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991.
Muhammad Abid Tahir A.H. Ratlamwala Ugur Atikol 《International Journal of Hydrogen Energy》2017,42(33):21429-21442
In this comparative study, a parabolic trough solar collector and a parabolic dish solar collector integrated separately with a Rankine cycle and an electrolyzer are analyzed for power as well as hydrogen production. The absorption fluids used in the solar collectors are Al2O3 and Fe2O3 based nanofluids and molten salts of LiCl–RbCl and NaNO3–KNO3. The ambient temperature, inlet temperature, solar irradiance and percentage of nanoparticles are varied to investigate their effects on heat rate and net power produced, the outlet temperature of the solar receiver, overall energy and exergy efficiencies and the rate of hydrogen produced. The results obtained show that the net power produced by the parabolic dish assisted thermal power plant is higher (2.48 kW–8.17 kW) in comparison to parabolic trough (1 kW–6.23 kW). It is observed that both aluminum oxide (Al2O3) and ferric oxide (Fe2O3) based nanofluids have better overall performance and generate higher net power as compared to the molten salts. An increase in inlet temperature is observed to decrease the hydrogen production rate. The rate of hydrogen production is found to be higher using nanofluids as solar absorbers. The hydrogen production rate for parabolic dish thermal power plant and parabolic trough thermal power plant varies from 0.0098 g/s to 0.0322 g/s and from 0.00395 g/s to 0.02454 g/s, respectively. 相似文献
992.
Seetharamulu Podila Hafedh Driss Sharif F. Zaman Arshid M. Ali Abdulrahim A. Al-Zahrani Muhammad A. Daous Lachezar A. Petrov 《International Journal of Hydrogen Energy》2017,42(38):24213-24221
This work deals with the effect of catalyst preparation method of the mixed Co, Mg and La oxide catalysts on their structure and catalytic properties for ammonia decomposition. Two methods are used for catalysts preparations impregnation and co-precipitation (in air and in pure O2 atmosphere), The Mg/La = 2 molar ratio and 5 wt% of cobalt content was maintained same in all catalysts. The catalyst performance was evaluated in the temperature range 300–550 °C at atmospheric pressure. The prepared catalysts were characterized by BET, XRD, TPR, XPS, CO2-TPD and SEM techniques. No pronounced differences were observed in BET among the catalysts. It was found that the 5CML-OXY (5 wt%Co over MgLa catalyst prepared by co-precipitation method in oxygen atmosphere) has superior activity among the other catalysts. This could be attributed to availability of easily reducible cobalt species determined by TPR studies and enhanced interaction between Mg and La determined by SEM and XPS. The moderate basic site density determined by CO2-TPD results was also increased in 5CML–OXY catalysts compared with other catalysts. These consequences are might be one of the reasons for enhanced activity of 5CML–OXY catalyst compared to other catalysts. Hence catalyst preparation by co-precipitation in oxygen atmosphere is the best method which might be one of the parameters that influenced on catalytic properties of the cobalt on MgOLa2O3 system, for ammonia decomposition. 相似文献
993.
994.
A systematic model is presented for a free expansion polymer foaming process that includes simultaneous nucleation and bubble growth. An influence volume approach, which couples nucleation and bubble growth, is used to account for the limited supply of dissolved gas. The melt rheology is described using the Larson viscoelastic model. The initial conditions are obtained at the upper bound of critical cluster size under conditions of elastic deformation. The resulting set of equations are solved using a combination of numerical techniques. A parametric study is conducted to examine the effects of key process variables on bubble growth, nucleation, and final bubble size distribution. It shows that the factors influencing nucleation and growth affect the ultimate bubble sizes and their distribution. The Gibbs number, a dimensionless measure of the barrier to overcome for nucleation, has the strongest impact on the cellular structure of the foam. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1353–1368, 1998 相似文献
995.
996.
Modelling of simultaneous methanogenesis and denitrification in an upflow packed-bed biofilm reactor
Muhammad Arshad S. Chaudhry Shafkat A. Beg 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1997,70(3):267-277
The performance of an upflow packed-bed biofilm reactor was investigated by considering simultaneous methanogenesis and denitrification reactions under step and sinusoidal variations of feed concentration and temperature. For simultaneous step inputs of 20 mg dm−3 of NO3−—N and 60 mg dm−3 of methanol, the proposed model shows that major conversion of both the substrates takes place in the first half of the reactor. However, when the inlet concentration of methanol is subjected to sinusoidal variation, while that of NO3−—N is maintained stepwise, the exit concentration of both methanol and NO3−—N follow a sinusoidal response. On the other hand, when the inputs are reversed (methanol stepwise and NO3−—N sinusoidal), the response exhibits similar behaviour. For sinusoidal variation of feed temperature the exit concentration profiles of both substrates also follow a sinusoidal pattern. For methanol, the mean steady state conversion under sinusoidal variation is higher than the corresponding steady state concentration when feed temperature is constant at 30°C. The model predictions are in good agreement with the experimental data available in the literature. ©1997 SCI 相似文献
997.
