bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization testing of the Northrop Grumman MiniCoolerPlus (MCP)
Authors: Rich N , Amouzegar L , Petach M , Colbert R , Dair E , Russo J , Durand D , Hua J 
Published: July 2024

Abstract
Northrop Grumman Space Park (NGSP) introduced the Mini Cooler Plus (MCP) to their family of pulse tube cryocoolers in 2019 [1] and presented the details of its TRL6 qualification testing in 2022 [2]. The thermal mechanical unit (TMU) of the MCP is an extension of space-qualified pulse tube coolers, all of which are designed to provide a long life (ten-plus years) of delivering low-mass, high-cooling capacity for hyperspectral and infrared imaging payloads in tactical airborne and space applications. The cooler is of modular split configuration allowing flexibility in the compressor (wave generator) and cold head placements to meet the available envelope of packaging constraints. The cold head assembly can be oriented at any position relative to the compressor assembly, and the transfer line (length and shape) can be customized to individual applications. The TMU (thermo-mechanical unit) weighs less than 3kg and can lift 1.5 W at 45 K or 11 W at 110K with 150 W electrical input at 300 K reject. The thermal performance has been characterized as a function of input voltage and as a function of cold tip load and temperature at variety of heat sink temperatures of -20C, 0C, +20C and +40C. Functional testing of the MCP was performed to higher input powers and MCP performance data versus operating conditions were collected. An analytical expression for cold tip load (Qc), impedance (Z) and power factor (PF) as a function of reject temperature (Trej), cold tip temperature (Tc), frequency (f), and input power (Pac) were generated. These tests were repeated with third party control electronics. All results will be presented here.
Simulation and analysis on heat leakage structure of cold compressor in large-scale refrigeration system
Authors: Chen H Y , Shang J , Wang J Z , Liu S H , Lv C , Wu J H 
Published: July 2024

Abstract
Large-scale helium cryogenic refrigeration facilities are indispensable equipment for many cutting-edge researches, and the cold compressor is the most advantageous pressurization scheme in superfluid helium systems with capacity of more than 200 watts. Due to the extremely low operating temperature zone of the cold compressor, the efficiency of the compression process decreases as the external heat leakage increases, especially when building systems with greater cooling capacity, this phenomenon becomes more significant. In order to reduce the influence of heat leakage, a conjugate heat transfer analysis is carried out on the cold compressor using commercial CFD software, and the internal structures, including thermal anchor, thermal insulation materials, are analysed and optimized base on the simulations.
High-speed tilting-pad gas journal bearing flow field analysis
Authors: Shi N Y , Li K R , Ke C L , Qiu S , Dong B , He M , Liu L Q , Zhang X H , Peng N 
Published: July 2024

Abstract
Tilting-pad gas journal bearing are widely used in the field of high-speed turbine machinery, especially in the special environment of low temperature. However, the performance is limited by structure, so a clear understanding of the field is particularly important. In this paper, finite volume method is used to simulate the three-dimensional flow field of high-speed tilting-pad gas bearing, then the effects of shaft speed, eccentricity and gas film thickness on the bearing capacity are studied. The simulation results show that the two factors of shaft speed and gas film clearance play a decisive role in producing sufficient bearing capacity of tilting tile radial gas bearings compared with other factors.
Cryogenic Modules for Synergistic O2 Generation and CO2 Retention in Closed-Circuit Escape Respirators
Authors: Swanger A.M. , Fernando R. , Mahony C. , Carro R. , Harrison A. 
Published: July 2024

Abstract
Since 2018, NASA and the National Institute for Occupational Safety and Health (NIOSH) have been developing a liquid oxygen storage module (LOXSM) based on the NASA patent-pending Cryogenic Flux Capacitor (CFC) technology. LOXSM’s could potentially replace the gaseous or chemical-based oxygen supply in current closed-circuit escape respirators (CCER), with reducing CCER size being a primary goal. By virtue of the CFC functionality, cryogenic oxygen stored within the LOXSM is released in response to heat input, ideally from the breathing loop. Prior efforts focused on the oxygen storage potential of silica aerogel materials that the CFC utilizes, and were previously reported. Current work explored the LOXSM’s potential to remove and retain CO2 produced by the CCER user, in conjunction with oxygen generation, creating a synergy that may be exploited to reduce or eliminate the chemical CO2 absorber used in current CCERs. A test program for determining CO2 retention is presented, as well as the evolution of LOXSM prototypes. Testing showed that it is possible to completely remove CO2 out of an effluent stream at the flowrate required for the capacity of the CCER for an appreciable time, and that the LOXSM prototype design progression had a positive effect on that duration.
Results of a nitrogen-based pulsating heat pipe with varied configurations
Authors: Jiang Zhiyi , Pfotenhauer John , Miller Franklin 
Published: July 2024

