Pub Date : 2024-08-16DOI: 10.1016/j.cryogenics.2024.103925
Density is a critical parameter in the liquefied natural gas (LNG) industry, which necessitates the study of measurement methods. Standard methods for calculating LNG density are employed in downstream LNG custody transfer, but it still faces challenges in density measurement in the upstream, such as in LNG plants and LNG refueling station. In this paper, a gravimetric density measurement method was established for LNG plants, which is SI-traceable as it relies on volume and mass. A home-made sampling device was developed and employed to obtain the LNG volume and mass. The principle involves trapping LNG in a known-volume quantitative tube within the sampling device. The LNG is then transferred to a vacuum sampling cylinder and weighed using a mass compactor. This approach not only provides representative samples but also enables compositional analysis while performing density calculations according to ISO 6578. Feasibility and practicality tests of this novel method were conducted in an LNG plant. The test results indicate that the reproducibility is 0.6 %(RSD), and the relative expanded uncertainty is 2.0 % (k = 2). Compared to the revised Klosek and McKinley method (RKM), it shows a relative difference of −0.3 % to 1.5 %, demonstrating the applicability to LNG plants.
{"title":"LNG density measurement by gravimetric method","authors":"","doi":"10.1016/j.cryogenics.2024.103925","DOIUrl":"10.1016/j.cryogenics.2024.103925","url":null,"abstract":"<div><p>Density is a critical parameter in the liquefied natural gas (LNG) industry, which necessitates the study of measurement methods. Standard methods for calculating LNG density are employed in downstream LNG custody transfer, but it still faces challenges in density measurement in the upstream, such as in LNG plants and LNG refueling station. In this paper, a gravimetric density measurement method was established for LNG plants, which is SI-traceable as it relies on volume and mass. A home-made sampling device was developed and employed to obtain the LNG volume and mass. The principle involves trapping LNG in a known-volume quantitative tube within the sampling device. The LNG is then transferred to a vacuum sampling cylinder and weighed using a mass compactor. This approach not only provides representative samples but also enables compositional analysis while performing density calculations according to ISO 6578. Feasibility and practicality tests of this novel method were conducted in an LNG plant. The test results indicate that the reproducibility is 0.6 %(RSD), and the relative expanded uncertainty is 2.0 % (<em>k</em> = 2). Compared to the revised Klosek and McKinley method (RKM), it shows a relative difference of −0.3 % to 1.5 %, demonstrating the applicability to LNG plants.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142007086","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}
Pub Date : 2024-08-14DOI: 10.1016/j.cryogenics.2024.103922
The prevalence of technologies that operate at cryogenic temperatures requires that the cooling systems used to maintain these systems be carefully designed. This research focuses on understanding the thermal performance of the heat path between the heat source (the technology being cooled) and the cooling source (the cryocooler). Specifically, this work characterizes through measurement the thermal properties of common heat path materials, with a focus on bulk thermal conductivity and thermal contact resistance of pressed contacts. A framework for using these measurements to optimize a bolted contact is proposed and demonstrated.
{"title":"Measurement of thermal contact resistance and the design of thermal contacts at cryogenic temperatures","authors":"","doi":"10.1016/j.cryogenics.2024.103922","DOIUrl":"10.1016/j.cryogenics.2024.103922","url":null,"abstract":"<div><p>The prevalence of technologies that operate at cryogenic temperatures requires that the cooling systems used to maintain these systems be carefully designed. This research focuses on understanding the thermal performance of the heat path between the heat source (the technology being cooled) and the cooling source (the cryocooler). Specifically, this work characterizes through measurement the thermal properties of common heat path materials, with a focus on bulk thermal conductivity and thermal contact resistance of pressed contacts. A framework for using these measurements to optimize a bolted contact is proposed and demonstrated.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142002290","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}
Pub Date : 2024-08-12DOI: 10.1016/j.cryogenics.2024.103924
Over the past few years, liquefied natural gas (LNG) evaporated gas re-liquefaction technology has rapidly developed. This technology is particularly useful in trans-oceanic LNG trade, which has grown to be a hot sector in the world’s energy trade. And there are several limitations on board. Reducing energy consumption, improving efficiency, and lowering costs are crucial factors in the BOG re-liquefaction process. This review provides a comprehensive review of the recent advancements in the design and optimization of BOG re-liquefaction processes. It includes a detailed analysis and comparison of existing BOG re-liquefaction technologies, and specifically discusses two types of re-liquefaction processes: dynamic and steady-state. Furthermore, this review examines different perspectives and directions for improving these two re-liquefaction technologies. Finally, the challenges faced by the BOG re-liquefaction process for LNG carriers are presented, along with future directions for addressing these challenges.
