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    Quantitative analysis of irreversibilities causes voltage drop in fuel cell (simulation & modeling)

    , Article Electrochimica Acta ; Volume 50, Issue 2-3 SPEC. ISS , 2004 , Pages 699-704 ; 00134686 (ISSN) Ghadamian, H ; Saboohi, Y ; Sharif University of Technology
    2004
    Abstract
    Power level of a fuel cell depends on its operating condition, which is product of voltage and current-density the highest level of voltage is identified as reversible open circuit voltage (ROCV), which represents an ideal theoretical case [J. Larmin, A. Dicks, Fuel Cell System Explained, Willy, 2000 (ISBN)]. Compared to that is ideal operating voltage which is usually characterized as open circuit voltage (OCV) [J. Larmin, A. Dicks, Fuel Cell System Explained, Willy, 2000 (ISBN)]. An evaluation of deviation of operating voltage level from ideal operational case may provide information on the extent of improving efficiency and energy efficiency of a fuel cell. Therefore, quantification of... 

    Rapid synthesis of hydroxyapatite nanopowders by a microwave-assisted combustion method

    , Article Journal of Ceramic Processing Research ; Volume 13, Issue 3 , Jan , 2012 , Pages 221-225 ; 12299162 (ISSN) Bovand, N ; Rasouli, S ; Mohammadi, M. R ; Bovand, D ; Sharif University of Technology
    2012
    Abstract
    Nano bioactive hydroxyapatite (Ca 10(PO 4) 6(OH) 2, HAp) ceramic powders have been synthesized by a microwave-assisted combustion method. The powders were synthesized using calcium nitrate tetrahydrate (as the source of calcium) and sodium phosphate dibasic anhydrous (as the source of phosphate ions). Glycine, citric acid and urea were used as fuesl. The influence of the fuel type on the structure and morphology of the samples was studied. Results by X-ray diffraction and Fourier-transform infrared spectroscopy showed the formation of hydroxyapatite as a major phase for all the samples. Using the Scherrer formula, the average crystallite size was found to be in the range of 10 to 28 nm.... 

    Total fuel reduction via formation flights: a new approach to air-corridor path optimization

    , Article AIAA AVIATION 2014 -14th AIAA Aviation Technology, Integration, and Operations Conference ; 2014 Asadi, F ; Malaek, S. M. B ; Sharif University of Technology
    Abstract
    This paper presents a new approach to better utilize international air-corridors for formation flights. Using Particle Swarm Optimization, we show how different long-range flights can be brought together to form a formation. The idea serves both to increase international air-corridor capacities together and to decrease fuel consumption up to 8-10%. Case studies show that there are many places which such an approach could effectively be implemented to help cope with increase in fuel price as well as the demand for aerial transport of passengers and goods  

    Investigation the Effect of Process Parameters on the Synthesis of Nanometric Yttrium Aluminum Garnet Powder via Sol-Gel Combustion Method

    , M.Sc. Thesis Sharif University of Technology Zareh, Arezoo (Author) ; Maddah Hosseini, Hamid Reza (Supervisor) ; Nemati, Ziarat Ali (Supervisor)
    Abstract
    Yttrium Aluminum Garnet powders possessing controlled size distribution has found applications in production of transparent ceramics, phosphors, laser host materials and composites. Sol-Gel Combustion process is one of the versatile methods to produce nanometeric garnet powders. This procedure is based on combustion of a concentrated gel of metal salts and fuel in an exothermic reaction which leads to nanoparticles formation. pH value of solution and employed fuel system strongly affect production quality and single phase nanopowder can be synthesized by well monitoring these parameters. In this study nanocrystalline Yttrium Aluminum Garnet powders was Synthesized via sol-gel combustion... 

    Application of coupled lattice boltzmann and Phase-field methods for multiphase flow simulations

    , Article ASME 2013 Heat Transfer Summer Conf. Collocated with the ASME 2013 7th Int. Conf. on Energy Sustainability and the ASME 2013 11th Int. Conf. on Fuel Cell Science, Engineering and Technology, HT 2013 ; 2013 ; ISBN: 9780791855492 Premnath, K. N ; Patil, D. V ; Banerjee, S ; Sharif University Of Technology
    Abstract
    Coupling of lattice Boltzmann (LB) and phase-field (PF) methods is discussed for simulation of a range of multiphase flow problems. The local relaxation and shifting operators make the LB method an attractive candidate for the simulation of the single-phase as well as multiphase flows. For simulating interface dynamics, LB methods require to be coupled with an appropriate scheme representing interfacial dynamics. To this end, we have used a model based on the order parameter, which could be either an index function or a phase-field variable, and coupled it with a LB solver for the simulation of various classes of complex multi-physics and multiphase flows. The LB method is used to compute... 

