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Total 113 records

    Conceptual design of a 5 MW OTEC power plant in the Oman Sea

    , Article Journal of Marine Engineering and Technology ; Volume 16, Issue 2 , 2017 , Pages 94-102 ; 20464177 (ISSN) Hamedi, A. S ; Sadeghzadeh, S ; Sharif University of Technology
    Taylor and Francis Ltd  2017
    Abstract
    Developing ocean energy extraction, including ocean thermal energy conversion (OTEC), has been of interest to researchers for many decades. OTEC is a free fuel technology and could be used as a baseline power generation. These advantages plus the engineering challenge have resulted in researchers striving to design and construct prototype devices. Making use of worldwide experience, all sections of a conceptual design including site selection, technical specifications and cost estimation were carried out for an Iranian OTEC power plant. A 5 MW closed cycle floating plant with an annual average temperature difference of 22°C was chosen at a 33 km distance from Chabahar harbour. Deep seawater... 

    Design algorithm evaluation of swirler-injector systems in liquid-burning combustion chambers

    , Article 7th International Conference on Fluid Flow, Heat and Mass Transfer, FFHMT 2020, 15 November 2020 through 17 November 2020 ; 2020 , Pages 194-1-194-10 Mousemi, A ; Mosadegh, S ; Khademi, A ; Sorrentino, G ; Sharif University of Technology
    Avestia Publishing  2020
    Abstract
    Liquid-burning combustion chambers have a wide range of applications in propulsion systems and energy conversion processes. The growing need for reliable and low-NOx combustion systems highlights the role of high-performance burners, where the main design criticalities are related to injectors and swirlers. In the current study, an algorithm for coupling the design procedure of pressure-swirl injectors and axial swirlers is introduced. Also, this algorithm emphasizes the interrelation between the design parameters of these two components via employing the length of the recirculation zone as the coupling parameter for building a relationship between the design characteristics of the injector... 

    Impulsive waves caused by subaerial landslides

    , Article Environmental Fluid Mechanics ; Volume 8, Issue 3 , 2008 , Pages 263-280 ; 15677419 (ISSN) Ataie Ashtiani, B ; Nik Khah, A ; Sharif University of Technology
    2008
    Abstract
    This paper presents the experimental results of impulsive waves caused by subaerial landslides. A wide range of effective parameters are considered and studied by performing 120 laboratory tests. Considered slide masses are both rigid and deformable. The effects of bed slope angle, water depth, slide impact velocity, geometry, shape and deformation on impulse wave characteristics have been inspected. The impulse wave features such as amplitude, period and also energy conversation are studied. The effects of slide Froude number and deformation on energy conversation from slide into wave are also investigated. Based on laboratory measured data an empirical equation for impulse wave amplitude... 

    PIDEC Batteries Simulation Accompany with Comparative Study of Key Parameters on its Efficiency

    , M.Sc. Thesis Sharif University of Technology Mirhadi, Hosna Sadat (Author) ; Moshkbar Bakhshayesh, Khalil (Supervisor) ; Mohtashami, Soroush (Co-Supervisor)
    Abstract
    Nuclear batteries have been attractive since the beginning of the twentieth century due to their longer life in comparison with other types of batteries. These batteries are produced in different types with different efficiencies depending on the method used to convert their energy. In this study, due to the lack of the resources in the country to study the types of nuclear batteries, first we did an overview of the classification and operation of different types of nuclear batteries, especially on the latest type of nuclear batteries, PIDEC, that has not been studied in the country so far. The most important feature of a PIDEC is that it has an intermediate stage to transmit the maximum... 

    Wind energy conversion system based on DFIG with open switch fault tolerant six-legs AC-DC-AC converter

    , Article Proceedings of the IEEE International Conference on Industrial Technology, Cape Town ; February , 2013 , Pages 1656-1661 ; 9781467345699 (ISBN) Shahbazi, M ; Zolghadri, M. R ; Poure, P ; Saadate, S ; The Institute of Electrical and Electronics Engineers (IEEE); IEEE Industrial Electronics Society (IES); IEEE Technology Management Council; IEEE Region 8; IEEE South Africa Section IE/IA/PEL Joint Chapter ; Sharif University of Technology
    2013
    Abstract
    Continuity of service of wind energy conversion systems as well as their reliability and performances are some of the major concerns in this power generation area. Six-legs AC/DC/AC converters are normally used in modern wind energy systems like as in the system with a doubly-fed induction generator (DFIG). A sudden failure of the converter can lead to the total or partial loss of the control of the phase currents and can cause serious system malfunction or shutdown. Therefore, to prevent the spread of the fault to the other system components and to ensure continuity of service, fault tolerant converter topologies associated to quick and effective fault detection and compensation methods... 

