One-cm-thick Si detector at LHe temperature

A silicon p-i-n diode of thickness 1 cm has been studied experimentally at liquid helium temperature. This preliminary study is aimed at the construction of a much bigger detector to detect low energy neutrino events.     

A universal hydrogen and deuterium liquefier

The design is given of an economical H₂ and D₂ liquefier which works by the boiling off of liquid He vapour. The decisive role played by the gas condenser in the operation of the liquefier is demonstrated. The relationships between the flow rates of He and of the liquefied gas are calculated and measured. The helium consumption is 2.85 l for liquefying 1 l of H₂ and 3.8 1 l of D₂, which agrees with the calculations.     

液氦传输管线的支撑设计和静力学分析

液氦传输管线是大型氦低温制冷设备高效运行和冷量运输的保障。为了设计出满足工程要求的管线,采用高真空多层绝热能减少管线的漏热。与此同时,选择合适的支撑结构和布置间距对减少漏热和满足强度要求是十分重要的。采用有限元软件ANSYS对液氦传输管线的支撑和补偿件等进行了静力学分析,结果表明:设计的液氦管线每间隔3 m布置一个支撑能很好的满足强度和减少漏热的要求;同时采用的波纹管进行低温应力补偿,对应力集中点进行了分析,模拟结果能满足强度要求,论证了管道设计的合理性和可行性。     

Critical withdrawal from a two-layer fluid through a line sink

The problem of withdrawing water through a line sink from a region containing two homogenous layers of different density is considered. Assuming steady, irrotational flow of an ideal fluid, a nonlinear integral equation is derived and solved numerically. Confirmation of earlier research is given, and some new results obtained in which the interface between the two layers rises up and then enters the sink vertically from above, even when the sink is located above the undisturbed level of the interface. A diagram is presented which summarises the work on this problem to this time.Part of this work was carried out while the author was at the Centre for Water Research, University of Western Australia.     

Selective withdrawal from an intake channel connected to a reservoir

This paper investigates selective withdrawal from an intake channel connected to a two-layer stratified reservoir using a line sink located at the downstream end of the intake channel. Such a withdrawal scenario is commonly observed at intake channels, skimming operations, and pump intake bays. This study formulates mathematical expressions for such a withdrawal scenario in order to extend our knowledge and to develop a mathematically simpler method in the case where a solution already exists. An expression to compute the incipient Froude number was developed considering the effect of a boundary. Expressions were developed to obtain discharge ratios for the scenarios when the line sink is located at the channel bottom and far away from the channel bottom. When the interface is located below the channel bottom and only at the reservoir, the intake channel itself behaves as a rectangular orifice, and an expression to compute the incipient Froude number for such a case was developed. The mathematical results were compared to the results obtained from a computational fluid dynamics solver and other relevant published studies.     

Dynamic simulation of the helium refrigerator/liquefier for LHD

A real-time dynamic simulation has been carried out for the 10 kW class helium refrigerator/liquefier of Large Helical Device (LHD) at National Institute for Fusion Science (NIFS). The refrigerator consists of eight screw compressors, seven expansion turbines, fourteen heat exchangers and a 20 m³ liquid helium reservoir. A simulation model was implemented to Cryogenic Process REal-time SimulaTor (C-PREST), developed as a platform for the plant process study and optimization. Validity of the simulation model has been confirmed based on the design values as well as the results of commissioning tests. This paper describes the cooldown process and expansion turbine trips during the operation. Difficulties of dynamic simulation for the large cryoplant are also discussed.     

粗氩液化器液氮调节阀阀后管道泄漏的分析和应急处理

KDON-15000/15000型空分设备粗氩液化器液氮调节阀阀后管道大量漏液,为了不影响空分设备正常供应氧、氮、氩产品,改变精氩系统的工艺流程后,保持空分设备继续运行。简介制氩系统的工艺流程和运行状况,分析应急处理措施的可行性和实施效果。     

Design and performance of a 30 l h helium liquefier/refrigerator with plastic piston expansion engines

An all-welded, simplified expansion engine with plastic piston and plastic piston rings was designed and tested. With expansion engines of this type, a helium liquefier/refrigerator of 30 l h⁻¹ capacity was built and its design, performance and controls are described. The liquefaction cycle is a Claude cycle with the helium gas being purified by a low temperature purification circuit added inside the liquefier.This liquefier produced about 30 000 litres of liquid helium during the last twelve months.     

Coning during withdrawal from two fluids of different density in a porous medium

The steady response of the interface between two fluids with different density in a porous medium is considered during extraction through a line sink. Supercritical withdrawal, or coning as it is often called, in which both fluids are being withdrawn, is investigated using a coupled integral equation formulation. It is shown that for each entry angle of the interface into the sink there is a range of supercritical solutions that depend on the flow rate, and that as the flow rate decreases the cone narrows. As the magnitude of the entry angle increases this range of flow-rate values decreases to a narrow range as the entry becomes vertical. Only one branch of solutions (that with horizontal entry) has the property that the interface levels off at a finite height, and this is investigated as a separate branch of solution.     

Harder Better

正Two momentous events will take place in China in October.The second largest economy in the world is set to celebrate its 70th anniversary of its founding on October 1,remembering lessons learned from the past,and presenting remarkable achievements and future outlooks.Laterin the same month,the IEC General Meeting,themed onBetter Quality,Better Life--Reliability,Safety,Efficiency,will be held in Shanghai,a financial hub and     

Design and performance of a 30 l h−1 helium liquefier/refrigerator with plastic piston expansion engines

An all-welded, simplified expansion engine with plastic piston and plastic piston rings was designed and tested. With expansion engines of this type, a helium liquefier/refrigerator of 30 l h^?1 capacity was built and its design, performance and controls are described. The liquefaction cycle is a Claude cycle with the helium gas being purified by a low temperature purification circuit added inside the liquefier.This liquefier produced about 30 000 litres of liquid helium during the last twelve months.     

Microneedle Makers Seek to Engineer a Better Shot

In its Top 10 Emerging Technologies report published in November 2020,the World Economic Forum-advised by experts convened by the journal Scientific American-pl...     

YPON-3000/3250型氧氮液化装置开车调试总结

简述了YPON-3000/3250型氧氮液化装置的设备配置、工艺流程特点,详细介绍了开车过程中遇到的一些问题及处理办法,并总结了操作体会。     

Thickness of a film obtained by the vertical withdrawal of a plate from a suspension described by the shvedov-bingham model

A model for describing the film flow of a liquid during the withdrawal of a plate from it has been checked experimentally. It has been established that the material of the solid substrate influences the thickness of the coating which is applied.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 55, No. 6, pp. 920–924, December, 1988.