Search for: fuels
0.009 seconds
Total 725 records

    Two-stage thermocatalytic upgrading of fuel oil to olefins and fuels over a nanoporous hierarchical acidic catalyst

    , Article Petroleum Science and Technology ; Volume 37, Issue 16 , 2019 , Pages 1910-1916 ; 10916466 (ISSN) Ghashghaee, M ; Shirvani, S ; Ghambarian, M ; Eidi, A ; Sharif University of Technology
    Taylor and Francis Inc  2019
    A two-stage thermocatalytic upgrading process using a novel catalyst was investigated to produce light olefins and liquid fuels from fuel oil. The upgraded oil from the first thermal stage demonstrated lower viscosity and higher crackability compared to the virgin feedstock. In the next step, the vapor-phase catalytic cracking of the upgraded fraction was implemented over a novel nanoporous composite catalyst, characterized by the XRD, FTIR, NH3- TPD, and N2 physisorption techniques. In total, more than 55 wt% of light olefins, particularly propylene (25.5 wt%) together with 25.4 wt% and 32.5 wt% of gasoline and diesel fuel were obtained in this process. © 2019, © 2019 Taylor & Francis... 

    Electrocatalytic oxidation of ethanol on flexible three-dimensional interconnected nickel/gold composite foams in alkaline media

    , Article Electroanalysis ; Volume 31, Issue 3 , 2019 , Pages 504-511 ; 10400397 (ISSN) Hatamie, A ; Rezvani, E ; Sedighian Rasouli, A ; Simchi, A. R ; Sharif University of Technology
    Wiley-VCH Verlag  2019
    In this work, a porous and flexible three-dimensional (3D) nickel/gold nanoparticle electrode (NiF/AuNPs) is presented as an efficient electrocatalyst for ethanol oxidation in alkaline media. The 3D nanocomposite electrode consists of interconnected porous nickel foam (NiF) with large pores (500±200 μm diameter) surrounded by interconnected struts (∼100 μm) that are decorated with gold nanoparticles (AuNPs, 37±8 nm) through in-situ electrochemical deposition. The catalytic performance of the 3D electrode was evaluated by different electrochemical methods. An enhancement in the performance (about 253 %) and a remarkable decline in onset potential (about ∼0.63 V) in comparison with pristine... 

    High temperature proton exchange membrane fuel cells: Advantages and technical challenges

    , Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 Amjadi, M ; Rowshanzamir, S ; Eikani, M. H ; Sedghid, S ; Peighambardoust, S. J ; Sharif University of Technology
    High temperature proton exchange membrane fuel cells (HT-PEMFC) are polymeric fuel cells that can operate at 120°-200°C). Preparation of new heat-resistant HT-PEMFC materials, e.g., membrane and electrodes, is the most challenging problem for these kinds of fuel cells. A discussion covers the benefits of HT-PEMFC; challenges in developing novel materials for membranes preparation; polymeric membranes of HT-PEMFC; improvement of high temperature membranes; high temperature membranes characteristics and types; and importance of electrodes porosity for HT-PEMFC. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech... 

    Exergetic optimization of a PEM fuel cell for domestic hot water heater

    , Article Journal of Fuel Cell Science and Technology ; Volume 2, Issue 4 , 2005 , Pages 284-289 ; 1550624X (ISSN) Saidi, M. H ; Abbassi, A ; Ehyaei, M ; Sharif University of Technology
    In this paper, a 5 kW PEM fuel cell including burner, steam reformer, and water heater for domestic application has been considered. Water is used for cooling of the fuel cell. Cold water is passed through a cooling channel, warmed up and used for domestic water heating. To increase the efficiency, outlet steam of fuel cell is fed to the reformer. The perfomance of the system is optimized by exergy analysis based on the second law of thermodynamics. Also, the effect of burner, fuel cell temperature and stoichiometric air fuel ratio are investigated. In this analysis, pressure loss in the fuel cell and heat transfer of the cooling channel are taken into account whereas, pressure loss in... 

    Optimized cooling system for pem fuel cell stack based on entropy generation minimization

    , Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 97-103 ; 0791841731 (ISBN); 9780791841730 (ISBN) Saidi, M. H ; Mozafari, A. A ; Sharifian, L ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    Cell temperature in fuel cells is an important parameter which highly affects fuel cell stack efficiency. A suitable cooling system should satisfy an acceptable temperature range. In this research a relevant cooling system for a specified PEM fuel cell stack has been proposed complying with the criteria and cooling requirements of the fuel cell. The effect of various parameters on the entropy generation and temperature distribution in the cooling plates are surveyed. The number of cooling plates, the number of channels in each cooling plate and the channel width is determined. Two flow regimes namely laminar and turbulent flows of the cooling fluid in channels are analyzed and a design... 

