In Part I [Wei et al., 2004, 2004 ASME Int. Mech. Eng. Conference], we presented the experimental results for swirling flows of water and cetyltrimethyl ammonium chloride (CTAC) surfactant solution in a cylindrical ve...
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The swirling flows of water and CTAC (cetyltrimethyl ammonium chloride) surfactant solutions (50-1000 ppm) in an open cylindrical container with a rotating disc at the bottom were experimentally investigated by use of...
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The liquid kinematic viscosity of the binary mixtures of methanol and castor oil are reported over the temperature range from 243~353 K made with a calibrated Ubbelohde-type capillary viscometer. The total experimenta...
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The liquid kinematic viscosity of the binary mixtures of methanol and castor oil are reported over the temperature range from 243~353 K made with a calibrated Ubbelohde-type capillary viscometer. The total experimental uncertainty is less than 1.06%. In addition, the results were correlated as a function of temperature as the kinematic viscosity equation of the binary mixtures. The absolute average deviation and the maximum deviation of the experimental results from the correlated equation are 1.11% and 3.31%, respectively.
Synthesis of solid solution ZnS-CuInS2 has been demonstrated. The crystallinity and stability of catalysts were highly improved by the combination of two usual ways used for improving the crystallinity of materials-ca...
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Synthesis of solid solution ZnS-CuInS2 has been demonstrated. The crystallinity and stability of catalysts were highly improved by the combination of two usual ways used for improving the crystallinity of materials-calcination at high temperature or hydrothermal, so was the activity of photocatalytic splitting water for hydrogen production. The catalysts were characterized by XRD, BET, SEM, XRF and UV-Vis. The results of the photocatalytic hydrogen production showed that the catalyst had the highest stability and activity by H2S inflowing to the metal cation solution following with calcination and hydrothermal. After the catalyst was loaded with 3% Pt, the velocity of hydrogen production has been further improved to 127 μmol/h. And its apparent quantum efficiency at 420 nm was up to 4.43%.
The periodically fully developed laminar heat transfer and fluid flow in a two-dimensional wavy channel in a compact heat exchanger are investigated numerically. Calculations are performed at Pr = 0.7, in the range of...
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The periodically fully developed laminar heat transfer and fluid flow in a two-dimensional wavy channel in a compact heat exchanger are investigated numerically. Calculations are performed at Pr = 0.7, in the range of Re = 100-1100 with non-orthogonal non-staggered grids. The Semi-Implicit Method for Pressure Linked Equations Revised (SIMPLER) algorithm in the curvilinear body-fitted coordinates is used. The effect of the wavy height and distance on momentum and heat transfer is studied. Performance of model parameters is evaluated. It is shown that the overall Nusselt numbers and friction factors increase with the increase of Reynolds numbers. The friction factors and overall Nusselt numbers increase as increasing the wavy height or decreasing the wavy distance. The overall Nusselt numbers increase significantly with the wavy height, especially at high Reynolds numbers. The best wavy height and distance are 1.15 mm and 13 mm, respectively.
The structural properties of CdS thin films obtained by ultrasonic spray pyrolysis at different substrate temperature were studied by X-ray diffraction (XRD), scan electron microscope (SEM), Raman spectrum and Uv-vis ...
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The structural properties of CdS thin films obtained by ultrasonic spray pyrolysis at different substrate temperature were studied by X-ray diffraction (XRD), scan electron microscope (SEM), Raman spectrum and Uv-vis absorption spectrum. The experimental results show that the crystallinity level gets higher with increasing substrate temperature while the bandgap remains constant. This deposition method should be an effective method as the deposited film looks uniform and smooth in the SEM image. Furthermore, the photoelectrochemical activities of CdS thin films used as electrode to split water to hydrogen and oxygen were investigated. The photoelectrochemical activity increases and then decreases with increasing substrate temperature which forms a peak value at 300 °C . Under a light intensity of 187 mW/cm, the electrode deposited at 300 °C gives a saturated photocurrent of 4.1 mA/cm with increasing electrode potential. The highest energy conversion efficiency was calculated as 0.68% at electrode potential of -0.13 V (vs SCE).
