斯特林制冷机回热器密封间隙内泄漏率分析

斯特林制冷机回热器采用间隙密封,可以在完成密封作用的同时消除接触磨损和因此而产生的污染。但由于间隙内气体的泄漏,引起了冷量损失,使制冷量减少。文中建立了间隙密封式斯特林制冷机间隙泄漏率的数学物理模型,并获得了密封间隙的泄漏率的表达式。     

自由活塞斯特林制冷机间隙密封技术研究

间隙密封作为自由活塞斯特林制冷机中的一项关键技术,可以在完成密封作用的同时消除接触磨损和因此而产生的污染,同时由于间隙内气体的泄漏,引起了冷量损失,使制冷量减少。文中建立了层流工况下间隙密封的数学模型,推导了密封间隙的泄漏率。针对自由活塞斯特林制冷机的结构,对三处不同位置的间隙密封分别进行分析,提出了不同位置的间隙密封设计要求。对于直线压缩机的间隙密封,压缩机间隙密封的泄漏会带来压力波损失并同时影响压缩机固有频率;为消除压缩活塞的偏置,要求周期泄漏量为零,对于膨胀机的间隙密封,除了泄漏损失还包括了穿梭损失和摩擦损失等。最后,考虑实际加工和装配工艺的局限性,对间隙密封的偏心影响进行了分析,并对自由活塞斯特林制冷机间隙密封的安装技术和检测手段提出了简单的建议。     

气动分置式斯特林制冷机间隙密封优化

气体泄漏及间隙传热会导致制冷机性能恶化,因此间隙密封技术是气动分置式斯特林制冷机的一项关键技术.对三种不同间隙密封结构展开研究,搭建Sage模型分析结构参数对制冷机性能的影响,模拟结果显示:间隙高度H不仅影响泄漏率,还与穿梭损失及泵气损失相关;双段式间隙密封的密封1长度比例越大,制冷量越大.当长度比例及密封1、间隙1高...     

10W@80K分置式气体轴承斯特林制冷机研究

为了同时满足冷量、重量、振动、寿命以及环境适应性的需求,开展了分置式气体轴承斯特林制冷机的研发。以气体轴承线性压缩机为驱动源,设计了一款大冷量分置式气体轴承斯特林制冷机。优选了制冷机的设计参数,系统研究了制冷机的运行频率、充气压力、降温时间与制冷量的变化规律,进行了相关实验研究,压缩机输入240Wac,制冷机输出性能指标达到10.2W@80K,验证了制冷机设计的合理性。     

基于气体轴承斯特林制冷机的低温冰箱

基于斯特林制冷机的低温冰箱具有体积小、重量轻、便于携带运输的优点,同时可以实现+4~-80℃宽温区冷冻冷藏功能。为了提高降温速率,提升冰箱寿命,通过箱体绝热设计、制冷机冷量传输设计及箱内温度均匀性仿真分析等,设计并制作了一台基于2台气体轴承斯特林制冷机对置式布置的低温冰箱样机,搭建测试系统对其性能进行了初步测试。基于气体轴承斯特林制冷机的低温冰箱冷冻腔容积为27L,在不放置样品的情况下,冷冻腔能够在5h内降温至-80℃。     

小型分置式斯特林制冷机理论冷量的计算方法

分置式斯特林制冷机由于连接管和室温腔等死容积的存在,其理论冷量的计算方法更是有别于整体式斯特林制冷机。文中着重以数值计算的思路计算了小型分置式斯特林制冷机的理论冷量,并通过实验测定。最后分析了主要工作参数诸如充气压力、工作频率等对分置式斯特林制冷机性能的影响。     

高温超导用自由活塞斯特林制冷机理论研究

制冷机是制约高温超导器件的瓶颈.文中针对自由活塞式斯特林制冷机进行了理论研究,建立了自由活塞斯特林制冷机的热声模型,对充气压力、活塞的位移振幅、热端换热器温度和密封间隙进行了模拟.模拟结果显示,以最大制冷量为目标最佳充气压力为1.9MPa,增加活塞位移振幅、降低回热器热端温度以及减小密封间隙可提高制冷机的性能.     