Abstract
In this paper, the results of a nitrogen-based pulsating heat pipe (PHP) with the ability to change the number of turns are presented. The experiment assembly consists of two identical PHP subsections with their own fill lines. The length of the condenser, the adiabatic section, and the evaporator section of each PHP are 90mm, 1000mm, and 60mm respectively. Because of the unique design of the condenser section of the PHP, it can change the configuration into 1-turn, 3-turn, 5-turn, and 7-turn PHP. The PHP was tested at the condenser temperatures 77.4K, and 84.5K, which are at, and above the boiling point of the liquid nitrogen at ambient pressure. At each condenser temperature, the PHP was tested at three different initial fill ratios (50%, 63%, and 75%). The experimental results and analysis for the 1-turn setup of this nitrogen-based PHP assembly are presented in this paper.
The design and development of the cryogenic compressed gas refueling system
Authors: Lv Cui , He Ming , Wang Jinzhen , Zhou Gang , Wu Jihao , Gong Linghui 
Published: July 2024

Abstract
As a new economical, efficient and feasible high density hydrogen storage method, cryogenic compressed hydrogen has been widely explored by scholars in recent years. In this paper, a new cryogenic compressed hydrogen refueling system based on liquid nitrogen cooling is proposed on the basis of the existing high pressure hydrogenation station at normal temperature. The main operating modes of the system include precooling, refueling and standby mode. During the refueling process, it can generate cryogenic compressed hydrogen at 80K temperature and 35MPa pressure, with a mass flow rate of 1kg/min. Additionally, when the cryogenic compressed hydrogen tank requires refueling at high temperatures, the system can provide precooling to reduce hydrogen loss and increase the refueling speed. To validate the feasibility of key equipment and the proposed system, helium gas is used as the working medium for testing. The construction of the cold box, compressor, and cryogenic tank have been completed, and the system is expected to undergo commissioning in the near future.
Small-scale industrial hydrogen liquefaction and refrigeration
Authors: Higgins P , Fesmire J , Baik J , Williams M , Earls A 
Published: July 2024

Abstract
As the hydrogen economy expands, the need for point of use production with smaller liquid hydrogen (LH2) production capacities will increase. Examples of this are transportation hubs in remote locations and numerous other applications where the required LH2 production is less than 5 MT/day. In response to this need, a small-scale industrial 1,000 kg/day hydrogen liquefaction plant is being developed and is planned for operation in 2024. The plant will achieve localized, efficient production, on-demand, in remote locations or any location advantageous for use in transportation, where complicated logistics, with associated transportation costs and tanker evaporative losses are eliminated or minimized. The chief advantages of the design are small size/footprint, safety, reliability, low cost, lack of restrictions on site location, and ability to make practical use of renewable energy. The liquefaction plant utilizes a closed-loop helium reverse-Brayton cycle refrigerator where refrigerant temperatures significantly less than the hydrogen liquefaction temperature cause the hydrogen gas stream to be liquefied. The liquefied hydrogen is maintained in the liquid state via a helium side stream taken from the refrigeration loop routed through the LH2 storage tank. This optional system can maintain LH2 temperatures in the storage tank lower than 18 K to eliminate boiloff and facilitate zero loss transload from tanker trucks and eliminate losses in transfer/dispensing. The hydrogen liquefaction plant does not require liquid nitrogen (LN2) pre-cooling and so can be located in remote areas wherever there is 480 V electricity and hydrogen production capacity available. A slightly modified reverse-Brayton cycle is also used in the refrigeration/storage plants. These plants can facilitate zero loss tanker transload and zero boiloff for LH2 storage plants of virtually any capacity. The smallest of these reverse-Brayton cycle refrigerators, currently in detailed design, refrigeration system RS1500 (1000 W heat lift @ 20K) will be capable of eliminating boiloff losses of the largest storage tanks currently in operation with very low electrical energy consumption.
Hydrogen permeability testing of fibre reinforced thermoplastics under cryogenic conditions – validation of a test rig concept
Authors: Just T , Will J , Haberstroh C 
Published: July 2024

