Cryogenics最新文献

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Experimental study of initial frost surface coverage characteristics on cryogenic cold surfaces under natural convection 自然对流作用下低温冷面初始霜面覆盖特性的实验研究
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-07-10 DOI: 10.1016/j.cryogenics.2025.104147
Fengjiao Yu , Hongbing Chen , Yanxia Li , Zhenqiang Wang , Yi Li , Zhongliang Liu
{"title":"Experimental study of initial frost surface coverage characteristics on cryogenic cold surfaces under natural convection","authors":"Fengjiao Yu ,&nbsp;Hongbing Chen ,&nbsp;Yanxia Li ,&nbsp;Zhenqiang Wang ,&nbsp;Yi Li ,&nbsp;Zhongliang Liu","doi":"10.1016/j.cryogenics.2025.104147","DOIUrl":"10.1016/j.cryogenics.2025.104147","url":null,"abstract":"<div><div>Experimental investigations of frost formation initial stage on vertical cold plate surface under the conditions of natural convection reveal distinct growth patterns of initial frost crystals across temperatures ranging from −50 ℃ to −190 ℃. Frosting mechanism is significantly influenced by the cold plate temperature, which changes from the cold surface condensation/desublimation to the boundary layer condensation/desublimation as cold plate temperatures decrease. Correspondingly, frost crystal growth characteristics under different frost mechanisms are also different, which are first reflected in the frost formation initial stage. The effects of cold plate temperatures especially lower than −100 ℃ as well as the environmental parameters on the frost crystal coverage was focused. It has been discovered that frost crystal coverage increases as cold plate temperature drops from −50 ℃ to −100 ℃. Similarly, the rate of frost crystal coverage increases significantly first with air temperature and relative humidity, after that their influence weakens with higher air values. However, at lower temperatures from −100 ℃ to −170 ℃, frost crystal coverage decreases with further cooling, while air temperature and relative humidity exhibit negligible influence on early frost formation, with their effects weakening progressively at colder conditions. Changes in the frost formation mechanism are the primary reason for this phenomenon. This paper can enhance the comprehension of the frost formation initial stage and provide a reference for defrosting and frost suppression on cryogenic surfaces.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104147"},"PeriodicalIF":1.8,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144634007","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}
引用次数: 0
Numerical simulation and loss analysis on a two-stage GM cryocooler working at liquid helium temperatures 液氦温度下两级GM制冷机的数值模拟与损耗分析
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-29 DOI: 10.1016/j.cryogenics.2025.104145
Tian Gao, Chongtian Wu, Xin Chen, Xiaoqin Zhi, Limin Qiu
{"title":"Numerical simulation and loss analysis on a two-stage GM cryocooler working at liquid helium temperatures","authors":"Tian Gao,&nbsp;Chongtian Wu,&nbsp;Xin Chen,&nbsp;Xiaoqin Zhi,&nbsp;Limin Qiu","doi":"10.1016/j.cryogenics.2025.104145","DOIUrl":"10.1016/j.cryogenics.2025.104145","url":null,"abstract":"<div><div>Two-stage Gifford-McMahon Cryocoolers (GMC) working in liquid helium temperature range are widely utilized in various fields such as low-temperature superconductors, cryogenic medical instruments, and quantum computing. However, even though they have achieved mature commercialization, their current cooling capacity and efficiency remain low for a long time in the scientific and industrial applications. An in-depth analysis of the loss distribution characteristics of GM cryocooler is crucial for guiding further performance optimization. This study establishes a comprehensive numerical simulation model for a domestically produced GM cryocooler working at liquid helium temperatures. The coupling between compressor, rotary valve, and cold head is considered. Detailed investigation on the loss characteristics in different components at different cooling temperatures are carried out. Results indicate that as the cooling temperature decreases, the proportion of the loss in the compressor and rotary valve decreases, while that of the cold head increases due to the real gas effect. At cooling