600MW汽轮机组高压联合进汽阀变工况内部流场的特性分析

采用数值模拟方法对某600 MW汽轮机高压联合进汽阀的内部流动进行了分析.通过求解全三维N-S方程和k-ε湍流模型,得到了阀门内部的流场特性.在3种不同负荷下对主汽阀全开、调节阀阀门不同开启顺序时的流场进行模拟,并分析了流动损失产生的机理.结果表明:调节阀B的流量比调节阀A大,流动状态比调节阀A好;先开启调节阀B后开启调节阀A时,各截面的压损小,各阀门的流动状态好.     

600MW汽轮机组高压联合进汽阀变工况内部流场的特性分析

采用数值模拟方法对某600 MW汽轮机高压联合进汽阀的内部流动进行了分析.通过求解全三维N-S方程和k-ε湍流模型,得到了阀门内部的流场特性.在3种不同负荷下对主汽阀全开、调节阀阀门不同开启顺序时的流场进行模拟,并分析了流动损失产生的机理.结果表明:调节阀B的流量比调节阀A大,流动状态比调节阀A好;先开启调节阀B后开启调节阀A时,各截面的压损小,各阀门的流动状态好.     

东方超超临界二次再热660 MW汽轮机超高压主汽阀、调节阀气动性能研究

主汽阀和调节阀的气动性能影响汽轮机组的经济性。文章采用CFD数值分析软件对东方超超临界高参数二次再热汽轮机超高压主汽阀、调节阀的气动性能进行了分析,结果表明,通过优化设计,可改善主汽阀、调节阀的气动性能,确保了新开发的超超临界二次再热660 MW汽轮机组的经济性与可靠性。     

核电汽轮机阀门的动态分析

介绍核电阀门动态分析的目的、计算原理与方法。讨论３１０ＭＷ核电汽轮机摇板式主汽阀、调节阀与蝶阀（再热主汽阀与调节阀）的动态性能，最后对摇板式主汽阀动态应力过大情况作了分析并提出了改进措施。     

基于CFD的蒸汽调节阀流量特性研究之一

在以往调节阀的设计中,无论是理论计算还是试验研究,都无法准确掌握汽轮机进汽调节阀的调节特性以及流场细节,而数值模拟手段则可填补这一空缺。随着计算机水平以及CFD技术的不断发展完善,利用数值模拟方法来辅助设计成为了当今工程设计的趋势。结合调节阀结构尺寸,阀后喷嘴流量的计算,通过理论公式的推导,与CFD数值模拟相结合,得到了调节阀临界流量、彭台门系数的函数关系,从而得出阀门的流量特性。提供了一种新的阀门设计思路,得到了具有较高精度的阀门特性曲线,结果对今后汽轮机进汽调节阀的研究具有一定的指导借鉴意义。     

600MW超超临界汽轮机高压主汽调节联合阀内部流场的数值模拟分析

采用非结构化四面体网格,对某600MW超超临界汽轮机组高压主汽调节联合阀的额定工况进行了数值模拟.针对3种不同结构的模型分别进行了计算,分析研究了阀门内部流场的流动特性,以及在主汽阀内加置挡板和滤网对内部流场和阀门损失的影响.     

基于CFD的蒸汽调节阀流量特性研究之二

汽轮机蒸汽调节阀采用阀后联通的方式可有效减小在低负荷运行、小流量调节时叶片的汽流弯应力,提高机组运行的安全可靠性.对阀后联通结构的调节阀进行了理论推导和计算,结合CFD数值模拟手段得到了阀门的流量特性.运用倒推法对阀门型线做出了改进,得到新的型线并进行了验算,结果表明阀门流量特性曲线光滑、平稳,调节性能良好.     

核电汽轮机阀门的动态分析

本文介绍阀门动态分析目的、计算原理与方法。讨论３１０ＭＷ核电汽轮机摇板式主汽阀、调节阀与蝶阀的动态性能，最后对摇板式主汽阀动态应力过大情况作了分析，并提出了改进措施。     

核电汽轮机阀门的国产化研究

核电汽轮机的阀门与常规火电机组相比有很大的不同，对核电阀门的设计技术国内发电制造企业都没有太多的经验。东方汽轮机厂采用测绘、理论计算和模拟实验等方法掌握了百万等级核电汽轮机组高压主汽调节阀的特性并对其进行了优化，完成了核电阀门的国产化。     

核电汽轮机调节阀泄漏试验与分析

核电汽轮机调节阀泄漏试验与分析朱丹书１前言首台３１０ＭＷ核电汽轮机的进汽阀门系向美国西屋公司外购，它为１个摇板式主汽阀、２个立式调节间所构成的Ｙ形组件。２个进汽阀门分别置于高压缸的两侧，机组为节流配汽，４个调节阀同步开启。调节间结构见图１，它采用高度...     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

