this coating, along with test data is discussed.
Development of a space irradiance simulator for advanced studies and materials research
Authors: Swanger A M , Krenn A , Youngquist R , Gibson T L 
Published: June 2022

Abstract
A lab-scale experimental apparatus that mimics the solar-thermal environment of space has recently been developed and tested at NASA Kennedy Space Center in support of novel materials research for future space science and exploration applications. The Space Irradiance Simulator (SIRS) apparatus exposes specimens up to roughly 61 mm in diameter to a similar thermal environment that exists at distances as close as 0.4 AU from the Sun. This includes a high vacuum environment, access to a deep cryogenic background temperature with optical properties that closely imitate a blackbody, and irradiance from a broadband solar “point” source at fluxes as high as 9300 W/m2. Cooling is provided by a Gifford-McMahon cryocooler capable of 25 W of cooling power at 20 K, with a base temperature of 14 K. A commercially available Xenon lamp acts as the solar source, creating broadband electromagnetic radiation with a spectrum similar to that of the Sun. Light is beamed through the vacuum chamber and onto a sample suspended within the cold-mass via a flexible quartz fiber bundle in conjunction with a custom vacuum feedthrough. The system design, fabrication, and operation are discussed; and results from the initial checkout testing of the system are presented.
The effect of external heat inflow to the cryogenic liquid pressurized discharge process
Authors: Baek Seungwhan , Jung Youngsuk , Cho Kiejoo 
Published: June 2022

Abstract
The launch vehicle with a liquid propulsion system requires pressurization during the propellant discharge. While the launch vehicle is flying through the air layer, a process in which frictional heat is generated between the liquid propellant tank and the air layer can be assumed. External heat inflow occurs during the liquid discharging process, and it is necessary to investigate how the external heat influx affects the liquid pressurized discharge process. A test device was constructed to determine the effect of pressurization of external heat inflow. The test device consisted of a liquid tank located in a vacuum chamber and a heating device to simulate external heat inflow. The heating device is a halogen lamp. The cryogenic liquid discharge with and without external heat inflow was compared. It was confirmed that the amount of pressurant gas used was decreased when there was external heat inflow. External heat inflow contributes to the evaporation of the liquid, and the evaporated gas increases the pressure of the ullage.
Helium gas-gap heat switch for Sub-Kelvin refrigeration system
Authors: Xi Xiaotong , Yang Biao , Gao Zhaozhao , Chen Liubiao , Zhou Yuan , Wang Junjie 
Published: June 2022

Abstract
The heat switch is an indispensable thermal control device in the low-temperature system. The helium gas-gap heat switch plays a key role in Sub-Kelvin sorption coolers and adiabatic demagnetization refrigerators, and its effective switching between thermal conducting (ON state) and insulating (OFF state) is achieved by changing the pressure of the gas in the gap. In this paper, a4He gas-gap heat switch was designed. And the thermal characteristics at different cold block temperatures were experimentally tested, which provides a reference for the development of high-efficiency gas-gap heat switches.
Numerical study on pressure variation of marine liquefied natural gas (LNG) fuel tanks under sinusoidal sloshing excitation
Authors: Wu Sixian , Ju Yonglin 
Published: June 2022

Abstract
In this paper, a numerical model considering phase change and external heat leakage is established to study the pressure variation and temperature distribution of marine Liquefied Natural Gas (LNG) fuel tanks under sinusoidal sloshing excitation. The Volume of Fluid (VOF) method, coupled with the mesh motion treatment, is adopted to predict the movement of the vapor-liquid interface. The sinusoidal sloshing excitation is realized by a User-Defined Function (UDF). The feasibility of the numerical model is verified by comparisons with related fluid sloshing experiments. The thermal physical process in the LNG fuel tank under sloshing conditions and the static condition are compared, and the effects of sloshing amplitude and frequency on the pressure and temperature distribution of the tank are also studied. The results show that when the external sloshing excitation frequency is close to the first natural frequency of the LNG fuel tank, the tank pressure will drop rapidly in a short time, resulting in the shutdown of Natural Gas (NG) engine. Meanwhile, the influence of the sloshing excitation on the mass transfer is theoretically analyzed by the definition of the sloshing Nusselt number.
Thermodynamic analysis of ideal thermocompressor based on Euler view
Authors: Wu S S , Wang J , Zhang H C , Huang C J , Li L F , Zhou Y 
Published: June 2022

