Cryogenics最新文献

{"title":"Mass flow and entropy production in choked 4He gas flow through micro-orifices","authors":"Longyu Yang ,&nbsp;Xin Zhang ,&nbsp;Yu Yan ,&nbsp;Shengnan Meng ,&nbsp;Bingcheng Wang ,&nbsp;Zheng Cui ,&nbsp;Cheng Shao ,&nbsp;Lin Cheng","doi":"10.1016/j.cryogenics.2024.103979","DOIUrl":"10.1016/j.cryogenics.2024.103979","url":null,"abstract":"<div><div>Micro-orifice is a critical component in cryogenic refrigeration systems that determines the mass flow rate and total cooling power. However, a sophisticated model to accurately predict mass flow rates, especially for helium (He) below its maximum inversion temperature, where its properties differ significantly from those of an ideal gas, is lacking. This study investigated the mass flow characteristics and entropy production of ⁴He gas flow in micro-orifices using computational fluid dynamics (CFD) simulations. Various conditions, including upstream temperatures, upstream pressures, and downstream pressures, were analyzed and compared with the predictions from the Maytal model. Our results show that entropy production due to velocity and temperature gradient fluctuations plays a significant role in determining flow rates. Under upstream conditions of 15 K, 0.7 MPa, and a 20 μm diameter, the entropy increase coefficient (<em>δ</em>) is 0.083. Neglecting this entropy production leads to an overprediction of the mass flux by 39.8 %. A modified Maytal model that accounts for entropy production yields predictions in better agreement with CFD simulations, with a maximum deviation of less than 6.3 %. This work highlights the critical role of entropy production in ⁴He gas flow through micro-orifices and offers guidance for selecting micro-orifices in cryogenic applications.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103979"},"PeriodicalIF":1.8,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new fast and robust thermo-hydraulic code for ITER superconducting magnet simulation","authors":"Damien Furfaro ,&nbsp;Jacek Kosek ,&nbsp;Andrey Ovcharov ,&nbsp;Tyge Schioler ,&nbsp;Rossella Rotella ,&nbsp;Tim Luce","doi":"10.1016/j.cryogenics.2024.103978","DOIUrl":"10.1016/j.cryogenics.2024.103978","url":null,"abstract":"<div><div>A new software is being developed for plasma pulse scenario validation of the ITER magnet system behaviour and prediction of the margin to quench in superconductors. The principal idea behind this project has been to develop a software tool for the thermo-hydraulic simulation of superconducting magnets that is able to simulate different operations scenarios for the magnets at least an order of magnitude faster than real time. To achieve this level of performance, a tight coupling between the Cable-In-Conduit-Conductors and the structure of the magnet is performed. All the equations for the flow and heat conduction parts of the global model are put in a single sparse system that is integrated in time. Such tight coupling in combination with implicit time stepping allows much longer time steps whilst keeping high accuracy of the solution. The code named REIMS (Riemann Explicit Implicit Magnet Simulator) is still under development. Both central solenoid (CS) and toroidal field (TF) ITER magnets are available at this stage. The development of the different intermediate steps that led to the current version of the code required verification/validation against exact solutions, experimental data and/or comparisons with existing codes. In the same way, results obtained with REIMS for the simulation of both CS and TF loops after application of a short plasma pulse scenario have been compared to results from existing reference codes, showing a good agreement.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103978"},"PeriodicalIF":1.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two stage pulse tube cryocooler with intermediate heat exchanger for accessing regenerator cooling capacity","authors":"Jens Falter ,&nbsp;Jack Schmidt ,&nbsp;Xaver Herrmann ,&nbsp;Bernd Schmidt ,&nbsp;Dirk Dietzel ,&nbsp;André Schirmeisen","doi":"10.1016/j.cryogenics.2024.103976","DOIUrl":"10.1016/j.cryogenics.2024.103976","url":null,"abstract":"<div><div>Conventional operation of closed-cycle two-stage GM-type Pulse Tube Cryocoolers (PTCs) usually relies on utilizing the cooling power of both the 1<span><math><msup><mrow></mrow><mrow><mi>s</mi><mi>t</mi></mrow></msup></math></span> and the 2<span><math><msup><mrow></mrow><mrow><mi>n</mi><mi>d</mi></mrow></msup></math></span> stage. While the 1<span><math><msup><mrow></mrow><mrow><mi>s</mi><mi>t</mi></mrow></msup></math></span> stage is required to precool the 2<span><math><msup><mrow></mrow><mrow><mi>n</mi><mi>d</mi></mrow></msup></math></span> stage to reach the lowest accessible temperature below 