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71.
Asghar Mirzazadeh Ghanadi Amir Heydari Nasab Dariush Bastani Ali Akbar Seife Kordi 《Chemical Engineering Communications》2013,200(5):600-605
This article investigates the effect of nanoparticles on mass transfer in the liquid–liquid extraction for the chemical system of n-butanol–succinic acid–water. For this purpose, nanofluids containing various concentrations of ZnO, carbon nanotubes (CNT), and TiO2 nanoparticles in water, as base fluid, were prepared. To examine the flow mode effect on mass transfer rate, different fluid modes including dropping and jetting were employed in the process. Results show that mass transfer rate enhancement depends on the kinds and the concentration of nanoparticles and the modes of flow. It was observed that after adding nanoparticles, the mass transfer rate significantly increases up to two-fold for ZnO nanoparticles. Furthermore, the results indicate that under the circumstances in which the mass flow rate is high enough, the effect of nanoparticles on the mass transfer phenomenon is too slight. 相似文献
72.
S. A. Hashemi N. Hajialigol A. Fattahi K. Mazaheri R. Heydari 《Journal of Mechanical Science and Technology》2013,27(11):3505-3512
In this paper the effect of flame holder geometry on flame structure is studied. The obtained numerical results using realizable k-? and β-PDF models show a good agreement with experimental data. The results show that increasing in flame holder length decreases flame length and increases flame temperature. Additionally, it is observed that flame lengths decrease by increasing in flame holder radius and increase for larger radii. Furthermore in various radii, the flame temperature is higher for smaller flame lengths. It was found that behavior of flame structure is mainly affected by the mass flow rate of hot gases that come near the reactant by the recirculation zone. 相似文献
73.
In order to achieve a hydrogen economy, developing widespread hydrogen supply systems are vitally important. A large number of technological options exist and are still in development for hydrogen production, storage, distribution…, which cause various pathways for supplying hydrogen. Besides the technical factors, there are other effective parameters such as cost, operability, reliability, environmental impacts, safety and social implications that should be considered when assessing the different pathways as optimal and viable long-term alternatives. To aid this decision-making process, we have developed a generic optimization-based model for the long-range energy planning and design of future hydrogen supply systems. By applying Linear Dynamic Programming techniques, the model is capable of identifying optimal investment strategies and integrated supply system configurations from the many alternatives. Also, the environmental impacts of hydrogen supply system can be evaluated through scenario analysis. The features and capabilities of the model are illustrated through application to Iran as a case study. 相似文献
74.
Davoud Babakhani Meysam Soleymani 《International Communications in Heat and Mass Transfer》2009,36(9):969-977
This paper presents a new analytical solution of heat and mass transfer processes in a packed bed liquid desiccant dehumidifier based on the equilibrium humidity on the interface is assumed to be constant. In order to maintain the partial pressure difference on the interface, a high liquid desiccant flow rate is often applied in the practical absorber. Therefore, for a narrow range of operating conditions for practical dehumidification process, we can assume that the equilibrium humidity ratio on the interface is constant. The assumption of constant humidity ratio is applied in this paper for derivation of the analytical solution. The model and the analytical solution predictions were compared against a reliable set of experimental data available in the literature, with very good agreement. According to the Lewis definition in this present study, the Lewis number obtains 0.9. The effects of variables such as air and liquid desiccant flow rate, air temperature and humidity, desiccant temperature and concentration have been investigated on the condensation rate. The results present that design variables such as desiccant concentration, desiccant temperature, air flow rate, and air humidity ratio have the greatest impact on the performance of the dehumidifier. The liquid flow rate and the air temperature have not a significant effect. Furthermore, the effects of air and liquid desiccant flow rate have been reported on the humidity effectiveness of the column. 相似文献
75.
Ville Saarimaa Nuria Fuertes Dan Persson Tommy Zavalis Aaretti Kaleva Juha-Pekka Nikkanen Erkki Levänen Golrokh Heydari 《工业材料与腐蚀》2020,71(10):1619-1628
In this study, the local electrochemical activity of untreated and passivated (natural or chemical passivation) zinc specimens was observed during immersion in a 0.1-M NaCl solution. The localized anodic activity during the exposure, measured with the scanning vibrating electrode technique, was linked to zinc dissolution by the pitting corrosion mechanism. It was correlated to specific corrosion products characterized by Fourier transmission infrared (FTIR) microscopy. FTIR molecule maps were produced from individual pitting corrosion sites (100–200 µm in width). With argon ion beam milling and latest energy-dispersive X-ray spectroscopy (EDS) technology, element maps with a high spatial resolution (≪100 nm) were recorded from abrasion- and beam-sensitive corrosion products, showing a residual layer structure. This study demonstrates the capability of FTIR mapping, cross-section polishing, and state-of-the-art scanning electron microscopy imaging, and EDS element mapping to produce high-resolution elemental, molecular, and visual information about pitting corrosion mechanisms on a hot-dip galvanized steel sample. 相似文献
76.