Abstract
The thermocompressor is the driving source and the core heat-work conversion part of Vuilleumier (VM) refrigerator, which cause pressure fluctuation of the gas by converting the thermal energy at a constant volume. The thermocompressor is consists of cylinder, heater, generator, cooler, displacer, driving mechanism, load, hot cavity and cold cavity. Therefore, the ideal thermocompressor was introduced for thermal analysis to simplify the thermodynamic process and components. In order to better understand the principle of heat-work conversion in the ideal thermocompressor, firstly, the thermodynamic concept of the variable mass system that can be used in the ideal thermocompressor was introduced. Secondly, the thermodynamic process of the ideal thermocompressor under the Euler view was analyzed. Thirdly, the internal operation characteristics of the thermocompressor without load and driving displacer type refrigerator were discussed. At last, the distributions of enthalpy flow, entropy flow and exergy flow in all parts of the ideal thermocompressor were carried out. The results show that the thermocompressor does not output the net entropy flow to the load in one cycle and the flow exergy output by thermocompressor is equal in quantity to the acoustic power output by thermocompressor.
Study on reducing the impact to EAST cryogenic system caused by the failure of load devices
Authors: Yu Q , Lu X F , Zhou Z W , Zhuang M , Zhang Q Y 
Published: June 2022

Abstract
EAST tokamak has complicated supercritical helium loops for cooling the superconducting magnets and other thermal loads. When failures occur in these load devices, such as magnet quench or vacuum failure, a large amount of helium evaporated in the cryogenic circuits returns to the cryogenic distribution system, which makes the pressures rise and the helium returning to the refrigerator increases. The refrigerator will run in a supercooling state and the turbine protection shutdown will be triggered with probability, which further affects the operation of the cryogenic system. This paper analyzes the archive data of this undesired phenomenon, the EAST cryogenic system model based on EcosimPro is used to simulate the dynamic process during the failure. A split-range control scheme to stabilize the pressures in the distribution system under failure state is proposed. the control module is developed in EcosimPro, simulation results show that it could achieve a satisfactory control performance and reduce the impact caused by the failure.
Liquid helium level regulation improvement in the LHC electrical distribution feedboxes
Authors: Bradu B , Coppier H , Gery J , Pezzetti M , Tovar A 
Published: June 2022

Abstract
An important cryogenic equipment of the Large Hadron Collider (LHC) consists in the electrical distribution feedboxes (DFBs) which are used to power the superconducting magnets of the accelerator. These feedboxes contain the current leads achieving the electrical transition between the copper cables at ambient temperature to the Niobium-Titanium wires at cryogenic temperature, immersed in a liquid helium bath at 4.5 K. This liquid helium bath must be regulated at a defined level to allow the powering of the LHC, and this regulation often caused non-availabilities in the past. This paper presents the development of a new control scheme, coupled to the existing PID level controller, significantly improving this regulation, and rejecting disturbances in a highly efficient manner. First, a dynamic model of the DFBs was developed in the EcosimPro software using the CRYOLIB library to reproduce in simulation the regulation issues. In a second step, the new proposed regulation modes were tested and validated in simulation. Finally, the paper will present the results obtained in 2021 on a real DFBs operation in the LHC, validating the new control approach prior its massive deployment all around the LHC cryogenics.
Experimental study of different structural parameters on gas lubricated spiral groove thrust bearing for cryogenic turbo expander
Authors: Zhang X H , Li K R , Yan H , Zheng L W , Ke C L , Dong B , Peng N , Liu L Q , Gong L H 
Published: June 2022

Abstract
With the development of high speed and miniaturization of turbo expander, the gas-lubricated spiral groove dynamic pressure gas bearing plays an important role. An experimental study on the gas-lubricated spiral groove gas thrust bearing is carried out to research the relationship between the bearing loading capacity and the structural parameters such as the spiral angle, the groove length ratio, the groove width ratio and the rotating speed. The contrast experiment of spiral groove structure on thrust disc and bearing end face was also carried out. The experimental results show that the optimum spiral angle is 20°, the optimum groove length ratio is 0.61∼0.68, the optimum groove width ratio is 0.5∼0.55, and the new structure of the spiral groove on the thrust disc will increase the bearing loading capacity by 7.6% than the traditional structure.
Analysis of the effect of friction of hybrid ball bearings on grease evaporation in cold compressors
Authors: Su H , Shang J , Lv C , Wu J H 
Published: June 2022