液压系统常见的故障诊断及处理

任何工程机械式液压设备使用时出现故障是不可避免的。但是怎样确定故障的原因及找到好的解决方法，这是使用者最关心的问题。讲述了液压系统常见的故障及其排除方法。     

Economie d'énergie en trigénération

Trigeneration is defined as the production of three useful forms of energy—heat, cold and power—from a primary source of energy such as natural gas or oil. For instance, trigeneration systems typically produce electrical power via a reciprocating engine or gas turbine and recover a large percentage of the heat energy retained in the lubricating oil, exhaust gas and coolant water systems to maximize the utilization of the primary fuel. The heat produced can be totally or partially used to fuel absorption refrigerators. Therefore, trigeneration systems enjoy an inherently high efficiency and have the potential to significantly reduce the energy-related operation costs of facilities. In this paper, we describe a model of characterization of trigeneration systems trough the condition of primary energy saving and the quality index, compared to the separate production of heat, cold and power. The study highlights the importance of the choice of the separate production reference system on the level of primary energy saving and emissions reduction.     

Mineralogical characterization of the intraseam layers of Lofoi lignite deposits in Florina basin (western Makedonia,northwest Greece)

The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.     

Innovative methodologies in renewable energy: A review

This paper is concerned with innovative approaches to renewable energy sources computation methodologies, which provide more refined results than the classical alternatives. Such refinements provide additional improvements especially for replacement of fossil energy usages that emit greenhouse gas (GHG) into the atmosphere leading to climate change impact. Current knowledge gap among each renewable energy source calculation is rather missing fundamentals of plausible, rational, and logical explanations for the interpretation of results. In the literature, there are rather complicated and mechanically applicable methodologies, which require input and output measurement data match with missing physical explanations. The view taken in this review paper is to concentrate on quite plausible, logical, rational, and effectively applicable innovative energy calculation methodologies with simplistic fundamentals. For this purpose, a set of renewable energy methodological approaches is revisited with their innovative structures concerning solar, wind, hydro, current, and geothermal energy resources. With the increase in the renewable energy utilizations to combat the undesirable impacts of global warming and climate change, there is a need for better models that will include physical environmental conditions and data properties in the probabilistic, statistical, stochastic, logical, and rational senses leading to refined and more reliable estimations with application examples in the text. Finally, new research directions are also recommended for more refined innovative energy system calculations.     

Constrained Optimization of Heat Transfer from an Extended Surface

Two different zero‐order optimization techniques are used to maximize the rates of heat transfer from a fin assembly of a specified cost and in the shape of several annular fins that are mounted on a central stem. The problem is formulated to account for two‐dimensional steady‐state heat transfer that is limited by several inequality constraints. The dimensionless governing equations are used to identify the relevant decision variables. The number of fins making up the assembly is treated as an input parameter. A digital computer is used to determine the required temperature distributions and to implement the optimization search algorithms. Three different fin materials are assessed—aluminum, copper and carbon steel. Design optimizations of the extended surface assembly were made over a range of operating conditions, encompassing several different convection heat transfer coefficients that are representative of free and forced convection in air, and several different overall temperature differences between the substrate surface and air. A few recommendations based on trends in the predicted results are given. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(6): 504–521, 2014; Published online 3 October 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21093     

Synthesis and electrochemical properties of Li1−xFe0.8Ni0.2O2–LixMnO2 (Mn/(Fe + Ni + Mn) = 0.8) material

A new type of Li_1−xFe_0.8Ni_0.2O₂–Li_xMnO₂ (Mn/(Fe + Ni + Mn) = 0.8) material was synthesized at 350 °C in air atmosphere using a solid-state reaction. The material had an XRD pattern that closely resembled that of the original Li_1−xFeO₂–Li_xMnO₂ (Mn/(Fe + Mn) = 0.8) with much reduced impurity peaks. The Li/Li_1−xFe_0.8Ni_0.2O₂–Li_xMnO₂ cell showed a high initial discharge capacity above 192 mAh g⁻¹, which was higher than that of the parent Li/Li_1−xFeO₂–Li_xMnO₂ (186 mAh g⁻¹). We expected that the increase of initial discharge capacity and the change of shape of discharge curve for the Li/Li_1−xFe_0.8Ni_0.2O₂–Li_xMnO₂ cell is the result from the redox reaction from Ni²⁺ to Ni³⁺ during charge/discharge process. This cell exhibited not only a typical voltage plateau in the 2.8 V region, but also an excellent cycle retention rate (96%) up to 45 cycles.     

CY6D78Ti型柴油机的开发研制

本文介绍了CY6D78Ti型柴油机的开发研制过程及现状,CY6D78Ti型柴油机能满足国内中、重型卡车和豪华客车市场对柴油机动力性、经济性、可靠性的需求。由于该机型的高档配置,保证了其排放达到欧Ⅱ标准,同时为进一步提高性能、降低排放,采用电控及高压共轨等技术手段搭建了平台。