Kun Guo Meysam Sharifzadeh Mirshekarloo Kui Yao Francis Eng Hock Tay 《Journal of the American Ceramic Society》2019,102(5):2370-2376
The structural evolution of lead-free piezoelectric bismuth sodium titanate (BNT) coatings with excess Bi derived from thermal spray process was investigated with transmission electron microscopy (TEM). Bi-rich composition was identified as the nucleation agent of the BNT perovskite phase, and fine-grained microstructure was obtained with more excess Bi. The Bi-rich composition of the perovskite phase crystallized from melt was BixNayTiO3 (0.5 ≤ X ≤ 0.55, 0.46 ≤ y ≤ 0.5). The crystallization of the Bi-rich BNT perovskite phase first from liquid precursor phase would result in continuous depletion of Bi composition in the residual amorphous phase, and thus Ti-rich amorphous phase in the as-deposited coating and sodium titanate secondary phase in the heat-treated coating formed in the composition without enough access Bi. The results and analyses suggest only appropriate compensation with adequate amount of excess Bi can realize single perovskite phase in thermal sprayed BNT-based coatings and hence the superior piezoelectric performance property. 相似文献
77.
ABSTRACTIn this paper, the size-dependent vibration and instability of nanoflow-conveying nanotubes with surface effects using nonlocal strain gradient theory (NSGT) are examined. Hence, based on Gurtin-Murdoch theory, the nonclassical governing equations are derived by extended Hamilton's principle. To study the small-size effects on the flow field, the Knudsen number is applied. Applying Galerkin's approach, the partial differential equations converted to ordinary differential equations. The effects of the main parameters like nonlocal and strain gradient parameters, length to diameter ratio, thickness, surface effects, Knudsen number and different boundary conditions on the eigenvalue and critical fluid velocity of the nanotube are explained. 相似文献
78.
Ebadi Amirali Toutouni Reihaneh Farshchi Heydari Mohammad Javad Fathipour Morteza Soltani Madjid 《Microsystem Technologies》2019,25(10):3703-3711
Microsystem Technologies - In this work, we report on the design and implementation of a new method for the two dimensional (2D) simulation of rigid spherical particles trajectory which are to be... 相似文献
79.
Azim Heydari Davide Astiaso Garcia Farshid Keynia Fabio Bisegna Livio De Santoli 《Energy Sources, Part B: Economics, Planning, and Policy》2019,14(10-12):341-358
ABSTRACTThis paper proposes a novel hybrid strategy based on intelligent approaches to forecast electricity consumptions. The proposed forecasting strategy includes three main steps: (a) the evaluation of a correlation coefficient for socio-economic indicators on electric energy consumptions, (b) the classification of historical and socio-economic indicators using the proposed feature selection method, (c) the development of a new combined method using Adaptive Neuro-Fuzzy Inference System and Whale Optimization Algorithm to predict electrical energy consumptions. The simulation results have been tested and validated by real data sets achieved within 1992 and 2010 in two pilot cases in a developing country (Iran) and a developed one (Italy). The research findings pinpointed the greater accuracy and stability of the new developed method for electrical energy consumption forecasting compared to existing single and hybrid benchmark models. 相似文献
80.
Heydari P. Pedram M. 《IEEE transactions on circuits and systems. I, Regular papers》2006,53(4):879-891
This paper presents a spectrally weighted balanced truncation (SBT) technique for tightly coupled integrated circuit interconnects, when the interconnect circuit parameters change as a result of statistical variations in the manufacturing process. The salient features of this algorithm are the inclusion of the parameter variation in the RLCK interconnect, the guaranteed passivity of the reduced transfer function, and the availability of provable spectrally weighted error bounds for the reduced-order system. This paper shows that the variational balanced truncation technique produces reduced systems that accurately follow the time- and frequency-domain responses of the original system when variations in the circuit parameters are taken into consideration. Experimental results show that the new variational SBT attains, in average, 30% more accuracy than the variational Krylov-subspace-based model-order reduction techniques. 相似文献