Dissemination of units of mole fraction and mass concentration of gas components by means of first-grade working standards based on dynamic gas mixture generators

A comparison of static and dynamic methods of preparing gas mixtures is presented and requirements that working standards based on dynamic generators must satisfy are formulated. The basic sources of errors in the reproduction of mole fraction and mass concentration of components in gas mixtures are analyzed by a dynamic method and results from a study of methods of increasing the stability and precision of dynamic generators are presented. A new complex of first-grade working standards is described. Data of an experimental study of the metrological characteristics of dynamic generators based on the results gained from their use in international key comparisons are presented.     

燃料电池车用漩涡风机壳体辐射噪声数值预测

数值模拟燃料电池车用旋涡风机壳体的结构振动辐射噪声。首先给出燃料电池车上旋涡风机运行时振动噪声测量结果,然后使用Fluent模拟风机内部三维非定常流场,将作用在壳体表面的非定常力加载到壳体模型,使用Nastran对壳体进行动力响应计算,实现气体到结构的单向耦合。接着使用Virtual. Lab模拟风机壳体振动向外辐射的噪声,将试验测量和数值计算结果进行对比,表明此方法能够较为准确地模拟壳体的振动辐射噪声。最后采用这一方法研究散热片及结构阻尼对风机振动辐射噪声的影响。结果表明：无散热片以及增大结构阻尼系数可以降低漩涡风机壳体辐射噪声。     

A study of a commercial MHD power plant scheme

Power engineering specialists are currently interested in electrical power stations with magnetohydrodynamic generators. This interest has been generated by the fact that fossil fuels are becoming increasingly costlier, and with the exploitation of remote and practically inaccessible deposits, a more rational utilisation of fuel has become necessary. Research on magnetohydrodynamic generators is being conducted in many countries at present. In the USSR a composite pilot plant with an MHD generator whose output exceeds 20 MW has already been operative for several thousand hours. However the pilot plant has to be considerably modified to serve as a model for the 500–1000 MW industrial power unit. This paper is devoted to an investigation of one of the possible process flow diagrams of MHD electrical power plants. The structure of MHD electrical power plants, the interrelation between the aggregates, issues concerning the starting of the plant and the working of the power unit under various partial load conditions are discussed. With the availability of new theoretical and experimental data, the process flow diagrams of industrial MHD electrical power plants will naturally undergo changes. However, the methodical approach and the investigations, described in this paper should retain their validity for all process flow diagrams of electrical power plants with MHD generators.     

回热循环燃气轮机中回热器的动态特性研究

采用多段集中参数模型对具有分布参数特性的回热器建模，简化了由偏微分方程带来的大量计算，应用Matlab／Simlink软件作为仿真平台，采取数值方法求解，对具体回热燃气轮机中的回热器进行了仿真，结果表明，回热器时间常数较大，在回热循环燃气轮机仿真中回热器的热惯性不能忽略，而且是影响系统平衡稳定性的重要因素．     

Electric conductivity of molecular hydrogen plasma with alkali metal additive

The electric conductivity of a gas mixture as a possible working medium for a magnetohydrodynamic generator (a minor amount of cesium or potassium in argon and molecular hydrogen) is calculated in the 1000–5000 K temperature range at a constant pressure of 1 atm. The advantages of molecular hydrogen as a possible buffer gas for magnetohydrodynamic generators are discussed.     

Methods to lower the energy expenditures on rotor cryostatting in superconducting turbine generators

To lower the energy expenditure of a cryostat system for rotors of superconducting turbine generators, several methods have been analysed. A ‘warm’ electromagnetic shield requires less refrigeration power than a ‘cold’ shield. For the thermal bridge between the cold and warm parts of the rotor an idealized cooling system comprising many different coolant streams is compared to practical systems with one or two coolant paths. The energy expenditure of a system was analysed as a function of the co-ordinate of the point where the thermal shield is attached to the thermal bridge, temperature of the escaping vapour of the coolant, and working temperature of the inductor. A system with two-flow gas cooling of the thermal bridge is offered where the throttle stage of the helium refrigerator is located in the rotor. A special construction of the thermal bridge is described which leads to lowering of the energy expenditures in the system.     

Steam thermolysis of tire shreds: modernization in afterburning of accompanying gas with waste steam

On the basis of experience in the commercial operation of tire-shred steam thermolysis in EnresTec Inc. (Taiwan) producing high-grade commercial carbon, liquid pyrolysis fuel, and accompanying fuel gas by this method, we have proposed a number of engineering solutions and calculated-analytical substantiations for modernization and intensification of the process by afterburning the accompanying gas with waste steam condensable in the scrubber of water gas cleaning of afterburning products. The condensate is completely freed of the organic pyrolysis impurities and the necessity of separating it from the liquid fuel, as is the case with the active process, is excluded.     