过去几年来,液化天然气(LNG)蒸发气再液化技术发展迅速。这种技术在跨洋液化天然气贸易中特别有用,已发展成为世界能源贸易的热门领域。而船上有几个限制条件。减少能耗、提高效率和降低成本是 BOG 再液化过程中的关键因素。本综述全面回顾了近期在设计和优化 BOG 再液化工艺方面取得的进展。其中包括对现有 BOG 再液化技术的详细分析和比较,并特别讨论了两种类型的再液化工艺:动态和稳态。此外,本综述还探讨了改进这两种再液化技术的不同视角和方向。最后,介绍了液化天然气运输船 BOG 再液化工艺面临的挑战,以及应对这些挑战的未来方向。
{"title":"Review of the design and optimization of BOG re-liquefaction process for LNG carriers","authors":"","doi":"10.1016/j.cryogenics.2024.103924","DOIUrl":"10.1016/j.cryogenics.2024.103924","url":null,"abstract":"<div><p>Over the past few years, liquefied natural gas (LNG) evaporated gas re-liquefaction technology has rapidly developed. This technology is particularly useful in <em>trans</em>-oceanic LNG trade, which has grown to be a hot sector in the world’s energy trade. And there are several limitations on board. Reducing energy consumption, improving efficiency, and lowering costs are crucial factors in the BOG re-liquefaction process. This review provides a comprehensive review of the recent advancements in the design and optimization of BOG re-liquefaction processes. It includes a detailed analysis and comparison of existing BOG re-liquefaction technologies, and specifically discusses two types of re-liquefaction processes: dynamic and steady-state. Furthermore, this review examines different perspectives and directions for improving these two re-liquefaction technologies. Finally, the challenges faced by the BOG re-liquefaction process for LNG carriers are presented, along with future directions for addressing these challenges.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141979646","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}
Pub Date : 2024-08-06DOI: 10.1016/j.cryogenics.2024.103918
This study presents the measurement of the thermal expansion of aluminum alloy 6061 at cryogenic temperatures using Helium as the cooling medium. Three distinct tests were conducted to evaluate thermal expansion: two with gradual and natural heating of the material, and a third with temperature stabilization at key points. Measurements were carried out using Fiber Bragg Grating Sensors (FBGS), which provided precise and reliable data on the material's thermal behavior. The obtained results were compared with reference curves from the National Institute of Standards and Technology (NIST), showing good agreement and validation of the employed methods. This research highlights the effectiveness of using FBGS in measuring thermal expansion under cryogenic conditions and the importance of heating procedures in obtaining accurate data.