4K, it usually also provides enough cooling power to cool additional cryostat elements such as radiation shieldings. However, current applications in quantum physics have highlighted the need to additionally access heat sinks with intermediate temperatures and cooling powers, e.g. for cooling of superconducting wires. Here we will demonstrate a cooler configuration, where a third cooling stage is incorporated into the 2<span><math><msup><mrow></mrow><mrow><mi>n</mi><mi>d</mi></mrow></msup></math></span> stage regenerator. This third intermediate cooling stage allows to extract 4-5 W of cooling power at temperatures between 8 K and 9 K for a standard two-stage PTC with a cooling capacity of 1.6 W at 4.2 K. Most importantly, this approach does not reduce the performance of the main stage but the added intermediate regenerator stage instead allows to tap into hidden cooling power of the PTC.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103976"},"PeriodicalIF":1.8,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An experimental and analytical investigation to determine thermal conductivity of epoxy-filler composites for space applications","authors":"Manas Kumar ,&nbsp;Shubham Upadhyay ,&nbsp;Lalit Bansal ,&nbsp;Ravi Verma","doi":"10.1016/j.cryogenics.2024.103973","DOIUrl":"10.1016/j.cryogenics.2024.103973","url":null,"abstract":"<div><div>Thermal conductivity of epoxy-filler composite based Thermal Interface Materials (TIMs) is of utmost importance for thermal management systems used in space applications. Previous studies have shown that depending on the filler particle mixed into the epoxy, thermal conductivity of the composite can either be increased or decreased. Towards that, we have selected four different filler particles (micron sized) – aluminium, copper, zinc and silver to enhance the thermal conductivity of the base epoxy. Thermal conductivity of these 4 epoxy-filler composites has been determined experimentally using an indigenous developed setup at the temperatures ranging from 4.2 K to 323 K. The values have also been reported at various volume fractions (up to 15 %). In addition, after each preparation as the filler particles are mixed mechanically into the epoxy, they are randomly distributed, and this can affect the composite’s thermal conductivity (for the same volume fraction). The experimental determination of thermal conductivity for all the possible distributions is a time consuming, and cumbersome task. In the literature, thermal conductivity values are usually reported for few possible distributions. Therefore, we have developed a novel analytical model to predict all the possible values of thermal conductivity for a specific volume fraction. The predicted values compare well with our experimental data reported in this work at temperatures ranging between 338 K (above room temperature) to 4.2 K (liquid helium temperature). The predicted values are also in good agreement with the experimental values of different fillers such as red mud, pine wood dust and glass fiber etc. from the literature. Additionally, in comparison to other theoretical models like Lewis-Nielsen, Rule of mixture, and Poisson’s distribution, the present model predicts the thermal conductivity values more precisely. This work will be significant in the designing of components where heat transfer plays an important role towards the safety of the component.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103973"},"PeriodicalIF":1.8,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142659406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A modified dubinin-radushkevich model describing the cryogenic adsorption of 4He on carbon materials","authors":"Teng Pan ,&nbsp;Fangqiu Yu ,&nbsp;Ke Li ,&nbsp;Zhenxing Zhu ,&nbsp;Fei Wei ,&nbsp;Wei Dai ,&nbsp;Jun Shen","doi":"10.1016/j.cryogenics.2024.103977","DOIUrl":"10.1016/j.cryogenics.2024.103977","url":null,"abstract":"<div><div>The ⁴He and ³He adsorption characteristics of porous materials serve as important references for designing and optimizing cryogenic components or systems, including adsorption pumps, helium adsorption refrigerators, and gas-gap heat switches. In this study, various types of activated carbon and carbon nanotubes were measured for their ⁴He adsorption characteristics in the range of 3–20 K and 1–18000 Pa. Parameters such as micropore volume and adsorption potential energy of porous materials were analyzed through Dubinin-Radushkevich (DR) model. A modified DR model describing the monolayer adsorption of ⁴He on different carbon-based adsorbents was developed in this study, greatly facilitating the design of adsorption systems. Further, the ⁴He adsorption model was applied to gas-gap heat switches, and a numerical model of the ⁴He gas-gap heat switch was established, which accurately predicts the actuation characteristics of several heat switches.