共查询到20条相似文献,搜索用时 112 毫秒
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结合实际工程项目,针对某新型天然气冷箱液化流程中的三台钎焊板式换热器,采用双通道耦合换热模型,以分段线性插值法计算天然气物性,基于FLUENT软件进行了天然气冷却换热过程的CFD数值模拟仿真,并开展了该新型冷箱的实验测试研究。将数值模拟计算结果与HSYSY工艺流程设计值以及实验测试结果进行对比。结果表明,数值模拟计算结果与HSYSY设计值平均误差为4.94%,证明了采用CFD数值模拟方法对HYSYS工艺流程设计与设备选型进行校核具有一定的参考价值。数值模拟计算结果与实验测试结果平均误差为7.78%,证明了数值模拟仿真所采用的简化假设、换热模型以及求解方法对于板式换热器天然气冷却换热过程是合理的。 相似文献
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采用分子动力学的模拟方法计算了水在依次降温,中间充分弛豫的降温过程以及同时对直接降温到某个温度,未足够弛豫的过程的径向分布函数(radial distribution function,RDF)曲线。在依次冷却方式下,选取了5种压力以研究压力对玻璃化温度和径向分布函数的影响;在每个温度段选取了5种冷速以研究依次冷却方式下不同温度段的冷速对径向分布函数的影响。同时对两种降温方式的结果进行了比较。结果表明:降温均匀,静止的水体系玻璃化温度可以大大提高,同时冷速对其玻璃化温度影响不大;压力对玻璃化温度影响不大;证实影响玻璃化温度的主要因素是传热;不同冷速对体系的RDF有影响,但缩小温差并采取中间温度充分驰豫的方式可减小这种差异。 相似文献
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双孔径校正超导磁体是大型强子对撞机亮度升级项目的重要组成部分,在4.2 K低温环境下对该磁体进行励磁及性能测试。为避免磁体在降温过程中产生较大的热应力,要求降温过程中磁体各点最大温差不超过30 K。同时,为节省液氦与降温梯度均匀,特设计了一个铜筒体结构用于该磁体的降温和测试,降温过程分为液氮换热降温和液氦直冷降温两个阶段。实验测试结果表明静态液氦消耗速率为55.571 L/h,电流为407 A失超时液氦总消耗52 L、静态消耗16.116 L、内部泄能消耗22.08 L,即液氦消耗不仅包括测试系统的静态消耗、泄能消耗,还存在液氦溢出损耗。 相似文献
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基于空气源热泵在低温寒冷地区运行中遇到的结霜问题,对不同风速工况下,结霜过程中设备性能的变化进行分析,以换热量、换热系数为指标对不同翅型换热器的换热特性进行研究.实验结果显示:换热器结霜过程中,换热过程主要分为初始增加段、换热平稳段、缓慢衰减段、后期平稳等四段,结晶体在增加空气湍流度强化换热的同时,也增加了换热热阻使换... 相似文献
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Based on the theory of anisotropy semianalytical thermal analysis, the temperature field of rectangle Nd:GGG heat capacity laser crystal is investigated. Through an analysis of the working characteristics of the heat capacity laser crystal, a thermal model of heat capacity laser crystal is established. Using a new method for the anisotropic medium heat conduction equation, a temperature field expression of rectangle Nd:GGG heat capacity laser crystal for pumping stage and cooling stage is obtained, respectively. These results show that when using the output power of 300 W LD end-pumped rectangle Nd:GGG crystal for 10 seconds, the maximum temperature rise in the center of the pump face is 180.18°C, and after stopping pumping for 100 seconds, the maximum temperature rise drops to 0.74%. These results from this work provide a theoretical basis for the optimized design of a LD end-pumped heat capacity laser. 相似文献
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Yu. Ya. Gafner S. L. Gafner I. S. Zamulin L. V. Redel V. M. Samsonov 《Physics of the Solid State》2013,55(10):2142-2149
The problem of anomalously high experimental values of the heat capacity of metallic nanoclusters has been analyzed in terms of the thermodynamics of the surfaces, as well as based on the data of computer experiment. The heat capacity of ideal face-centered cubic (fcc) palladium clusters with a diameter of 6 nm in the temperature range of 150–300 K has been investigated using the molecular dynamics method with several tight-binding potentials. It has been found that, at a temperature T = 150 K, the heat capacity of a Pd nanoparticle exceeds the heat capacity of the bulk material by 12–16%. Based on the results of the theoretical treatment, computer simulation, and analysis of experimental data, it has been concluded that an increase in the heat capacity of the compacted nanomaterial is not determined by the high heat capacity of individual clusters. Apparently, the significant increase in the heat capacity of compact nanomaterials can be explained either by their disordered state or by the high content of different types of impurities, mainly hydrogen. 相似文献
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V.M. Shvartsberg V.A. Bunev T.A. Bolshova V.S. Babkin 《Combustion Theory and Modelling》2017,21(6):1176-1188
Fuel-rich laminar adiabatic flames of premixed dimethyl ether/air mixtures at a high initial temperature and atmospheric pressure have been studied by numerical simulation and sensitivity analysis. These flames, having two heat release zones, are of great interest as an unusual and little-studied subject. We have investigated the chemical processes occurring in the two zones and analysed the mechanism of heat release in the flame. It has been found that the key reactions that have a significant influence on the flame speed are those involving dimethyl ether and the products of its incomplete oxidation. Calculation of the heat release rate confirms the presence of two heat release zones in the flame. A comparison of the reactions making a major contribution to the heat release with those significantly affecting the flame speed indicates that the main factor determining the flame speed is the formation of hydroxyls, rather than heat release. Analysis of the flame speed sensitivity shows that in the case of a two-zone structure of the flame, its speed is mainly determined by the reactions taking place in the low-temperature zone. That is, the cool zone with a higher temperature gradient is the leading one. 相似文献
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The random matrices theory is applied to a study of the heat capacity of small metallic grains. The numerical calculations indicate that the level distribution and the difference between the particles respectively with an even and an odd numbers of electrons are important for the heat capacity of the small metallic grains at a low temperature and the level correlation mainly affects the heat capacity at a high temperature. 相似文献
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霜形成对翅片管换热器空气侧表面传热系数影响的实验研究 总被引:1,自引:1,他引:0
在空冷系统中,换热器空气侧的表面结霜问题是影响其应用和发展的主要问题。通过对结霜条件下翅片管换热器空气侧换热性能的实验研究,得出了空气湿度、翅片间距、风速等参数变化对空气侧当量表面传热系数的影响;结果表明在一定的范围内,结霜前期h0值随结霜时间τ急剧下降,在结霜后期,这些参数对h0值的影响大为削弱。 相似文献