An overview of reactive hydride composite (RHC) for solid-state hydrogen storage materials

Hydrogen storage using the metal hydrides and complex hydrides is the most convenient method because it is safe, enables high hydrogen capacity and requires optimum operating condition. Metal hydrides and complex hydrides offer high gravimetric capacity that allows storage of large amounts of hydrogen. However, the high operating temperature and low reversibility hindered the practical implementation of the metal hydrides and complex hydrides. An approach of combining two or more hydrides, which are called reactive hydride composites (RHCs), was introduced to improve the performance of the metal hydrides and complex hydrides. The RHC system approach has significantly enhanced the hydrogen storage performance of the metal hydrides and complex hydrides by modifying the thermodynamics of the composite system through the metathesis reaction that occurred between the hydrides, hence enhancing the kinetic and reversibility performance of the composite system. In this paper, the overview of the RHC system was presented in detail. The challenges and perspectives of the RHC system are also discussed. This is the first review report on the RHC system for solid-state hydrogen storage.     

Mild hydrogen production from the hydrolysis of Al–Bi–Zn composite powder

The development of mild hydrogen-generating materials is of great significance to improve the working life of hydrogen–oxygen fuel cells. In this study, Al–Bi–Zn composite powders were designed by phase diagram calculation and then prepared via the gas atomization method. The results indicated that the conversion yield of Al–12Bi–7Zn (wt.%) powder reached 98% with stable hydrogen production within 280 min at 50 °C. When composite powder reacted with NaCl solution to produce hydrogen, the dormant period of the reaction process was significantly shortened, but the conversion rate was slightly reduced. Additionally, the evolution of powder morphology during the reaction was investigated. The results showed that the continuous cracking of the powder led to the continuous exposure of fresh Al to react.     

EFPI-FBG复合光纤传感器高温大应变试验研究

由于缺乏航空发动机/燃气轮机服役环境下叶片温度、应变有效性检测的技术与装置，所以工作叶片的温度环境、载荷环境和应变分布等关键数据的缺失是故障检修工作中的最大困难之一。采用非本征型法布里-珀罗(Extrinsic Farby Perot Interferometric,EFPI)与光纤光栅(Fiber Bragg Grating,FBG)传感技术，研制了一种基于单模光纤的EFPI FBG复合光纤传感器及其解调设备。通过搭建高温拉伸试验平台，开展了基于DZ125材料试件的复合光纤传感器高温、大应变测量的性能测试。试验结果表明：复合光纤传感器的工作温度范围为26 ℃~1 100 ℃，温度测量精度不超过全量程的5%，分辨率为0.066 ℃；F-P传感器的应变测量范围为0~19 468 με，在1 100 ℃下的相对误差为1.96%，分辨率为0.053 με。     

γ射线法测量高压管束间气液两相流的截面含气率分布

在立式蒸汽发生器垂直管束间的气液两相流中，截面含气率是其中一个重要参数。使用γ射线法对高温高压下垂直管束间气液两相流截面含气率的分布规律进行了实验研究。实验压力分别为5、7、9 MPa，质量流速为300 kg/(m²?s)，热力学干度的范围为0.003 ~ 0.4。实验得到了垂直管束间截面含气率随热力学干度、体积含气率和压力的变化关系；并与经典公式的计算结果对比发现，在低干度区域，实验结果与Miropolskii模型、Smith模型和Armand模型偏差较大，均大于30%，在高干度区域偏差较小；基于Armand理论，通过多元线性回归法拟合出本文工况下平均截面含气率的计算关联式，与日本核动力工程公司(NUPEC)的实验数据偏差小于15%。本研究对蒸汽发生器的结构设计和流动特性研究具有重要意义。     