    Transient modeling of dual fuel catalytic converter

    , Article Iranian Journal of Science and Technology, Transaction B: Technology ; Volume 27, Issue 2 , 2003 , Pages 291-298 ; 03601307 (ISSN) Sallamie, N ; Kazemeini, M ; Badakhshan, A ; Soltanieh, M ; Estiri, M ; Sharif University of Technology
    Exhaust gas emissions from mobile sources and its importance in urban pollution have currently attracted lots of interests towards studying on alternative fuel systems for road vehicles usage. One of the best replacements is the natural gas/diesel dual fuel, which offers an alternative to standard compression-ignition diesel engines. In the dual fuel system the primary fuel is natural gas, which may replace as much as 90% of the diesel fuel with a small amount of diesel fuel required ensuring effective ignition. Methane, the main constituent of natural gas, has high combustion efficiency. Dual fuel engines produce lower NOx emissions and fewer particulates. However, at moderate engine loads,... 

    Neutron flux flattening in PWRs using neural networks in fuel management

    , Article IEEE Transactions on Nuclear Science ; Volume 49 IV, Issue 3 , 2002 , Pages 1574-1578 ; 00189499 (ISSN) Sadighi, M ; Setayeshi, S ; Salehi, A. A ; Sharif University of Technology
    The Hopfield network is studied from the standpoint of taking it as a computational model in optimizing the fuel management of pressurized water reactors (PWRs). In this paper, the flattening of the neutron flux is considered as the objective function. By this consideration, the power peaking inside the reactor core is also minimized. Regarding the local minimum problem of Hopfield network, the simulated annealing method is applied to improve the Hopfield solution. The method is applied to Bushehr Nuclear Power Plant (PWR design) and the result is compared with the core configuration purposed by the designer  

    Piloted ignition of solid fuels in turbulent back-step flows

    , Article Aerospace Science and Technology ; Volume 18, Issue 1 , 2012 , Pages 8-14 ; 12709638 (ISSN) Tahsini, A. M ; Sharif University of Technology
    Piloted ignition of solid fuels in dump combustor geometry subject to an igniter hot jet plume is numerically investigated. The objective of this work is to gain insight into the fuel ignition and subsequent flame spreading in this turbulent flow configuration. Conjugate heat transfer between gas and solid phases is considered to study the solid fuel heating and evaporation process; Solid phase energy equation is simultaneously solved coupled with flow governing equations. Finite rate one step second order chemistry is used in simulations. The gas phase equations along with the Spalart-Allmaras turbulence model are solved with a finite volume approach in which the AUSM + scheme is used to... 

    Application of minimum plutonium criteria at EOC to optimize the fuel loading pattern in VVER-1000 reactors

    , Article Annals of Nuclear Energy ; Volume 35, Issue 2 , 2008 , Pages 269-276 ; 03064549 (ISSN) Mohseni, N ; Boroushaki, M ; Ghofrani, M. B ; Raji, M. H ; Sharif University of Technology
    Most of the strategies yet implemented to optimal fuel loading pattern design in nuclear power reactors, are based on maximizing the core effective multiplication factor (Keff) to extract maximum energy and lowering the local power peaking factor (Pq) from a predetermined value. However, a new optimization criterion could be of interest, aiming at maximum burn-up of the plutonium content in fuel assemblies, i.e., minimization of remaining plutonium in spent fuel at the end of cycle (EOC). In this research, we developed a new strategy for optimal fuel core loading pattern of a VVER-1000 reactor, based on multi-objective optimization: lowering the Pq, maximization of the Keff and minimization... 

    A new strategy for optimal fuel core loading pattern design in PWR nuclear power reactors

    , Article Joint International Topical Meeting on Mathematics and Computations and Supercomputing in Nuclear Applications, M and C + SNA 2007, Monterey, CA, 15 April 2007 through 19 April 2007 ; 2007 ; 0894480596 (ISBN); 9780894480591 (ISBN) Mohseni, N ; Boroushaki, M ; Ghofrani, M. B ; Raji, M. H ; Sharif University of Technology
    Most of the strategies yet implemented to optimize fuel loading pattern design in the nuclear power reactors, are based on maximizing the core effective multiplication factor (Keff) in order to extract maximum energy and to reduce the local power peaking factor (Pq) from a set value. However, a new optimization criterion would be of interest in order to maximize the burn-up of the plutonium content (Pu) in the fuel assemblies. In this research we have developed a new strategy based on multi objective optimization, to optimize fuel core loading pattern for a VVER-1000 reactor. In this approach we simultaneously have reduced the Pq, maximized Keff and also minimized the plutonium content in... 

