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排序方式: 共有1328条查询结果,搜索用时 15 毫秒
1.
氦气具有强化学惰性和低沸点等独有特征,在高新技术产业和科研实验中具有不可替代的作用。氦在地球上以微量组分广泛分布,但从含氦、富氦天然气藏中提取氦气仍是工业制氦的唯一途径。目前全球已发现的氦储量主要分布在美国、卡塔尔、阿尔及利亚、俄罗斯和加拿大等国,上述五国氦储量占全球总储量的92%。天然气藏中的氦气有3个主要来源:大气源、壳源和幔源。目前主要根据3He/4He值来确定氦的来源,通常大气源的3He/4He值为1.4×10-6、壳源的3He/4He值为2×10-8和幔源的3He/4He值为1.1×10-5。富氦天然气的成藏条件和成藏特征与常规天然气藏既有共性又有明显的差异,一些有利于形成大型油气藏的高生烃强度地区,反而不利于富氦、高氦气藏的形成。而生烃强度相对低的隆起区则有利于富氦、高氦气藏的形成。全球已发现的氦气资源主要分布于晚元古代—古生代地台背景下的沉积盆地,此外在中—新生代构造—岩浆活动强烈且具有古老花岗岩的基底区也是富氦气藏发育的有利区带。现有资料表明,中国四川盆地、塔里木盆地、柴达木盆地、鄂尔多斯盆地和东部中新生界含油气盆地中已发现一些富氦气藏。同时非常规天然气领域亦展现出良好的氦资源勘探前景,如渭河盆地水溶气和四川盆地页岩气。中国富氦天然气具有点多、类型多、资源前景较好的特征,但氦气资源整体研究程度很低。 相似文献
2.
针对冰箱压缩机用永磁同步电机由于其固有的恶劣工况环境而无法安装机械类传感器问题,采用基于滑模观测器方案与基于高频信号注入法相结合的复合控制方案对其进行全速范围无传感器控制。在中高速区,采用基于滑模观测器的方案对冰箱压缩机用永磁同步电机进行无传感器控制,利用自适应法对传统滑模观测器进行改进提高了系统性能。在零低速区,采用基于高频信号注入方案对冰箱压缩机用永磁同步电机进行无传感器控制。在无传感器控制算法过渡过程,采用加权算法实现了算法平稳且可靠的过渡。通过仿真实验验证了方案可行性及有效性。 相似文献
3.
《International Journal of Hydrogen Energy》2021,46(57):28936-28948
There are dozens of hydrogen production methods and techniques from many sources such as fossil fuels, renewable energy sources and nuclear energy in the literature. Thermo-chemical methods are more efficient at higher temperatures to produce large quantities of hydrogen. In this study, a comparative overview of Generation VI nuclear reactor types for major hydrogen production methods have been researched in the literature and suggestions have been carried out.This research work is addressing that both electric power cycle and hydrogen production based on nuclear technologies need to be developed. Generation IV nuclear reactors can provide hydrogen for a worldwide hydrogen economy. Both thermo-chemical and electrolysis (hybrid) processes in hydrogen production have a promising future, especially when integrated with Generation IV nuclear power plants. Efficient heat transfer is required for both high temperature thermodynamic cycles and the high temperature steam electrolysis. Hence, highly efficient heat exchanger designs are one of the key technologies for that purpose. 相似文献
4.
为研究家用冰箱储藏室中挥发性有机化合物(VOCs)的释放量及主要来源,采用气相色谱–质谱法对工作状态下冰箱储藏室的VOCs含量进行检测;利用傅里叶变换红外光谱仪对冷藏室的物料进行成分分析,同时用密封舱法探究冷藏室不同物料对VOCs含量贡献。结果表明,冰箱冷藏室物料中发泡聚苯乙烯风道泡沫释放的总挥发性有机化合物(TVOC)、正戊烷及异戊烷最多,是造成异味的关键性物料,而正戊烷、异戊烷是冰箱异味的主要成分。聚氯乙烯门封条对异味的贡献也较大,通用聚苯乙烯抽屉体贡献的VOCs种类最多;在工作状态下,随着密闭时间的增加,冰箱储藏室的VOCs的种类及含量增加,但苯、甲苯、二甲苯、TVOC及戊烷类的含量均未超过国家标准。储藏室异戊烷含量较高,是冰箱的异味的主要来源。 相似文献
5.
