变风量系统外区进深划分及对应风量特性

从办公建筑的分区特性及变风量系统的设计计算方法出发,以上海某办公建筑标准层为模型,分析了各朝向外区的空调一次风风量特性差异。通过设定不同的外区进深,进一步分析了各朝向外区的风量特性受外区进深划分的影响。研究结果表明:外区进深划分差异不会影响各朝向外区的逐时风量变化趋势及波峰出现的时间;当进深由3m-4m-5m不断增大过程中,外区单位面积的一次风最大风量逐渐降低,且降幅明显,一次风最小风量与最大风量的比值呈增大趋势,但整体趋势较缓。

船用VAV末端装置风量传感器布置对风量传感特性的影响研究

船用变风量(VAV)空调系统能够根据空调负荷的变化,自动调节室内空调送风量,以满足室内热湿环境的要求,而末端装置风量传感器的风量传感特性对变风量系统的运行至关重要。以配置均速管流量传感器的船用压力无关型VAV末端装置为研究对象,该末端装置采用圆形平板叶片和多孔圆柱形阀片组成的风阀。搭建变风量末端装置风量测量实验台,设定三种典型进口基准风量条件,测量末端装置风道断面的动压分布。基于测得的风道断面动压分布,分析风量传感器布置对风量传感特性的影响,优化传感器布置来提高末端装置风量传感特性,为VAV末端装置的改造提供了参考。

1000 MW燃煤机组旋流燃烧器及燃尽风风门差异化调节特性

对冲燃烧煤粉锅炉因二次风系统结构复杂、布置紧凑,难以对燃烧器及燃尽风内、外二次风进风量进行准确监测,热态运行时风门调节盲目,普遍存在炉膛宽度方向两侧燃烧严重缺风问题。为充分提升对冲燃烧煤粉锅炉炉膛两侧旋流燃烧器及燃尽风进风量,获得理想风门开度组合,以某电厂1000 MW燃煤机组为研究对象,对二次风系统进行完整建模及流动数值模拟,系统性定量研究旋流燃烧器及燃尽风内、外二次风门差异化调节特性。结果表明:燃烧器及燃尽风风门均一全开初始状态下,沿炉膛宽度方向二次风量呈中间大、两边小的分配特性,与对冲燃烧锅炉实际运行炉膛两侧缺风现象相符;燃烧器/燃尽风内、外二次风开度两侧向中间依次为100%/100%、60%/50%、50%/40%、40%/40%时,炉膛宽度方向上,燃烧器及燃尽风进风量均呈两侧向中间递减的理想状态,与均一全开初始状态相比,炉膛两侧进风量增大8.3个百分点,按初始侧边氧量1.80%计,侧边氧量将显著提升1.15个百分点,同时,燃尽风占总二次风量的比例略微提升0.6个百分点,基本不影响炉膛高度方向上的分级燃烧程度。

从鼓风机电流反推系统风量阻力特性曲线

从整车鼓风机电流表现,利用台架标定得到空调系统风量和流道阻力的关系,进而得到整车空调系统鼓风机工作点,为系统的优化和改进提供帮助和借鉴。

综采工作面配风量对其风阻的影响规律分析

为了揭示综采工作面配风量对其风阻的影响规律,以河南新郑煤电有限责任公司11208综采工作面为研究对象,现场实测不同配风量下工作面风阻,利用CFD方法构建11208工作面风流场计算模型,通过模拟分析工作面内气压场与风速场结构特征论证了工作面通风阻力属于局部阻力,并模拟计算不同配风量下工作面风阻值,拟合得到二次抛物线型的工作面风量-风阻特性曲线,风量-风阻拟合函数计算结果与实测结果之间相对误差小于6%,研究所得的工作面风量-风阻特性曲线可用于矿井通风网络解算。

Study on the Characteristics of Ecological Water Requirement in Maijishan Scenic Spot

[Objective] This study aimed to explore the characteristics of ecological water requirement in Maijishan Scenic Spot. [Methed] The characteristics of ecologi- cal water requirement in Maijishan Scenic Spot were analyzed based on,the data of soil humidity and meteorology of the spot. [Result] The result showed that the actual annual ecological water requirement in the spot was 678×10^6 m^3, and the proportion of soil water and evapotranspiration were 21% and 79%, respectively; the minimum annual ecological water requirement quota in the spot was 480.27×10^6 m^3, and the proportion of soil water and evapotranspiration were 16% and 84%, respectively; the minimum annual suitable ecological water requirement quota in the spot was 624.22×10^6 m^3, and the proportion of soil water and evapotranspiration were 18% and 82%, respectively. The precipitation was 614×10^6 m^3, and consumptive water surplus reached up to 78×10^6 m^3. The years when the precipitation was higher than the evapotranspiration accounted for 76%. Since 1980s, the evapotranspiration showed a linearly increasing trend. The precipitation was higher than the evapotranspiration from Jun. to Oct. and less than the evapotranspiration from Nov. to Dec. and Jan. to May. Evapotranspiration water requirement was regulated by soil water. The dis- parity between precipitation and evapotranspiration was huge in spring, thus having certain influence on waterfalls and streams in the spot. [Conclusion] The results of this study provided a basis for the rational use and long-term planning of the water sources in Maijishan Scenic Spot.