    Spare parts management algorithm for wind farms using structural reliability model and production estimation

    , Article IET Renewable Power Generation ; Volume 10, Issue 7 , Volume 10, Issue 7 , 2016 , Pages 1041-1047 ; 17521416 (ISSN) Mani, S ; Oraee, A ; Oraee, H ; Sharif University of Technology
    Institution of Engineering and Technology 
    Abstract
    Doubly fed induction generators (DFIGs) are widely used in wind power systems; hence their reliability model is an important consideration for production assessment and economic analysis of wind energy conversion systems. However, to date mutual influences of reliability analysis, production estimations and economic assessments of wind farms have not been fully investigated. This study proposes a reliability model for DFIG wind turbines considering their subcomponent failure rates and downtimes. The proposed production estimation algorithm leads to an economic assessment for wind farms. A comprehensive spare parts management procedure is then presented in the study. As a case study,... 

    Laboratory investigations on impulsive waves caused by underwater landslide

    , Article Coastal Engineering ; Volume 55, Issue 12 , December , 2008 , Pages 989-1004 ; 03783839 (ISSN) Ataie Ashtiani, B ; Najafi Jilani, A ; Sharif University of Technology
    2008
    Abstract
    Laboratory investigations have been performed on the submarine landslide generated waves by performing 120 laboratory tests. Both rigid and deforming-slide masses are considered. The effects of bed slope angle, initial submergence, slide geometry, shape and deformation on impulse wave characteristics have been inspected. Impulse wave amplitude, period, energy and nonlinearity are studied in this work. The effects of bed slope angle on energy conversion from slide into wave are also investigated. Laboratory-based prediction equations are presented for impulse wave amplitude and period in near and far-field and are successfully verified using the available data in previous laboratory and... 

    Urchin-like hierarchical ruthenium cobalt oxide nanosheets on Ti3C2T: XMXene as a binder-free bifunctional electrode for overall water splitting and supercapacitors

    , Article Nanoscale ; Volume 14, Issue 4 , 2022 , Pages 1347-1362 ; 20403364 (ISSN) Asen, P ; Esfandiar, A ; Mehdipour, H ; Sharif University of Technology
    Royal Society of Chemistry  2022
    Abstract
    Synthesizing efficient electrode materials for water splitting and supercapacitors is essential for developing clean electrochemical energy conversion/storage devices. In the present work, we report the construction of a ruthenium cobalt oxide (RuCo2O4)/Ti3C2Tx MXene hybrid by electrophoretic deposition of Ti3C2Tx MXene on nickel foam (NF) followed by RuCo2O4 nanostructure growth through an electrodeposition process. Owing to the strong interactions between RuCo2O4 and Ti3C2Tx sheets, which are verified by density functional theory (DFT)-based simulations, RuCo2O4/Ti3C2Tx MXene@NF can serve as a bifunctional electrode for both water splitting and supercapacitor applications. This electrode... 

    Simulation of Plasma Gasification and Power Generation Based on Solid Waste

    , M.Sc. Thesis Sharif University of Technology Ghandi Falizani, Mehdi (Author) ; Saboohi, Yadollah (Supervisor)
    Abstract
    Along with the development of social and economical development and expansion of urban areas the rate of municipal solid waste (MSW) generation has been increased. Waste-to-Energy technologies consist of any waste treatment process that enables generating energy from a waste source. In recent years many studies have shown that plasma gasification has a considerable potential as an effective method for solid waste treatment and energy recovery. Plasma gasification converts MSW to a clean syngas and its application could reduce MSW volume and the environmental risks of waste landfill. In the present study the methods of waste conversion to energy has been reviewed, then plasma gasification of... 