Abstract
The need to decrease the gross weight of cryogenic hydrogen fuel systems in future zero emission mobility leads to increasing activities in the field of cryogenic lightweight engineering. Fibre reinforced thermoplastic composite materials (FRT) are considered for cryogenic applications despite their bias towards permeation. However, permeation through plastic materials is of major concern in cryogenic applications. Even tiny fluxes can very much compromise the insulating power of high vacuum spaces required for insulation of cryogenic systems such as tank structures or transfer lines. Hence, it is essential to qualify those FRT in terms of their hydrogen permeability for future usage in mobile cryogenic applications. The conventional concepts for measuring permeability in plastic materials are not sufficient for cryogenic measurements of FRT as shown in a previous paper. For that, a novel laboratory test rig concept was proposed. In this paper, we validate this concept and show its eligibility for measuring permeation of hydrogen through thermoplastic materials. Therefore, we report results of helium permeation through polytetrafluoroethylene (PTFE) at room temperature and compare those results to literature permeability data.
Preparing the cryogenic moderator system for higher beam power
Authors: Howell M , Armstrong R , DeGraff B , Denison J , Fabre Y , Maekawa R 
Published: July 2024

Abstract
The Spallation Neutron Source (SNS) incorporates a 20 K helium refrigeration system to cool three circuits supplying cold hydrogen to neutron moderators. The helium refrigeration system consists of a warm compressor, oil removal, purifier, 20 K cold box, and three helium-hydrogen heat exchangers. The hydrogen loops consist of a circulator, moderator, accumulator with expandable bellows, and the heat exchangers. Historically, the cryogenic system has had periods of instability and has operated with a reduced capacity. While performing the Proton Power Upgrade, the proton beam power on the first target station will increase from 1.4 MW to 2 MW. This will result in a 43% increase in dynamic load to the cryogenic system. The first directive in preparing the system for higher beam power was to achieve consistent operational stability at 1.4 MW beam power. After this was achieved, the next task was to increase the system capacity. This paper will describe the initiatives taken to produce consistent high-capacity performance.
Development status of the in-situ measurement system for ortho-to-parahydrogen fractions for the ESS cryogenic moderator system
Authors: Tatsumoto H , Sakamoto Y , Hasegawa T , Kobayashi H , Shiro Y , Horikawa Y , Horvath A , Sina H , Hartl M , Arnold P , Kickulies M , Beßler Y , Teshigawara  
Published: July 2024

Abstract
The Cryogenic Moderator System (CMS) is equipped with a catalyst to convert hydrogen from the ortho state to the para state in order to keep desirably high parahydrogen fractions of 99.5%. An in-situ measurement system for the ortho and para fractions of liquid hydrogen (OPMS) by means of a Raman spectroscopy with an accuracy of 0.1% is being developed to detect any undesirable shift towards a high orthohydrogen fraction caused by neutron scattering driven para-to-ortho back conversion. We have demonstrated that our developed sapphire window, through which the laser and backscattered photon travel, has endured the required pressure and thermal cycles in a liquid hydrogen environment. Meanwhile, a Raman optics system has been developed using normal hydrogen. Eventually, we have succeeded in detecting the parahydrogen peak at J = 4, which is our primary goal, because the peak ratio of parahydrogen at 1245 cm−1 to ortho hydrogen at 587 cm−1 corresponds to 0.5%. It can be expected that it would achieve our requirement for liquid hydrogen with higher density.
Current status of main distribution box for Korean heavy ion accelerator, RAON
Authors: Yoo J , Yoon S , Park I , Lee D , Ki T 
Published: July 2024