{"title":"Thermal expansion calculation using FBGS in cryogenic applications","authors":"","doi":"10.1016/j.cryogenics.2024.103918","DOIUrl":"10.1016/j.cryogenics.2024.103918","url":null,"abstract":"<div><p>This study presents the measurement of the thermal expansion of aluminum alloy 6061 at cryogenic temperatures using Helium as the cooling medium. Three distinct tests were conducted to evaluate thermal expansion: two with gradual and natural heating of the material, and a third with temperature stabilization at key points. Measurements were carried out using Fiber Bragg Grating Sensors (FBGS), which provided precise and reliable data on the material's thermal behavior. The obtained results were compared with reference curves from the National Institute of Standards and Technology (NIST), showing good agreement and validation of the employed methods. This research highlights the effectiveness of using FBGS in measuring thermal expansion under cryogenic conditions and the importance of heating procedures in obtaining accurate data.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0011227524001383/pdfft?md5=2ad4821479c5659188c2e86250f6c394&pid=1-s2.0-S0011227524001383-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935742","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}
Pub Date : 2024-08-05DOI: 10.1016/j.cryogenics.2024.103919
Epoxy resin (EP) plays a crucial role in safeguarding superconducting magnets. One of the major concerns related to its usage is its inherent susceptibility to cracking under cryogenic temperatures and the strong electromagnetic forces experienced during the operation of superconducting magnets. In this study, we utilize molecular dynamics (MD)simulation and cryogenic experiments to conduct a comprehensive investigation aimed at gaining a profound understanding of the cryogenic toughening mechanism in hyperbranched polymers-toughened (HBPs) EPs. Five different crosslinking models of EP composites were established by MD simulations. The performance parameters obtained from the MD simulation calculations are highly consistent with the experimental results, which included the glass transition temperature, coefficient of thermal expansion, mechanical properties, free volume and atomic mean square displacement. Moreover, the relationship between structural changes and properties of the MD models was investigated. This research method provides a new avenue of exploration for superconducting magnet encapsulation resin materials.
环氧树脂(EP)在保护超导磁体方面起着至关重要的作用。与使用环氧树脂有关的一个主要问题是,环氧树脂在低温条件下和超导磁体运行过程中的强电磁力作用下容易开裂。在本研究中,我们利用分子动力学(MD)模拟和低温实验进行了全面研究,旨在深刻理解超支化聚合物增韧 EPs 的低温增韧机制。通过 MD 模拟建立了五种不同的 EP 复合材料交联模型。MD 模拟计算得到的性能参数与实验结果高度一致,包括玻璃化转变温度、热膨胀系数、力学性能、自由体积和原子均方位移。此外,还研究了 MD 模型的结构变化与性能之间的关系。该研究方法为超导磁体封装树脂材料提供了一条新的探索途径。
{"title":"Enhancing the cryogenic performance of superconducting magnet encapsulation resins with hyperbranched polymers: A molecular dynamics simulation and experimental study","authors":"","doi":"10.1016/j.cryogenics.2024.103919","DOIUrl":"10.1016/j.cryogenics.2024.103919","url":null,"abstract":"<div><p>Epoxy resin (EP) plays a crucial role in safeguarding superconducting magnets. One of the major concerns related to its usage is its inherent susceptibility to cracking under cryogenic temperatures and the strong electromagnetic forces experienced during the operation of superconducting magnets. In this study, we utilize molecular dynamics (MD)simulation and cryogenic experiments to conduct a comprehensive investigation aimed at gaining a profound understanding of the cryogenic toughening mechanism in hyperbranched polymers-toughened (HBPs) EPs. Five different crosslinking models of EP composites were established by MD simulations. The performance parameters obtained from the MD simulation calculations are highly consistent with the experimental results, which included the glass transition temperature, coefficient of thermal expansion, mechanical properties, free volume and atomic mean square displacement. Moreover, the relationship between structural changes and properties of the MD models was investigated. This research method provides a new avenue of exploration for superconducting magnet encapsulation resin materials.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141951228","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}
Pub Date : 2024-08-05DOI: 10.1016/j.cryogenics.2024.103921
Stacked structures of high-temperature superconducting (HTS) tapes are usually employed to enhance current-carrying capacity in cable or magnet applications, but their multilayer characteristics may result in local hot spots due to uneven cooling. Besides, the inconsistencies along the length of tapes introduced during manufacturing process and the significant transverse Lorentz forces experienced in magnet operations can lead to weak parts, bringing uncertainties to thermal stability. Finite-element methods are widely used to predict thermal propagations, but 3D models encounter challenges such as distorted mesh elements and convergence issues, particularly when combining electromagnetic and heat transfer modules for long-distance wires. In this work, we have developed a Dimensional Coupling Method (DCM) to assess the thermal impact of weak parts in stacked wires applying coupled 1D and 2D models. The 2D model analyzes the electromagnetic and heat characteristics of stacked surfaces, and provides an initial heat source for the 1D model, which evaluates thermal propagation longitudinally. Simulation results of the 1D module are then transferred back to update the 2D outcomes. Models of distinct dimensions are coupled sequentially in physical steps but simultaneously in the time domain. Our approach is verified by 3D model benchmarks and offers a computational cost reduction of approximately 60 % compared to the benchmarks, making it more suitable for applications with large Iop/Ic ratios. Specially, multi-layer stacked wires under low ratios cases are also been analyzed. What’s more, two influencing factors of heat propagation, the weak-part length and position, are also investigated.
