低温热虹吸管传热性能的初步研究

作为一种高效传热方式,低温热管可望在空间探索、超导磁体冷却等方面获得广泛应用.介绍了低温热虹吸管的设计过程,实验分析了低温热虹吸管的工质质量、倾斜角度对低温热虹吸管传热性能的影响.研制的低温热虹吸管平均传热能力达2 W/K.     

低温热管的最新研究进展

作为一种高效传热方式，低温热管可望在空间探索、超导磁体冷却等方面获得广泛应用。简要介绍了低温热管的工作原理，着重分析了各种传热极限对低温热管性能的影响，总结了近几年低温热管研究与应用的最新发展情况。     

低温热管的设计制造与应用

主要介绍重力氖热管的设计计算和制造方法。并提出了一种简单有效、经济可靠的热管工质灌注法,即利用小型低温制冷机(GM制冷机)进行的冷凝充气法。同时还描述了1W/4．2K小型制冷机应用氖热管缩短开机降温时间的情况。图5参7。     

低温热色谱分离氢同位素

叙述了用“６０１”碳分子筛作托卡马克废气排出气的收集、纯化和低温热色谱的进样单元，以５Ａ分子筛柱在液氮（ＬＮ２）温度下吸附氕、氘，氚，随后把柱温回升至室温（２０℃～３０℃），为了提高分离效率、缩短分离时间和分离柱总长度，在两根分离柱间添加了ＨＤ、ＨＴ等歧化平衡器，经过四根分离柱组成的级联分离柱后氕、氘、氚获得了清晰分离。该装置的单次进样量为５标准升，日处理量为１２０～１８０标准升，流程气体总回收率＞９７％，氘丰度＞９９．９％时，氘、氚损失量（不计加热３００℃活化再生分离柱回收的氘、氚）＜５％，除氕效率＞９８％。     

多排并联分离式热虹吸管性能的实验研究

用煮沸法在多排并联分离式热虹吸管内部建立一定的真空度，并对这种热虹吸管的传热特性和内部流动特性进行了实验研究。通过实验得出了多排分离式热管的壁面温度分布规律以及充液量对系统传热性能和内部流动特性的影响。在实验基础上发现了多排分离式热虹吸管内部的停滞和倒流现象．并从理论上论证了这一现象发生的条件和预防措施。     

座便器虹吸管改进设计的噪声分析

由于噪声计算的复杂性，国内用CFD（Computational Fluid Dynamics）的方法预测流体流动引起的噪声尚处于开始阶段。利用CFD软件对座便器内部水和空气混合物的流动情况进行数值模拟，分析了某型号座便器虹吸管的结构缺陷，并据此进行改进设计。模拟分析表明，改进设计后产品的虹吸管已没有明显的缺陷。进行实机测量发现，改进设计后产品的冲水噪声完全符合国家的相关标准。     

水厂虹吸管安装工程水下钻孔爆破设计及施工

对贵阳市西郊水厂虹管安装工程进行水下爆破的爆破设计、施工工艺等方面及水下钻孔控制爆破技术进行探讨。     

重力式气-液型热管换热器的设计及应用

重力热管是一种依靠工质介质相变传热,具有传热温差小、热响应速度快、换热量大等优点的传热元件.为研究由重力热管组装而成的热管换热器在余热回收方面的优势,以西安某工程为例,根据设计要求,依据常规设计方法、整体设计思路,完整详细地介绍了重力式气-液型热管换热器的选型设计.最终经计算,选取54根长度为1500mm的重力热管,按...     

1K～100K温区He-3低温热物性数据计算

由于量子效应的影响，低温下He-3的性质与He-4有很大差异，对于4K－20K气相He-3的性质可利用改进的Strobridge方程来计算，而在20K－100K温区，通过引入对比德布罗意波长作为第三参数来描述量子效应而建立的改进量子对比态模型可用于计算该温区He-3的性质，基于上述计算方法，采用计算机程序设计，建立了He-3低温热物性数据库，该数据库可以计算压力在10MPa以下，温度介于1K－100K之间He-3的pVT性质，焓、内能、熵，热导率和粘度，其计算精度基本可以满足工程需要。     

氦-3低温热物性数值研究

在广泛收集和整理文献数据的基础上，自行开发了氦—3热物性数据计算程序，它适用于温度1K-100K，压力10MPa以内的使用范围。以压力、温度、比容(或密度)、焓、熵、内能中任意两个作为输入参量，可以计算其余热力参量、热导率以及动力粘度等输运性质。输入输出单位制种类齐全，可任意互换。在上述区间内，计算具有连续性，最大误差在5‰以内。     

The thermal conductivity of cryogenic insulation materials and its temperature dependence

For the presentation of the thermal conductivity of cryogenic insulation materials and their integral mean values an empirical function is suggested, with which experimentally found values can be extrapolated to other temperature levels.The selection of materials includes granulated and fibrous insulations under atmospheric pressure as well as under vacuum and a multilayer insulation for most high performances.It is shown theoretically, how the constants in the empirical function can be determined. Their calculation is demonstrated practically by using real measurements.For a multilayer insulation a theory is developed, with which a measured value can be extrapolated to other temperatures, gas pressures and numbers of layers. Its application to a real insulation system is demonstrated too.The results are listed in a tabular summary.     

Analysis of self-pressurization phenomenon of cryogenic fluid storage tank with thermal diffusion model

Self-pressurization phenomenon is one of the most important problems in the storage of cryogenic liquid. Until now, it has been difficult to predict exact pressurization process due to its complex non-equilibrium thermal behavior. This paper analyzes the self-pressurization with the trend of pressurization curves from experiment using liquid nitrogen with various heat leaks and liquid fractions. The trend of pressurization curves are classified on the basis of shape of pressurization curve. The qualitative relation between transient period, heat leak and liquid fractions is suggested. Thermal diffusion model (TDM) considering thermal stratification and thermal equilibrium model (TEM) can properly predict the respective pressurization curves with suitable condition for each model.     

