斯特林制冷机分层回热器优化设计与实验

为了提高斯特林制冷机在低温下的性能,把分层填充回热器结构应用于低温斯特林制冷机中。利用REGEN3.3对自行研制的斯特林制冷机用分层回热器进行了优化设计,并对此进行了实验研究。研究结果表明,回热器采用恰当的分层方式能大幅度提高制冷机的性能。该斯特林制冷机与优化前相比,其膨胀机效率提高了52.8%,整机效率提高了79.8%。     

斯特林制冷机回热器热损研究

讨论了回热器的各种损失对斯特林制冷机的影响,对斯特林制冷机回热器的结构和丝网填料进行了分析,并模拟分析各种损失的影响.研究表明,回热器的结构、丝网填料对制冷机的性能有重大影响.     

小型斯特林制冷机回热器热损分析

对斯特林制冷机回热器的各项热损失进行分析研究,表明回热器的尺寸以及填料的选取对于小型斯特林制冷机的性能影响较大.对于给定尺寸各个参数以及循环参数的回热器,要想获得最大净制冷量,存在一个最佳当量直径.当当量直径的取值小于最佳值时,回热器的性能主要由压降损失决定;当取值大于该值时,系统性能主要由回热损失决定.     

斯特林制冷机污染失效研究进展

斯特林制冷机内部放气造成的失效严重影响制冷机寿命。制冷机内部放气气体会在回热器冷端及膨胀腔低温表面凝结,降低回热器的回热效率和冷头换热面传热能力,并加大制冷工质流动阻力。主要介绍了斯特林制冷机加速寿命试验和污染放气模拟数值计算方法等,提出了制冷机污染失效研究发展方向。对今后主要研究方向进行了展望。     

斯特林制冷机的计算机辅助调机

通过对双自由度斯特林制冷机振动系统模型的分析 ,建立了计算机仿真调相角模型。在模型求解过程中 ,通过改变弹簧参数来优化斯特林制冷机的压力波和制冷机回热器位移之间的相位差 ,使其接近最优相角要求 ,来辅助调节系统的工作参数。模型模拟的结果与实验结果能较好的吻合     

20K以下温区斯特林型脉管制冷机的最新研究进展与损失机理分析

系统介绍了20 K以下温区斯特林型脉管制冷机的最新研究进展,指出了多级斯特林型脉管制冷机的应用前景与发展趋势.深入分析了多级斯特林型脉管制冷机20 K以下温区的主要损失特性,以及其难以达到更低制冷温度和更高制冷效率的内在原因,着重说明进一步提高高频回热器效率、发展高效线性压缩机技术是实现突破的关键.     

-80℃斯特林制冷机设计及实验研究

为满足低温存储领域对小型化、大冷量、高效率斯特林制冷机的应用需求,研究基于斯特林制冷机的特点,结合实际现状,设计了一台可用于低温存储领域的-80℃自由活塞式斯特林制冷机。根据其运行原理,通过数值模拟及实验验证重点分析了设备运行频率和工作压力对整机性能的影响,在此基础上讨论并提出了制冷机的优化思路。实验结果表明回热器采用丝网填充,工作压力为2.9 MPa,运行频率为63 Hz时,该制冷机在175.1 W输入功率下,可在-85℃提供29 W冷量输出,COP为0.166;当使用PET材料时,无热负载状态下最快可在42分钟左右冷端温度达到-86℃,其性能表现满足现有小型低温冰箱的冷量需求。通过数值模拟和实验结果的对比,讨论了出现性能差异的原因。     

低温冰箱自由活塞式斯特林制冷机模拟与优化

自由活塞斯特林制冷机具有高效紧凑,适合中低温制冷等优点。对用于低温冰箱自由活塞式斯特林制冷机进行了一维建模,并实现整机性能的模拟与优化。在考虑各种空体积的情况下,模拟分析了压缩活塞PV功和相位角的变化对整机性能的影响,获得了制冷机运行的最佳相位。对比了环形回热器的填料及填充方式对自由活塞式斯特林制冷机的性能影响,及对应材料下回热器的轴向导热损失情况。模拟了制冷机性能随回热器空隙率和制冷温度的变化情况,计算分析了回热器内部的不可逆损失随空隙率的变化情况,并且获得了不同温度下的最佳空隙率。最后,为了获得好的制冷性能,优化不同制冷温度的回热器设计参数及膨胀活塞与气缸壁的密封间隙宽度。     

斯特林制冷机混合填料回热器性能优化及试验研究

针对旋转整体式斯特林制冷机的回热器性能优化,讨论了回热器丝网填料选型的原则,分析了不同温区采用不同丝网参数的回热器模型,并利用REGEN软件对混合丝网模型进行了优化分析。通过实验数据对模拟优化的结果进行了分析和讨论,验证了混合丝网模型优化结果的正确性,为旋转整体式斯特林制冷机回热器性能优化提供依据。     

深冷文献消息(国内)

2007001 300Hz脉冲管制冷机特性研究；2007002　压比对回热器性能影响的理论分析；2007003　斯特林型脉冲管制冷机中压缩机与冷指耦合实验研究；2007004　液氮浴中不锈钢板动态冷却过程试验及模拟分析；2007005　EAST装置2kW／4．5K氦制冷机透平膨胀机的测试     

Flow characteristics of a cyclic flow regenerator

The results of experimental investigations on the cyclic flow characteristic of the regenerator of a split cycle Stirling cryocooler is presented. A mathematical model has been proposed to describe the action of regenerator and other main components of the cryocooler system on its dynamic response.     