temperature of 4.2 K, the loss proportions of these three components are 2689.0 W (46.2 %), 1138.9 W (19.6 %), and 1879.6 W (32.3 %), respectively. In the rotary valve, more than 70 % of its total loss is caused by friction (e.g. 793.8 W at 4.2 K). To compare the effects of different loss on the 2<sup>nd</sup>-stage cooling capacity, gross cooling capacity <span><math><mrow><msub><mover><mi>Q</mi><mo>̇</mo></mover><mi>g</mi></msub></mrow></math></span> is used. When lower than 8 K, the <span><math><mrow><msub><mover><mi>Q</mi><mo>̇</mo></mover><mi>g</mi></msub></mrow></math></span> of loss in the cold head is mainly due to the real gas effect (e.g. 17.53 W at 4.2 K). When higher than 8 K, the <span><math><mrow><msub><mover><mi>Q</mi><mo>̇</mo></mover><mi>g</mi></msub></mrow></math></span> of 1<sup>st</sup>-stage irreversible heat transfer loss dominates (e.g. 15.95 W at 12 K), followed by the pressure drop loss. Therefore, to improve the performance of the cold head, best to reduce the real gas loss when lower than 8 K, and adjusting the porosity and specific heat of the fillers in the regenerator should be considered.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104145"},"PeriodicalIF":1.8,"publicationDate":"2025-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144549440","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}
引用次数: 0
Effect of heat exchanger configuration and operating conditions of thermal energy storage unit for liquid air energy storage 储热机组换热器配置及运行条件对液气储能的影响
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-26 DOI: 10.1016/j.cryogenics.2025.104144
Kyoung Joong Kim, Jinwook Kim, Sangkwon Jeong
{"title":"Effect of heat exchanger configuration and operating conditions of thermal energy storage unit for liquid air energy storage","authors":"Kyoung Joong Kim,&nbsp;Jinwook Kim,&nbsp;Sangkwon Jeong","doi":"10.1016/j.cryogenics.2025.104144","DOIUrl":"10.1016/j.cryogenics.2025.104144","url":null,"abstract":"<div><div>This paper presents the study on a thermal energy storage unit (TESU) with its effectiveness greater than 0.9. A heat diffusion model is developed to predict the precise thermal behavior of the TESU and determine its detailed specifications. Based on this model, the TESU is designed and manufactured for laboratory-scale experiments. The TESU is tested with various shuttle masses (6 g–18 g) of cryogenic nitrogen at an operating pressure of 30 bar. Under the experimental conditions, a higher mass flow rate in the range increases the efficiency of the TESU. Using the spiral-plate type heat exchanger instead of the coil type improves thermal performance by reducing the thermally dead volume and enhancing the active heat exchange. The effectiveness of each spiral-plate type or coil type heat exchangers is achieved up to 0.92 or 0.82, respectively. The comparative analysis between the thermal model and the experiments reveals the strong influence of the operating conditions on thermally dead volume, emphasizing the need for precise TESU design tailored to the specific LAES system requirements. The validated heat diffusion model shows that minimizing temperature non-uniformity in the heat exchanger reduces entropy generation and exergy loss due to heat diffusion. This study experimentally demonstrates the feasibility of achieving high effectiveness value of a TESU and suggests that the proposed approach should be extended to actual-scale LAES systems.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104144"},"PeriodicalIF":1.8,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656679","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}
引用次数: 0
Electromechanical properties and microstructural evolution of REBCO coated conductor tapes under fatigue loading 疲劳载荷下REBCO涂层导体带的机电性能及微观组织演变
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-24 DOI: 10.1016/j.cryogenics.2025.104143
Yuanzhou Pan , Xingzhe Wang , Mingzhi Guan , Xiaoke Mu