    Secondary organic aerosol formation from untreated exhaust of gasoline four-stroke motorcycles

    , Article Urban Climate ; 2021 , Volume 36 ; 22120955 (ISSN) Esmaeilirad, S ; Setyan, A ; Wang, J ; Hosseini, V ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    This study investigates the secondary organic aerosol (SOA) formation potential of carburetor motorcycles exhaust. This type of two-wheeler is a popular means of transport in many Asian cities. A volatility-based numerical model was employed to predict SOA formation from a fleet of motorcycles in Tehran, capital of Iran. The fleet was a combination of four-stroke, gasoline-powered motorcycles with different engine displacement volumes. Total hydrocarbon (THC) emission factors of all motorcycles were previously measured in a chassis dynamometer laboratory according to cold start Euro-3 emissions certification test procedures. Due to incomplete combustion and lack of control on exhaust... 

    Hydrogen distribution in refinery with non-linear programming

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 18, Issue 2 , 2005 , Pages 165-176 ; 1728-144X (ISSN) Shahraki, F ; Kashi, E ; Rashtchian, D ; Sharif University of Technology
    Materials and Energy Research Center  2005
    Abstract
    Growth of the world population, increasing demand for fossil fuel consumption and consequently increasing threat of global warming, has extended the need for production and use of clean fuels and normal hydrogen is an important utility in the production of clean fuels. In this paper, a mathematical optimization method is applied which is based on non-linear programming of superstructure for minimizing the consumption of hydrogen. The method considers all the pressure constraints and is suited for revamping industrial systems. The optimum placement of new equipments like purification unit has been also considered. It is tried to verify the method adopted, in addition, an industrial case study... 

    PWR fuel management optimization using neural networks

    , Article Annals of Nuclear Energy ; Volume 29, Issue 1 , 2002 , Pages 41-51 ; 03064549 (ISSN) Sadighi, M ; Setayeshi, S ; Salehi, A. A ; Sharif University of Technology
    2002
    Abstract
    This paper presents a new method to solve the problem of finding the best configuration of fuel assemblies in a pressurized water reactor (PWR) core. Finding the optimum solution requires a huge amount of calculations in classical methods. It has been shown that the application of continuous Hopfield neural network accompanied by simulated annealing method to this problem not only reduces the amount of calculations, but also guarantees finding the best solution. In this study flattening of neutron flux inside the reactor core of Bushehr NPP is considered as the objective function. The result is the optimum configuration which is in agreement with the pattern proposed by the designer. © 2001... 

    Metal hydrides show potential under stress

    , Article Metal Powder Report ; Volume 64, Issue 7 , 2009 , Pages 24-26,28 ; 00260657 (ISSN) Simchi, H ; Kaflou, A ; Simchi, A ; Sharif University of Technology
    2009
    Abstract
    Work carried out in Iran seems to indicate that nanostructured materials may hold a key to fuel storage in a future hydrogen economy.... © 2009 Elsevier Ltd. All rights reserved  

    Corrigendum to “Investigation of fuel dilution in ethanol spray MILD combustion” [Appl. Therm. Eng. 159 (2019) 113898] (Applied Thermal Engineering (2019) 159, (S1359431118371308), (10.1016/j.applthermaleng.2019.113898))

    , Article Applied Thermal Engineering ; Volume 180 , November , 2020 Karimi Motaalegh Mahalegi, H ; Mardani, A ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The authors regret to inform that the corresponding author is altered from Hamed Karimi Motaalegh Mahalegi to Amir Mardani with the email address of: Amardani@sharif.edu updated as above. The authors would like to apologise for any inconvenience caused. © 2020 Elsevier Ltd  

    Evaluating the effect of using different sets of enrichment for FAs on fuel management optimization using CA

    , Article Annals of Nuclear Energy ; Volume 38, Issue 4 , 2011 , Pages 835-845 ; 03064549 (ISSN) Moghaddam, N. M ; Fadaei, A. H ; Zahedi, E ; Sharif University of Technology
    Abstract
    In nuclear reactor core design, achieving the optimized arrangement of fuel assemblies (FAs) is the most important step towards satisfying safety and economic requirements. In most studies, nuclear fuel optimizations have been performed by using a finite number of different types of FAs. However the effect of FA numbers with different enrichments and the difference between their maximum and minimum enrichment values can be important and should be evaluated in the optimization process. This research is aimed at evaluating the effect of using different enrichment values for FAs. This issue has been investigated by focusing on two parameters, namely, the initially selected enrichment and the... 

