PEMFC引射器的设计及特性分析

以索科洛夫的引射器设计方法为基础,对一个高压质子交换膜燃料电池系统(PEMFC)的引射器进行结构设计以及CFD仿真分析,研究了引射器的使用特性.研究表明:随着压缩流体出口压力和引射流体压力的增加,引射器的引射系数随之增大;工作流体压力对引射器性能的影响随引射器出口所处工况的变化而变化.     

可调式引射器内流动的数值计算

在对可调式引射器结构和流动特点进行分析的基础上,建立了其内部流动的数学模型.给出了可调式引射器工作流体和引射流体入口、引射器出口的边界条件以及初始条件,并进行了相应的数值处理.用PHOENICS软件对可调式引射器内部流动进行了数值模拟,得出了可调式引射器内部流场分布、不同截面比下从喷嘴出口到扩散室出口之间轴线上的压力分布、引射比随喷嘴截面积变化的曲线,数值计算结果与理论结果较为吻合.     

甲醇混合燃料引射式燃烧器配风性能数值研究

采用数值方法研究了甲醇混合燃料引射式燃烧器的配风性能,重点研究了不同位置的喷嘴出口面以及喉部直径DH与喷嘴出口直径DJ之比α对引射器摩尔引射系数(MER)的影响,以及引射器的工作压力和背压对MER的作用规律,获得了优化的甲醇混合燃料引射式燃烧器结构参数.发现当喷嘴出口位于引射器吸入室中时,MER保持稳定.增加α会导致MER的增大,直到α=8.5之后,MER保持不变.MER受引射器工作压力的影响较弱,但随背压的增加而骤减.优化后的燃烧器能实现随负荷变化(25%—120%)的自适应配风,且MER变化率2.3%,燃烧温度可达2000K,燃烧效率达99%以上.     

跨临界CO2引射制冷循环临界背压分析

为了优化设计或控制引射系统的性能,建立了跨临界CO2引射制冷循环中引射器性能的设定背压模型,定义引射器临界背压为忽略引射器出口动能时的引射器迭代背压,分析了引射器背压和出口速度对系统性能的影响.结果表明:当引射器背压低于临界值时,引射系数保持不变,且在不同系统高压侧压力下均成立;系统性能系数(COP)随着背压升高而增大,在系统状态可控的情况下引射器背压应尽量靠近临界值.同时,不同背压下COP随高压侧压力变化的趋势相同,背压作为设计或控制参数不会影响高压侧压力的优化.引射器出口动能会因流动摩擦和冲击而转化成热量并造成系统的热力学损失,背压选取不当会造成较大的引射器出口速度,且随着背压降低,出口速度增大,随着系统高压侧压力升高,出口速度先急剧降低,再缓慢变化.     

液液引射器性能的数值模拟与实验

建立了液液引射器的三维数学模型,采用R134a制冷剂作为工质,模拟引射器主要结构参数与引射性能之间的变化关系.模拟结果表明:引射系数随喷嘴出口直径的减小而急剧增大,随混合室直径的增大而增大,随喷嘴与混合室之间距离的增大急剧下降;引射系数随着工作流体流量、喷嘴长度和扩散室长度的增大而缓慢上升;混合室长度对混合流体的压力场有较大影响,为使混合流体获得最佳的压力场,混合室最佳长度取45 mm.搭建了水平管降膜式空气源冷热水测试机组,试验结果表明:该引射器具有优良的引射性能;制冷系统负荷随着循环喷淋量的增加而增大,系统的性能系数随着循环喷淋量的增大呈现先增后减的趋势.     

基于虚拟风室模型的排气引射流动三维流场的数值计算

提出了一种虚拟风室模型,以精确计算引射器在各种主流速度下的引射空气量.在数值建模中,将引射器置于一个仅具有主流和引射入口的虚拟整流风室内,通过人工调整引射入口空气流量直至引射器附近监测面积的平均总压与环境大气压相等,以预测该环境下引射器的引射空气量.求解了全三维N-S方程和k-w湍流模型,并采用多孔介质模型处理虚拟风室内的整流格栅,对不同主流速度下的引射流动进行了数值模拟.结果表明,引射空气量的计算值与已有文献实验测量结果之差小于7%,所采用的虚拟风室模型能有效预测大气环境下的引射流量.并通过流向涡和正交涡等理论对引射流动的卷吸和掺混进行了分析.     