Orthogonal array tests were carried out to investigate the optimal temperature(T), hydraulic retention time (HRT), pH and C/N ratio of anaerobic fermentative hydrogen production using a 20 L continuous stirred-tank re...
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Orthogonal array tests were carried out to investigate the optimal temperature(T), hydraulic retention time (HRT), pH and C/N ratio of anaerobic fermentative hydrogen production using a 20 L continuous stirred-tank reactor (CSTR). The results showed that hydrogen production rate, hydrogen content, glucose utilization ratio and hydrogen yield reached the maximum of 6.00 L/h, 55.0%, 99.0%, 157.86 mL/g in appropriate conditions, respectively. The optimal pH, T, HRT and C/N ratio were 5.0, 33.5-36.5 °C, 8.34 h, 112/1.55, respectively. A confirmation experiment was carried out to verify the optimal parameters obtained by orthogonal array tests. Hydrogen production rate, hydrogen content, glucose utilization ratio and potential hydrogen yield reached the maximum of 5.66 L/h, 54.0%, 0.97, 191.18 mL/g, respectively. The results of the confirmation experiment showed that hydrogen production with the optimal parameters was more efficient than that in the orthogonal array tests, and that suggested the orthogonal array tests were successful.
As an important performance diagnosis tool, in-situ measurement of current distribution in PEM fuel cells is helpful for better understanding of internal transport phenomena and optimization of fuel cell structures an...
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As an important performance diagnosis tool, in-situ measurement of current distribution in PEM fuel cells is helpful for better understanding of internal transport phenomena and optimization of fuel cell structures and operating parameters. With a specially developed current distribution measurement gasket, the effects of reactant gas flow rates on the current distribution in a PEM fuel cell with single serpentine flowfield were investigated. Experimental results show that insufficient hydrogen or air leads to decreased current density along the gas flow direction. Higher reactant gas flow rate favors not only the local performance but also the homogeneity of current distribution. But current distribution almost ceases to change with further increase of hydrogen flow rate when it reaches certain value.
The velocities of liquid slugs in continuous slug flow were studied experimentally in a 133 m long horizontal pipeline. Measurements were performed by cross-correlating the signals of two pairs of probes installed alo...
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The velocities of liquid slugs in continuous slug flow were studied experimentally in a 133 m long horizontal pipeline. Measurements were performed by cross-correlating the signals of two pairs of probes installed along the pipeline. Correlations of liquid slug velocities with the mixed velocities are presented. It is found that the correlations depend on Froude numbers. At low Froude numbers, the correlation from the measurements of the upstream probes is consistent with that from the measurements of the downstream probes and both correlations agree well with the results of other researchers. But there is difference between the correlation of the upstream probes and that of the downstream probes at high Froude numbers. Compared with the experimental data of other researchers, it is expected that the velocities of liquid slugs are affected by the void fraction in liquid slugs and the evolution of the lengths of liquid slugs and elongated bubbles along pipeline. However, the wake effect may have no influence on the liquid slug velocities.
Cadmium sulfide photocatalyst was prepared by hydrothermal methods with one-step and two-step methods, respectively. Platinum was loaded on the surface of prepared photocatalysts and its optimal loading amount was exa...
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Cadmium sulfide photocatalyst was prepared by hydrothermal methods with one-step and two-step methods, respectively. Platinum was loaded on the surface of prepared photocatalysts and its optimal loading amount was examined. All the prepared photocatalysts were characterized by XRD, UV-Vis, XRF, SEM and TEM and their pohtocatalytic activity was evaluated by H2 evolution from water under visible light. It was found that the photocatalyst prepared by two-step showed markedly improved hydrogen production activity.
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