Measurement of cryogenic regenerator characteristics under oscillating flow and pulsating pressure

This paper describes an experimental apparatus developed to investigate detailed thermal and hydrodynamic characteristics of a regenerator at cryogenic temperature under oscillating flow and pulsating pressure conditions. Cold-end of the regenerator is maintained at approximately 85 K for G-M cryocooler type and 100 K for Stirling cryocooler type operations by means of two cryogenic heat exchangers. At both ends of the regenerator, fine hot wire probes are installed to measure the fast oscillating gas temperature and mass flow rate. The gas temperature sensors installed very close to the ends of the regenerator matrix assure precise gas temperature measurement in the regenerator. In this study, thermal and hydrodynamic behaviors of the well-defined wire-screen regenerator are fully characterized. First, pressure drop characteristics are discussed for different frequencies under room temperature. Second, ineffectiveness of the regenerator is obtained for different cold-end temperatures.     

Numerical analysis on performance and contaminated failures of the miniature split Stirling cryocooler

A mathematical model based on thermodynamic theory of variable mass is developed for the split Stirling refrigerator, in which, the whole machine is considered by one-dimensional approach while the processes in the regenerator are simulated by two-dimensional approach. First, the influence of the ideal frost layer distributions on the flow and heat transfer in the regenerator and the performance of the Stirling cryocooler are simulated. Then, the distribution of the contaminated water vapor and its coagulated and deposited process is qualitatively analyzed. Finally, the lifetime of the refrigerator is evaluated based on the calculated data. The results show that when the refrigerator is operated at uniform distribution of the water vapor partial pressure in the regenerator, the cooling capacity is reduced over 10% at about 631 h, and the power consumption of compressor is increased over 20% at about 1168 h. However, for the linear distribution of water vapor partial pressure, the refrigerator can work properly because the frost never reaches the criterion of failure. Also, it is found that when the Stirling cryocooler restarts after a shutdown, the cooling capacity is reduced by 10% once the frost mass is over 7.05 mg, and there is no cooling capacity once the frost mass reaches 41.2 mg.     

Optimal performance of regenerative cryocoolers

The key component of a regenerative cryocooler is its regenerative heat exchanger. This device is subject to losses due to imperfect heat transfer between the regenerator material and the gas, as well as due to viscous dissipation. The relative magnitudes of these losses can be characterized by the ratio of the Stanton number St to the Fanning friction factor f. Using available data for the ratio St/f, results are developed for the optimal cooling rate and Carnot efficiency. The variations of pressure and temperature are taken to be sinusoidal in time, and to have small amplitudes. The results are applied to the case of the Stirling cryocooler, with flow being generated by pistons at both sides of the regenerator. The performance is found to be close to optimal at large ratio of the warm space volume to the regenerator void volume. The results are also applied to the Orifice Pulse Tube Refrigerator. In this case, optimal performance additionally requires a large ratio of the regenerator void volume to the cold space volume.     

Parameter effect analysis for a Stirling cryocooler

In this paper, an isothermal model is used for modeling the Stirling cryocooler. Various losses including regenerator imperfection thermal loss, piston finite speed loss, gas spring hysteresis loss, displacer shuttle heat loss, clearance heat pump loss, heat conduction loss, and flow viscosity loss are taken into consideration at the same time step, as they could interact with each other. Energy and exergy balance analysis of the cryocooler shows that the mechanical friction loss is the biggest mechanical loss; conduction loss is the biggest heat loss. Effects of parameters consisting of cold end temperature, hot end temperature, average pressure, rotation speed, displacer clearance size, phase shift between piston and displacer, and ratio between diameter and stroke of piston on the cryocooler's performance are investigated. It shows that, there is optimum displacer clearance size, optimum phase shift between piston and displacer, and optimum ratio between diameter and stroke of piston for the studied cryocooler. The isothermal model was verified by the PPC-102 Stirling cryocooler.     

Anisotropic steady-flow hydrodynamic parameters of microporous media applied to pulse tube and Stirling cryocooler regenerators

The hydrodynamic parameters associated with steady longitudinal and lateral (radial) flow of helium in several widely-used pulse tube and Stirling cryocooler regenerator fillers were measured and correlated in this investigation. Pressure drops in test sections packed with regenerator fillers were experimentally measured. Computational fluid dynamics (CFD) models of the regenerator test sections and their vicinities were developed and simulations were performed in which the regenerator test sections were modeled as porous media. By iterative repetition of the simulations, the longitudinal and radial permeability and Forchheimer inertial coefficients were determined such that they would lead to agreement between experimental measurements and the simulations. The regenerator fillers included 325 and 400 mesh stainless steel screens, stainless steel metal foam, sintered 400 mesh stainless steel screens, and a stack of micromachined perforated plates. The hydrodynamic response of the regenerator fillers were also correlated as friction factors. The results confirm that the aforementioned regenerator fillers are anisotropic.     

基于DSP的星载小型化斯特林制冷机控制器设计

斯特林制冷机控制器对制冷机性能有很大影响。介绍了基于DSP系统的斯特林制冷机控制器设计,主要包括硬件、软件设计,为进一步实现斯特林制冷机的自适应控制打下较好的基础。     

斯特林型脉冲管制冷机的最新进展

介绍了斯特林型脉冲管制冷机在理论分析和实用化方面的进展。与斯特林制冷机相比 ,由于低温端没有运动部件 ,脉冲管制冷机在寿命、可靠性和振动等方面有明显的优势 ,同时直流现象的发现和对它的抑制 ,以及双向进气、长颈管等调相机构的应用 ,使得斯特林型脉冲管制冷机的效率也可以达到或超过斯特林制冷机 ,从而使斯特林型脉冲管制冷机在空间、红外器件和超导器件冷却等方面有广泛的应用     

斯特林控制器的研制

斯特林控制器是根据斯特林制冷机在工作时需对多种物理量进行测控而研制的设备。较详细地介绍了斯特林控制器的设计与实测以及性能指标等