{"title":"Electromechanical properties and microstructural evolution of REBCO coated conductor tapes under fatigue loading","authors":"Yuanzhou Pan ,&nbsp;Xingzhe Wang ,&nbsp;Mingzhi Guan ,&nbsp;Xiaoke Mu","doi":"10.1016/j.cryogenics.2025.104143","DOIUrl":"10.1016/j.cryogenics.2025.104143","url":null,"abstract":"<div><div>Various types of fatigue loading conditions, including exposure to periodic electromagnetic forces and repeated thermal cycles, are unavoidable in applications utilizing Rare-Earth-Barium-Copper-Oxide (REBCO) coated conductor (CC) tapes. Fatigue loadings might irreversibly degrade the superconducting properties of REBCO CC tapes and significantly influence the long-term reliability of superconducting magnets winded by the REBCO CC tapes, warranting extensive analysis. However, most studies in literature use quasi-static tensile tests to evaluate the electromechanical characteristics of REBCO CC tapes. Detailed analysis of the electromechanical behavior and microstructural evolution of REBCO CC tapes subjected to fatigue loadings are scarce and the relationship between the microstructural changes and macro-multi-field responses for REBCO CC tapes subjected to fatigue loading conditions remain unclear. Elucidating the microstructural changes and macro-behavior of REBCO CC tapes subjected to fatigue loadings is critical to assess the reliability of superconducting magnets. In this study, the electromechanical fatigue properties of EuBCO CC tapes manufactured by Shanghai Superconductor Technology Co., Ltd. were investigated under different values of maximum stress (σ<sub>max</sub>), number of fatigue cycles (N) and stress ratio (R). The effects of σ<sub>max</sub> and R on the superconducting properties for EuBCO CC tapes were compared. At the microscopic level, scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were used to observe microcracks formations and analyze the local plastic strain and the misorientation angles in the superconducting film during fatigue loading. Based on experimental results, the deterioration in the superconducting properties of EuBCO CC tapes on fatigue loading was ascribed to the increased misorientation angles and the local plastic strain, which led to the destruction of the original texture of the superconducting layer in the system. The findings of this study are expected to assist manufacturers in improving the electromechanical properties of commercial REBCO tape, facilitating their application in advanced technologies.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104143"},"PeriodicalIF":1.8,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144489943","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}
引用次数: 0
Deep learning-based super-resolution reconstruction model for cavitation images in cryogenic flow fields 基于深度学习的低温流场空化图像超分辨重建模型
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-18 DOI: 10.1016/j.cryogenics.2025.104142
Zhao Zidong , Wang Ximing , Wei Aibo , Xu Zhengnan , Zhang Xiaobin
{"title":"Deep learning-based super-resolution reconstruction model for cavitation images in cryogenic flow fields","authors":"Zhao Zidong ,&nbsp;Wang Ximing ,&nbsp;Wei Aibo ,&nbsp;Xu Zhengnan ,&nbsp;Zhang Xiaobin","doi":"10.1016/j.cryogenics.2025.104142","DOIUrl":"10.1016/j.cryogenics.2025.104142","url":null,"abstract":"<div><div>Obtaining cavitation images of cryogenic fluid flow fields with high temporal and spatial resolution has important scientific value for revealing the mechanism of cryogenic cavitation. This study develops a super-resolution (SR) reconstruction model for cryogenic cavitation flow fields based on deep learning architectures (SRCNN, SRResNet, SRGAN, SwinIR) trained on the datasets obtained from Venturi tube liquid nitrogen (LN<sub>2</sub>) cavitation flows. Results show that the proposed model achieves ×4 and ×8 spatial resolution enhancement of the cavitation images, thus restoring flow field details well. By analyzing the performance of the model under different pressure ratios <em>P<sub>r</sub></em> inside and outside the dataset, and combining it with the convergent-divergent nozzle LN<sub>2</sub> flow field data for verification, it is found that the proposed model can accurately recover fine cavitation flow features from low-resolution inputs while maintaining the temporal coherence and exhibiting good generalization across operational conditions. Quantitative analysis shows that the model based on SwinIR performs better in peak signal-to-noise ratio (PSNR), structural similarity index measure (SSIM), and image standard deviation metrics, maintaining robustness even in severe cavitation information loss. The proposed method provides an effective SR analysis tool for cavitation experiments and has important application value for exploring the cryogenic cavitation mechanism.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104142"},"PeriodicalIF":1.8,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144338912","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}