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103977"},"PeriodicalIF":1.8,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of a numerical methodology for the simulation of active-pressurization of cryogenic tanks","authors":"Francesca Rossetti ,&nbsp;Marco Pizzarelli ,&nbsp;Rocco Carmine Pellegrini ,&nbsp;Enrico Cavallini ,&nbsp;Matteo Bernardini","doi":"10.1016/j.cryogenics.2024.103959","DOIUrl":"10.1016/j.cryogenics.2024.103959","url":null,"abstract":"<div><div>In this study, a numerical methodology, which is suitable to describe the main thermo-fluid-dynamics phenomena characterizing the active-pressurization inside cryogenic tanks, is proposed. This task is carried out comparing the numerical predictions obtained with several models with experimental results, retrieved from the literature, of a ground-based active-pressurization experiment of a liquid nitrogen (N₂) tank pressurized with high temperature gaseous N₂. The tank is modeled as 2D axisymmetric, and the solution of the heat conduction through the tank wall is coupled to the fluid-dynamic solution by means of a conjugate heat transfer model. The two-phase fluid interface is tracked using the Volume-of-Fluid (VOF) method, and the phase transition is calculated with the Lee model. Temperature varying thermophysical properties are considered for the vapor and the wall, given the wide operational temperature range. The proposed methodology allows to accurately reproduce both the pressure rise rate during gas injection and the pressure drop occurring after the end of gas injection. Finally, the results show that the introduction of a turbulence model is necessary to describe, with higher fidelity, the active-pressurization phase and that, among the tested models, the SST <span><math><mi>k</mi><mo>−</mo><mi>ω</mi></math></span> with low-Reynolds corrections is the most adequate to represent the pressure decrease occurring after the end of gas injection.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103959"},"PeriodicalIF":1.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142578789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative analysis of the impact of room temperature stability on cryostat performance","authors":"Siqi Liu ,&nbsp;Xiangjie Kong ,&nbsp;Haiyang Zhang ,&nbsp;Bo Gao ,&nbsp;Huilun Jia ,&nbsp;Zongwei Han","doi":"10.1016/j.cryogenics.2024.103974","DOIUrl":"10.1016/j.cryogenics.2024.103974","url":null,"abstract":"<div><div>The constant temperature in laboratories is crucial for precise low-temperature measurements. Currently, there are no reports on the specific temperature needs for such experiments or quantitative analyses of how room temperature fluctuations affect cryostat control. This paper proposes a method to quantitatively analyze these fluctuations and their impact on cryostat temperature control. Taking the cryostat using for 2 K-5 K thermodynamic temperature measurement as the research object, and conducts model simulation and experimental validation. The research results indicate the primary influence on the sphere’s temperature is the time-dependent fluctuation of the room temperature. As temperature fluctuations propagate from the cryostat’s outer casing to the sphere, heat conduction is the dominant factor. The temperature fluctuations inside the system caused by environmental temperature fluctuations can be quantitatively expressed by a simple linear formula, with the coefficient being the fluctuation attenuation rate, which is 6.590 × 10^-4 in this system. The deviation between experimental results and simulation results is within 5 %. To keep the sphere’s ambient temperature influence below 0.077mK, or 20 % of cryocooler-induced fluctuations, the room temperature must be controlled within 0.12 °C. In addition, the fluctuation period of room temperature is controlled below 1 h, the 0th flange is thickened, the rod is lengthened, and the material of the rod is changed to G10 above 4.2 K and stainless steel below 4.2 K can also effectively attenuate the influence on system temperature control.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103974"},"PeriodicalIF":1.