真空与低温应用集绵珠光砂微量水分测定的重要性

真空与低温应用集绵珠光砂微量水分测定的重要性低温液体贮槽及低温工程设备中为了减少冷损，通常使用珠光砂作为绝热介质材料。特别是低温贮槽真空夹层中，作为真空粉末绝热介质材料的珠光砂的微量水分含量将会直接影响绝热真空度及绝热效果。其原因是珠光砂中的微量水分...     

固定式真空粉末绝热低温液体贮槽

前言本标准是对ZBJ76003－88《固定式真空粉末绝热低温液体贮槽》进行的修改。本标准与ZBJ76003－88相比,主要技术内容改变如下：——增加了“前言”。——第1章范围中,增加了“内容器由低温压力容器用低合金钢板制作的固定式真空粉末绝热液体二氧化碳贮槽可参照执行”的规定     

真空粉末绝热低温液体贮槽的焊接

奥氏体不锈钢的低温力学性能优良,很适合于制造低温贮槽和装置,空分行业中用于贮存液氮、液氧、液氩等的真空粉末绝热低温液体贮槽就是由奥氏体不锈钢制成。本文详细介绍了这类贮槽的焊接技术。图2表1。     

真空粉末绝热低温液体贮槽封结真空度探讨

介绍真空粉末绝热低温液体贮槽需要的工作真空度,通过实例计算得出:提高封结真空度对增加贮槽的真空寿命的程度有限,漏率才是影响真空寿命的关键因素。比较国内外对封结真空度的要求后,阐明降低封结真空度指标的可行性和重要意义。     

深冷文献消息(国内部分)

<正>965101 我国首例200m3低温液体球形贮槽的研制吴同文等《低温工程》1996 №4 1~5论述了 200 m3真空粉末绝热低温液体球体贮槽的研制过程。该产品于1994年投用,运行正常。经测试,1995年通过部级鉴定,其中,液氮日蒸发     

苏州杜尔气体化工装备有限公司

<正>大型常压低温液体贮槽大型常压低温液体贮槽是目前最经济的液体储存方法,具有储存量大、压力低、安全可靠的特点,广泛应用子工业气体LN2、LAr、LO2、LNG等低温液体的储存,贮槽采用平底拱盖、圆柱双层壁粉末绝热结构,主要由内胆、外槽、绝热结构、管路系统及安全装置等组成。LO2、LN2大型常压LNG大型常压低温液体贮槽工艺流程系统低温贮槽流程系统     

论低温贮运设备吸附剂的设置

根据真空绝热的形式,论述了高真空多层绝热必须设置低温吸附剂和常温吸附剂。根据珠光砂在低温下的特性,论述了真空粉末绝热贮槽在通常情况下（真空寿命不大于5年）不设置吸附剂的缘由,要使贮槽超过常规要求的真空寿命,必须同时解决真空闽,外筒防爆装置密封圈的材质,只有在此时设置吸附剂才有作用。     

苏州杜尔气体化工装备有限公司

<正>大型常压低温液体储罐大型常压低温液体贮槽是目前最经济的液体储存方法,具有储存量大、压力低、安全可靠的特点,广泛应用于工业气体LN2、LAr、LO2、LNG等低温液体的储存,贮槽采用平底拱盖、圆柱双层壁粉末绝热结构,主要由内胆、外槽、绝热结构、管路系统及安全装置等组成。LO2、LN2大型常压低温液体贮槽工艺流程系统LNG大型常压低温贮槽流程系统     

大型低温液体贮槽绝热系统设计

简介大型低温液体贮槽绝热系统的绝热材料及其主要性能指标;叙述了绝热系统的结构设计、氮封系统设计和基础设计,并分析了目前大型低温液体贮槽在订货、设计和使用中可能存在的几个问题和解决方法。     

