共查询到20条相似文献,搜索用时 93 毫秒
1.
2.
第一部分给出了脉冲管制冷机数值模拟的基本方程和改进的数值计算方法。这一部分采用第一部分的方法对脉冲管制冷机的内部交变流动,换热以及制冷过程进行了详尽的数值模拟研究,得到了脉冲管制冷要内部各参数的动态变化,分析了各动态参数变化对制冷机整机性能的影响,并与实验结果进行了比较,数值模拟分析与实验结果符合良好, 相似文献
3.
针对脉冲管制冷机的特点建立了数值模拟模型,采用改进的数值模拟方法对脉冲管制冷机的内部交变流动,换热以及制冷过程进行了详尽的数值研究,得到了脉冲管制冷机内部各参数的动态变化,并分析了各动态参数变化对制冷机整机性能的影响。数值模拟分析与实验结果符合良好。该模拟方法从基本流动换热微分方程出发,尽可能多地考虑实际制冷机工作过程中的各种不可逆因素,包括实际气体的物性变化,各部件的流动阻力和传热损失。 相似文献
4.
切换式脉管制冷机的性能分析 总被引:1,自引:0,他引:1
切换式脉管制冷机用于天然带压气源获取冷量,具有一定的优势。本文着重在理论数值分析上对其性能进行了研究,建立了切换式脉管制冷机的数学模型,对制冷机内部过程进行了数值模拟计算,并用实验验证数值分析的可靠性,计算结果揭主要结构参数和操作参数同性能指标的关系,理论数值分析的切换式脉管制冷机的进一步结构优化提供了具有重要的参考价值的依据。 相似文献
5.
6.
蓄冷器是脉冲管制冷机等回热式制冷机的关键部件,它性能的好坏直接影响到回热式制冷机的效率和性能。交变流动蓄冷器中的热量和动量传输及转换过程是一个十分复杂的传热学,流体力学及热力学问题。低温中心针对交变流动蓄冷器的特点建立了动态参数测试实验台。实验台可以模拟各种脉冲管制冷机的真实运行条件。针对50Hz的交变流动蓄冷器的阻力特性进行了系统的实验研究,第一部分介绍实验装置及数据处理系统。 相似文献
7.
8.
提出切换式脉管制冷机在利用天然带压气源获取冷量方面具有一定的结构优势,因而开展了对切的切脉管制冷机的实验研究。探讨了主要操作参数对性能的影响,基本的实验研究为进一步的功能性研究和优化研究准备了基础,同时可以寻求它在衫上的可能性。 相似文献
9.
10.
11.
在驻波管中用双传声器法测量声学材料的隔声性能。通过测量不同背衬条件(即待测样品的后表面阻抗)下对应的前表面阻抗,可以求解与传递矩阵四个元素相关的中间变量,即可计算声学材料的隔声量。在驻波管中进行了单层多孔均匀材料、双层和三层复合非均匀材料的隔声性能测量,通过与四传声器法直接测量结果的对比,验证了采用双传声器法间接测量声学材料的隔声量是可行的。 相似文献
12.
A high temperature superconductivity cable must be cooled below the nitrogen liquefaction temperature to apply the cable to power generation and transmission systems under superconducting state. To maintain the superconducting state, a reliable cryocooler system is also required. The design and fabrication of a cryocooler system have been performed with a reverse Brayton cycle using neon gas as a refrigerant. The system consists of a compressor, a recuperator, a cold-box, and control valves. The design of the system is made to have 1 kW cooling capacity. The heat loss through multilayer insulators is calculated. Conduction heat loss is about 7 W through valves and access ports and radiation heat loss is about 18 W on the surface of a cryocooler. The design factors are discussed in detail. 相似文献
13.
E. Thorin 《International Journal of Thermophysics》2000,21(4):853-870
Tillner-Roth and Friend have presented a new correlation for the thermodynamic properties of ammonia–water mixtures. In this study, the new correlation has been compared to other correlations used in simulations of power cycles using ammonia–water mixtures as working fluids. The saturation properties for mixtures, calculated with the different correlations, have been examined at different temperatures and pressures. Available experimental data have been included in the comparison. The variation of the enthalpy with temperature at different pressures for a mixture has also been compared. The correlations have been examined for use in power cycle simulations as well. The comparison reveals that the new correlation shows a more reasonable behavior when the critical point of the mixture is approached. At lower temperatures and pressures, the compared correlations give very similar results. The differences in the results from the cycle simulations, using different correlations, are small but they tend to increase with increasing maximum pressure in the cycle. 相似文献
14.
对频繁出现轮齿早期断裂的变速箱六档齿轮进行了分析。通过对齿轮断裂特征、显微组织、硬度等方面的综合分析,确定了其断裂形式为低应力高周疲劳断裂。由裂纹扩展过程判断齿轮轮辐设计强度不足是导致其大批量早期疲劳失效的根本原因。据此通过改进齿形、油孔等设计措施,降低齿根部的设计应力水平,解决了这一问题。 相似文献
15.
16.
联合制冷循环的有限时间热力学 总被引:1,自引:0,他引:1
研究由两个内可逆卡诺制冷循环构成的无中间热源的联合制冷循环有限时间热力学最优性能。基于一类较为普遍的物理模型,导出其制冷量与制冷系数间的基本关系,再根据活塞式模型循环和定常流模型循环的基本特征,得到两种模型联合到冷循环的最佳制冷率密度与制冷系数间的关系。对前者,与前人所得结果相同;对后者,获得了一些新的有意义的结论。有关结果还可推广到由两个以上制冷循环构成的联合制令循环。 相似文献
17.
Arpan Das S. SivaprasadP.C. Chakraborti S. Tarafder 《Materials Science and Engineering: A》2011,528(27):7909-7914
Quantification, formation and nucleation micro-mechanisms of deformation induced martensite during low cycle fatigue behaviour of austenitic stainless steel have been investigated at various strain amplitudes tested at ambient temperature. The evolutionary deformation induced martensite has been quantified through magnetic measurement technique. It has been found that as strain amplitude increases, the volume fraction of deformation induced martensite increases. Extensive analytical transmission electron microscopy studies showed more than one nucleation site for martensitic transformation and the transformation micro-mechanisms have been observed to be: γ (fcc) → ? (hcp), γ (fcc) → α′ (bcc), γ (fcc) → deformation twins → α′ (bcc) and γ (fcc) → ? (hcp) → α′ (bcc). 相似文献
18.
19.
H. M. Tawancy 《Journal of Failure Analysis and Prevention》2013,13(5):643-650
A C-1/2Mo steel pipe of a heat recovery economizer in a steam reforming process used in the production of high-purity hydrogen has developed large pits at the inner surface. Light optical microscopy, x-ray diffraction, scanning electron microscopy combined with energy dispersive x-ray spectroscopy and transmission electron microscopy have been used to characterize the microstructure of the pitted pipe. Degradation of the pipe has been correlated with higher than normal temperature enhancing metal dusting as well as a material not intended to function in such an environment. Microstructural characterization shows that the sequence of events leading to the observed pitting follow a model proposed to explain metal dusting of carbon and low-alloy steels. 相似文献