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on AC loss of stacked REBCO cable wrapped with magnetic strip","authors":"Wei Chen ,&nbsp;Rong Jin ,&nbsp;Fei Chi ,&nbsp;Yunyang Ye ,&nbsp;Wenan Wang ,&nbsp;Xinsheng Yang ,&nbsp;Yunpeng Zhu ,&nbsp;Lijun Cai ,&nbsp;Xiaguang Sun ,&nbsp;Xiaojuan Li","doi":"10.1016/j.cryogenics.2024.103975","DOIUrl":"10.1016/j.cryogenics.2024.103975","url":null,"abstract":"<div><div>REBCO stacked cables have great potential for application in high-temperature superconducting (HTS) power devices due to their compact structure and easy scalability. However, when the cable runs in an alternating external field, it will generate AC losses, and excessive AC losses will increase the cooling cost and even cause the cable quench. This article proposes a magnetic material wrapped REBCO cable that can effectively reduce the AC loss of the cable under external magnetic fields. Firstly, the AC losses of REBCO cables wrapped with magnetic and non-magnetic materials were compared under different strength external fields. The results showed that cables wrapped with strong magnetic materials had lower AC losses. Secondly, the AC losses of cables prepared with strong magnetic wrapping materials of different thicknesses were studied under different external fields. The results showed that the thicker the magnetic material, the more significant the reduction in AC losses of the cable. Overall, this article presents new analysis and results that are useful for future design of HTS cables.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103975"},"PeriodicalIF":1.8,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and analysis of a HTS internally cooled cable for the Muon Collider target and capture solenoid magnets","authors":"L. Bottura ,&nbsp;C. Accettura ,&nbsp;A. Kolehmainen ,&nbsp;J. Lorenzo Gomez ,&nbsp;A. Portone ,&nbsp;P. Testoni","doi":"10.1016/j.cryogenics.2024.103972","DOIUrl":"10.1016/j.cryogenics.2024.103972","url":null,"abstract":"<div><div>The Muon Collider is one of the options considered as the next step in High Energy Physics. It bears many challenges, last not least in superconducting magnet technology. The target and capture solenoid is one of them, a channel of approximately 18 m length consisting of co-axial solenoid magnets with a 1.2 m free bore and peak field on axis of 20 T. One of the main concerns come from the nuclear radiation environment that may influence the stable operation of the coil, as well as its material integrity. Energetic photons cause large radiation heat load, of the order of several kW in the cold mass, and deposit a considerable dose, several tens of MGy. Neutrons cause material damage, at the level of 10^-3 DPA. These values are at the present limit of superconducting coil technology. We describe here the conceptual design of the target and capture solenoid, focusing on the HTS cable design, which is largely inspired by the VIPER concept developed at MIT. We show how to address margin and protection, cooling and mechanics specific to the HTS cable selected.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103972"},"PeriodicalIF":1.8,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"AC loss and shielding in stacks of coated conductors: Analytic modelling and comparison to experiment","authors":"M.D. Sumption ,&nbsp;C. Ebbing ,&nbsp;G. Panasyuk ,&nbsp;C. Kovacs ,&nbsp;G.J.P. Murphy ,&nbsp;T. Haugan ,&nbsp;E.W. Collings","doi":"10.1016/j.cryogenics.2024.103963","DOIUrl":"10.1016/j.cryogenics.2024.103963","url":null,"abstract":"<div><div>This work explores the effects of the stacking of coated conductor tapes on their AC loss and penetration fields (<em>B_p</em>). The penetration field <em>B_p</em> and AC loss of short lengths of coated conducted tape stacks are analyzed, measured, and compared to a simple analytic model. The tape widths (<em>w</em>) and number of tapes in the stacks (<em>N_s</em>) were 4 mm (<em>N_s</em> = 1, 3, 5, series-305) and 12 mm (<em>N_s</em> = 1–40, series-244). Experimentally, the losses of the series-244 and series-305 tape stacks were measured in a spinning magnet calorimeter (SMC) in which the samples are exposed to a spinning field of frequency, <em>f</em>, up to 110 Hz and amplitude <em>B₀</em> = 566 mT and the power is measured by a calibrated boil-off calorimeter. These results were compared to calculated loss as a function of <em>N_s</em> for both tapes. In addition, the calculated <em>B_p</em> was plotted vs <em>N_s</em>. The basic effect observed was that stacking coated conductor tapes tended to form an effective composite with an increase <em>B_p,comp</em> and modified loss (For <em>B₀</em> &lt; <em>B_p,comp</em>, <em>P_tot</em> was reduced with <em>N_s,</em> the effect saturating for <em>N_s</em> &gt; 20). This could be understood in terms of treating a stack of conductors as a composite described in terms of a Brandt equations applied to a dilute superconductor. The results show and model the significantly reduced loss that stacks of conductors can have significantly for moderate levels of applied field. Such results are directly transferrable to cables of stacked strands.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"144 ","pages":"Article 103963"},"PeriodicalIF":1.8,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}