引用次数: 0
Experimental characterization of neon pulsating heat pipes for cryocooler-based HTS magnets 低温冷却器基高温超导磁体霓虹脉动热管的实验表征
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-16 DOI: 10.1016/j.cryogenics.2025.104138
Q. Gorit , J.C. Maris , C. Zoller
{"title":"Experimental characterization of neon pulsating heat pipes for cryocooler-based HTS magnets","authors":"Q. Gorit ,&nbsp;J.C. Maris ,&nbsp;C. Zoller","doi":"10.1016/j.cryogenics.2025.104138","DOIUrl":"10.1016/j.cryogenics.2025.104138","url":null,"abstract":"<div><div>Pulsating heat pipes (PHPs), i.e. passive devices employing two-phase flow, are increasingly studied in cryogenic conditions to improve heat transfer between cryocoolers and high temperature superconducting (HTS) magnets. This paper presents the experimental characterization of PHPs tested in vertical orientation using neon as working fluid. The main objective is to carry out a parametric study to assess the optimum parameters for a potential application to the cooling of HTS magnets. A summary of the literature on PHPs experiments under cryogenic conditions justifies the choice of neon as the working fluid for this specific application. It also leads to the selection of high-performance PHP designs for the parametric study. The PHP designs, the experimental setup, procedures, and campaigns are described. The results of the individual characterization of two PHPs, having 5 and 10 turns respectively, are analyzed and their performances are compared. In addition, a specific configuration operating simultaneously two 5-turn PHPs in parallel is investigated. The experiments are performed for two condenser temperatures (27 and <figure><img></figure>), a wide range of filling ratios (15 to 90%) and of heat loads (2 to <figure><img></figure>). The effect of the number of turns and the series or parallel configuration on the thermal performance is quantified and discussed, along with the effect of condenser temperature, filling ratio and heat load. The optimum parameters are found to be the two 5-turn PHPs in parallel, the filling ratio of 35% and the condenser temperature of <figure><img></figure>. These conditions lead to the lowest evaporator temperatures with thermal resistances ranging from 0.15 to <figure><img></figure>, while keeping a reliable working stability and no dry-out phenomena occurrence in the heat load range tested.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104138"},"PeriodicalIF":1.8,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144290644","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}
引用次数: 0
Operation of helium sub-atmospheric multistage cryogenic centrifugal compressor trains: Part 2 – Transient modeling and pump-down path selection 氦亚大气压多级低温离心压缩机组的运行:第2部分-瞬态建模和泵降路径选择
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-13 DOI: 10.1016/j.cryogenics.2025.104140
Jonathon Howard, Nusair Hasan, Venkatarao Ganni
{"title":"Operation of helium sub-atmospheric multistage cryogenic centrifugal compressor trains: Part 2 – Transient modeling and pump-down path selection","authors":"Jonathon Howard,&nbsp;Nusair Hasan,&nbsp;Venkatarao Ganni","doi":"10.1016/j.cryogenics.2025.104140","DOIUrl":"10.1016/j.cryogenics.2025.104140","url":null,"abstract":"<div><div>Low-pressure conditions required for operation of helium cryogenic systems below the normal boiling point (<em>i.e.