燃油系统旋涡泵压力脉动的控制研究

为了改善燃油泵噪声、振动、声振粗糙度(noise,vibration and harshness,NVH)性能,提高燃油泵声音品质,开展了燃油系统旋涡泵压力脉动的控制研究。采用计算流体动力学(Computational Fluid Dynamics,CFD)数值模拟方法和理论分析方法分析燃油系统微型旋涡泵的压力脉动特性,并采用随机叶片分布方法设计了2种非均布程度不同的非等距叶轮。基于CFD数值模拟结果和理论分析结果,提出一种改进的非等距叶轮设计方法。燃油泵噪声试验结果验证了该设计与控制方案的可行性。结果显示:相较于等距叶轮,随机非等距叶轮燃油泵的中高频段尖锐噪声消失,NVH性能提升;随机非等距叶轮能够显著分散叶频峰值,非均布程度的增加显著增大了随机非等距叶轮的叶频脉动幅值下降幅度。因此,采用随机叶片分布方法,有助于改善旋涡泵的压力脉动特性,对改善燃油泵的NVH性能具有重要的工程应用价值。     

Spectral measurements of the gas and electron temperatures in the flame of a single-phase ac plasma generator

High-power electric-arc ac plasma generators find extensive application which is primarily associated with the problem of processing of organic waste and production of synthesis gas. The structure of a high-power single-chamber multiphase ac plasma generator with rail-type electrodes includes an injector of primary charge carriers which is a single-phase high-voltage plasma generator with a power of 10 kW or lower. This latter plasma generator may be further employed for solving other problems. Results are given of spectroscopic measurements of gas temperature fields at the nozzle exit section of a high-voltage plasma generator with rod electrodes located in a cylindrical channel. The pattern of variation of the temperature fields as a function of working gas flow rate is investigated.     

Entwicklung und experimentelle Untersuchung neuer Regeneratorkonzepte für regenerative Gaskreisprozesse am Beispiel einer Vuilleumier-Wärmepumpe

The Stirling cycle and the Vuilleumier-cycle are well-known representatives of regenerative gas cycles. Regenerators are a fundamental component of these cycles. The task of a regenerator is to take up heat from the working fluid passing through the regenerator matrix and to restore this heat to the working fluid on its way back. These tasks define the requirements that have to be met by the regenerator material. The heat transfer and the pressure drop characteristics of the regenerator matrix must be in an acceptable range. Additionally, with regard to series production, the confectioning of the matrix material and the cost of production and after costs are of great interest. Up to now, as a rule, wire screens and wire gauzes have been used in regenerative gas cycle machines. Indeed, these solutions are suitable from a thermodynamic point of view, but they suffer from the disadvantage of high manufacturing costs. For that reason new regenerator concepts have been developed in the present work. The applicability of new materials as well as of new configurations of common materials in regenerative gas cycle machines has been investigated. Finally, all these regenerator concepts have been evaluated with regard to manufacturing, engineering and economic aspects.     

Entwicklung und experimentelle Untersuchung neuer Regeneratorkonzepte für regenerative Gaskreisprozesse am Beispiel einer Vuilleumier-Wärmepumpe

The Stirling cycle and the Vuilleumier-cycle are well-known representatives of regenerative gas cycles. Regenerators are a fundamental component of these cycles. The task of a regenerator is to take up heat from the working fluid passing through the regenerator matrix and to restore this heat to the working fluid on its way back. These tasks define the requirements that have to be met by the regenerator material. The heat transfer and the pressure drop characteristics of the regenerator matrix must be in an acceptable range. Additionally, with regard to series production, the confectioning of the matrix material and the cost of production and after costs are of great interest. Up to now, as a rule, wire screens and wire gauzes have been used in regenerative gas cycle machines. Indeed, these solutions are suitable from a thermodynamic point of view, but they suffer from the disadvantage of high manufacturing costs. For that reason new regenerator concepts have been developed in the present work. The applicability of new materials as well as of new configurations of common materials in regenerative gas cycle machines has been investigated. Finally, all these regenerator concepts have been evaluated with regard to manufacturing, engineering and economic aspects.     