THE COMBUSTION CHARACTERISTICS OF A MOVABLE LINEAR FIRE SEAT IN MINE FIRES

Because of the difficulties of describing the process of combustion of underground mine fires, usually the fire seat is considered as a fixed point in the methods of mine fire computer simulation, however this is not in keeping with the feature of the distribution of the combustibles and the process of combustion in mine fires. A conception about movable linear fire seat is put forward first by the authors, together with the calculated models of the thermal decomposition rate, flame spreading velocity and the steady burning length of a linear fire seat etc. The paper also introduces the results of the application of these models.

Assessment of Wind Characteristics and Wind Potential Energy Yield in the Jordanian Southern Region

This study presents investigation and assessment of wind characteristics and wind energy potential for four sites at the Jordanian southern region （Hareer, Ma＇an, Aqaba and Fujaij）. Based on the available measured data sources, the data were analyzed using hourly and mean monthly WS （wind speed） data at different heights, using a two-parameter probability distribution of Weibull function. The recognized monthly and yearly Weibull functions were considered for the second analysis step. The wind potential energy yields assessment for an ideal capable wind turbine was implemented. Finally, for energy yield estimation, a wind turbine from Vestas with a 660 kW rated power was chosen. The wind turbine characteristics： AF （availability factor）, CF （capacity factor） and wind turbine efficiency （η）, were defined and calculated for each site. The result of the analysis showed that, all sites have good wind energy potential, the Hareer site at Tafila has the best wind resources.

The FAHP-based Risk Assessment in the Conclusion of Equipment Procurement Contract

The risk assessment of contract conclusion is the primary and key part of equipment purchase contract risk management. In this paper, based on the fuzzy characteristics of contract risks, and overcoming the traditional disadvantages of analytic hierarchy process （AHP）, the fuzzy analytic hierarchy process （FAHP） of contract conclusion is proposed for meeting the actual need of equipment procurement contract risk assessment, and implementing the risk factors qualitative and quantitative assessments of different working nodes in contract conclusion. Thus, a scientific and reliable important basis is provided for the risk management of equipment procurement contract.

Experimental study on pressure and aeration characteristics in stepped chute flows

The free flow on the step surfaces has received much attention for its representative body type,flow structure,water-air two phase flow,cavitation,and many complex issues.The experiments about the time-averaged pressure and aeration concentration distribution on the step surface show that the vertical plane of steps will inevitably experience negative pressure,which must rely on adequate aeration concentration to avoid cavitation damage.However,the self-aerated flow at the head section has a relatively low aeration concentration,and the concentration of the entire steps decreases with the increasing of weir head,the minimum appears in the vicinity of the corner,and the location is close to the minimum pressure.Thus,it is necessary to set aerator in the upstream end of the step surfaces to avoid cavitation damage.

Flow Fields with Vortex in a Small Semi-open Axial Fan

In order to clarify the effect of tip clearance （TC） size on fan performance and the flow field at rotor outlet in a small semi-open axial fan, the experimental investigation was carried out. The tip diameter of test fan rotor was 180mm and test TC sizes were lmm （TC=1mm） and 4mm （TC=4mm）. Fan characteristics tests were carried out for two cases of TC size and three-dimensional velocity fields at rotor outlet were measured using a single slant hot-wire probe at four flow-rate conditions. As a result, it was found that the pressure - flow-rate characteristics curves for two cases showed almost the same tendency. However, the ensemble averaged velocity profiles along radial measurement stations of TC-4mm largely changed compared with that of TC=1mm in cases of small flow-rate condition. From the phase-locked averaging results, it was also found that the vortex existed in the rotor outlet flow field of high flow-rate condition for each TC case. Compared with the vortices for TC=1mm and TC=4mm, the vortex for TC=4mm was stronger than that for TC=1mm.

Thermo-flow characteristics and air flow field leading of the air-cooled condenser cell in a power plant

Special A-frame geometry of the air-cooled condenser cell and the complicated flow field at the exit of the axial flow fan bring on the air mal-distribution on the surface of the finned tube bundles and the deteriorated thermo-flow performances of a condenser cell. It is of benefit to the design and operation optimization of the direct dry cooling system in a power plant to investigate the thermo-flow characteristics of the condenser cell and propose the flow leading measures of cooling air. On the basis of the representative configuration of the air-cooled condenser cell in a 600 MW direct dry cooling power plant, the computa- tional models of the air side fluid and heat flows are built, in which the actual fan blade geometric details are considered. Various flow field leading ways of cooling air are presented and the thermo-flow characteristics in the A-frame condenser cell and through the finned tube bundles are compared. Results show that the flow field leading measures can result in the increased volumetric flow rate and heat rejection, thus bringing on the improved performance of the condenser cell. The improvement of thermo-flow oerformances depends upon the geometric details of the flow guiding device.