一种HgCdTe探测器微型杜瓦的设计和工艺研究

介绍一种用于冷却HgCdTe探测器微型制冷杜瓦组件,该组件由旋转马达驱动型斯特林制冷机冷却,杜瓦采用插入式结构,制冷机与杜瓦之间用耦合单元来传递冷量。设计中的关键技术是尽可能减少漏热损失、高效传递冷量以降低斯特林制冷机的热负荷,同时为了达到长期保持杜瓦内真空度的要求,制造过程中还需要进行一系列的工艺处理。本文重点介绍插入式杜瓦用于冷却HgCdTe探测器芯片的结构设计以及工艺解决方案。     

斯特林制冷机型号中制冷量的标注方法研究

针对业内部分人士仅关心斯特林制冷机高温环境的制冷量,倾向用高温制冷量作为斯特林制冷机型号中制冷量的观点,收集、整理和分析了家用空调器、军用方舱空调以及斯特林制冷机的型号冷量标注方法,分析了常温冷量标注方法的优点和高温冷量标注方法的不足,认为以常温状态下的制冷量统一作为斯特林制冷机的额定制冷量,是一种数值相对稳定、符合标注惯例、满足实际应用要求的标注方法。     

大冷量气体轴承斯特林制冷机与杜瓦耦合漏热分析

对大冷量气体轴承斯特林制冷机及其与杜瓦耦合方式进行了论述,对插拔式杜瓦耦合漏热损失进行了理论计算及试验分析,结果表明,插拔式杜瓦耦合损失为76.1%,制冷量仅有2 W@80 K。经分析可知,制冷机冷指与杜瓦内胆之间产生的环隙漏热是影响耦合性能的主要因素,通过对环隙采用真空密封方式和减小环隙引起的漏热损失,耦合损失降至16.5%,制冷量提升至7 W@80 K。该耦合方式简单可靠,易于操作,满足制冷机可拆卸更换和维修的工程化需求。     

微燃机气封装置的数值模拟

为了将旋转部件与静止部件之间不同压力的空间隔开,微燃机中采用了气封装置以减少泄流量。泄漏流量的大小,以及其对主流的干扰,微燃机设计时必须加以认真考虑。工作时通过间隙而泄漏的流量过大,必然会对其整体效率产生重大影响。通常,在间隙处采用特殊结构来控制泄流量的大小,减少间隙对微燃机总体效率的影响。本文采用三维数值模拟对微燃机压气机与透平之间的间隙流动进行模拟分析,通过不同工况的比较以及对其内部流场进行分析,研究了气封内部流动特性,使得微燃机总体计算可考虑间隙引起的泄流对微燃机总体效率的影响。     

The effect of surface roughness on thermal-elasto-hydrodynamic model of contact mechanical seals

In this paper,the effect of surface roughness on sealing clearance,pressure distribution,friction torque and leakage is studied by the thermal-elasto-hydrodynamic mixed lubrication model.A convergent nominal clearance is formed by the pressure deformation and thermal deformation of the seal faces.This causes more serious wear in the inner side than that of the outer side of the contact area.Mass leakage increases with the growing of the surface roughness.The temperature and thermal deformation on the seal surface increases substantially if the roughness is reduced.The contact mechanical seals have consistent performance when the standard deviation of surface roughness is approximately 0.2μm.In order to validate the theoretical analysis model,a method combining the measurement of three-dimensioned profile and Raman spectrum is proposed.     

基于LabVIEW的机械密封模糊控制系统软件设计

机械密封的泄漏特性和摩擦特性相悖,为了提高机械密封的可靠性、延长使用寿命,必须对机械密封进行可控性研究,使机械密封工作在最佳工况。机械密封的泄漏率和端面摩擦扭矩之间无法建立精确的数学模型,因此在研制测控装置时使用基于模糊集合理论的模糊控制方式。目前大部分模糊控制类论文仅仅停留在论述模糊控制器的设计原理及流程上,本文结合实际应用完整的阐述了基于LabVIEW设计模糊控制软件的过程。     

Phenomenon of labyrinth seal with low static pressure difference and large clearance