铸坯热送热装工艺对加热炉能效的影响

为了探究热送热装工艺的节能优势,本文以某钢厂热送热装生产线为研究对象,通过测量铸坯温度、收集连铸坯生产参数,建立了铸坯在炉加热模型,利用有限元法计算了铸坯的温度云图分布和热量变化情况,比较了不同热履历铸坯在炉加热过程中的异同。同时,测量了不同装炉温度下的加热炉炉况,结合加热炉各段温度、空煤气流量、烟气流量等生产参数与铸坯吸热量的数值模拟计算结果,分析了不同装炉温度下加热炉的热平衡和燃耗。研究表明:相较于冷装,现有热装加热工艺可减少燃耗约11.81 kgce/t;通过调节生产节奏,解决了现有热送热装工艺存在的铸坯在炉时间过长的问题,优化后的工艺较冷装吨钢生产可节省燃耗约19.62 kgce/t。     

Study of the co-pyrolysis of biomass and plastic wastes

This work aimed to study the recovery of two types of waste by the process of pyrolysis. The obtained results show that the adding of a plastic mix improves the overall efficiency of the slow pyrolysis of pine. Therefore, it was possible to achieve higher liquid yields and less solid product than in the classic slow pyrolysis carbonization of biomass. The obtained liquids showed heating values similar to that of heating fuel oil. The gas products had energetic contents superior to that of producer gas, and the obtained solid fractions showed heating values higher than some coals. There were also identified some typical products of fast biomass pyrolysis used as raw material in several industries. The effects of experimental conditions in product yield and composition were also studied. The parameters that showed higher influence were (with its increase): reaction time on gas product composition (increase of the alkane content) and on liquid composition (increase in aromatics content); reaction temperature on product yield (decrease of liquid yield with increase of solids and gases) and on gas product composition (increase in alkane content); initial pressure on liquid composition (increase in the aromatics content) and mainly the pine content of the initial mixture on products yield (increase of gas and solid yield with a decrease in liquids) and on the gas product composition (favouring CO and CO₂ formation). An erratum to this article can be found at     

适合分布式冷热电联供系统的中小型发电装置

分布式冷热电联供（combined cooling,heating and power,CCHP）系统是一种小型、临近用户的新型供能方式,可避免能量长距离传输过程损失,同时具有灵活、高效、环保特点,成为大规模、集中式供能方式的重要补充。中小型发电装置是分布式冷热电联供系统的核心,制冷和制热也都围绕发电装置余热展开。对适合分布式冷热电联供系统的2类中小型发电装置的基本工作原理、热力性能和相关研究进展进行综述。一类是以化石燃料为能源输入的中小型发电装置,包括微型燃气轮机、燃气内燃机、小型燃气轮机和燃料电池;另一类是以发电装置余热或太阳能集热等其他热源为能源输入的中小型发电装置,包括有机朗肯循环、正逆耦合循环、热声发电机等。最后,对2类中小型发电装置的优缺点进行对比分析,为分布式供能系统的发电装置选型、系统方案设计等提供参考。     

Analysis of temperature and pressure changes in liquefied natural gas (LNG) cryogenic tanks

Liquefied natural gas (LNG) is being developed as a transportation fuel for heavy vehicles such as trucks and transit buses, to lessen the dependency on oil and to reduce greenhouse gas emissions. The LNG stations are properly designed to prevent the venting of natural gas (NG) from LNG tanks, which can cause evaporative greenhouse gas emissions and result in fluctuations of fuel flow and changes of fuel composition. Boil-off is caused by the heat added into the LNG fuel during the storage and fueling. Heat can leak into the LNG fuel through the shell of tank during the storage and through hoses and dispensers during the fueling. Gas from tanks onboard vehicles, when returned to LNG tanks, can add additional heat into the LNG fuel. A thermodynamic and heat transfer model has been developed to analyze different mechanisms of heat leak into the LNG fuel. The evolving of properties and compositions of LNG fuel inside LNG tanks is simulated. The effect of a number of buses fueled each day on the possible total fuel loss rate has been analyzed. It is found that by increasing the number of buses, fueled each day, the total fuel loss rate can be reduced significantly. It is proposed that an electric generator be used to consume the boil-off gas or a liquefier be used to re-liquefy the boil-off gas to reduce the tank pressure and eliminate fuel losses. These approaches can prevent boil-off of natural gas emissions, and reduce the costs of LNG as transportation fuel.     