20000m~3双层金属低温液体贮罐的设计

介绍20000m3双层金属低温液体贮罐的主要设计参数、外形结构和设计程序,阐述了内罐、保冷措施、外罐以及阀门和仪表等的设计方案和特点。     

Numerical simulation of cryogenic cavitating flow by an extended transport-based cavitation model with thermal effects

Thermodynamic effects on cryogenic cavitating flow is important to the accuracy of numerical simulations mainly because cryogenic fluids are thermo-sensitive, and the vapour saturation pressure is strongly dependent on the local temperature. The present study analyses the thermal cavitating flows in liquid nitrogen around a 2D hydrofoil. Thermal effects were considered using the RNG k-ε turbulence model with a modified turbulent eddy viscosity and the mass transfer homogenous cavitation model coupled with energy equation. In the cavitation model process, the saturated vapour pressure is modified based on the Clausius-Clapron equation. The convection heat transfer approach is also considered to extend the Zwart-Gerber-Belamri model. The predicted pressure and temperature inside the cavity under cryogenic conditions show that the modified Zwart-Gerber-Belamri model is in agreement with the experimental data of Hord et al. in NASA, especially in the thermal field. The thermal effect significantly affects the cavitation dynamics during phase-change process, which could delay or suppress the occurrence and development of cavitation behaviour. Based on the modified Zwart-Gerber-Belamri model proposed in this paper, better prediction of the cryogenic cavitation is attainable.     

大型低温液体贮罐设计制造

介绍了大型低温液体贮罐的结构特点,以及结构尺寸、内罐、外罐、保温和基础等设计要点,阐述了大型低温液体贮罐抗震设计、施工安装、清洗和试验等有关问题。     

Design and development of a direct injection system for cryogenic engines

The cryogenic engine has received increasing attention due to its promising potential as a zero-emission engine. In this study, a new robust liquid nitrogen injection system was commissioned and set up to perform high-pressure injections into an open vessel. The system is used for quasi-steady flow tests used for the characterisation of the direct injection process for cryogenic engines. An electro-hydraulic valve actuator provides intricate control of the valve lift, with a minimum cycle time of 3 ms and a frequency of up to 20 Hz. With additional sub-cooling, liquid phase injections from 14 to 94 bar were achieved. Results showed an increase in the injected mass with the increase in pressure, and decrease in temperature. The injected mass was also observed to increases linearly with the valve lift. Better control of the injection process, minimises the number of variables, providing more comparable and repeatable sets of data. Implications of the results on the engine performance were also discussed.     

Cryogenic thermal conductivity measurements on candidate materials for space missions

Spacecraft and instruments on space missions are built using a wide variety of carefully-chosen materials. It is common for NASA engineers to propose new candidate materials which have not been totally characterized at cryogenic temperatures. In many cases a material’s cryogenic thermal conductivity must be known before selecting it for a specific space-flight application. We developed a test facility in 2004 at NASA’s Goddard Space Flight Center to measure the longitudinal thermal conductivity of materials at temperatures between 4 and 300 K, and we have characterized many candidate materials since then. The measurement technique is not extremely complex, but proper care to details of the setup, data acquisition and data reduction is necessary for high precision and accuracy. We describe the thermal conductivity measurement process and present results for ten engineered materials, including alloys, polymers, composites, and a ceramic.     

低温传输管线的设计与研究

以北京正负离子对撞机二期改造项目(BEPCⅡ)第一对撞厅液氮传输管线与液氮、液氦多通道传输管线为例,介绍低温传输管线的结构设计,有限元分析与实验结果表明,它是合理、可靠的,为国内今后大型低温系统的设计和实施提供了成功的范例。     

低温用膨胀珍珠岩绝热性能的实验研究

本文以常用低温保温材料膨胀珍珠岩 (珠光砂 )为研究对象 ,实验测量了在稳态和非稳态传热条件下的导热性能、热扩散性能及其随温度的变化规律 ,并对两种传热条件下的绝热特性进行了分析和研究 ,为工程应用提供可靠的理论依据 ,也为低温绝热方案的选择及优化提供参考资料     

Design thermal values for unfired clay bricks

This paper reports on a laboratory and theoretical method for determining the design values for thermal conductivity and thermal resistance of unfired clay masonry bricks from both experimental and theoretical design point of view. The paper describes the methodology of obtaining these values using the measured lower and upper lambda limits. In order to determine the basic design thermal value and the design thermal resistance, a Laser-comp FOX 200 thermal conductivity meter equipped with WinTherm32an software package was employed for the laboratory data collection and analysis. Lime or Portland cement (PC)-activated Ground Granulated Blastfurnace Slag (GGBS) binder was used to stabilise Lower Oxford Clay (LOC) for unfired masonry brick specimen production. The major influence of the design values on the thermal conductivity and thermal resistance are illustrated in this study, using two different types of unfired clay bricks (LG and PG) at 2% moisture content prior to test. This paper covers conductivity test for each unfired clay bricks within the temperature range 2.5–17.5 °C. The measured thermal properties of the unfired clay bricks were compared to the design thermal properties of fired bricks. The results were used to predict the design thermal values of unfired clay masonry bricks at varied density and moisture contents prior to testing. A comparison of the measured thermal values for the unfired bricks to the design thermal values of fired clay bricks can also be seen. The results demonstrate that the unfired clay bricks were able to comply with the design thermal requirements for clay masonry units, suggesting that the unfired clay bricks can be used for low-medium cost housing and energy efficient masonry structures.