采用可逆质子交换膜燃料电池/膨胀机的综合能源系统性能研究

为提高可再生能源在冷热电联供系统中的利用率,提出一种以可逆质子交换膜燃料电池(RPEMFC)和膨胀机为主要部件的新型冷热电联供综合能源系统,通过引射器和膨胀机回收电解池氧气侧的压力能,以RPEMFC电堆的冷却回路和膨胀机出口冷气分别对外供热和制冷。为获得系统中主要设备运行参数对系统性能的影响,建立了系统的热力学模型,进而揭示了系统效率、效率、压缩机耗功、膨胀机回收功、系统制热制冷量等参数的变化规律。研究结果表明:当RPEMFC电堆以50kW的发电功率运行时,系统发电效率为56.2%,热效率为35.2%,总效率为91.4%,效率为54%,且在15～85kW的发电功率变化范围内系统能效均超过89%;系统能量效率及效率对引射器流量比及引射器工作流压力的变化较为敏感,并以影响系统发电效率为主;压缩机出口压力变化对系统能效影响不大,但压缩机出口压力增大有利于系统增加产冷量。     

风室压力损失对引射器流动的影响

实验测量了存在风室压损时引射器引射的二次流流量和风室压损；将测量的风室压损作为数值边界条件，利用有限体积法对存在风室压损时的引射器流动进行了三维数值模拟，并将数值和实验的二次流流量进行了对比，在此基础上，对实际运行情况下不存在风室压损时的引射器三维流动进行了数值模拟，并同存在风室压损时的流动进行了对比．结果表明，数值模拟结果与实验结果吻合较好，最大误差不超过4％，说明数值算法是合理可行的；压力损失使引射器的流动和引射流量等发生了较大变化，并且使测量的引射流量大大低于无压损时的情况。     

RPEMFC/膨胀机可再生能源驱动的综合能源系统性能研究

为提高可再生能源在冷热电联供系统中的利用率，提出一种以可逆质子交换膜燃料电池RPEMFC和膨胀机为主要部件的新型冷热电联供综合能源系统，通过引射器和膨胀机回收电解池氧气侧的压力能，以RPEMFC电堆的冷却回路和膨胀机出口冷气分别对外供热和制冷。为获得系统中主要设备运行参数对系统性能的影响，建立了系统的热力学模型，进而揭示了系统效率、?效率、压缩机耗功、膨胀机回收功、系统制热制冷量等随参数的变化规律。研究结果表明，当RPEMFC电堆以50kW的发电功率运行时，系统发电效率为56.2%，热效率35.2%，总效率91.4%，?效率54%，且在15kW-85kW的发电功率变化范围内系统能效均超过89%。系统能量效率及?效率对引射器流量比及引射器工作流压力变化较为敏感，并以影响系统发电效率为主；压缩机出口压力变化对系统能效影响不大，但压缩机出口压力增大有利于系统增加产冷量。     

一种考虑壁面摩擦作用的发射井引射器设计方法

针对发射井优化设计问题,基于引射器函数方法提出了一种考虑壁面摩擦作用的发射井引射器准一维设计方法,建立了考虑壁面摩擦作用的引射器函数和静压协调函数.证明了考虑壁面摩擦作用时驻点速度小于声速,引射器不能达到第三极限,只能达到驻点极限.以实际算例分析了发动机总压、发射井横截面积、混合室出口压强变化时的引射器工作特性,画出了工作特性曲线.采用计算流体力学（computational fluid dynamics,CFD）方法,分别建模分析了发动机总压、发射井横截面积、混合室出口压强变化时发射井引射器中超声速射流流动形态,将CFD方法得到的混合室入口压强与准一维方法的结果进行了对比.结果表明,准一维方法得到的工作特性曲线与CFD方法的计算结果差距较小,在混合室背压变化时最大误差为4.31%,验证了准一维方法的准确性.      

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.