Abstract
Bearings are the essential part of the cold compressor rotor system, which has a great influence on the operation of cold compressor. Hybrid ball bearing has been successfully applied in cold compressors with the lubrication of grease. With the high-speed rotation of the cold compressor, the bearing will be affected by the axial thrust of the impeller, which will cause friction, and the grease will be impacted by the frictional heat. To understand the influence of frictional heat on grease evaporation, it is important to study the bearing heat generation. In this article, the application of grease-lubricated hybrid ball bearings in cold compressors was introduced. Based on the parameters of a successfully applied impeller and a ball bearing of the cold compressor, the axial thrust of impeller was calculated, and a bearing frictional heat generation model was proposed, which considered the dynamic change of the axial thrust of the cold compressor impeller. The heat generation and temperature of the bearing was analyzed and calculated using the proposed model. According to the results of the calculation and practical experience, a test was performed on high-speed greases, and the adding amount of grease was estimated with reference to the bearing temperature.
Process analysis and control flow design of the 1kW @ 4.5K helium refrigerator for NNBI
Authors: Li J Q , Zhou Z W , Zhang Q Y , Zhu Z G 
Published: June 2022

Abstract
A helium cryogenic system with a cooling capacity of 1kW@4.5K was designed in order to support the NNBI(Negative ion based Neutral Beam Injection system) test facility, cryopumping test facility and beam source test facility, which consists of a helium compressor with its storage and recovery system, 1kW@4.5K helium refrigerator, a cryogenic distribution valve box, cryogenic transfer lines and a helium Dewar, etc. Based on the SIMATIC S7-1500H PLC, the cryogenic control system can realize seven major operational modes, including the independent refrigeration mode and independent liquefaction mode, etc. On the basis of process analysis, the control flow of the NNBI helium cryogenic system in each operational modes was designed and will be presented in this paper. It will direct the control system to realize automatic control in multiple operational modes.
Experimental investigation of vertical neon pulsating heat pipe for superconducting magnet cooling application
Authors: Dixit T , Authelet G , Mailleret C , Gouit F , Baudouy B 
Published: June 2022

Abstract
Pulsating heat pipes (PHPs) are two-phase flow, thermal transport carriers characterized by ease of fabrication, flexibility of compactness and variable heat transfer capability. Conventionally, cooling of superconducting magnets is realized by using cryogen cooling system. Cryogenic PHPs are emerging as the new-age economical alternative that can passively contribute in efficient transport of generated heat to active cryocoolers. Nevertheless, a number of challenges must be addressed to materialize this union. For this objective, a multipurpose experimental test-rig has been developed which will allow different critical parameters of cryogenic PHPs to be investigated. The preliminary tests are conducted using neon as the working fluid. The PHP capillaries, made of SS304, have an outer diameter of 2.5 mm and a projected length of 400 mm with the adiabatic part having twice the length as compared to that in the condenser and evaporator. It consists of 20 parallel tubes forming a closed-loop and are tested in gravity-assisted environment. Employing the Sumitomo RDE-418D4 4K Cryocooler, the condenser temperature is controlled at the neon saturation temperature, around 27 K. The thermal performance of this cryogenic PHP is recorded at different evaporator heat load conditions. We report here the temperature evolution of PHP evaporator, and condenser as well as the pressure oscillations with time.
Overview and status of the Long-Baseline Neutrino Facility Far Site cryogenics system
Authors: Montanari D , Adamowski M , Bremer J , Delaney M , Doubnik R , Freitag J , Haaf K , Nichols T , Parchet A , Young I 
Published: June 2022

Abstract
The Sanford Underground Research Facility (SURF) will host the Far Detector of the Deep Underground Neutrino Experiment (DUNE), an international multi-kiloton Long-Baseline neutrino experiment that will be installed about one and a half kilometers underground in Lead, SD. Detectors will be located inside four cryostats filled with almost 70,000 metric tons of ultrapure liquid argon, with a level of impurities lower than 100 parts per trillion of oxygen equivalent contamination. The cryogenics infrastructure supporting this experiment is provided by the Long-Baseline Neutrino Facility (LBNF). This contribution presents modes of operation, layout, and main features of the LBNF Far Site cryogenic system, which is composed of three subsystems: Infrastructure, Proximity, and Internal cryogenics. The Infrastructure cryogenics supports the needs of the cryostat and Proximity cryogenics. It includes the equipment to receive the argon in liquid phase, vaporize it and transfer it underground as a gas, the nitrogen system (composed of the refrigeration system, liquid nitrogen buffer tanks and liquid and gaseous nitrogen distribution), liquid and gaseous argon distribution and process controls. The Proximity cryogenics receives fluids from the Infrastructure cryogenics and delivers them to the Internal cryogenics at the required temperature, pressure, purity and mass flow rate. It includes the argon condensers, liquid and gaseous argon purification and regeneration systems, nitrogen and argon phase separators, piping, valves, and instrumentation. The Internal cryogenics comprises the liquid and gaseous argon distribution inside the cryostats for the commissioning, cool down, fill, and steady state operations of the cryostats and detectors. An international engineering team is designing these systems and will manufacture, install, commission, and qualify them. This contribution describes the main features, performance, functional requirements, and modes of operation of the LBNF Far Site cryogenics system. It also presents the status of the design, along with present and future needs to support the DUNE experiment.
Energy efficient large-scale storage of liquid hydrogen
Authors: Fesmire J , Swanger A , Jacobson J , Notardonato W 
Published: June 2022