《International Journal of Hydrogen Energy》2019,44(17):8904-8913
Hydrogen, producing electricity in fuel cells, is a versatile energy source, but with risks associated with flammability. Fuel cells use enclosures for protection which need ventilating to remove hydrogen emitted during normal operation or from supply system leaks. Passive ventilation, using buoyancy driven flow is preferred to mechanical systems. Performance depends upon vent design, size, shape, position and number. Vents are usually plain rectangular openings, but environmentally situated enclosures use louvres for protection. The effect of louvres on passive ventilation is not clear and has therefore been examined in this paper. Comparison ‘same opening area’ louvre and plain vent tests were undertaken using a 0.144 m3 enclosure with opposing upper and lower vents and helium leaking from a 4 mm nozzle on the base at rates from 1 to 10 lpm, simulating a hydrogen leak. Louvres increased stratified level helium concentrations by typically in excess of 15%. The empirical data obtained was also used in a validation exercise with a SolidWorks: Flow Simulation CFD model, which provided a good qualitative representation of flow behaviour and close empirical data correlations. 相似文献
6.
《Ceramics International》2021,47(20):28357-28366
Lithium titanium oxide (Li2TiO3) tritium breeder ceramic plates with nano- and coarse-grain size were fabricated. The preparation methods contained CTAB-modifying precursor, combining dry-pressing with isostatically cold-pressing, and calcinating at optimized sintering temperature in turn. Then their properties were characterized after radiation by 280 keV helium (He+) ion. Extensive characterization analyses were performed to reveal the changes in nano-grained and coarse-grained Li2TiO3 after radiation. They contained glancing angle X-ray diffraction (GIXRD), atomic force microscopy (AFM), electron spin resonance (ESR), and scanning electron microscopy (SEM). The results showed as follows, GIXRD peak position of the nano-grained Li2TiO3 was more stable than the coarse-grained Li2TiO3 after radiation. Nano-grained Li2TiO3 was less rough and swollen than the coarse-grained one after radiation. Nano-grained Li2TiO3 had more excellent structural stability and less defect concentration of Eʹ-center after radiation. As a result, nano-grained Li2TiO3 might have much better radiation tolerance than the coarse-grained one by comparing characterization results. 相似文献
7.
This study evaluates the influence of latent heat storage elements on the condenser temperature of a commercial household refrigerator. In order to determine the power consumption and the temperature distribution, a standard wire-and-tube condenser is equipped with different heat storage elements (containing water, paraffin or copolymer compound). The results indicate that particularly the application of phase change materials (PCM) lowers the condenser temperature, which leads to a significantly reduced power consumption. 相似文献
8.
利用UG二次开发技术与Visual C++6.0相结合,同时结合Access数据库技术在UG二次开发中的应用,开发建立了一套冰箱发泡模标准件库。该标准件库与UG的集成环境有机结合,可以准确、快速地生成模具标准件,提高工作效率,具有良好的可移植性和可扩充性。 相似文献
9.
李海军 《建筑热能通风空调》2015,(3):56-58
制冷机换热铜管的蚁穴腐蚀问题在近年来为人们逐渐认识,但国内相关的案例较少,本文通过对某核电站DEG制冷机发生的冷媒泄漏原因调查、铜管腐蚀机理分析,找出了导致铜管腐蚀的来源,根据分析的结果,给出了处理方案,最后,根据蚁穴腐蚀的分析结论,提出了防止蚁穴腐蚀发生的对策。 相似文献
10.
Hui Liu Shiling Min Menglei Jiang Fuzhong Chu Ying Li Zhuoer Chen Kai Zhang Juan Hou Aijun Huang 《金属学报(英文版)》2022,35(9):1509
The abundancy of defect sinks in the microstructure of laser powder bed fusion (LPBF) processed austenitic stainless steels was found to be beneficial for helium resistance. In the current study, the influence of the novel microstructure in LPBF processed 304L on the helium bubble growth behaviour was investigated using transmission electron microscopy in samples implanted with He+ ion and post-irradiation annealing treated at 600 °C for 1 h. Two variants of LPBF processed 304L samples were used, one in as-built condition and the other solution-annealed. The comparison between the two samples indicated that the helium bubble growth was inhibited and remained stable in the as-built sample but coarsened significantly in the solution-annealed sample. The sub-grain boundaries and oxide nano-inclusions acted as defect sinks to trap helium atoms and inhibited the growth of helium bubble in the as-built sample under the post-irradiation annealing conditions used. 相似文献