This paper discusses the straight-through type labyrinth seal. This labyrinth seal is used for axial flow fans, which h ave an outer ring at the blade tip to seal the clearance between the ring tip and the fan shroud, in order to prevent the reverse flow or leakage. These fans are used for the cooling of automobile radiators . In these cases, the labyrinth seal is used in an extremely low static pressure difference and a large clearance . A significant decrease of the leakage rate was reported even when the labyrinth seal rotated in comparatively low speed in this unique condition according to the authors’ former report. However, this phenomen on is differ ent from past research. Further more the cause of th is phenomenon has not been determined. Therefore, the internal flow was depicted with Computational Fluid Dynamics (CFD) in or der to clarify the ca use of this phenomenon. The results of CFD show that the leakage rate decreases significantly because the carry -over flow is intercepted in the expansion groove. This is the newly discovered phenomenon which occurs under the unique condition of an extremely low differential pressure. It has not been pointed out before as the reason why the rotation decreases the leakage rate.     

Phenomenon of labyrinth weal with Low static pressure difference and large clearance

The low pressure axial flow fans with an outer ring, used for cooling automobile radiators, have a significantly large tip clearance between the ring tip and the fan shroud. It has been found that the turbulent reverse flow, or leakage flow, which occurs at the tip clearance, greatly affects the fan performance and noise level. Therefore, in order to improve the fan performance and noise level it is important to decrease the effect of leakage at the tip clearance. The authors investigated the performance of the straight-through type of labyrinth seal which operates in an extremely low static pressure difference with a large clearance. It was hoped that by sealing this clearance with the labyrinth seal the performance would be improved. It was verified that the labyrinth seal satisfied almost the same performance as that predicted by the previous theory. This theory was established by experimental studies in the condition of quite high static pressure difference when the labyrinth is stationary. However, it was later discovered that the leakage rate decreased significantly even though there was far lower ring speed in comparison to past research results where the ring rotated. This phenomenon is conspicuous in a lower differential pressure. However, the cause of this phenomenon has not been determined.     

Irreversibilities associated with a rotary regenerator and the efficiency of a steam power plant

In the present study a number of expressions determining the irreversible entropy generation in a rotary regenerator are presented. Adding to them formulae: (i) concerning the efficiency of a steam power plant, (ii) describing heat transfer and the pressure losses in a rotary heat exchanger, a computational model has been obtained in order to show how these irreversibilities and the efficiency of a steam power plant depend on the design parameters of a rotary regenerator. Here it was useful to assume an air cycle i-s for flue gas in a steam boiler. The numerical results are presented mainly in graph form making it possible to show the results obtained clearly and to easily draw some conclusions. By first, varying the values of the rotary regenerator matrix height, distribution factor of regenerator flow area on the hot and cold sides, total leakage factor, distribution factor of total leakage on the hot and cold ends and density of gas mass rates flowing through each side of the regenerator, the dependence of the entropy generation rates on the above parameter values is demonstrated. The direct effects of changes in values of the above parameters on a normalized energy measure or irreversibilities and the efficiency of a steam power plant are then evaluated. Having these results presented in juxtaposition, some general and practical conclusions are formulated.     

旋转状态下篦齿-蜂窝结构封严特性研究

本文对篦齿-蜂窝封严结构的封严特性进行了三维数值仿真,研究了不同结构参数、旋转速度及气动参数对其封严特性的影响,并与篦齿-涂层封严结构进行了对比.结果表明:采用蜂窝结构能改变篦齿腔内气体的流动,有效降低泄漏;篦齿前后腔气动参数一定时,齿数增加、篦齿节流间隙宽度减小或转速增加,泄漏量和泄漏系数都会相应减少.     

蓄冷器空体积对脉冲管制冷机性能的影响

基于理想气体与蓄冷器的假设,运用热力学第一、二定律对蓄冷器进行热力学分析,研究工质温度在蓄冷器单元内的变化,以及脉管制冷机运行频率对工质温度的影响,并运用Matlab软件,对蓄冷器单元内温度进行模拟。研究表明:对于理想蓄冷器,同等压力波幅下,增大频率和蓄冷器空体积,都会增大气体的温度波动幅值。