{"title":"Thermal propagation analysis of 2G HTS stacked wires based on a dimensional coupling method","authors":"","doi":"10.1016/j.cryogenics.2024.103921","DOIUrl":"10.1016/j.cryogenics.2024.103921","url":null,"abstract":"<div><p>Stacked structures of high-temperature superconducting (HTS) tapes are usually employed to enhance current-carrying capacity in cable or magnet applications, but their multilayer characteristics may result in local hot spots due to uneven cooling. Besides, the inconsistencies along the length of tapes introduced during manufacturing process and the significant transverse Lorentz forces experienced in magnet operations can lead to weak parts, bringing uncertainties to thermal stability. Finite-element methods are widely used to predict thermal propagations, but 3D models encounter challenges such as distorted mesh elements and convergence issues, particularly when combining electromagnetic and heat transfer modules for long-distance wires. In this work, we have developed a Dimensional Coupling Method (DCM) to assess the thermal impact of weak parts in stacked wires applying coupled 1D and 2D models. The 2D model analyzes the electromagnetic and heat characteristics of stacked surfaces, and provides an initial heat source for the 1D model, which evaluates thermal propagation longitudinally. Simulation results of the 1D module are then transferred back to update the 2D outcomes. Models of distinct dimensions are coupled sequentially in physical steps but simultaneously in the time domain. Our approach is verified by 3D model benchmarks and offers a computational cost reduction of approximately 60 % compared to the benchmarks, making it more suitable for applications with large <em>I<sub>op</sub></em>/<em>I<sub>c</sub></em> ratios. Specially, multi-layer stacked wires under low ratios cases are also been analyzed. What’s more, two influencing factors of heat propagation, the weak-part length and position, are also investigated.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935743","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}
Pub Date : 2024-08-03DOI: 10.1016/j.cryogenics.2024.103920
Liquid hydrogen plays an important role in the large scale storage and long-distance transportation. The development of hydrogen turbo-expander is the key to increase the efficiency of hydrogen liquefaction, reducing the cost of liquid hydrogen production, storage and transportation. In this paper, a numerical model of hydrogen nozzle is established and validated against experimental data. The performance of four traditional nozzle profiles in hydrogen turbo-expanders is simulated and analyzed. The poor uniformity of outlet flow angle is generally found in these nozzle profiles, leading to nozzle passage and impeller incidence losses in turbo-expanders. A genetic algorithm based method is proposed to optimize the nozzle profiles. The optimization objectives involve the nozzle efficiency, the uniformity of the nozzle outlet angle and the uniformity of the outlet Mach number. The deviations in the outlet angle and Mach number of the optimized nozzle are reduced by 50.26 % and 14.03 %, respectively, while the nozzle efficiency reaches 98.64 %. The matching characteristics of the optimized nozzle with the impeller are obtained via simulation of a hydrogen turbo-expander, and the results indicate the expansion efficiency can be increased by 1.53 %.