Abstract
A main distribution box is a large cryogenic valve box which connects two cryoplants with two superconducting linear accelerators (LINACs) of Korean heavy ion accelerator. A major role of the main distribution box is transferring cryogenic helium from the cryoplants to LINACs and controlling flow rate of the helium. It can take other several roles when it encounters special situations. It has total 44 cryogenic valves to manage the helium. DN10 to DN250 valves are applied according to sizes of the cryogenic lines in the main distribution box. Designed heat loads of the main distribution box are 440 W for thermal shield, 24 W for 4.5 K lines and 43 W for 2 K line. At present, the main distribution box keeps its cold status and is operated well although it needs some improvements. The improvements will be gradually carried out when our cryogenic system will be warmed up. Some occurred issues, our solutions and current status of the main distribution box are shared in this paper.
Design of GRETA Cooling Systems
Authors: Wang L , Buice E , Crawford H , Doyle J , Fallon P , Hodgkinson A , Loew T , Regis M , Zimmermann S 
Published: July 2024

Abstract
The Gamma-Ray Energy Tracking Array (GRETA) is a full 4π gamma-ray tracking detector capable of reconstructing the energy and three-dimensional position of gamma-ray interactions within a compact sphere of high-purity germanium crystals. The GRETA Detector Array Sphere will have the capacity to accommodate a total of 30 Germanium Quad Detector Modules (QDM). The 30 QDMs are to be cooled and maintained below 100 K using liquid nitrogen (LN) at all times while the array is in normal operation, and will require regular filling of a LN Dewar on each module. The Dewar is designed to allow the Quad Module to be operated in any orientation with a LN holding time of no less than 12 hours when the detector module is fully powered. An automated LN cooling and refilling system is required to supply LN to the 30 QDMs and ensure them maintained below 100 K. Each of the GRETA QDMs houses a total of 148 pre-amplifier units within the module, and with the high power consumption of each pre-amplifier, active cooling of the pre-amplifier compartment is required. Additionally, each Quad Module will have 4 digitizer modules attached to it, which generate heat and require cooling as well. A closed-loop liquid (Glycol) cooling system will provide the required temperature stability and dissipate power generated heat for electronics. This paper presents design of the GRETA LN cooling system for detectors and the closed-loop liquid cooling system for electronics including technical requirements, design schemes, key components, operation modes, and so on.
Co-simulation of cool down process from 300 to 80 K for ITER Tokamak
Authors: Takami S , Iwamoto A , Maekawa R , Qiu L , Grillot D 
Published: July 2024

Abstract
Dynamic simulation of Tokamak superconducting magnet system has been conducted to investigate the cool-down process from 300 to 80 K. The simulation focuses on the cool-down speed variations with respect to the global temperature gradients in the different coils; Toroidal Field (TF) coil, TF STructure (TF-ST), Central Solenoid (CS) and Poloidal Field (PF)/Correction Coil (CC) systems. As imposing the maximum temperature gradients dT
max ≤ 50K, the speed should be adjusted, ensuring the limited mechanical stresses due to thermal contractions. So far, the process simulation of Tokamak cryogenic system has been concentrated on the Deuterium Tritium (DT) operation phase; therefore, it is necessary to revise the model to extend its capability for the cool-down; for example, the thermo-hydraulic properties of Cable-in-Conduit Conductor (CICC) for each coil, mechanical properties of materials for the magnet system. The cool-down process is implemented at the helium refrigerator by utilizing LN2 heat exchanger up to 80 K. Its speed is set at -0.8 K/hr as a baseline, which can be controlled by the global temperature gradients in the magnet system. The process will be on hold as dT
max ≥ 50K, and resumed once dT
max < 50K. The paper discusses the cool-down processes of the Tokamak and identifies the impact on the speed, dT
i/dt, of each component.
Overview and status of the PIP-II cryogenic system
Authors: Martinez A , Creus Prats J , Soyars W , Dhuley R , Hansen B , Jia Y , Chakravarty A , Goyal M , Banaszkiewicz T , Duda P , Stanclik M 
Published: July 2024

Abstract
The Proton Improvement Plan-II (PIP-II) is a major upgrade to the Fermilab accelerator complex, featuring a new 800-MeV Superconducting Radio-Frequency (SRF) linear accelerator (Linac) powering the accelerator complex to provide the world’s most intense high-energy neutrino beam. The PIP-II Linac consists of 23 SRF cryomodules operating at 2 K, 5 K, and 40 K temperature levels supplied by a single helium cryoplant providing 2.5 kW of cooling capacity at 2.0 K. The PIP-II cryogenic system consists of two major systems: a helium cryogenic plant and a cryogenic distribution system. The cryogenic plant includes a refrigerator cold box, a warm compressor system, and helium storage, recovery, and purification systems. The cryogenic distribution system includes a distribution box, intermediate transfer line, and a tunnel transfer line consisting of modular bayonet cans which supply and return cryogens to the cryomodules. A turnaround can is located at the end of the Linac to turnaround cryogenic flows. This paper describes the layout, design, and current status of the PIP-II cryogenic system.
First results of the cryogenics operation from the LHC physics Run 3 at the increased energy to 6.8 TeV
Authors: Delprat L , Bradu B , Brodzinski K , Ferlin G , Ferrand F , Gahier V , Herblin L , Wagner U 
Published: July 2024

