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    Efficiency improvement of a high step up high efficiency converter for photovoltaic applications based on three-state switching cell

    , Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 454-458 ; 9781467344845 (ISBN) Babaee Zarch, M. J ; Zolghadri, M. R ; Hajimoradi, M. R ; Sharif University of Technology
    2013
    Abstract
    This paper suggests methods for improving efficiency of a high step up high efficiency converter based on three state commutation cells. A loss analysis has been performed to identify the source of power loss. Based on this analysis, methods are presented to reduce losses in the most power dissipating elements. These methods include replacing some power diodes with large conduction losses with MOSFETs having small on-state resistance. Efficiency improvement up to %1.25 percent is verified in simulation and experimental results  

    Blade shape optimization of marine propeller via genetic algorithm for efficiency improvement

    , Article Proceedings of the ASME Turbo Expo ; Volume 5 , 2012 , Pages 235-242 ; 9780791844717 (ISBN) Taheri, R ; Mazaheri, K ; Sharif University of Technology
    2012
    Abstract
    In this paper, a numerical optimization method has been carried out to optimize the shape and efficiency of a propeller. For analysis of the hydrodynamic performance parameters, an extended vortex lattice method was used by implementing an open-source code which is called OpenProp. The method of optimization is a non-gradient based algorithm. After a trade-off between a few gradient-based and non-gradient based algorithms, it is found that the problem of being trapped in local optimum solutions can be easily solved by choosing nongradient based ones. Hence, modified Genetic algorithm is used to implement the so-called hydrodynamic performance analyzer code. The objective function is to... 

    Comparison of efficiency for different switching tables in six-phase induction motor DTC drive

    , Article Journal of Power Electronics ; Volume 12, Issue 1 , 2012 , Pages 128-135 ; 15982092 (ISSN) Taheri, A ; Rahmati, A ; Kaboli, S ; Sharif University of Technology
    2012
    Abstract
    In this paper, different switching tables proposed for the Direct Torque Controlled (DTC) of a six-phase induction machine are simulated and implemented. A six-phase induction motor has 64 space voltage vectors which result in increased complexity in the selecting of inverters switching. The unsuitable selection of a switching table leads to large harmonics especially at low speed and it also reduces drive efficiency. A six-phase induction machine has large zero sequence harmonic currents of the order 6k ±1. These harmonic currents are varied in various techniques. Decreasing this loss is essential in a six-phase induction machine. The main purpose of this paper is to improve the ST-DTC of... 

    Additional slag doors for increased EAF efficiency: A conceptual study

    , Article ISIJ International ; Volume 57, Issue 8 , 2017 , Pages 1394-1399 ; 09151559 (ISSN) Saboohi, Y ; Fathi, A ; Skrjanc, I ; Logar, V ; Sharif University of Technology
    Iron and Steel Institute of Japan  2017
    Abstract
    The paper presents a conceptual study on modification of the electric arc furnace (EAF) slag doors in order to allow removal of the excess slag from the EAF. The idea behind additional slag doors is to allow deslagging of the bath in certain unfavorable cases when the slag height is too great. Slags which exceed the optimal height cause unnecessary refractory corrosion and additional energy losses. The study proposes symmetric slag doors comprised of two hatches, i.e. upper and lower. The upper hatch is intended to decrease the slag height to the optimal level, while the lower hatch can be used to completely deslag the EAF at tapping. In this manner, tilting of the EAF is not necessary. A... 

    Projection of passenger cars’ fuel demand and greenhouse gas emissions in Iran by 2050

    , Article Energy Conversion and Management: X ; Volume 12 , 2021 ; 25901745 (ISSN) Hassani, A ; Maleki, A ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    Passenger cars (PCs) not only are a major contributor to greenhouse gas (GHG) emissions in Iran but also pose severe energy security challenges due to their dependence on gasoline. This study aimed to understand the future trends of the gasoline demand and GHG emissions from PCs in Iran and assess the effectiveness of mitigation policies. The data were collected from multiple sources and used to develop the survival rate function of PCs. The study used back-calculation to compensate for the short period of stock data availability. The use intensity of PCs was estimated based on the gasoline consumption statistics. Econometric models were developed to project the future PC stock and use... 

    What is energy efficiency and emission reduction potential in the Iranian petrochemical industry?