Abstract
The world’s largest liquid hydrogen storage tanks were constructed in the mid-1960s at the NASA Kennedy Space Center. These two vacuum-jacketed, perlite powder insulated tanks, still in service today, have 3,200 m3 of useable capacity. In 2018, construction began on an additional storage tank at Launch Complex 39B. This new tank will give an additional storage capacity of 4,700 m3 for a total on-site storage capacity of roughly 8,000 m3. NASA’s new Space Launch System (SLS) heavy lift rocket for the Artemis program includes an LH2 tank that makes up the bulk of the vehicle, holding 2,033 m3 of LH2 in its 8.4-m diameter by 40-m height. The new storage tank includes two new energy-efficient technologies: a glass bubbles insulation system in lieu of perlite, and an Integrated Refrigeration and Storage (IRAS) heat exchanger for controlled storage capability. The evacuated glass bubbles insulation system is based on the prior two decades of research to prove the thermal performance benefits as well as the mechanical and vacuum integrity; and has been shown to reduce LH2 boiloff by 46% versus perlite in field demonstrations. The IRAS capability is centered on a heat exchanger system that is built within the inner vessel to reject heat from the bulk liquid through the future implementation of an external helium refrigerator. Controlled storage via IRAS, when fully implemented, will provide full control of the ullage pressure, zero boiloff, and even production of densified LH2 pending its adoption on future launch vehicles. The design basics are described along with main construction and testing processes involved. The key features of the new technology items and implications on simplified operations and long-term energy savings are addressed.
Conceptual layout of a helium cooling system for the Einstein Telescope
Authors: Busch L , Grohmann S 
Published: June 2022

Abstract
The Einstein Telescope (ET) is a 3rd generation gravitational-wave detector planned in triangular shape with 10 km arm lengths in an underground installation at a depth of 200m to 300 m. While 2nd generation detectors and the ET high-frequency interferometer are operated at room-temperature, the ET low-frequency (LF) interferometer shall be operated at cryogenic mirror temperatures of 10K to 20K in order to reduce the thermal noise. Considering thermal dissipation limits in the heat extraction path from the mirror to the heat sink, He-II provides ultra-low-noise cooling to allow for an interferometer sensitivity at levels below 1 × 10−20 m/

Hz

in the detection band. In order to limit particle adsorption on the cold mirror surface, the total pressure in the cryostat must be reduced to p ≤ 1 × 10−10 mbar, i.e. partial pressures of water and heavier components pi
≤ 1 × 10−14 mbar, respectively, using a cryopump/shield around the mirror that is cooled with supercritical helium to T ≈ 5K.
We present the conceptual layout of a helium cooling system that can provide cooling power for several ET-LF cryostats and their corresponding cryotraps, including mirror cooling at 2K as well as thermal shielding at 5K and at 50K to 80K. A process flow diagram focuses on the cooling system’s key components with their locations and their interconnections. On the diagram’s basis, we explain the cooldown process and steady-state operation, ranging from outer shield and cryotrap cooling to the formation of He-II in the mirror heat extraction path.
Dynamic simulation of the cool down process of double-pressure helium liquefaction cycle
Authors: Su H K , Li Z Y , Gong L H , Zhu W P , Zhang M M , Jia Q M 
Published: June 2022

Abstract
A double-pressure helium liquefaction cycle, which consists of two compressors, six heat exchangers, two expanders and several valves, was proposed in this paper. The thermodynamic parameters of the process were calculated and analyzed. The mathematical models of the above-mentioned key equipment are established, and the cool down process of the helium refrigerator is dynamically simulated. By adjusting the parameters of each valve in the process, the working process of the compressor was simulated, and the cool-down process of heat exchangers and the expanders was obtained and analyzed. Finally the stable refrigeration capacity was obtained. The simulation of the dynamic process has a great guiding role for the actual experimental process afterwards.