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81.
天然气井下节流嘴前后压力温度分布的数值计算 总被引:6,自引:0,他引:6
针对天然气井安装井下节流装置以后很难测得节流嘴上游压力的情况,从空气动力学的原理出发,提出根据井口采集的数据,从节流嘴下游向上游计算其喉部和上游的压力温度综合值的数值计算方法。采用临界状态判别的新方法,即依据节流嘴出口处的马赫数的值,对节流嘴附近的流态进行判别,再分别计算节流嘴出口处,节流嘴喉部以及节流嘴上游的各参数。对宝1井进行了实例计算,计算结果表明:节流后压力温度骤降,经过激波面后压力温度急剧升高的变化情况。 相似文献
82.
The coalescence behavior of two droplets with different viscosities in the funnel-typed expansion cham-ber in T-junction microchannel was investigated experimentally and compared with droplet coalescence of the same viscosity.Four types of coalescence regimes were observed:contact non-coalescence,squeeze non-coalescence,two-droplet coalescence and pinch-off coalescence.For droplet coalescence of different viscosities,the operating range of non-coalescence becomes narrowed compared to the droplet coalescence of same viscosity,and it shrinks with increasing viscosity ratio η of two droplets,indicating that the difference in the viscosity of two droplets is conducive to coalescence,especially when 1 < η< 6.Furthermore,the influences of viscosity ratio and droplet size on the film drainage time (Tdr) and critical capillary number (Cac) were studied systematically.It was found that the film drainage time declined with the increase of average droplet size,which abided by power-law relation with the size dif-ference and viscosity ratio of the two droplets:Tdr ~ (ld)0.25±0.04 and Tdr ~ (η)-0.1±002.For droplet coales-cence of same viscosity,the relation of critical capillary number with two-phase viscosity ratio and dimensionless droplet size is Cac =0.48λ0.26l-2.64,while for droplet coalescence of different viscosities,the scaling of critical capillary number with dimensionless average droplet size,dimensionless droplet size difference and viscosity ratio of two droplets is Cac =0.11 η-0.07ls-2.23ld0.16. 相似文献
83.
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85.
James?A.?KenarEmail author Gerhard?Knothe Robert?O.?Dunn Thomas?W.?RyanIII Andrew?Matheaus 《Journal of the American Oil Chemists' Society》2005,82(3):201-205
Carbonates are a class of compounds that have recently found increasing interest in commercial applications owing to their
physical properties and relatively straightforward synthesis. In this work, physical and fuel properties of five straight-chain
C17–39 and three branched C17–33 oleochemical carbonates were investigated. These properties included cetane number (CN), low-temperature properties, (kinematic)
viscosity, lubricity, and surface tension. The carbonates studied had CN ranging from 47 to 107 depending on carbon chain
length and branching. For the same number of carbons, the CN of carbonates were lower than those of FA alkyl esters owing
to interruption of the CH2 chain by the carbonate moiety. Kinematic viscosities at 40°C ranged from 4.9 to 22.6 mm2/s whereas m.p. ranged from +3 to below −50°C depending on the carbonate structure. High-frequency reciprocating rig testing
showed the neat carbonates to have acceptable lubricity that improved as chain length increased. Finally, the carbonate's
ability to influence cold-flow properties in biodiesel (methyl soyate) and lubricity in low-lubricity ultra-low sulfur diesel
were examined. The carbonates studied did not significantly affect cold flow or lubricity properties at concentrations up
to 10,000 ppm (1 wt%). The properties of the carbonates resemble those of fatty alkyl esters with similar trends resulting
from compound structure. 相似文献
86.
The library PRAND for pseudorandom number generation for modern CPUs and GPUs is presented. It contains both single-threaded and multi-threaded realizations of a number of modern and most reliable generators recently proposed and studied in Barash (2011), Matsumoto and Tishimura (1998), L’Ecuyer (1999,1999), Barash and Shchur (2006) and the efficient SIMD realizations proposed in Barash and Shchur (2011). One of the useful features for using PRAND in parallel simulations is the ability to initialize up to 1019 independent streams. Using massive parallelism of modern GPUs and SIMD parallelism of modern CPUs substantially improves performance of the generators. 相似文献
87.
《Expert systems with applications》2014,41(17):7878-7888
For monitoring online manufacturing processes, the proportion of weights imposed on each type of product’s defects (nonconformities or demerits) has a profoundly effective impact on control charts’ performance. Apparently, the demerit-chart approach is superior than the widely-used c-chart scheme, because it allows us to place relative precise weights (real numbers) on defects according to their distinctly inferior degrees affecting the product quality so that the abnormal variations of processes can be literally exposed. However, in many applications, the seriousness of defects is evaluated partially or entirely by the inspectors’ perceptive judgement or knowledge, so with the precise-weight assignment, the demerit rating mechanism is considered to be somewhat constrained and subjective which inevitably leads to the targeted manufacturing process with limited and possibly biased information for online surveillance. To cope with the drawback, a demerit-fuzzy rating system and monitoring scheme is proposed in this paper. We first incorporate fuzzy weights (fuzzy numbers) to properly reflect the severity measures of defects which are categorized linguistically. Then, based on properties of fuzzy set theory and proposed approaches for fuzzy-number ranking, we develop the demerit-fuzzy charting scheme which is capable of discriminating process conditions into multi-intermittent statuses between in-control and out-of-control. This approach improves the traditional process control techniques with the binary-classification restraint for the process conditions. Finally, the proposed demerit-fuzzy rating system, monitoring scheme, and classification is elucidated by an application in garment industry to monitor textile-stitching nonconformities conditions. 相似文献
88.
通过分析聚氯乙烯树脂中杂质粒子产生的主要原因,提出了在采购、保管、生产、清理、分析等环节的解决措施。 相似文献
89.
OCT-M技术生产清洁汽油的工业应用 总被引:1,自引:0,他引:1
石家庄炼油化工股份有限公司60万t/a OCT-M FCC汽油选择性加氢脱硫装置2005年3月首次开工,开工初期硫醇偏高,辛烷值损失较多.根据抚顺石油化工研究院的建议,优化了OCT-M装置的催化剂装填方案和操作工艺条件.2005年11月,在装置累计运转6个月之后,对OCT-M装置进行了满负荷标定,标定结果表明硫含量由606~676 μg/g降低到114~180 μg/g,RON损失0.4~0.6个单位.2006年11月,在装置累计运转17个月之后,对OCT-M装置又进行了一次标定,标定结果表明MIP汽油硫含量由417~442 μg/g降低到24~53 μg/g,RON损失0.7~1.8个单位,标定结果表明OCT-M技术可为我国炼厂生产硫含量≯150 μg/g)和硫含量≯50 μg/g的清洁汽油提供经济、灵活的技术方案. 相似文献
90.