调峰机组汽轮机转子剩余寿命的合理分配方案

采用8节点三维有限元法对汽轮机转子温度场、应力场、硬度值进行计算和分析,计算出某电厂5号机投产15年来转子低周疲劳寿命和高温蠕变寿命消耗。对承担两班制调峰机组的设备进行了解和试验,根据某该机投产15年来寿命消耗情况和试验的有关数据,计算出机组剩余寿命合理化分配方案和该机组年两班制调峰次数。     

热处理工艺对GH909板材TIG焊缝析出相的影响

为改善GH909板材的焊接工艺及使用性能,采用扫描电镜和EDX分析研究了GH909板材在TIG焊后不同热处理工艺焊缝析出相的变化规律,对提高GH909板材TIG焊接接头质量具有重要的应用价值.研究结果表明：焊缝形成的相有针片状ε/ε″相、γ/Laves低熔点共晶相,且都在γ晶间分布;焊缝中心低熔点共晶相所占比例均比离焊...     

Mechanism of the reversibility of asphaltene precipitation in crude oil

Asphaltene precipitation and deposition occur in petroleum reservoirs as a change in pressure, temperature and liquid phase composition and reduce the oil recovery considerably. In addition to these, asphaltene precipitates may deposit in the pore spaces of reservoir rock and form plugging, which is referred to as a type of formation damage, i.e. permeability reduction. In all cases above, it is of great importance to know under which conditions the asphaltenes precipitate and to what extent precipitated asphaltenes can be re-dissolved. In other words, to what extent the process of asphaltene precipitation is reversible with respect to change in thermodynamic conditions. In present work, a series of experiments was designed and carried out to quantitatively distinguish the reversibility of asphaltene precipitation upon the change in pressure, temperature and liquid composition. Experiments were conducted in non-porous media. Generally it was observed that the asphaltene precipitation is a partial reversible process for oil under study upon temperature change with hysteresis. However, the precipitation of asphaltene as a function of mixture composition and pressure is nearly reversible with a little hysteresis.     

不同物理参数化方案对黄河源区降雨模拟的适用性研究

为分析不同物理参数化方案在模拟黄河源区降水时的适用性,采用中尺度WRF模式中常用的5种微物理方案和3种积云对流方案进行组合,模拟黄河源区的一次降水过程,利用直方图曼哈顿距离相似度对模拟结果和实况降水空间分布进行对比,并分析各方案组合模拟的降水中心(河南站)逐小时降水分布和24h累积降水量,以得到WRF模式模拟黄河源区降水的最优方案配置,提高模拟精度。结果表明,WRF模式的各方案基本可以再现降水强度、中心和范围,基于Morrison方案的组合对降水的还原能力较好;就降水中心的降水时间序列和24h累积降水量来看,基于Morrison方案的组合与实际降水的一致性较好;Morrison微物理方案和Grell 3积云对流方案组合的模拟结果与实际降水的空间分布相似度最高,表明该方案组合是WRF模式模拟黄河源区降水过程的最优模拟方案。研究成果对于提高黄河源区降水模拟的精度有重要意义。     

Sickle bush (Dichrostachys cinerea L.) field performance and physical–chemical property assessment for energy purposes

The sickle bush (Dichrostachys cinerea (L.) Wight & Arn.) comprises a woody legume shrub which is widely distributed throughout of the tropical areas of Africa, Asia and Oceania, being found as well in Cuba where it represents a difficult to control invasive plant. It holds great silvopasture and energy crop potentials. In southwestern Spain a two year field trial was conducted contemplating also another six hardwood taxa commonly used as energy crops. The sickle bush above ground dry biomass fraction was 60.4%; sickle bush displayed a high transpiration rate during hot days (3.02 kg m⁻² d⁻¹ to 6.82 kg m⁻² d⁻¹); cold winter temperatures (<−2 °C) together with hot and dry summer air (<20% relative humidity) committed survival and growth. The physical-chemical wood properties and the pellets thereof derived were analyzed and compared to those of the other energy crop taxa. The within other woody species normal chemical composition range coupled to a high wood density and energetic use properties (19.2 MJ kg⁻¹ higher heating value, 29 g kg⁻¹ ash content) all allow for an industrial use. Pellets evidenced also good physical and mechanical properties (690 kg m⁻³ bulk density, 42 g kg⁻¹ moisture content). However, the mechanical durability (93.9%) was slightly less than that required by the non-industrial use standards, therefore further improvements should be studied. All of the above could encourage scrubland cuts in Cuba as a mechanical control method, in addition to the expansion of plantations within of their tropical climate based natural habitats.     

加强管理,提高机车运用效率

在机车运用效率指标体系的基础上 ,加强机车管理 ,合理支配机车 ,提出如何提高机车运用效率的问题     

梯级水电站最优曰运行及非稳定流对航运影响

本文研究建立在主航道上且在电力系统中担负骨干调峰任务的梯级水电站的最优调峰方式以协调调峰方式引起的非稳定流与航道航运的矛盾,提出了最优控制模型和预估—关联协调混合的梯级计算结构及算法。本文以国内的三峡葛洲坝梯级水电站作为研究对象。     

柴油机排气微粒静电捕集的初步研究

本文通过对柴油机排气微粒电阻率的测量及其微粒固有荷电量与电晕荷电量的比较,分析了用静电技术捕集柴油机排气微粒的可行性。用485Q型柴油机进行了排气微粒静电捕集器模型的台架试验,证实了柴油机排气微粒的固有电荷不能满足静电捕集的需要,而强化荷电是必需的。     

土壤-空气换热系统流动与供冷性能的计算模拟

以土壤热传导方程和K_1—ζ湍流模型为基础,采用温度场叠加法对土壤—空气埋管换热系统进行了三维动态数值模拟,计算了埋管出口温度随时间的动态变化。研究了埋管管长、管径、风速等对换热器出口温度的影响。模拟结果表明：①换热器出口温度随外界气温和土壤表面获得的辐射能的周期性变化而呈周期性变化；②随着管长增加和管径减小,出口温度降低,而且受气温和太阳辐射的影响减小；③随着人口风速减小,出口温度降低且变化幅度减小,供冷性能提高。并进行了实验验证,实测数据与模拟结果之差不超过0.8℃。     

Simulation of the daily change of soil temperature under different conditions

In this paper, by employing a mathematical model which was established to describe the physical mechanisms of heat and mass transfer in unsaturated porous media, some comparisons between the daily changes of soil temperatures under five different conditions have been conducted. The numerical simulations show that the ambient temperature, solar radiant heat flux, soil initial water content, ambient wind speed, atmospheric relative humidity, and soil porosity exert significant effects on the daily change of soil temperature. The differences between the daily changes of soil temperatures in those cases are also discussed and analyzed, which may provide some useful information for agriculture applications. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(6): 533–544, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10106