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141.
The pressure variations during polymer flooding of oil reservoirs for oil recovery projects can be used to analyze the flow in the reservoir which is especially useful for the partially perforated reservoirs. This paper presents a relationship between the viscosity and the shear rate which is similar to forms developed for radial flow (Odeh, A. S., Yang, H. T. ([1979]). SPEJ. AIME (Jun.) 155). The power-law viscosity model is used to give the variation of the fluid viscosity with the spherical radius for a mathematical model of unsteady spherical flow for non-Newtonian fluids with wellbore storage and skin. An analytical solution for the wellbore pressure responses derived in Laplace space is used to analyze the behavior characteristics at early and later times to interpret the well-test parameters. The pressure variations are similar to those for a Newtonian fluid at the early times, but at later times, the variation of the viscosity with the power-law exponent is important, so the pressure response differs from that for a Newtonian fluid. The solution has significance for interpreting well test parameters for non-Newtonian spherical flow. 相似文献
142.
撞击流管式反应制备超细氧化锆粉体 总被引:6,自引:0,他引:6
我国氧化锆粉体产业目前基本上“精进粗出”,迫切需要开发氧化锆粉体备新工艺,特别是具有高附加值的纳米氧化锆粉体制备技术,液相反应沉淀法具有成本低,易于工业化等优点而成为研究的热点。本文采用撞击流管式反应新工艺,撞击流接触反应强化了过程的微观混合。实现了均匀成核,使得成核过程易于控制,而管式反应器的独特设计克服了返混,因而使得反应沉淀过程易于控制,粒子分布窄。用该工艺结合醇热处理表面改性制备的超细氧化锆粉体。平均粒径约为14nm,粒度分布窄并无硬团聚发生。该方法过程简单,易于工业化大生产。 相似文献
143.
144.
本文通过对偏转磁芯用的铁氧体材料的磁滞损耗特性的分析 ,提出了通过改变偏转磁芯外表面形状以减小磁滞损耗的方法。优化计算结果表明 ,对于Philips 17″CMT的 3C2材料 5mm壁厚的磁芯 ,改用椭圆外表面的磁芯后 ,磁滞损耗降低了 2 7 5 %。 相似文献
145.
李大为 《哈尔滨建筑大学学报》2002,35(3):92-95
9·11恐怖撞击事件,促使人们重新认识摩天大楼的安全性,由于这类建筑规模越大,其安全性受到的损害就越大,同时也带来其他方面的问题.因此,为减少灾害发生后的损失,必须控制其规模,确保摩天楼建设有序进行. 相似文献
146.
In this paper we propose a new method to extract the vortices, sources, and sinks from the dense motion field preliminary estimated between two images of a fluid video. This problem is essential in meteorology for instance to identify and track depressions or convective clouds in satellite images. The knowledge of such points allows in addition a compact representation of the flow which is very useful in both experimental and theoretical fluid mechanics. The method we propose here is based on an analytic representation of the flow. This approach has the advantage of being robust, simple, fast and requires few parameters. 相似文献
147.
148.
传统的火焰燃气炉往往会产生不同数量的氮氧化物(NO和NO2)、一氧化碳等不完全燃烧产物,造成了环境污染和能源浪费.催化燃烧作为一种新的燃烧方式,打破了传统火焰燃烧的可燃界限,实现了贫甲烷/空气混合物在可燃界限以下的燃烧,燃烧效率高,提高了能源利用率.将催化燃烧应用于燃气炉,可以解决燃气炉由于火焰燃烧带来的燃烧效率低等缺点,达到节约能源的目的.以催化燃烧和燃气炉为依据,在催化燃烧炉Ⅰ型的基础上研制出催化燃烧炉Ⅱ型,分析了催化燃烧炉的热损失以及热效率,并与传统火焰燃烧炉做了比较.结果表明,催化燃烧炉Ⅱ型的热损失并不大,热效率较高,且其污染物排放量极低. 相似文献
149.
R.A. Jacques J.G. Santos C. Dariva J. Vladimir Oliveira E.B. Caramo 《The Journal of Supercritical Fluids》2007,40(3):354-359
This work presents a study concerning the chemical characteristics and analytical separation process of the essential oil obtained from high-pressure carbon dioxide extraction of Ilex paraguariensis. The experiments were performed in a laboratory-scale unit in the temperature range of 20–40 °C, from 100 to 250 bar. A blend of the I. paraguariensis extracts was percolated through a preparative chromatographic column, containing silica gel, and successively eluted with 150 mL of each of the following solvents: hexane, toluene, dichloromethane, ethyl acetate, acetone and methanol. The raw extract and its fractions were analyzed by gas chromatography coupled to mass spectrometry detection (GC/MS). The fractionation procedure showed to be a good clean up technique due to the isolation of different classes of compounds in each fraction. Chromatographic analyses allowed the identification of caffeine, fatty acids and esters, phytol, squalene, Vitamin E, stigmasterol derivatives and saturated hydrocarbons. 相似文献
150.
Rates of ammonia (NH3) loss from a ryegrass sward measured using a system of small wind tunnels were compared with concurrent measurements made using a micrometeorological mass balance method. Measurements were made during two experiments within a circular plot (radius 10m) treated with urea at a rate of 200kgNha?1. In the first experiment, air speed through the tunnels was adjusted as necessary to maintain a value of approximately 1ms?1. This value differed on most occasions from the mean ambient wind speed which was measured at a height of 250mm and which ranged from 0.61 to 2.95ms?1. Rates of loss measured using the wind tunnels differed by a factor of between two and five from those measured using the mass balance method; there was no consistent pattern in the differences between the rates of loss. The total losses of NH3 measured during 15 days were equivalent to 49.1 and 30.2kg Nha?1 for the mass balance and wind tunnel methods, respectively. In the second experiment, air speed through the tunnels was adjusted as necessary to maintain a value as close as possible to the mean ambient wind speed measured at a height of 250mm. Rates of NH3 loss measured using the two methods did not differ significantly; total losses of NH3 during 17 days were equivalent to 96.9 and 101kg Nha?1 for the mass balance and wind tunnel methods, respectively. The difference between the findings of the two experiments could be attributed to the direct effect of air speed through the tunnels rather than to differences between ambient temperatures and those inside the tunnels. During and following periods of rain the rates of loss measured using the tunnels were up to six times greater than those observed with the mass balance method. Rates of loss measured by the two methods became similar again when the tunnels were moved following rain. The study demonstrates that enclosures can be designed and operated to provide reliable measurements of the rate of NH3 loss from grassland. Potential applications of the two methods are discussed. 相似文献