    Geometrical optimization of parallel infinitely variable transmission to decrease vehicle fuel consumption

    , Article Mechanics Based Design of Structures and Machines ; Vol. 42, Issue. 4 , 2014 , Pages 483-501 ; ISSN: 15397734 Delkhosh, M ; Foumani, M. S ; Boroushaki, M ; Sharif University of Technology
    Abstract
    One solution to reduce fuel consumption (FC) of vehicles is to use infinitely variable transmission (IVT) as the power train. However, inappropriate design of IVT leads to an inadequate decrease in the vehicle FC. Therefore, in order to reach a maximum fuel economy, an optimization on the power train proves to be necessary. The present article aims to optimize IVT to decrease the vehicle FC in a driving cycle. The results have revealed that the FC of the vehicle equipped with the optimized IVT is approximately 7% and 4.7% compared to the cases of using the optimized six-speed and nine-speed manual transmissions, respectively  

    Neutronic analysis of HPLWR fuel assembly cluster

    , Article Annals of Nuclear Energy ; Volume 50 , December , 2012 , Pages 38-43 ; 03064549 (ISSN) Tashakor, S ; Salehi, A. A ; Jahanfarnia, G ; Abbaspour Tehrani Fard, A ; Sharif University of Technology
    2012
    Abstract
    In the present study the neutronic analysis of fuel assembly cluster of the HPLWR is discussed. Neutronic calculations are performed using WIMS-D4 and CITATION codes. Thermal-hydraulic code containing the properties and specifications of the fuel assembly of HPLWR is utilized. The calculated axial power in each selected control volume is used in the thermal-hydraulic code to get the properties of the fluid and fuel needed for further neutronic analysis. The process of coupling continues until convergence is achieved. Finally, the obtained neutronic results including axial power distribution, neutron flux, and power peaking factors are discussed in the present article  

    Calculation of fuel burn up and radioactive inventory for HEU fuel element of Tehran Research Reactor

    , Article International Conference on Nuclear Engineering, Proceedings, ICONE, 17 May 2010 through 21 May 2010 ; Volume 2 , 2010 ; 9780791849309 (ISBN) Hosseini, S. A ; Vosoughi, N ; Hosseini, M ; Nuclear Engineering Division ; Sharif University of Technology
    Abstract
    This paper presents a new approach for fuel burn up evaluation and radioactive inventory calculation used in Tehran Research Reactor. The approach is essentially based upon the utilization of a program written by C# which integrates the cell and core calculation codes, i.e., WIMSD-4 and CITVAP, respectively. Calculation of fuel burn up and radioactive inventories has been done for 26 core configuration of Tehran Research Reactor with HEU fuel element. The present inventory and fuel enrichment of each fuel element have been calculated  

    Design, Construction and Analysis of Fuel Cell and Battery Hybrid Power System Based on Optimal Power Strategy

    , M.Sc. Thesis Sharif University of Technology Ghodsian, Nasser (Author) ; Roshandel, Ramin (Supervisor)
    Abstract
    Focusing on fossil fuel to secure energy demand lead to big challenges. Hydrogen as alternative for fossil fuel has attracted a lot of attentions. Fuel cell with an electrochemical reaction which it’s byproducts are water and heat convert Hydrogen into electricity. High efficiency and low environmental pollution, persuade many researchers toward fuel cell commercialization. But problems such as high cost, high power oscillation and inertia, avoid fuel cell from significant development. One way to deal with these problems is using the fuel cell and battery hybrid system. In recent decade too many research has been made in utilizing this hybrid system in transportation. This project... 