干熄焦锅炉炉管失效机理分析

通过对干熄焦锅炉炉管及腐蚀产物开展系统研究，提出炉管失效原因为氧化/硫腐蚀＋高温粉尘冲刷。长寿命炉管仅耐磨层发生了较为严重的氧化及硫腐蚀，而近基体层发生了轻微氧化及硫腐蚀，基体只发生了轻微氧化；短寿命炉管耐磨层、近基体层以及基体裂纹内均发生了较为严重的氧化及硫腐蚀，且存在珠光体球化、内表面产生全脱碳层等缺陷。推测短寿命炉管存在超温现象，而超温可加剧氧化及硫腐蚀反应。此外，短寿命炉管遭受了较为严重的高温粉尘冲刷，不仅可造成炉管减薄，还会导致炉管表面温度升高。因此，减少循环气体中粉尘量尤其是大颗粒，可有效减弱冲刷以及控制炉管表面温度，是提高炉管使用寿命的关键。     

Heat transfer trait simulation of H finned tube in ventilation methane oxidation steam generator for hydrogen production

With the steam obtained by the energy released from ventilation air methane oxidation, the hydrogen production through gasification method is considered more commercial. In order to constrain the steam parameter fluctuation, the shunt honeycomb ceramics are adopted to fill between the heat exchange tubes. However, transient heat transfer characteristics of this kind of heat exchanger have not been fully studied. This paper carried out a numerical simulation study on the transient heat transfer characteristics of H finned tube under periodic reverse-flow conditions. Results show that the existence of shunt honeycomb ceramics enhances the effect of radiation. Gas flow direction reversing destructs the original boundary layer, achieving a sudden rise of the convective heat flux in the new upstream. It takes about 12s to form a new relative stable boundary layer. The apparent heat transfer coefficient achieves a maximum of 108.77 W m⁻² K⁻¹ and an average of 99.1 W m⁻² K⁻¹.     

防振条约束失效对蒸汽发生器传热管面内流弹失稳的影响研究

根据防振条布置以及面内支承连续失效个数，将防振条面内约束失效分析划分为多种工况，分析了不同工况下面内约束失效对传热管面内模态的影响，采用各位置阻尼在振型函数上进行加权平均的方法计算了各阶模态的阻尼比，进而研究了防振条面内不同约束对传热管面内流弹失稳的影响。分析结果表明，随着面内支承连续失效位置的增多，弯管段面内首阶模态频率不断降低，出现在弯管段的振型越加明显；弯管段面内首阶模态不一定是最大流弹失稳比值出现的模态，最大流弹失稳比值出现模态的振型几乎都出现在弯管段；随着面内支承连续失效位置的增多，面内流弹失稳比值不断增大，当连续3个及以上防振条面内约束失效时，将出现流弹失稳现象。     

碳纤维复合材料薄壁圆筒的轴向导热系数测试

碳纤维复合材料薄壁圆筒为各向异性导热，其轴向导热系数是筒体温度场理论计算、成型工艺优化的重要参数。碳纤维复合材料圆筒由于较小的截面面积给筒体加热、热量有效传递带来了较大困难。本文以平板材料导热系数的稳态法测试国家标准为基础，基于傅里叶一维稳态导热原理，设计了一套用于薄壁圆筒轴向导热系数测试的装置，采用双试件对称加热、辐射换热防护及热对流环境控制等实现了热量沿筒体轴向的有效传导，利用该装置对导热系数已知的铝筒进行测试，验证了该装置设计的可行性，得到了碳纤维复合材料薄壁圆筒的轴向导热系数为（4.60±0.13） W/(m•K)。     

镁对非调质钢中组织及硫化物的影响

摘要：为了探究不同镁含量对非调质钢中组织和硫化物形态、尺寸、分布及成分的影响，采用蔡司金相显微镜、扫描电子显微镜、小样电解等方法，分析了经高温电阻炉冶炼不同镁添加量的49MnVS3非调质钢。结果表明，由于镁蒸气压较高，在实验室冶炼中大量挥发，导致钢中镁的实际平均收得率仅为310%；镁的质量分数为0～22×10-6时，随着镁的质量分数的增加，钢中硫化物形态由Ⅱ类逐渐向Ⅰ类、Ⅲ类转变；钢中硫化物尺寸增大，硫化物的分布均匀性得到显著改善；钢中复合夹杂物比例明显增加，但MnS的比例出现下降；形成了细小弥散的氧化物，增加了奥氏体形核质点，具有细化组织的趋势。