燃料电池电极板材料工艺发展趋势

电极板是燃料电池的关键核心部件,起到分隔气体、提供反应界面、传导电流的作用。根据燃料电池应用工况的不同,电极板的材料选择与制造工艺路线也有所不同。材料工艺是决定燃料电池设计、质量、成本的核心要素。着重论述了金属、石墨、树脂作为电极材料的工艺路线。针对金属电极板材料,论述了车载、航空航天2种工况下不锈钢、钛材的成形设计准则、工艺路线、产品性能,并分析比较了不同成形方法中设备、模具工装和工艺路线的适用性。针对石墨电极材料,对比了硬石墨一次模压成形和柔性板石墨模压成形2种工艺,并根据各自的基材状态选择了合适的工艺路线,同时根据工艺路线的特点分析了产品的优缺点。在复合材料中主要选择了金属、石墨、树脂3种材料,根据制备原理,复合材料双极板有结构复合电极、材料复合电极和工艺复合电极3个研究方向。在结构复合电极方面,主要论述了石墨与金属复合的设计思路和结构特点;在材料复合电极方面,主要论述了热固性树脂和热塑性树脂与石墨复合的工艺路线和产品特点;在工艺复合电极方面,主要论述了微型燃料电池极板的制造理念和方法,并借鉴了微机械加工工艺路线,设计制造了复合工艺极板。最后展望了燃料电池电极板的箔材研发方向、级...     

A Laser System for Real-Time Measurement of the 129I and NO2 Concentrations in a Spent Nuclear Fuel Reprocessing Medium

A laser system was developed for real-time detection of the global radionuclide ¹²⁹I and NO₂ during spent nuclear fuel reprocessing. This system was used for determining the concentrations of these substances in a gas stream under actual conditions of nitric acid dissolution of spent nuclear fuel at the Khlopin Radium Institute, Research and Production Association. The tests showed that the laser system is suitable for measuring both the ¹²⁹I and NO₂ concentrations directly in the gas phase during spent nuclear fuel reprocessing (this is essential for monitoring this process and controlling the dissolution cycle safety) and in the gases emitted by radiochemical enterprises. The sensitivity with respect to ¹²⁹I, achieved with the laser system developed, also makes it suitable for real-time monitoring of ¹²⁹I and NO₂ at the maximum permissible concentration (MAC) level. This will allow evaluation of the environmental condition of air in the working areas of radiochemical enterprises, as well as in residential areas.     

Gas/Water and Heat Management of PEM-Based Fuel Cell and Electrolyzer Systems for Space Applications

Hydrogen/oxygen fuel cells were successfully utilized in the field of space applications to provide electric energy and potable water in human-rated space mission since the 1960s. Proton exchange membrane (PEM) based fuel cells, which provide high power/energy densities, were reconsidered as a promising space power equipment for future space exploration. PEM-based water electrolyzers were employed to provide life support for crews or as major components of regenerative fuel cells for energy storage. Gas/water and heat are some of the key challenges in PEM-based fuel cells and electrolytic cells, especially when applied to space scenarios. In the past decades, efforts related to gas/water and thermal control have been reported to effectively improve cell performance, stability lifespan, and reduce mass, volume and costs of those space cell systems. This study aimed to present a primary review of research on gas/water and waste thermal management for PEM-based electrochemical cell systems applied to future space explorations. In the fuel cell system, technologies related to reactant supplement, gas humidification, water removal and active/passive water separation were summarized in detail. Experimental studies were discussed to provide a direct understanding of the effect of the gas-liquid two-phase flow on product removal and mass transfer for PEM-based fuel cell operating in a short-term microgravity environment. In the electrolyzer system, several active and static passive phaseseparation methods based on diverse water supplement approaches were discussed. A summary of two advanced passive thermal management approaches, which are available for various sizes of space cell stacks, was specifically provided     

Mathematical modeling and distribution characteristics evaluation of fuel particles in iron ore sintering process

The distribution characteristics of fuel particles is a key factor affecting the thermal state of sintering. To find out the fuel distribution under different granulation conditions, a mathematical method based on the particle population balance and Lister’s model was established in this study. In combination with experiments including granulation and the fixed carbon and sulfur content of detection, the relative error of this model is within ±1.5. The proportion and particle size composition of fuel are selected to evaluate quantitatively the distribution characteristics. The result shows that the fuel distribution in granules mostly accumulates in the middle size granules. The increase of proportion and fine particles content of the fuel leads to the decline of the fuel content in +5 mm granules. With a higher ratio and higher content of fine particles in the fuel, the fuel distribution in the upper and middle of the sintering beds rises while that of the bottom layer is down, which is conducive to changing the nonuniform distribution of thermal. The fuel particle size composition has greater impact on fuel distribution than its proportion. To better investigation, further parameter simulation and optimization of granulation is necessary.     

Chinese power-station coal mills use Espey shaft-seals to contain ‘coal dust’

This brief case study looks at a sealing system that is being used in coal mills at a power station in Dezhou, China. The mills produce ‘coal dust’ which is used to fuel steam generators. Designed and developed by German company Gustav Espey GmbH, the seals have proved to be highly reliable and robust, preventing any ‘coal dust’ from being discharged into the atmosphere.