    Acousto-refrigerator with an adjustable mechanical resonator

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 21, Issue 2 , 2008 , Pages 183-196 ; 1728-144X (ISSN) Amjadi, A ; Abolhassani, M. R ; Jafari, S. B ; Sharif University of Technology
    Materials and Energy Research Center  2008
    Abstract
    Thermoacoustics describes energy conversion processes, activated by interaction temperature oscillation, accompanying the pressure oscillation in a sound wave, with solid boundaries. In ordinary experience this interaction of sound and heat cannot be observed, because of the very low temperature differences, but under suitable conditions, it can be emphasized and amplified to create remarkable thermodynamic effects such as, steep thermal gradients, powerful convective heat fluxes, and strong sound fields. We designed and constructed a simple thermoacoustic refrigerator with an adjustable mechanical resonator, coupled with the acoustic resonator. Our experimental data showed about % 10... 

    Five-leg converter topology for wind energy conversion system with doubly fed induction generator

    , Article Renewable Energy ; Volume 36, Issue 11 , 2011 , Pages 3187-3194 ; 09601481 (ISSN) Shahbazi, M ; Poure, P ; Saadate, S ; Zolghadri, M. R ; Sharif University of Technology
    Abstract
    In this paper, application of a five-leg converter in Doubly Fed Induction Generator (DFIG) for Wind Energy Conversion Systems (WECS) is investigated. The five-leg structure and its PWM control are studied and performances are compared with the classical six-leg topology. The main drawback of five-leg converter with respect to the six-leg back-to-back converter is the need to increase the dc-link voltage for the same operation point, i.e. the same powers in case of WECS. So, different methods for the reduction of the required dc-link voltage in the five-leg case are studied. The five-leg converter is used to replace the conventional six-leg one, with the same ability. For the performance... 

    Optimal Design of Induction MHD Generator for Electrical Power Generation from Exhaust of the Gas Turbine Power Plants

    , M.Sc. Thesis Sharif University of Technology Barzegar, Iran (Author) ; Boroushaki, Mehrdad (Supervisor)
    Abstract
    Today, due to increasing electricity consumption and demand, the use of conventional systems such as thermal, hydro and nuclear power plants is not enough to convert energy. Over the past century, scientists have sought to discover new technologies for exploiting different forms of energy and converting them into high-efficiency electrical energy. One of these ways is to use the phenomenon of magnetohydrodynamics (magnetic fluid dynamics) to convert thermal energy directly into electrical energy. Magnetohydrodynamics is a theoretical field that studies the dynamics of fluids with electrical conductivity. Induction magneto-hydrodynamic generators use ionized hot plasma (a quasi-neutral gas of... 

    Using an all-speed method to predict high frequency pressure spikes of water hammer with column separation

    , Article 13th International Energy Conversion Engineering Conference, IECEC 2015, 27 July 2015 through 29 July 2015 ; July , 2015 ; 9781624103766 (ISBN) Darbandi, M ; Beige, A. A ; Schneider, G. E ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc, AIAA  2015
    Abstract
    To extend a procedure to ensure the safe operation of a water reactor, we develop a numerical method to compute the high frequency pressure spikes of water hammer with liquid column separation in pipes. In this regard, we first extend a finite-volume all-speed method to solve the full one-dimensional Navier-Stokes equations. This method is capable of simulating gas and liquid phases as well as the vapor-liquid one. On the other hand, the current extended method should be capable of capturing high frequency pressure spikes, which are formed due to water hammer and column separation in pipes. The existence of such high frequency spikes has been recently reported experimentally by other... 

    A new configuration of switched reluctance motor for reducing the torque ripple

    , Article 2009 International Conference on Electric Power and Energy Conversion Systems, 10 November 2009 through 12 November 2009 ; 2009 ; 9789948427155 (ISBN) Sheikhi, A ; Oraee, H ; Kaboli, S ; Dorkhah, M. R ; Sharif University of Technology
    Abstract
    Switched reluctance motors (SRM) are one of the most reliable and cost effective motors and their applications are increasing in industry. However, it suffers from high level of torque ripple. In this paper, a new configuration for stator and rotor of SRM is presented. In the proposed method, a new saliency is developed to remove negative torque and therefore decrease torque ripple and acoustic noise, increase efficiency and as a result, expand speed range. The simulation results demonstrate that the new motor structure has a smooth torque profile with possibility to work at higher speed lower acoustic noise  

    Carbon dioxide reforming of methane by pulsed glow discharge at atmospheric pressure: the effect of pulse compression