    , Article International Journal of Greenhouse Gas Control ; Volume 12 , 2013 , Pages 460-471 ; 17505836 (ISSN) Mohammadi, A ; Soltanieh, M ; Abbaspour, M ; Atabi, F ; Sharif University of Technology
    2013
    Abstract
    In this study, the prospects of energy efficiency potential, clean development mechanism (CDM) and carbon income up to and beyond 2012 are investigated in the petrochemical industries of Iran as a major oil-producing country. This paper is to address four questions of: (1) the GHGs emission in Iranian petrochemical complexes, (2) the most energy-consuming processes, (3) units with the highest energy efficiency potentials and (4) potentials of CDM or similar carbon projects based on post-2012 scenarios. The petrochemical processes are investigated in two categories of non-polymeric and polymeric productions. Based on capital expenditure, economic saving, simple payback period, CO2 equivalent... 

    Drag performance of divergent tubular-truncated cones: A shape optimization study

    , Article International Journal of Environmental Science and Technology ; Volume 9, Issue 1 , 2012 , Pages 105-112 ; 17351472 (ISSN) Lotfi, A ; Rad, M ; Sharif University of Technology
    2012
    Abstract
    The use of more efficient energy consuming devices, which are closely associated with reduction of environmental pollution, has gained significant interest in the recent decades. The reduction of drag coefficient also improves safety and durability of environmental structures subjected to high-velocity fluid flow, and causes the noise and vibration to decrease as well. This paper describes the efficiency improvement in energy management by means of reducing drag coefficient in a practical divergent tubular- truncated cone. Extensive numerical simulations with emphasis on the shape optimization study were performed in order to find minimum drag coefficient for both laminar and turbulent flows... 

    Improved photon to current conversion in nanostructured TiO2 dye-sensitized solar cells by incorporating cubic BaTiO3 particles deliting incident

    , Article Solar Energy ; Volume 132 , 2016 , Pages 1-14 ; 0038092X (ISSN) Asgari Moghaddam, H ; Mohammadi, M. R ; Seyed Reyhani, S. M ; Sharif University of Technology
    Elsevier Ltd 
    Abstract
    Different structures of dye-sensitized solar cells (DSCs) were fabricated with various compositions and arrangement modes of the photoanodes. The solvothermally grown TiO2 nanoparticles and sol-gel derived spherical TiO2 and BaTiO3 particles were employed as the active and scattering layers of DSCs. TiO2 nanoparticles and spherical particles had pure anatase structure with particle size of 15-30 nm and 200-400 nm, respectively, whereas 300-800 nm BaTiO3 particles showed cubic perovskite structure. The efficiency improvement of mono-layer cells made of TiO2 nanoparticles (i.e., 7.22%) was achieved by light harvesting mechanism. Further enhancement of photovoltaic performance was achieved by... 

    Influence of photoanode architecture on light scattering mechanism and device performance of dye-sensitized solar cells using TiO2 hollow cubes and nanoparticles

    , Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 86 , May , 2018 , Pages 81-91 ; 18761070 (ISSN) Sarvari, N ; Mohammadi, M. R ; Sharif University of Technology
    Taiwan Institute of Chemical Engineers  2018
    Abstract
    Herein, we report the impact of light scattering mechanism on photovoltaic and photoelectrochemical performance of dye-sensitized solar cell (DSC) devices composed of TiO2 nanoparticles and hollow cubes. DSCs are designed by two different light scattering modes (i.e., mode I in form of single layer electrode containing nanoparticles and hollow cubes and mode II in the form of double layer electrode comprising active and scattering layers made of nanoparticles and mixtures of nanoparticles and hollow cubes, respectively). The synthesized anatase-TiO2 hollow cubes (200–400 nm) and nanoparticles (15–30 nm) are employed to enhance the optical length and light harvesting of photoanodes,... 

    Feed-forward modelling and fuzzy logic based control strategy for powertrain efficiency improvement in a parallel hybrid electric vehicle

    , Article Mathematical and Computer Modelling of Dynamical Systems ; Volume 15, Issue 2 , 2009 , Pages 191-207 ; 13873954 (ISSN) Amiri, M ; Esfahanian, V ; Hairi Yazdi, M. R ; Esfahanian, M ; Fazeli, A. M ; Nabi, A ; Sharif University of Technology
    2009
    Abstract
    With the stricter limitations on both fuel consumption and air pollution, the advantages of a hybrid electric vehicle are becoming more evident than ever. In the present study, an energy management system for a hybrid electric vehicle is developed. Because the plant under consideration is nonlinear, multi-domain, time-varying, has multiple uncertainties and, in addition, the designed control strategy must be able to obey the driver's commands and achieve the par-internship for a new generation of vehicle regulations, the fuzzy logic approach is chosen. A feed-forward hybrid vehicle simulation model is used to demonstrate the validity and the convenience of the current approach and its... 