Abstract
Back in 2018, LHC completed its Run 2 physics period. Consolidation, maintenance, and upgrade activities performed during the subsequent Long Shutdown 2 period (LS2), based on a data-driven approach, allowed for full potential availability of the LHC cryogenics infrastructure before tackling the 2021 magnet quench training campaign, preparing the whole machine for operation at the increased energy of 6.8 TeV. This paper will first give a summary of the main upgrades, consolidations and maintenance performed during the LS2. Magnet training of the machine to the increased energy of 6.8 TeV will be addressed. Results of the first year (2022) of Run 3 physics will be presented, achieving high cryogenic availability in a heavily sustained operational context of the accelerator (beams energy increase, induced heat load, peak & integrated luminosity). Helium inventory management aspects will be discussed, with a particular highlight on the necessary operational adjustments taken to cope with the present supply market evolution. Implementation of several operational modes for cryogenic plants will be presented, towards significant electrical power savings while maintaining nominal physics production at the highest availability rate.
Design of nonflammable mixed refrigerants based on the partial molar enthalpy difference in mixed-refrigerant Joule-Thomson refrigerators with/no pre-cooling stage
Authors: Wang Yunxiao , Zhao Yanxing , Sun Yuwei , Wang Haocheng , Gong Maoqiong 
Published: July 2024

Abstract
Mixed-refrigerant Joule-Thomson refrigeration (MJTR) is an important cooling method at temperatures from 80 to 230 K. It can be used in cryosurgery, high-temperature superconductivity and sensor cooling etc. However, most of the studies are on nitrogen-hydrocarbon refrigerants, which are not allowed in applications where there is a special need to avoid flammability risks. Therefore, non-flammable mixed refrigerants were investigated in this study.
The composition of the mixed refrigerant is a key factor in the system performance (refrigeration temperature, refrigeration capacity, etc). However, the purely mathematical optimization methods lack system knowledge in the optimization of the process, and may have the disadvantages of being a time-consuming process. In this study, the isothermal throttling effect of mixed refrigerants is optimized, and the optimization process is based on the partial molar enthalpy difference of each component. The method is based on thermodynamic properties and is time-saving relative to purely mathematical optimization techniques.
Non-flammable mixed refrigerants (NFMR) with refrigeration temperatures from 100 K to 140 K were designed in this study. The results show that the designed mixed refrigerant has a higher COP compared to the reference. Argon has an advantage at refrigeration temperatures from 120 K to 140 K, while nitrogen has an advantage from 100 K to 120 K. In addition, mixed refrigerants for systems with pre-cooling stage were optimized and the results showed that the highest exergy efficiency is achieved at a pre-cooling temperature of 250 K. The exergy efficiencies with pre-cooling stage are nearly twice as high as those without that. Therefore, a pre-cooling stage for nonflammable mixed refrigerants is necessary where there is no requirement for system size.
LCLS-II Helium Refrigeration System : A comprehensive overview of the project
Authors: Fauve E. , Pflueckhahn D. , Sevilla J. , Ravindranath V. , Chung C. , Hogan J. , Bevins M. , Bhattacharya R. 
Published: July 2024

Abstract
SLAC National Accelerator Laboratory has upgraded to LCLS-II, featuring a 4 GeV superconducting accelerator composed of 37 cryomodules and two large helium refrigeration systems with a total cooling capacity of 8 kW at 2.0 K. The cryogenic system at SLAC is the successful outcome of a nine-year partnership between SLAC, Fermilab, and Jefferson Lab. This paper highlights the joint efforts between Jefferson Lab and SLAC in the development and implementation of the LCLS-II Cryogenic Plants. It details the project organization, schedule, budget, staffing profile and procurement strategy.