{"title":"Genetic algorithm based optimization of nozzle profiles for a hydrogen turbo-expander","authors":"","doi":"10.1016/j.cryogenics.2024.103920","DOIUrl":"10.1016/j.cryogenics.2024.103920","url":null,"abstract":"<div><p>Liquid hydrogen plays an important role in the large scale storage and long-distance transportation. The development of hydrogen turbo-expander is the key to increase the efficiency of hydrogen liquefaction, reducing the cost of liquid hydrogen production, storage and transportation. In this paper, a numerical model of hydrogen nozzle is established and validated against experimental data. The performance of four traditional nozzle profiles in hydrogen turbo-expanders is simulated and analyzed. The poor uniformity of outlet flow angle is generally found in these nozzle profiles, leading to nozzle passage and impeller incidence losses in turbo-expanders. A genetic algorithm based method is proposed to optimize the nozzle profiles. The optimization objectives involve the nozzle efficiency, the uniformity of the nozzle outlet angle and the uniformity of the outlet Mach number. The deviations in the outlet angle and Mach number of the optimized nozzle are reduced by 50.26 % and 14.03 %, respectively, while the nozzle efficiency reaches 98.64 %. The matching characteristics of the optimized nozzle with the impeller are obtained via simulation of a hydrogen turbo-expander, and the results indicate the expansion efficiency can be increased by 1.53 %.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-08-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935825","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}
Pub Date : 2024-07-31DOI: 10.1016/j.cryogenics.2024.103911
In order to carry out vibration reduction work on a cryogen-free dilution refrigerator system pre-cooled by a GM cryocooler, this paper first introduces the method of vibration measurement, particularly presenting the results and verification of displacement measurement obtained through acceleration integration. Subsequently, based on the construction of our dilution refrigerator, the paper reports experimental evidence of the direct impact of vibration on temperature and provides an effective vibration reduction scheme for the system. The study finds that vibrations transmitted through the path of “low-temperature part of GM- copper braid − support structure − various cold plates” have the most significant impact, hence making good internal soft connections is key. The influence of vibrations from the room-temperature part of GM can be mitigated to some extent by suspending the cold head, either by a separate frame or using the dilution refrigerator’s own frame. The use of a structure composed of air springs and honeycomb rubber in the suspension system has proven to be effective. Our final experimental results have demonstrated that with adequate vibration damping, the impact of vibrations from the GM on temperature can be essentially eliminated, allowing the dilution refrigerator to achieve a temperature level close to that when pre-cooled by a PT. The research in this paper has certain reference value for the construction and vibration mitigation of ultra-low temperature refrigeration systems.
{"title":"Experimental study on vibration reduction of a cryogen-free dilution refrigerator system pre-cooled by a GM cryocooler","authors":"","doi":"10.1016/j.cryogenics.2024.103911","DOIUrl":"10.1016/j.cryogenics.2024.103911","url":null,"abstract":"<div><p>In order to carry out vibration reduction work on a cryogen-free dilution refrigerator system pre-cooled by a GM cryocooler, this paper first introduces the method of vibration measurement, particularly presenting the results and verification of displacement measurement obtained through acceleration integration. Subsequently, based on the construction of our dilution refrigerator, the paper reports experimental evidence of the direct impact of vibration on temperature and provides an effective vibration reduction scheme for the system. The study finds that vibrations transmitted through the path of “low-temperature part of GM- copper braid − support structure − various cold plates” have the most significant impact, hence making good internal soft connections is key. The influence of vibrations from the room-temperature part of GM can be mitigated to some extent by suspending the cold head, either by a separate frame or using the dilution refrigerator’s own frame. The use of a structure composed of air springs and honeycomb rubber in the suspension system has proven to be effective. Our final experimental results have demonstrated that with adequate vibration damping, the impact of vibrations from the GM on temperature can be essentially eliminated, allowing the dilution refrigerator to achieve a temperature level close to that when pre-cooled by a PT. The research in this paper has certain reference value for the construction and vibration mitigation of ultra-low temperature refrigeration systems.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935636","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}
Pub Date : 2024-07-29DOI: 10.1016/j.cryogenics.2024.103910
Cryogenic memristor-based DC sources offer a promising avenue for in situ biasing of quantum dot arrays. In this study, we present experimental results and discuss the scaling potential for such DC sources. We first demonstrate the operation of a commercial discrete operational amplifier down to which is used on the DC source prototype. Then, the tunability of the memristor-based DC source is validated by performing several -DC sweeps with a resolution of at room temperature and at . Additionally, the DC source prototype exhibits a limited output drift of at . This showcases the potential of memristor-based DC sources for quantum dot biasing. Limitations in power consumption and voltage resolution using discrete components highlight the need for a fully integrated and scalable complementary metal–oxide–semiconductor-based (CMOS-based) approach. To address this, we propose to monolithically co-integrate emerging non-volatile memories (eNVMs) and CMOS circuitry. Simulations reveal a reduction in power consumption, down to per DC source and in footprint. This allows for the integration of up to one million eNVM-based DC sources at the stage of a dilution fridge, paving the way for near term large-scale quantum computing applications.
