Particle Image Velocimetry (PIV) technique was employed to study experimentally gas-liquid two-phase flow in an aeration tank. In terms of the PIV principles, an algorithm of PIV based on the Fast Fourier Transforma...
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Particle Image Velocimetry (PIV) technique was employed to study experimentally gas-liquid two-phase flow in an aeration tank. In terms of the PIV principles, an algorithm of PIV based on the Fast Fourier Transformation (FFT) was worked out. The PIV program was developed and verified, and then was used to measure three kinds of states in the testing device. The program was also used to calculate and analyze the related parameters. The experimental data indicate that the bubbles in testing device have the longest resident time and stronger turbulent intensity for the gas-liquid two-phase flow in a special case (Case 3), resulting in great increase of the oxygen transferring speed and efficiency, whereby providing the basis for the selection design of aeration tank.
The photocatalytic performance of ZnO/ZnS hybrid nanocomposite was largely higher than that of the mere ZnO or ZnS nanoparticles,but the complicated procedure and misdistribution of final products limited its large-sc...
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The photocatalytic performance of ZnO/ZnS hybrid nanocomposite was largely higher than that of the mere ZnO or ZnS nanoparticles,but the complicated procedure and misdistribution of final products limited its large-scale *** exploration of a novel synthesis route of ZnO/ZnS hybrid photocatalysts with high catalytic performance is becoming a crucial step for the large-scale application of ZnO/ZnS hybrid photocatalytic *** and characterization of nanosized ZnO/ZnS hybrid photocatalysts were studied in this *** photocatalysts were obtained via microwavehydrothermal crystallization with the help of sodium *** products were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),particle size distribution(PSD),and Fourier transformed infrared spectroscopy(FT-IR).The results indicated that so-synthesized ZnO/ZnS samples consisted of the high pure cubic(sphalerite)ZnS and hexagonal ZnO nanocrystallines with a narrow particle size *** possible formation mechanisms of ZnO/ZnS nanocrystallines were mainly attributed to the superficially protective effect of *** photocatalytic experiments demonstrated that the ZnO/ZnS photocatalysts exhibited a higher catalytic activity for the degradation of acid fuchsine than other monocomponents.
A new tandem double-capillary tube refrigeration system for refrigerator-freezers is proposed. A capillary tube was added between the two evaporators in the fresh and frozen food storage chests to raise the evaporatio...
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Brownian dynamics simulation is conducted for a dilute surfactant solution under a steady uniaxial elongational flow. A new inter-cluster potential is used for the interaction among surfactant micelles to determine th...
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Brownian dynamics simulation is conducted for a dilute surfactant solution under a steady uniaxial elongational flow. A new inter-cluster potential is used for the interaction among surfactant micelles to determine the micellar network structures in the surfactant solution. The micellar network is successfully simulated. It is formed at low elongation rates and destroyed by high elongation rates. The computed elongational viscosities show elongation- thinning characteristics. The relationship between the elongational viscosities and the mierostructure of the surfactant solution is revealed.
In this paper, the statues and development trends of combustion research in internal combustion engines are discussed from several aspects. Some key issues in combustion of internal combustion engines are raised. The ...
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In this paper, the statues and development trends of combustion research in internal combustion engines are discussed from several aspects. Some key issues in combustion of internal combustion engines are raised. The combustion in internal combustion engines is a complex process with chemical reaction and energy conversion and there are still many aspects needed to be clarified, especially the chemical reaction mechanism and soot formation. Meanwhile, combustion diagnostic is playing an increasing role in the understanding of combustion. The motivation to deepen the research is the continuous requirement of high-efficiency and low-emission engines. Remarkable progress has been achieved in developing low-emission combustion concept like HCCI and low-temperature combustion. Alternative fuel engines become an important aspect in engine research and development. Advanced combustion technology combined with fuel control technology and after-treatment can realize the high-efficient and low-emission target.
The processing of interference fringe is the most important step in holographic interferometric technique. The interference fringe of mass diffusion were gathered and proposed, and 3 key steps in the process which red...
