Performance analysis of the ejector-expansion refrigeration cycle using zeotropic mixtures

To evaluate the performance of the ejector-expansion refrigeration cycle (EERC) using zeotropic mixtures, a numerical study is conducted. A constant-pressure two-phase ejector model for zeotropic mixtures is established. The effects of both the fluid composition and the working conditions are investigated. Mixture R134a/R143a is selected as the working and the simulation results reveal that, the cycle COP increases first and then decreases as MF_t (the mass fraction of R134a) increases in the researched condition. The COP gets a maximum value of 4.18 with MF_t of 0.9 and yields a minimum value of 3.66 with MF_t of 0.5. With mixture 0.9/0.1, the COP improvement reaches a maximum value of 10.47%. This improvement rises at high condensing temperature or low evaporating temperature. The exergy analysis shows that the compressor and ejector contribute the most exergy destruction, and the cycle exergy efficiency achieves a maximum value with MF_t of 0.7.     

红河流域径流演变分异及其特征

红河流域径流演变分异研究对于揭示流域径流的形成、演变规律及跨境水管理具有重要意义。选取红河流域9个代表站点,利用累积距平法、滑动t检验和Mann-Kendall-Sneyers法研究了红河流域的径流演变分异。结果表明,径流演变空间差异显著,各控制断面波动不一致;流域各站点(除大东勇站)均出现径流突变,但突变时间不一致,且越往下游,突变时间越晚;此外,各站点丰枯转化时段不一致。     

35kV动态无功补偿装置在30t电弧炉系统的应用

针对30t电弧炉在生产中给电网造成污染和冲击，设计选用了35kV动态无功补偿装置，并介绍了装置的有关参数计算和工作原理；装置投运后，改善了35kV系统的供电质量，提高了功率因数，获得了良好的经济效益和社会效益。     

Partikelform und Porosität von biogenen Pyrolysekoksen

Char particles from pyrolyzed biomass vary in particle size and shape. On average, the particles are more elongated the larger their size. The average size‐specific elongation is almost alike for all investigated samples, i.e. independent from their source material and process. The particle collectives cannot be characterized accurately with classical particle size distributions, which assume spherical particle shape. Accounting for their shape, they can be described more accurately with particle size distributions that are based on an ellipsoid model. The high bulk porosity is mainly attributed to the spaces between particles.     

On the solid state heat transport phenomena measurement

The paper deals with theoretical and experimental aspects of lumped capacitance model (LCM) application for the study of heat transport in different materials. Patented construction of the measuring chamber together with special software the fundamental features of which are presented here allows evaluating thermal conductivity k, specific heat capacity c_p and thermal diffusivity α. Obtained results are in relatively very good agreement with those obtained from independent measurement or table values.     

A quantitative metallographic assessment of the evolution of porosity during processing and creep in single crystal Ni‐base super alloys

The present work reviews previous research on the evolution of porosity. It presents new results from a detailed study on the evolution of porosity during casting, heat treatment and creep of a single crystal Ni‐base superalloy subjected to uniaxial tensile creep at 1050 °C and 160 MPa in [001] and [110] directions. A quantitative metallographic study was performed on carefully polished metallographic cross sections, monitoring sampling fields of 4500 × 1000 µm² using the back scatter contrast of an analytical scanning electron microscope; evolutions of pore sizes and pore form factors were analyzed and all important details which were previously revealed in a synchrotron study could be reproduced. In addition, it was observed that micro cracks form at larger cast pores. They interlink and thus initiate final rupture. The [110] tensile creep tests showed lower rupture strains than the [001] experiments. In agreement with earlier work, this can be rationalized on the basis of aligned porosity along primary dendrites.     

Antoni Gaudí and Frei Otto: Essential Precursors to the Parametricism Manifesto

As Senior Architect to the Basilica of the Sagrada Família in Barcelona, Mark Burry has been ‘thinking parametrically’ for almost his entire career. Here he describes how his longstanding role overseeing the completion of Antoni Gaudí's masterpiece has afforded unique insights into the work of a great geometer and parametric thinker. Burry places the contribution of Gaudí alongside that of Frei Otto – the other eminent 20th-century Proto-Parametricist.     

10 000 t/d回转窑液压挡轮装置的优化设计

结合中国中材国际工程股份有限公司设计的某10000t/d熟料生产线的回转窑挡轮装置,介绍了挡轮装置的优化设计,其中创新设计了不同与以往1个挡轮的3个挡轮的设置;对其挡轮装置的结构也作了优化,采用了3组轴承,使挡轮受力更加合理,寿命延长。2012年该10000t/d回转窑装备被评为科技进步二等奖,至今已应用于国内外多条生产线,均取得了良好的业绩和效果。     

Fine structure characterization of martensite/austenite constituent in low‐carbon low‐alloy steel by transmission electron forward scatter diffraction

Transmission electron forward scatter diffraction and other characterization techniques were used to investigate the fine structure and the variant relationship of the martensite/austenite (M/A) constituent of the granular bainite in low‐carbon low‐alloy steel. The results demonstrated that the M/A constituents were distributed in clusters throughout the bainitic ferrite. Lath martensite was the main component of the M/A constituent, where the relationship between the martensite variants was consistent with the Nishiyama–Wassermann orientation relationship and only three variants were found in the M/A constituent, suggesting that the variants had formed in the M/A constituent according to a specific mechanism. Furthermore, the Σ3 boundaries in the M/A constituent were much longer than their counterparts in the bainitic ferrite region. The results indicate that transmission electron forward scatter diffraction is an effective method of crystallographic analysis for nanolaths in M/A constituents.