苏州杜尔气体化工装备有限公司

<正>大型常压低温液体储罐大型常压低温液体贮槽是目前最经济的液体储存方法,具有储存量大、压力低、安全可靠的特点,广泛应用于工业气体LN2、LAr、LO_2、LNG等低温液体的储存,贮槽采用平底拱盖、圆柱双层壁粉末绝热结构,主要由内胆、外槽、绝热结构、管路系统及安全装置等组成。LO2、LN2大型常压低温液体贮槽工艺流程系统     

Electrical resistivity and thermoelectric power of polycrystalline and amorphous Se-Te-Cu system

The dark electrical resistivity and thermoelectric power have been measured for the bulk ternary alloy Se-Te-Cu. The samples were both polycrystalline and amorphous in structure. The measurements were carried out below room temperature. Depending on Cu addition, crystallographic structure, and amorphous or polycrystalline state, the samples manifested semiconducting or metallic behaviour. The maximum difference in electrical resistivity magnitude was of 14 orders. The activation energy ΔE of charge carriers determined for all semiconducting samples ranged from 0.07 to 0.25 eV. An increase in thermoelectric power resulting from the electron–phonon mass enhancement was estimated.     

Measurement of the thermal expansion of metal and FRPs

Thermal expansion is an important parameter for characterization of different binding forces, lattice dynamics, band and crystal structure of any solids. Many investigators have focused their attention to study this property theoretically and experimentally at different temperatures. It is one of the important properties of metals and its alloys, which helps to calculate the thermal stress. This parameter is also used to determine the compatibility of an insulator as load bearing materials. Different experimental setups have been developed to study thermal expansions of the materials using different techniques namely capacitance method, interferometric principle, LASER, optical, quartz tube etc. This paper reviews most of the experimental setups available to measure thermal expansion of metals, alloys, polymers and fibre-reinforced plastics at temperature ranging from 1 to 1100 K.     

Thermal design and performance of the SCUBA-2 instrument 1-K and mK systems

Various research fields require large and complex instruments containing detectors operating at millikelvin temperatures. The materials and techniques traditionally used in cryogenics are often unsuitable for the demanding requirements of such instruments. We describe the thermal design and performance of the 1-K and millikelvin systems of the SCUBA-2 instrument. This is an astronomical “camera” operating at wavelengths of 450 and 850 μm. It is the largest and most complex instrument ever built for sub-mm astronomy, and the first to use a cryogen-free dilution refrigerator. The design consists of a mix of traditional techniques (but used in demanding situations) as well as novel elements. The thermal performance has been stable and very successful, and we hope that the details described here will be useful to the designers of future large instruments.     

As-cast microstructures and behavior at high temperature of chromium-rich cobalt-based alloys containing hafnium carbides

Hafnium is often used to improve the high temperature oxidation resistance of superalloys but not to form carbides for strengthen them against creep. In this work hafnium was added in cobalt-based alloys for verifying that HfC can be obtained in cobalt-based alloys and for characterizing their behavior at a very temperature. Three Co–25Cr–0.25 and 0.50C alloys containing 3.7 and 7.4 Hf to promote HfC carbides, and four Co–25Cr– 0 to 1C alloys for comparison (all contents in wt.%), were cast and exposed at 1200 °C for 50 h in synthetic air. The HfC carbides formed instead chromium carbides during solidification, in eutectic with matrix and as dispersed compact particles. During the stage at 1200 °C the HfC carbides did not significantly evolve, even near the oxidation front despite oxidation early become very fast and generalized. At the same time the chromium carbides present in the Co–Cr–C alloys totally disappeared in the same conditions. Such HfC-alloys potentially bring efficient and sustainable mechanical strengthening at high temperature, but their hot oxidation resistance must be significantly improved.     