    A sequential approach for hybridizing conventional vehicles and an approval example

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Esfahanian, M ; Khanipour, A ; Nabi, A ; Fazeli, A. M ; Amiri, M ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    Hybridization of conventional vehicles is considered an important step to achieve high fuel economy and low emissions. In this study, principle considerations involved in a hybridizing process are discussed and consequently, a sequential approach for designing hybrid components for both series and parallel configurations has been introduced. The so called approach has then been applied to one of the productions of Iran-Khodro Company called SAMAND. Having designed the hybrid components, the conventional SAMAND and its series and parallel hybrid configurations were defined and evaluated using the ADvanced VehIcle SimulatOR (ADVISOR) software. It is observed that compared to the conventional... 

    Optimization of the pem fuel cell cooling system by entropy generation minimization

    , Article 3rd International Conference on Fuel Cell Science, Engineering, and Technology, 2005, Ypsilanti, MI, 23 May 2005 through 25 May 2005 ; 2005 , Pages 441-448 ; 0791837645 (ISBN); 9780791837641 (ISBN) Sharifian, L ; Saidi, M. H ; Sharif University of Technology
    American Society of Mechanical Engineers  2005
    Cooling system is essential for high power fuel cells to maintain cells temperature in an acceptable limit. In this paper a suitable cooling system for the PEM fuel cell has been designed and optimized. The design includes the number of the cooling plates, the proper circuit of the cooling channels in the plates, the channel dimensions, the flow rate of the cooling fluid and its temperature. The optimization technique is minimization of the entropy generation through the cooling plates. The design of the cooling channels and plates is such that the plate temperature doesn't exceed from a desired temperature and the temperature variation in the plate becomes minimized. In this design, the... 

    Effects of catalyst loading gradient in catalyst layers on performance of polymer electrolyte membrane fuel cells

    , Article Renewable Energy ; Volume 50 , February , 2013 , Pages 921-931 ; 09601481 (ISSN) Roshandel, R ; Ahmadi, F ; Sharif University of Technology
    In this paper, numerical and analytical approaches are presented to evaluate the effect of catalyst loading gradient in the catalyst layer (CL) of a polymer electrolyte membrane (PEM) fuel cell. The model is developed based on agglomerate catalyst and accounts for reactant spices and charge (ion and electron) transport in the cathode side of a PEM fuel cell. The special variation of catalyst loading is considered in two direction, "across the layer" from membrane/CL interface to gas diffusion layer (GDL) and "in catalyst plane" under the channels and land areas in the channel direction. A fuel cell test stand is designed and built to facilitate experimental validation of the model. The... 

    Exergy, economic, and environmental analysis of a PEM fuel cell power system to meet electrical and thermal energy needs of residential buildings

    , Article Journal of Fuel Cell Science and Technology ; Volume 9, Issue 5 , 2012 ; 1550624X (ISSN) Ashari, G. R ; Ehyaei, M. A ; Mozafari, A ; Atabi, F ; Hajidavalloo, E ; Shalbaf, S ; Sharif University of Technology
    ASME  2012
    In this paper, a Polymer Electrolyte Membrane (PEM) fuel cell power system including burner, steam reformer, heat exchanger, and water heater has been considered. A PEM fuel cell system is designed to meet the electrical, domestic hot water, heating, and cooling loads of a residential building located in Tehran. Operating conditions of the system with consideration of the electricity cost has been studied. The cost includes social cost of the environmental pollutants (e.g. CO 2, CO and NO). The results show that the maximum energy needs of the building can be met by 12 fuel cell stacks with nominal capacity of 8.5 kW. Annual average electricity cost of thissystem is equal to 0.39 US$/kWh and... 

    Development of a VVER-1000 core loading pattern optimization program based on perturbation theory

    , Article Annals of Nuclear Energy ; Volume 39, Issue 1 , 2012 , Pages 35-41 ; 03064549 (ISSN) Hosseini, M ; Vosoughi, N ; Sharif University of Technology
    In-core nuclear fuel management is one of the most important concerns in the design of nuclear reactors. Two main goals in core fuel loading pattern design optimization are maximizing the core effective multiplication factor in order to extract the maximum energy, and keeping the local power peaking factor lower than a predetermined value to maintain the fuel integrity. Because of the numerous possible patterns of fuel assemblies in the reactor core, finding the best configuration is so important and challenging. Different techniques for optimization of fuel loading pattern in the reactor core have been introduced by now. In this study, a software is programmed in C# language to find an... 