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The processing of interference fringe is the most important step in holographic interferometric technique. The interference fringe of mass diffusion were gathered and proposed, and 3 key steps in the process which reduce the precision mostly were improved in this paper. The improvements include the following steps: wavelet de-noise, frequency-domain wave filtering, phase unwrapping. The categories of noise were analyzed and some specific methods were used to reduce the noise. The improvements increased the precision greatly, and established a solid foundation for the using of laser holographic interferometric technique.
In present paper a turbulent mixing layer with the velocity ratio 4:1 which was produced by a special designed splitter plated placed in a vertical rectangular channel was experimentally investigated by PIV. The Reyno...
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In present paper a turbulent mixing layer with the velocity ratio 4:1 which was produced by a special designed splitter plated placed in a vertical rectangular channel was experimentally investigated by PIV. The Reynolds number based on the velocity difference of two steams and hydraulic diameter of the channel ranges from 4400-158400. It is found that the scale of coherent vortex structure increases with increasing the Reynolds number and then decreases with continuously increasing the Reynolds number. The injected bubble will delay or hinder the evolution of the coherent structures. Afterwards the statistical and instantaneous distributions of Reynolds stress, turbulent intensity, vorticity and swirling strength are obtained. The results show that all these turbulent parameters exist only in a very narrow conical region in the downstream of the mixing layer. The Reynolds stress and turbulent intensity first increase and then decrease with increasing the Reynolds number and decrease with the evolution of mixing layer, while vorticity and swirling strength increase with increasing the Reynolds number and decrease with the evolution of mixing layer.
An experimental study has been performed to investigate pool water instantaneous flash evaporation in a rectangle chamber. The water level was at 40 mm, 60 mm, 100 mm, 150 mm. Initial conditions of the liquid varied f...
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An experimental study has been performed to investigate pool water instantaneous flash evaporation in a rectangle chamber. The water level was at 40 mm, 60 mm, 100 mm, 150 mm. Initial conditions of the liquid varied from 55 to 88C temperature and 3 to 35C superheat. Visualization of the phenomenon using a CCD camera lets us firstly point out the influence of the initial conditions on the flashing phenomenon. The experimental results show that at a constant initial water temperature, the greater the superheat approaches, the more quickly the liquid temperature will decrease. At a constant superheat, the initial water temperature has little influence on the decrease rate of the water temperature. The higher the water level will be, the slower the water temperature will decrease as well as the higher the water temperature will be when the flashing is finished. Experimental study allows us to correlate the water temperature with the initial water temperature and the superheat while flashing is going.
In this paper, an experimental system for the measurement of mass diffusion coefficient using Michelson laser holographic Interferometry was designed and constructed. The experimental system include: the subsystem of ...
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In this paper, an experimental system for the measurement of mass diffusion coefficient using Michelson laser holographic Interferometry was designed and constructed. The experimental system include: the subsystem of Michelson interferometer, the diffusion cell for the mass diffusion of liquid-liquid, the subsystem of thermostatic water bath, the subsystem of image collecting and image processing. The mass diffusion coefficients of 0.33 molL-1 KCI solution with water at the temperature of 289.15 K were measured, and the result shows that the average of relative deviations is 1.30% compared with the literature values, and it verified the accuracy and reliability of the system. The mass diffusion coefficients of 0.1 molL-1 saccharose with water at 5 different temperature were measured, and the result shows that the biggest relative deviations is within 5% which verified the reliability of the system further.
The conversion of nitrogenous gas products during coal pyrolysis is investigated in a drop tube reactor. Four raw coals and two demineralized coals have been used for pyrolysis at 500°C, 700°C, 900°C an...
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The conversion of nitrogenous gas products during coal pyrolysis is investigated in a drop tube reactor. Four raw coals and two demineralized coals have been used for pyrolysis at 500°C, 700°C, 900°C and 1100°C. The results indicate that the yields of N 2 and NO precursors, such as HCN and NH 3 , increase with increasing temperature. Coal type has significant effect on the yield of nitrogenous gas products. For lower rank coal, the conversion of fuel nitrogen is higher. Majority of fuel nitrogen in high rank coals is built into condensed aromatic structures to form Char-N. The mineral matters in coal can promote the conversion of fuel nitrogen to N 2 , but they can also suppress the conversion of fuel nitrogen to HCN and NH 3 .
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