</em> 4.2 K) are established through a transient process, commonly referred to as ‘<em>pump-down’</em>. This process is defined as the transition from pressures above atmospheric conditions to the saturation pressure which corresponds to a specified operational temperature. The FRIB 2 K system consists of five cryogenic centrifugal compressors which are operated in series. Historically, the pump-down process path has been established through empirical methods and system operator experience. Investigation into the pump-down process at FRIB aimed to develop a pump-down methodology which relies on theoretical model predictions rather than empirically developed process paths. Ensuring stable operation during the pump-down process involved application of a centrifugal compressor performance prediction model, which is described in Part 1 of this paper. Compressor performance maps can be directly used to evaluate the stability of a selected pump-down path and anticipate the overall reliability of the selected path. In conjunction with the compressor performance maps, a system pressure model was developed to estimate the transient pressure response during the pump-down process. Lastly, an explicit equation was developed to establish a mass flow rate profile for the pump-down process. Implementation of the presented methodology (including the developed models) allows for the system operator to determine a continuous pump-down path which maintains compressor stability while conforming to overall system capabilities. Overall, the methodology presented has resulted in simplification of transient pump-down operations and increased the reliability, stability and efficiency of the pump-down process.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104140"},"PeriodicalIF":1.8,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297586","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}
引用次数: 0
Development of a 187 K free-piston Stirling cryocooler with wound wire mesh regenerator 187k带绕丝网蓄热器的自由活塞斯特林制冷机的研制
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-13 DOI: 10.1016/j.cryogenics.2025.104141
Shuling Guo , Shilin Pan , Ankuo Zhang , Wenhui Yu , Chao Xiong , Haitao Chen
{"title":"Development of a 187 K free-piston Stirling cryocooler with wound wire mesh regenerator","authors":"Shuling Guo ,&nbsp;Shilin Pan ,&nbsp;Ankuo Zhang ,&nbsp;Wenhui Yu ,&nbsp;Chao Xiong ,&nbsp;Haitao Chen","doi":"10.1016/j.cryogenics.2025.104141","DOIUrl":"10.1016/j.cryogenics.2025.104141","url":null,"abstract":"<div><div>Stirling cryocoolers are widely used in low-temperature storage because the advantages such as high reliability and efficiency. To meet the demands of commercialization, the production process of Stirling cryocoolers needs to reduce costs. Compared to stacked wire mesh regenerator, wound wire mesh regenerator has emerged as a new option to reduce the cost of regenerators, as it eliminates the need for manual filling of regenerator matrix and consumes less metal. In this manuscript, an investigation is conducted focusing on the characteristics of this wound wire mesh regenerator. To cool the −86℃ ultra-low temperature refrigerators, a free-piston Stirling cryocooler with a wound wire mesh regenerator was developed, and one-dimensional simulation and experiments were conducted on the cryocooler. To better optimize cryocooler design, theoretical research was conducted on refrigeration losses of cryocooler. Analysis and simulation of the theoretical and actual energy flow distribution in the cryocooler were conducted. The proportion of internal losses for different components was analyzed. Simulations were performed to investigate the impact of on internal losses within the regenerator and the refrigeration efficiency of the cryocooler, working parameters and cold end temperature. The simulation results were experimentally validated, and the performance of the cryocooler was tested in terms of cooling characteristics and operational stability. The prototype of the optimized cryocooler design achieved a cooling capacity of 120 W@187 K, with a minimum attainable cold end temperature of 121.1 K.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104141"},"PeriodicalIF":1.8,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144297585","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}
引用次数: 0
Role of secondary phases on the magnetic properties of MnFe2O4 nanoferrite studied at room and cryogenic temperatures: VSM, Mössbauer and FC-ZFC techniques 利用VSM、Mössbauer和FC-ZFC技术研究了室温和低温下二次相对MnFe2O4纳米铁氧体磁性能的影响
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-13 DOI: 10.1016/j.cryogenics.2025.104139
Ch. Srinivas , Sher Singh Meena , E. Ranjith Kumar , V. Rajendran , P. Balraju , D.L. Sastry