    , Article Journal of Applied Physics ; Volume 101, Issue 12 , 2007 ; 00218979 (ISSN) Ghorbanzadeh, A. M ; Modarresi, H ; Sharif University of Technology
    2007
    Abstract
    Methane reforming by carbon dioxide in pulsed glow discharge at atmospheric pressure is examined. The plasma pulse is compressed to less than 50 ns. This compression enables one to work at higher frequencies, over 3 kHz, without glow-arc transition. The main products of the reaction are synthetic gases (H2, CO) and C2 hydrocarbons. Approximately 42% of plasma energy goes to the chemical dissociation, when the reactant ratio is C O2 C H4 =1. At this point, the energy expense is less than 3.8 eV per converted molecule while reactant conversions are relatively high reaching to 55% (C H4) and 42% (C O2). The reactor energy performance even gets better at higher C O2 C H4 ratios. While energy... 

    The effects of recombination lifetime on efficiency and JV characteristics of InxGa1-xN/GaN quantum dot intermediate band solar cell

    , Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 42, Issue 9 , July , 2010 , Pages 2353-2357 ; 13869477 (ISSN) Es'Haghi Gorji, N ; Movla, H ; Sohrabi, F ; Hosseinpour, A ; Rezaei, M ; Babaei, H ; Sharif University of Technology
    2010
    Abstract
    We introduce a new third generation of solar cell structure which inserts different-sized quantum dots in the active region of a pin structure. Generating an intermediate band in the bandgap of the host material makes a good overlap with a part of solar spectrum. The effect of the recombination mechanisms on efficiency and currentvoltage characteristics of this intermediate band solar cell is calculated. We deduce that the increase in recombination lifetime of the excited carriers can improve the characteristics of this structure. This result can be a route which helps us to take the effect on solar cell characteristics into consideration  

    Numerical simulation of collision between two droplets in the T-shaped microchannel with lattice Boltzmann method

    , Article AIP Advances ; Volume 6, Issue 11 , 2016 ; 21583226 (ISSN) Merdasi, A ; Ebrahimi, S ; Moosavi, A ; Shafii, M. B ; Kowsary, F ; Sharif University of Technology
    American Institute of Physics Inc 
    Abstract
    In this study, the Lattice Boltzmann Method (LBM) is used to investigate the deformation of two droplets within microfluidic T-junctions (MFTD). In order to increase the accuracy the two immiscible fluids are modeled using the He-Chen-Zhang model. First, this model is applied to ensure that the surface tension effect existing between the droplets and the continuous fluid is properly implemented in the model. Then the collision and merging of the two droplets within the intersection of a T-shaped microchannel is investigated. For generating droplet formation the effects of relevant dimensionless parameters such as the Reynolds, the Weber numbers as well as a collision parameter affecting the... 

    Effect of samarium oxide on the electrical conductivity of plasma-sprayed SOFC anodes

    , Article JOM ; Volume 68, Issue 10 , 2016 , Pages 2569-2573 ; 10474838 (ISSN) Panahi, S. N ; Samadi, H ; Nemati, A ; Sharif University of Technology
    Minerals, Metals and Materials Society 
    Abstract
    Solid oxide fuel cells (SOFCs) are rapidly becoming recognized as a new alternative to traditional energy conversion systems because of their high energy efficiency. From an ecological perspective, this environmentally friendly technology, which produces clean energy, is likely to be implemented more frequently in the future. However, the current SOFC technology still cannot meet the demands of commercial applications due to temperature constraints and high cost. To develop a marketable SOFC, suppliers have tended to reduce the operating temperatures by a few hundred degrees. The overall trend for SOFC materials is to reduce their service temperature of electrolyte. Meanwhile, it is... 

    Open-circuit switch fault tolerant wind energy conversion system based on six/five-leg reconfigurable converter

    , Article Electric Power Systems Research ; Volume 137 , 2016 , Pages 104-112 ; 03787796 (ISSN) Shahbazi, M ; Saadate, S ; Poure, P ; Zolghadri, M ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    In this paper, an FPGA-controlled fault tolerant back-to-back converter for DFIG-based wind energy conversion application is studied. Before an open-circuit failure in one of the semiconductors, the fault tolerant converter operates as a conventional back-to-back six-leg one. After the fault occurrence in one of the switches, the converter will continue its operation with the remaining five healthy legs. Design, implementation, simulation and experimental verification of a reconfigurable control strategy for the fault tolerant six/five leg converter used in wind energy conversion are discussed. The proposed reconfigurable control strategy allows the uninterrupted operation of the converter... 

    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
    Abstract
    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...