{"title":"Towards scalable cryogenic quantum dot biasing using memristor-based DC sources","authors":"","doi":"10.1016/j.cryogenics.2024.103910","DOIUrl":"10.1016/j.cryogenics.2024.103910","url":null,"abstract":"<div><p>Cryogenic memristor-based DC sources offer a promising avenue for in situ biasing of quantum dot arrays. In this study, we present experimental results and discuss the scaling potential for such DC sources. We first demonstrate the operation of a commercial discrete operational amplifier down to <figure><img></figure> which is used on the DC source prototype. Then, the tunability of the memristor-based DC source is validated by performing several <figure><img></figure>-DC sweeps with a resolution of <figure><img></figure> at room temperature and at <figure><img></figure>. Additionally, the DC source prototype exhibits a limited output drift of <figure><img></figure> at <figure><img></figure>. This showcases the potential of memristor-based DC sources for quantum dot biasing. Limitations in power consumption and voltage resolution using discrete components highlight the need for a fully integrated and scalable complementary metal–oxide–semiconductor-based (CMOS-based) approach. To address this, we propose to monolithically co-integrate emerging non-volatile memories (eNVMs) and <figure><img></figure> CMOS circuitry. Simulations reveal a reduction in power consumption, down to <figure><img></figure> per DC source and in footprint. This allows for the integration of up to one million eNVM-based DC sources at the <figure><img></figure> stage of a dilution fridge, paving the way for near term large-scale quantum computing applications.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0011227524001309/pdfft?md5=f329da1adfb66f9af0882dddffa8eef5&pid=1-s2.0-S0011227524001309-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141935637","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}
Pub Date : 2024-07-26DOI: 10.1016/j.cryogenics.2024.103900
A cryogenic circulation pump (CCP) with the small flow rate and low heat leakage, which is the key equipment of the cooling system for the cryogenic permanent magnet undulator (CPMU) and synchrotron monochromator in High Energy Photon Source(HEPS), is developed according to the design parameters and operation experiences. The mechanic structure of the CCP including a motor at room temperature, an impeller and a volute in the cryogenic environment is designed, and numerical simulation on the rotating shaft and internal flows are performed to predict the mechanical and hydrodynamic performances of the pump. Meanwhile, the experimental investigation of the CCP is carried out in the liquid nitrogen (LN2) cryogenic system, and the hydrodynamic performances of the CCP are verified experimentally. The results are shown that the calculated performances of the CCP are in reasonable agreement with the experimental results, which indicates that the numerical calculation model of the CCP is more effective. Moreover, the deviations of pressure drop and efficiency between the calculation and measurement are analyzed in this paper.
{"title":"Design, construction and testing of the prototype cryogenic circulation centrifugal pump for the high energy photon source","authors":"","doi":"10.1016/j.cryogenics.2024.103900","DOIUrl":"10.1016/j.cryogenics.2024.103900","url":null,"abstract":"<div><p>A cryogenic circulation pump (CCP) with the small flow rate and low heat leakage, which is the<!--> <!-->key<!--> <!-->equipment of the cooling system for the cryogenic permanent magnet undulator (CPMU)<!--> <!-->and synchrotron monochromator in High Energy Photon Source(HEPS), is developed according to the design parameters and operation experiences. The mechanic structure of the CCP including a motor at room temperature, an impeller and a volute in the cryogenic environment is designed, and numerical simulation on the rotating shaft and internal flows are performed to predict the mechanical and hydrodynamic performances of the pump. Meanwhile, the experimental investigation of the CCP is carried out in the liquid nitrogen (LN<sub>2</sub>) cryogenic system, and the hydrodynamic performances of the CCP are verified experimentally. The results are shown that the calculated performances of the CCP are in reasonable agreement with the experimental results, which indicates that the numerical calculation model of the CCP is more effective. Moreover, the deviations of pressure drop and efficiency between the calculation and measurement are analyzed in this paper.</p></div>","PeriodicalId":10812,"journal":{"name":"Cryogenics","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141840944","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}