Khalid Hussain Afsheen Aman Asad Ullah Muhammad Qamar Khan Asma Ansari 《Water and Environment Journal》2024,38(1):108-120
Wastewater generated by textile industry needs to be treated to reduce its toxicity before final disposal and/or for recycling purposes. In the current study, several bacterial strains were screened for dye decolorization potential. UV–visible spectroscopy was used to determine maximum absorption wavelength of disperse dyes. HPLC and MTS assay were used to confirm the degradation and detoxification of disperse dyes, respectively. Results revealed that indigenously isolated Bacillus licheniformis, Glutamicibacter uratoxydans and Pseudomonas aeruginosa showed strong decolorization of red, blue and violet, respectively in 6–9 h. MTS assay revealed 100% viability of NIH/3T3 cell lines in presence of treated dyes. Enzyme screening assay confirmed the production of intracellular and membrane bound oxidoreductases in presence of specific dye as substrate. To resolve this issue, bacterial consortia were prepared, and better decolorization of all dyes was achieved in synergistic behaviour of Consortia 1 and 4 with 85% and 88% decolorization potential, respectively. 相似文献
998.
C S Cheow S Y Yu N K Howell Y Che Man Karidah Muhammad 《Journal of the science of food and agriculture》1999,79(6):879-885
Light microscopy studies on the fish cracker gel and expanded product (‘keropok’) emphasised the role of fish proteins in the starch expansion process. The addition of salt (20 g kg−1) in the ‘keropok’ helped to distribute evenly the starch in the fish protein. Formation of thin fish muscle bundles assisted the expansion of ‘keropok’. At 700–900 g kg−1 fish content, the fish muscle bundles formed a continuous network that caused a drop in the ‘keropok’ expansion. From the scanning electron microscopy study, ridges were found in samples (containing 600–900 g kg−1 fish content) with 20 g kg−1 salt at high magnification. © 1999 Society of Chemical Industry 相似文献
999.
Yunhai Zhao Shuo Chen Muhammad Ishaq Michel Cathelinaud Chang Yan Hongli Ma Ping Fan Xianghua Zhang Zhenghua Su Guangxing Liang 《Advanced functional materials》2024,34(8):2311992
The double gradient bandgap absorber has the potential to enhance carrier collection, improve light collection efficiency, and make the performance of solar cells more competitive. However, achieving the double gradient bandgap structure is challenging due to the comparable diffusion rates of cations during high-temperature selenization in kesterite Cu2ZnSn(S,Se)4 (CZTSSe) films. Here, it has successfully achieved a double gradient bandgap in the CZTSSe absorber by spin-coating the K2S solution during the preparation process of the precursor film. The K2S insertion serves as an additional S source for the absorber, and the high-affinity energy of K-Se causes the position of the spin-coated K2S solution locally Se-rich and S-poor. More importantly, the position of the bandgap minimum (notch) and the depth of the notch can be controlled by varying the concentration of K2S solution and its deposition stage, thereby avoiding the electronic potential barrier produced by an inadvertent notch position and depth. In addition, the K─Se liquid phase expedites the selenization process to the elimination of the fine grain layer. The champion CZTSSe device achieved an efficiency of 13.70%, indicating the potential of double gradient bandgap engineering for the future development of high-efficiency kesterite solar cells. 相似文献
1000.
Weiyuan Duan Gilbert Mains Habtamu Tsegaye Gebrewold Karsten Bittkau Andreas Lambertz Binbin Xu Volker Lauterbach Alexander Eberst Nathan Nicholson Lars Korte Muhammad Ainul Yaqin Kai Zhang Qing Yang Uwe Rau Kaining Ding 《Advanced functional materials》2024,34(3):2310552
An intrinsic hydrogenated amorphous silicon (a-Si:H(i)) film and a doped silicon film are usually combined in the heterojunction contacts of silicon heterojunction (SHJ) solar cells. In this work, a post-doping process called catalytic doping (Cat-doping) on a-Si:H(i) is performed on the electron selective side of SHJ solar cells, which enables a device architecture that eliminates the additional deposition of the doped silicon layer. Thus, a single phosphorus Cat-doping layer combines the functions of two other layers by enabling excellent interface passivation and high carrier selectivity. The overall thinner layer on the window side results in higher spectral response at short wavelengths, leading to an improved short-circuit current density of 40.31 mA cm−2 and an efficiency of 23.65% (certified). The cell efficiency is currently limited by sputter damage from the subsequent transparent conductive oxide fabrication and low carrier activation in the a-Si:H(i) with Cat-doping. Numerical device simulations show that the a-Si:H(i) with Cat-doping can provide sufficient field effect passivation even at lower active carrier concentrations compared to the as-deposited doped layer, due to the lower defect density. 相似文献