    Economic assessment of hydrogen fueling station, a case study for Iran

    , Article Renewable Energy ; Volume 33, Issue 12 , 2008 , Pages 2525-2531 ; 09601481 (ISSN) Qadrdan, M ; Shayegan, J ; Sharif University of Technology
    In recent years there have been many efforts to develop a hydrogen energy system in Iran. For instance, the Iranian fuel cell steering committee conducted a project and determined some targets to implement hydrogen in different sectors, especially transportation. In this paper, the costs of building stations and the levelized cost of hydrogen for two types of stations, SMR and electrolysis, with various sizes and capacity factors have been investigated. Also, in the case of electrolysis, hydrogen cost sensitivity to the price of electricity has been examined. According to the cost analysis conducted here, it is understandable that hydrogen costs ($/kg) vary considerably based on station... 

    Strategies for utilizing alternative fuels by Iranian passenger cars

    , Article International Journal of Environmental Science and Technology ; Volume 3, Issue 1 , 2006 , Pages 59-68 ; 17351472 (ISSN) Rassafi, A. A ; Vaziri, M ; Azadani, A. N ; Sharif University of Technology
    CEERS  2006
    The current paper is an attempt to find a sustainable fuel strategy for passenger cars in Iran. Currently, most of Iran's passenger cars consume gasoline, a non-renewable fossil fuel. This fuel has well-known environmental impacts, including various kinds of pollutions, as well as the threat of quick running out. These general negative characteristics of gasoline are amplified by the high consumption rate of Iran's transportation sector, (e.g. about three times more than that of UK). The objective of this paper is firstly selecting possible alternative fuels for Iran's transportation sector, and then proposing the percent of cars consuming these alternative fuels (along with gasoline). The... 

    Effect of casting solvent on the characteristics of nafion/TiO2 nanocomposite membranes for microbial fuel cell application

    , Article International Journal of Hydrogen Energy ; Volume 41, Issue 1 , 2016 , Pages 476-482 ; 03603199 (ISSN) Bazrgar Bajestani, M ; Mousavi, S. A ; Sharif University of Technology
    Elsevier Ltd  2016
    Synthesis and characterization of Nafion/TiO2 membranes (TiO2 1 wt%) with different solvents (DMF, DMAc, NMP) for proton exchange membrane operating at Microbial Fuel Cell (MFC) was investigated in this study. Nanocomposite membranes are studied due to their better physical properties and higher production voltage in comparison with Nafion 112 in MFC systems. Nafion/TiO2 nanocomposite membranes were prepared by solution casting Method. The structures of membranes were investigated by Scanning Electron Microscopy (SEM). In addition, water uptake, proton conductivity, and ion exchange capacity (IEC) of membranes were measured and compared with Nafion 112 in microbial fuel cell. The... 

    Theoretical and experimental modeling of vortex engine in ramjet application

    , Article 45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, 2 August 2009 through 5 August 2009, Denver, CO ; 2009 ; 9781563479762 (ISBN) Besharat Shafiei, S ; Ghafourian, A ; Saidi, M. H ; Mozafari, A. A ; Sharif University of Technology
    A new experimental facility was designed, fabricated and tested to model and study the possibility of applying the bidirectional swirl flow on the combustion chamber of airbreathing subsonic ramjet engine. Appropriate intake was designed to convert axial external air to tangential swirl flow inside the combustion chamber. Inlets with appropriate angles conduct the swirl flow into the chamber and create bidirectional swirl flow field in the combustion chamber. This flow field has been modeled theoretically to determine the velocity field characteristics by previous researchers. Bidirectional swirl flow in liquid fuel ramjet engines has the proven advantage of keeping the combustion chamber... 

    Long term performance degradation analysis and optimization of anode supported solid oxide fuel cell stacks

    , Article Energy Conversion and Management ; Volume 133 , 2017 , Pages 20-30 ; 01968904 (ISSN) Parhizkar, T ; Roshandel, R ; Sharif University of Technology
    Elsevier Ltd  2017
    The main objective of this work is minimizing the cost of electricity of solid oxide fuel cell stacks by decelerating degradation mechanisms rate in long term operation for stationary power generation applications. The degradation mechanisms in solid oxide fuel cells are caused by microstructural changes, reactions between lanthanum strontium manganite and electrolyte, poisoning by chromium, carburization on nickel particles, formation of nickel sulfide, nickel coarsening, nickel oxidation, loss of conductivity and crack formation in the electrolyte. The rate of degradation mechanisms depends on the cell operating conditions (cell voltage and fuel utilization). In this study, the degradation...