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31.
《Chemical engineering science》1985,40(2):259-267
The terminal velocity of dense particles in an air-fine particle heterogeneous medium defines the upper operating limit of the gas velocity in the multisolid pneumatic transport bed reactor. The terminal velocity of dense particles in an air-fine particle medium was experimentally determined from the turbulent fluidized bed voidage vs air velocity relationship in this study. It was found that the terminal velocity of dense particles decreases with the increase of the fine particle flow rate. The fine particle and dense particle interaction coefficient was defined based on the momentum balance equation for a dense particle. The interaction coefficient was empirically correlated and utilized to account for the terminal velocity of dense particles in the air-fine particle heterogeneous medium. 相似文献
32.
《International Journal of Hydrogen Energy》2022,47(77):33000-33013
In this paper, the corrosion behavior of low alloy steel in H2S-saturated solution is systematically studied through immersion experiment in terms of microstructure morphology, corrosion kinetics, surface morphology, cross-sectional morphology, crystal characteristic and elemental distribution. The experimental results suggest that the corrosion rate decreased gradually with corrosion time. The corrosion products were immediately formed after the steel was immersed in corrosion solution and the structure and thickness became denser and thicker, which improved corrosion resistance. The corrosion products transformed from mackinawite, greigite and molybdenite to mackinawite, greigite, pyrrhotite and molybdenite. For the alloying elements, Cr and Mo tended to be accumulated in corrosion products compared with the steel substrate. A schematic model of corrosion process was proposed according to experimental results. 相似文献
33.
应用于油墨固化领域的UV固化灯常采用密集阵列排布的UV-LED模组作为高辐射高能量的光源,而高能量的UV固化灯对其散热器的结构设计提出很高的要求。本文结合数值模拟与实验,提出一种基于强制风冷的热管式散热器,通过理论计算证明该散热器结构的可行性,研究了300~1500 W功率下基板温度变化情况,对比分析了不同抽风量与散热片数量下热源基板温度变化情况,得出抽风量7 m^3/min、散热片数量为35片时散热效果最佳。实验所测结果与仿真结果误差为4%,证实了仿真结果的准确性,对大功率UV固化灯风冷散热器设计具有参考价值。 相似文献
34.
In the present investigation, a new design vortex flow meter with novel pressure detection chamber has been optimized and investigated numerically as well as experimentally. Instead of implementing the standard configuration with paddle for vortex detection, a pressure chamber of optimized size and position has been investigated, allowing much higher temperatures of the metered fluid. Whereas the standard design is limited to 240 °C, the new design allows temperature in access of 500 °C. The present paper describes the results of numerical simulation of the corresponding high temperature flow field. 相似文献
35.
《Thin》2014
Buckle propagation is an essential concern in offshore pipeline design. Once the propagation occurs, it may cause unavoidable failure of an entire pipeline. With the consideration of both longitudinal and hoop deformation behavior of pipeline, a ring-truss theory was analytically established in this study. Laboratory experiments were conducted in full-scale hyperbaric chamber in order to verify the analytical equation. It was observed that the length of transition zone has great influence on determination of propagation pressure. Due to the difficulties of measurement during test process, the length of transition zone was obtained using the finite element simulation. The comparison of propagation pressure between the current study and published model shows that for small diameter to thickness ratio, the ring-truss model is the one that is closest to the actual situation. 相似文献
36.
《Materials Letters》2003,57(16-17):2523-2529
In the present study, the diversified morphologies of Si phase and La-rich phase in as-casted hypereutectic Al–Si–xLa alloys are presented and investigated. The morphological features were examined using conventional optical microscopy and SEM for observations conducted on the optical samples and deep-etched samples, respectively. The results show that primary Si crystals show several morphologies, such as feathery, star-shaped, faceted polygonal, platelet and so on. There are three types of fivefolded Si crystals existing in the present study, fivefold symmetry as radial growth alone: thin-branched, coarse-branched and well-defined star-shaped growing from the preferred growth from the tips of branches. The eutectic Si in unmodified Al–Si alloys appears only in fibrous morphology, while discrete and interconnected coral and rodlike eutectic Si particles were observed in alloys with the addition of La. The La-rich phase also grows into a variety of morphologies, such as needlelike, broken rodlike in pores, spherical, and flat platelet. In optical microscopy, La-rich phase is observed to envelope some small polygonal Si crystals. 相似文献
37.
《Advanced Powder Technology》2020,31(6):2285-2292
To reduce the power consumption of a horizontal-vertical pneumatic conveying system, an oscillator is mounted with a 45° oblique plane through the pipe axis in this study. This experimental study focuses on the effect of oscillatory flow using the oscillator on the horizontal-vertical pneumatic conveying system in terms of the overall pressure drop of the system, power consumption, local pressure drop, and particle velocity. Compared with conventional pneumatic conveying (axial-flow), the pressure drop and power consumption can be reduced using the oscillatory flow in a lower air velocity range. Meanwhile, the particle axial velocity of the oscillatory flow is higher than that of the axial-flow near the bottom of pipe. This outcome indicates that the accelerating effect of oscillatory flow is obvious near the bottom of the pipe, and the particle vertical velocity of the oscillatory flow is positive, whereas the particle vertical velocity of the axial-flow is almost negative. This result shows that the particles of the oscillatory flow are suspended sufficiently, but the particles of the axial-flow have a tendency of deposition. Furthermore, the fluctuation intensity of the particle velocity of the oscillatory flow is higher than that of the axial-flow, especially near the bottom of the pipe. 相似文献
38.
Fei Yan PanPan Tu Xin Li Yun Chen Yan Zheng Rui Zhu 《Advanced Powder Technology》2021,32(5):1399-1409
The pneumatic system is frequently operated in the high air velocity region, which aggravates the power consumption and erosion of bend, and the dynamic analysis of particles in bends with different radius of curvature in a horizontal-vertical pneumatic conveying system is necessary. This experimental study focuses on the particle motion characteristic of bend on the horizontal-vertical pneumatic conveying in terms of on pressure drop, particle velocity, power spectral characteristics of particle fluctuation velocity, the energy distribution of the proper orthogonal decomposition (POD) modes, time coefficients of POD, and spatial mode of POD mode during flowing through bends. The results indicate that the particle rope is the large-scale motion of particles containing high energy, which dominates the motion of particles in the bend, and the suppression of small-scale motion leads to the low pressure drop in a large radius ratio of the bend. 相似文献
39.
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