{"title":"Role of secondary phases on the magnetic properties of MnFe2O4 nanoferrite studied at room and cryogenic temperatures: VSM, Mössbauer and FC-ZFC techniques","authors":"Ch. Srinivas ,&nbsp;Sher Singh Meena ,&nbsp;E. Ranjith Kumar ,&nbsp;V. Rajendran ,&nbsp;P. Balraju ,&nbsp;D.L. Sastry","doi":"10.1016/j.cryogenics.2025.104139","DOIUrl":"10.1016/j.cryogenics.2025.104139","url":null,"abstract":"<div><div>MnFe<sub>2</sub>O<sub>4</sub> nanoparticles synthesized by sol–gel auto-combustion method have been subjected to heat treatment in order to understand phase change in the sample. The XRD patterns indicated the ferrite phase with secondary phases. The experimental lattice parameter (<em>a</em>) of as-prepared and sintered sample was found to be 8.3603 and 8.3409 Å while average crystallite size (&lt;<em>D<sub>XRD</sub></em> &gt;) 9.3 and 15.7 nm. From FE-SEM micrographs, the nature of ferrite nanoparticles is nearly spherical and agglomerated into bigger particles with strong magnetic interactions. The particles are distributed in between 11–23 nm with an average particle size (&lt;<em>D<sub>FE-SEM</sub></em> &gt;) 16.6 nm. Mössbauer spectrum consists of three sextets including a paramagnetic doublet. The sextet having higher hyperfine field (<em>H<sub>hf</sub></em>) equal to 51.2 T with <em>δ</em> = 0.356 and <em>Δ</em> = 0.222 is assigned to the secondary phase of α-Fe<sub>2</sub>O<sub>3</sub>. The inversion parameter (<em>λ</em>) from the Mössbauer data is evaluated as 0.73. M−H loops indicated the soft magnetic nature of present ferrite system. The saturation magnetization (<em>M<sub>S</sub></em>) obtained is equal to 21 emu/g at 300 K and 41.4 emu/g at 5 K. The value of <em>λ</em> that fit to the <em>M<sub>S</sub></em> at 300 K is equal to 0.087. The blocking temperature (<em>T<sub>B</sub></em>) is evaluated as 153 K in the presence of 100 Oe while it is 72 K in the presence of 1000 Oe. The magnetocrystalline anisotropy of present nanoscaled Mn-ferrite is high and is equal to 2.2 × 10<sup>4</sup> J/m<sup>3</sup>.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104139"},"PeriodicalIF":1.8,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307385","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}
引用次数: 0
Simplified numerical model for steady-state He II forced flow 稳态He II强迫流动的简化数值模型
IF 1.8 3区 工程技术
Cryogenics Pub Date : 2025-06-10 DOI: 10.1016/j.cryogenics.2025.104137
Sławomir Pietrowicz , Przemysław Błasiak , Marcin Opalski , Bertrand Baudouy
{"title":"Simplified numerical model for steady-state He II forced flow","authors":"Sławomir Pietrowicz ,&nbsp;Przemysław Błasiak ,&nbsp;Marcin Opalski ,&nbsp;Bertrand Baudouy","doi":"10.1016/j.cryogenics.2025.104137","DOIUrl":"10.1016/j.cryogenics.2025.104137","url":null,"abstract":"<div><div>The main objective of this study is to reproduce the heat and mass processes in He II forced flows in steady-state condition using a modified simplified two-fluid model with an open source CFD environment. The model is derived from the so-called two-fluid model by assuming that the dominant terms in the superfluid momentum equation are the thermo-mechanical, the Gorter-Mellink mutual friction and the pressure gradient terms. From this simplification, a new system of equations describing the heat and mass transfer in He II is obtained with a conventional continuity equation, a modified momentum equation for the total fluid, and an energy equation revealing the unique counter-flow heat transport mechanism as in other simplified models, but here with the addition of the pressure gradient effect in He II. The model has been validated and compared with other models available in the literature, such as the original two fluid model and simplified models, as well as experimental data. Our model has been implemented using the OpenFOAM software and we have demonstrated here its good accuracy with experimental results and shorter computational time by 2-6% compared to the two-fluid model.</div></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":"150 ","pages":"Article 104137"},"PeriodicalIF":1.8,"publicationDate":"2025-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144253697","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}
引用次数: 0
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