    An experimental study on combustion dynamics and NOx emission of a swirl stabilized combustor with secondary fuel injection

    , Article Journal of Thermal Science and Technology ; 2010 , Pages 266-281 ; 18805566 (ISSN) Riaz, R ; Farshchi, M ; Shimura, M ; Tanahashi, M ; Miyauchi, T ; Sharif University of Technology
    2010
    Abstract
    To investigate the effects of flow rate, diameter and offset of secondary fuel injection on combustor noise level, pressure fluctuation and NOx emission, four types of injectors were examined in a swirl-stabilized combustor for overall equivalence ratio (Ø) of 0.7 ~ 0.9 and flow rate of secondary fuel (Qsec) from 0.6 to 4.2 L/min. As for the reference injector used in previous related studies, secondary fuel injection of 3.0 L/min is the best condition for the reduction of pressure fluctuation and combustion noise with tolerable NOx emission. For lower secondary fuel rate of 1.8 L/min, reduction of the injection diameter of reference injector results in a better performance in terms of... 

    Use of technology mapping in identification of fuel cell sub-technologies

    , Article International Journal of Hydrogen Energy ; Volume 35, Issue 17 , 2010 , Pages 9516-9525 ; 03603199 (ISSN) Arasti, M. R ; Bagheri Moghaddam, N ; Sharif University of Technology
    2010
    Abstract
    Technology Identification involves developing a list of technologies which are, or may be, incorporated into products or processes. After reviewing Technology Assessment, Technology Strategy, Management of Technology and New Product Development in literature, four methods of Technology Identification are investigated: Value Chain of Technologies, Process-based Approach, Quality Function Deployment and Technology Mapping. A model facilitating decision making process is then proposed by which the most appropriate method to be employed is identified. The proposed model is examined in specific case of fuel cell technologies while preparing the Fuel cell Development Strategic Plan of Iran. 1... 

    Modeling of pressure line behavior of a common rail diesel engine due to injection and fuel variation

    , Article Journal of the Brazilian Society of Mechanical Sciences and Engineering ; Volume 39, Issue 3 , 2017 , Pages 661-669 ; 16785878 (ISSN) Mohebbi, M ; Aziz, A. A ; Hamidi, A ; Hajialimohammadi, A ; Hosseini, V ; Sharif University of Technology
    Springer Verlag  2017
    Abstract
    Common rail diesel engines with electronic fuel injection can accurately meter the fuel injection quantity with more accurate fuel injection control capability. In this work a common rail fuel injection system of a single cylinder diesel engine has been proposed and the important parameters like injection pressure, energizing time and high pressure pipes diameter and length are designed such that to be compatible with the engine basic design in case of pressure waves and injected mass variations. A one-dimensional approach has been used to model the injector using AMESim code in which Adiabatic models have been used to model injector system. Injected mass quantity has been calculated for... 

    Experimental study of fuel regression rate in an HTPB/N2O hybrid rocket motor

    , Article Scientia Iranica ; Volume 25, Issue 1 , 2018 , Pages 253-265 ; 10263098 (ISSN) Rezaei, H ; Soltani, M. R ; Mohammadi, A. R ; Sharif University of Technology
    Sharif University of Technology  2018
    Abstract
    The performance of an HTPB/N2O hybrid motor was experimentally investigated. A hybrid motor was designed and manufactured in a laboratory with the purpose of studying the effects of various parameters on the motor's performance, including fuel regression rate and specific impulse. A series of tests were conducted to find a correlation between the fuel regression rate and the oxidizer's mass flux. The effects of chamber's pressure on the regression rate as well as other performance parameters were investigated. While the burning rate did not change dramatically, both the efficiency and ISP of the motor increased. The local fuel regression rate and the fuel port were also calculated. In... 

    Development of a 3-D multigroup program for Dancoff factor calculation

    , Article Annals of Nuclear Energy ; Volume 36, Issue 10 , 2009 , Pages 1486-1497 ; 03064549 (ISSN) Zahedinejad, E ; Vosoughi, N ; Sohrabpour, M ; Sharif University of Technology
    2009
    Abstract
    Several parameters, one of which is the Dancoff Factor (DF), are used to calculate the resonance integral (RI) and reduced flux in the resonance region of heterogeneous systems as well as to accurately determine the group constants for criticality calculations. This paper is a report on the development of a program to calculate the DF correction factor using Monte Carlo method and collision probability definition in three-dimensional (3-D) geometries and with multi energy groups. Hence, the DF for any arbitrary arrangement of cylindrical and slab fuel elements is hereby calculated. The fuel elements are monitored and kept at equal levels, though different material compositions and formations...