Gas gap thermal switches using neon or hydrogen and sorption pump

The very low pressure obtained thanks to adsorption phenomenon at low temperature can be used to build cryogenic heat switches, which offer the possibility to make or break thermal contact between two parts of a cryogenic system. The ON (conducting) and OFF (insulating) states of the switch are obtained by varying the gas pressure between two copper blocks separated by a gap of 100 μm. This pressure is controlled by acting upon the temperature of a small sorption pump (activated charcoal) connected to the gap space. For a “high” sorption pump temperature, the gas previously adsorbed in the sorption pump is released to the gap between the two blocks, allowing a good thermal conduction through the gas (ON state). On the opposite, cooling the sorption pump allows a very good vacuum between the copper blocks, which efficiently break the thermal contact (OFF state). Experimental thermal characteristics (Conductance in the ON and OFF state, ON-OFF switching temperature) of such a “Gas Gap Heat Switch” are described using hydrogen or neon as exchange gas and are compared with theoretical calculations.     

Development of a miniature cryogenic fluid circuit and a cryogenic micropump

This article presents the development of a miniaturized cryogenic fluid circuit for distributed cooling of low-temperature tracking detectors in high-energy physics (HEP). The heart of the circuit is a prototype cryogenic micropump. This volumetric pump is compatible with cooling powers of about 10-100 W, and capable of producing pressure heads of up to around 0.3 MPa. Besides detector and electronics cooling in HEP, potential applications are found in the field of superconductor technology.     

Integrated Resonant Self-Pumped Loop and pulse tube cryocooler for cryogenic cooling distribution

Cooling distribution is a vital technology concerning cryogenic thermal management systems for many future space applications, such as in-space, zero boil-off, long-term propellant storage, cooling infrared sensors at multiple locations or at a distance from the cryocooler, and focal-plane arrays in telescopes. These applications require a cooling distribution technology that is able to efficiently and reliably deliver cooling power (generated by a cryocooler) to remote locations and uniformly distribute it over a large-surface area. On-going efforts by others under this technology development area have not shown any promising results.This paper introduces the concept of using a Resonant Self-Pumped Loop (RSPL) integrated with the proven, highly efficient pulse tube cryocooler. The RSPL and pulse tube cryocooler combination generates cooling power and provides a distributive cooling loop that can be extended long distances, has no moving parts, and is driven by a single linear compressor. The RSPL is fully coupled with the oscillating flow of the pulse tube working fluid and utilizes gas diodes to convert the oscillating flow to one-directional (DC) steady flow that circulates through the cooling loop. The proposed RSPL is extremely simple, lightweight, reliable, and flexible for packaging. There are several requirements for the RSPL to operate efficiently. These requirements will be presented in this paper. Compared to other distributive cooling technologies currently under development, the RSPL technology is unique.     

Analytical and finite element investigations of shear/compression test fixtures

Insulation systems are critical components of the international thermonuclear experimental reactor (ITER). They must meet the super conducting magnets design requirements, including mechanical strength under combined shear and compressive stresses at cryogenic temperatures. Past cryogenic magnet systems often relied on woven glass/epoxy materials for insulation. An important point is to find a reliable shear/compression test method for these materials. The present work investigates a commonly used shear/compression setup and aims at measuring the reliability of the obtained test results. Therefore, the stress and failure analysis is performed analytically and numerically using the finite element method. The model is based on woven glass fiber reinforced materials which are subjected to combined shear and compressive stresses as well as to thermal loading, that results from cooling from 293 K to the test temperature of 77 K. A short analytical section shows the problems of common failure criteria which are used to describe the interaction of the shear and compression stresses. The numerical—finite element—section is based on three-dimensional linear elastic finite element models under thermo-mechanical loading. The locations of high stress gradients are investigated using an average stress criterion. Three different model geometries (15°, 45°, and 70°) are analyzed and finally compared with respect to their reliability.     

Cryogenic propellant liquefaction and storage for a precursor to a human Mars mission

An analysis of cryogenic liquefaction and storage methods for in-situ produced propellants (oxygen and methane) on Mars is presented. The application is to a subscale precursor sample return mission, intended to demonstrate critical cryogenic technologies prior to a human mission. A heat transfer analysis is included, resulting in predicted cryogenic tank surface temperatures and heat leak values for different conditions. Insulation thickness is traded off against cryocooler capacity to find optimum combinations for various insulation configurations, including multilayer insulation and microspheres. Microsphere insulation is shown to have promise, and further development is recommended.