    Solar energy systems – Potential of nanofluids

    , Article Journal of Molecular Liquids ; Volume 289 , 2019 ; 01677322 (ISSN) Wahab, A ; Hassan, A ; Qasim, M. A ; Ali, H. M ; Babar, H ; Sajid, M. U ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Global warming escalation has extended average temperature of earth beyond its safe limit. To avert this environmental-threat, solar energy has acquired substantial attention of remarkable researchers in this century. To effectively utilize solar energy by transforming into thermal and electrical energy, the involvement of nanofluids having intensified thermal, optical and magnetic properties, has become very popular. The foremost objective of this article is to provide a comprehensive review on the applications of nanofluids in solar energy systems like solar collectors, photovoltaic cells, solar stills, and thermal energy storage, which are thoroughly discussed in this paper. The effect of... 

    Efficiency improvement of solar stills through wettability alteration of the condensation surface: An experimental study

    , Article Applied Energy ; Volume 268 , 2020 Zanganeh, P ; Soltani Goharrizi, A ; Ayatollahi, S ; Feilizadeh, M ; Dashti, H ; Sharif University of Technology
    Elsevier Ltd  2020
    Abstract
    The condensation process is of great importance in many heat transfer devices in which a large amount of energy must be transferred. Furthermore, condensation is a crucial part of energy conversion and affects the energy efficiency of thermal desalination plants and solar stills. During the condensation process in solar stills, an essential part of the energy is transferred through the condensation surface to produce fresh water. Therefore, the condensation surface plays a significant role in the working efficiency of solar stills. The wettability of the condensation surface influences the condensation mechanism, which, in turn, affects the efficiency of solar stills. This study aims to... 

    Effect of high-efficient electric motors on efficiency improvement and electric energy saving

    , Article 3rd International Conference on Deregulation and Restructuring and Power Technologies, DRPT 2008, Nanjing, 6 April 2008 through 9 April 2008 ; 2008 , Pages 533-538 ; 9787900714138 (ISBN) Zabardast, A ; Mokhtari, H ; Sharif University of Technology
    2008
    Abstract
    In this paper, advantages of energy-efficient motors over standard-motors in terms of electrical energy saving and demand reduction in a tire-rubber factory are thoroughly evaluated. Energy-efficient motors reduce losses because of their better design, materials, and manufacturing. These motors are 2 to 8% more efficient than standard ones. Lengthening the core and using lower-electrical-loss steel, thinner stator laminations, and more copper in the windings reduce electrical losses. Because a motor consumes energy worth 4 to 10 times its own cost each year, energy-efficient motors often make economic sense in a wide variety of applications. At the end of this study, the amount of energy... 

    Comparison among various configurations of hybrid distillation–membrane setups for the energy efficiency improvement of bioethanol distillery: a simulation study

    , Article Journal of Chemical Technology and Biotechnology ; October , 2021 ; 02682575 (ISSN) Iftikhar, S ; Aslam, Z ; Ali, U ; Akhtar, A ; Sharif University of Technology
    John Wiley and Sons Ltd  2021
    Abstract
    BACKGROUND: Hybrid distillation–membrane setups have attracted attention in recent years due to their lower energy usage for ethanol purification. Membrane separation processes operate without heating that reduces energy demand. However, it is somewhat challenging to select the optimal material and process for a membrane purifying ethanol, especially to get an ethanol purity of 99.99% with maximum recovery. RESULTS: In this study, three different configurations of hybrid distillation–membrane setups are proposed consisting of distillation–pervaporation/vapor permeation processes by considering ceramic, polymeric and composite membranes. The design of hybrid processes is performed by coupling... 

    Controlling electron transport rate and recombination process of TiO 2 dye-sensitized solar cells by design of double-layer films with different arrangement modes

    , Article Electrochimica Acta ; Volume 78 , 2012 , Pages 384-391 ; 00134686 (ISSN) Bakhshayesh, A. M ; Mohammadi, M. R ; Fray, D. J ; Sharif University of Technology
    Abstract
    TiO 2 dye-sensitized solar cells (DSSCs) in the form of double-layer films, containing an under-layer and an over-layer, with various crystal structures (i.e., anatase and rutile phases) and morphologies (i.e., nanoparticle and nanowire) were reported. It was found that the photovoltaic performance of TiO 2 DSSCs depends on the morphology, crystal structure, light scattering effect, optical band gap energy and arrangement of the under- and over-layer films. The double-layer solar cell made of anatase-TiO 2 nanoparticles as the under-layer and anatase-TiO 2 nanowires as the over-layer (i.e., AW solar cell) showed the highest power conversion efficiency and fill factor of 6.34% and 62.6%,...