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A low cost Hydrokinetic Wells turbine system for oceanic surface waves energy harvesting
, Article Renewable Energy ; Volume 156 , 2020 , Pages 610-623 ; Abbaspour, M ; Taeibi Rahni, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper provides a feasibility study on a low cost system called Hydrokinetic Wells turbine for surface wave energy conversion without using plenum chambers. The elimination of the plenum chamber and its complicated valve systems can reduce the expenses of wave energy conversion up to 23%.The feasibility process were done for high and low frequency conditions. For the low frequency waves, we offer the 300 rpm angular velocity as an optimum selection for further studies. For the high frequency condition a reliable analytical approach based on validated methods was developed. The analytical results indicate that a wells turbine with 60 cm diameter could produce up to 1600 Watts power in...
Efficiency improvement of solar stills through wettability alteration of the condensation surface: An experimental study
, Article Applied Energy ; Volume 268 , 2020 ; 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...
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 ; 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...
Laboratory investigations on impulsive waves caused by underwater landslide
, Article Coastal Engineering ; Volume 55, Issue 12 , December , 2008 , Pages 989-1004 ; 03783839 (ISSN) ; 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...
Observability and estimation of transformer tap setting with minimal PMU placement
, Article IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES, Pittsburgh, PA, 20 July 2008 through 24 July 2008 ; 2008 ; 9781424419067 (ISBN) ; Hosseini, S. H ; Sharif University of Technology
2008
Abstract
One of the most important applications of phasor measurement units (PMUs) is power system state estimation. Some models have been proposed for including phasor measurements in the state estimation. But, all of these models have treated transformer tap settings (voltage transformer turns ratio and phase-shift transformer angle) as fixed parameters of the network. The accuracy of state estimation may decrease when a tap changes or the true value is unknown. In this paper, each transformer tap setting is added as a new state variable to the states vector, converting the linear PMU based state estimation to a nonlinear one. Also, the network observability is analyzed including the observability...
Concept of best energy transfer scenario and a true expression for power factor
, Article IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES, Pittsburgh, PA, 20 July 2008 through 24 July 2008 ; 2008 ; 9781424419067 (ISBN) ; Khajehoddin, S. A ; Bakhshai, A ; Sharif University of Technology
2008
Abstract
The best energy transfer scenario (BETS) is a situation under which the optimum transfer of power (or energy) from the electric utility to an electric power consumer is achieved. Such a scenario is important because it is used as a reference point to evaluate how efficient the load operates. The index of power factor (PF) is used to quantify such an efficiency. The closer the PF to unity corresponds to more efficient performance of the load. This paper is to show that the conventional definition of the BETS is inadequate and results in an unfair value for the PF unless the transmission line is perfect and lossless (which is an unrealistic condition). The paper also investigates an...
Is the unity power factor realizable at the load terminals?
, Article IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES, Pittsburgh, PA, 20 July 2008 through 24 July 2008 ; 2008 ; 9781424419067 (ISBN) ; Khajehoddin, S. A ; Bakhshai, A ; Sharif University of Technology
2008
Abstract
Contrary to the widespread understanding, this paper shows by means of mathematics and numerics that a perfect power factor correction cannot be made at the load terminals only. To achieve a perfect power factor correction, the supply commitment is required as well. In the absence of such commitment, the power factor cannot reach unity unless we refine the very definition of power factor. But the refined power factor is then slightly higher than the conventional one. The refined expression for power factor is a function of the load parameters as well as the line characteristics. For an ideal power system (with no line losses), this coincides with the conventional formula. © 2008 IEEE
Optimum simultaneous clearing of energy and spinning reserve markets using cost/benefit analysis
, Article IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES, Pittsburgh, PA, 20 July 2008 through 24 July 2008 ; 2008 ; 9781424419067 (ISBN) ; Fotuhi Firuzabad, M ; Zareipour, H ; Sharif University of Technology
2008
Abstract
Considering the high level of interactions between energy and reserve markets, simultaneous clearing of these markets has been shown to provide more efficient solutions, than a sequential market clearing process. In addition, determining reserve requirements based on probabilistic approaches results in more economical efficiency, while maintaining an acceptable level of reliability, compared to deterministic approaches. This paper proposes a new method for clearing energy and spinning reserve markets simultaneously, while at the same time, spinning reserve requirements are determined based on a cost/benefit analysis as a probabilistic-based approach. This cost/benefit analysis considers both...
Limiting fault currents in wind power plants using superconductive shielded core reactors
, Article IEEE Power and Energy Society 2008 General Meeting: Conversion and Delivery of Electrical Energy in the 21st Century, PES, Pittsburgh, PA, 20 July 2008 through 24 July 2008 ; 2008 ; 9781424419067 (ISBN) ; Salehfar, H ; Varahram, H ; Sharif University of Technology
2008
Abstract
In this paper we investigate the effects of superconducting shielded core reactor (SSCR) on the operation of induction generators. Large number of induction generators used in wind power plants generally increase the short circuit current level of the system. The reason is that they provide parallel reduced-impedance paths for the fault currents. Taking advantage of SSCR in wind power plants allows for using these generating units in large numbers with no concerns about the system fault current increments. The study is performed on a test system using the conventional model of an induction generator and a new effective model for SSCR based on its shielding behavior. Mathematical equations...
Impulsive waves caused by subaerial landslides
, Article Environmental Fluid Mechanics ; Volume 8, Issue 3 , 2008 , Pages 263-280 ; 15677419 (ISSN) ; 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...
Analytical study of dissipative solitary waves
, Article Physica Scripta ; Volume 77, Issue 2 , 2008 ; 00318949 (ISSN) ; Emamzadeh, M. M ; Khorasani, S ; Bobin, J. L ; Amrollahi, R ; Sodagar, M ; Khoshnegar, M ; Sharif University of Technology
2008
Abstract
In this paper, the analytical solution to a new class of nonlinear solitons is presented with cubic nonlinearity, subject to a dissipation term arising as a result of a first-order derivative with respect to time, in the weakly nonlinear regime. Exact solutions are found using the combination of the perturbation and Green's function methods up to the third order. We present an example and discuss the asymptotic behavior of the Green's function. The dissipative solitary equation is also studied in the phase space in the non-dissipative and dissipative forms. Bounded and unbounded solutions of this equation are characterized, yielding an energy conversation law for non-dissipative waves....
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) ; 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...
A compact mixer and DAC for implementation of a direct conversion OQPSK transmitter
, Article 2007 IEEE Region 10 Conference, TENCON 2007, Taipei, 30 October 2007 through 2 November 2007 ; 2007 ; 1424412722 (ISBN); 9781424412723 (ISBN) ; Mehrmanesh, S ; Zamanlooy, B ; Atarodi, M ; Sharif University of Technology
2007
Abstract
A compact low power circuit for implementation of a direct conversion OQPSK modulator is proposed. The circuit consists of a digital to analog converter, a low pass filter and an up-converter mixer. By embedding these three blocks, the circuit performance is enhanced and the total power consumption is reduced. The mixer is designed base on a Gilbert cell with on chip inductor loads. Instead of transconductance transistors of Gilbert cell, a fully deferential current mode DAC is used and proficiently a low pass filter is embedded between them and therefore the linearity of total system is improved. All of circuits are designed based on 0.18 μm CMOS technology with a single 1.8 volt power...
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) ; 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...
PIDEC Batteries Simulation Accompany with Comparative Study of Key Parameters on its Efficiency
, M.Sc. Thesis Sharif University of Technology ; 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...
Robust optimization of renewable-based multi-energy micro-grid integrated with flexible energy conversion and storage devices
, Article Sustainable Cities and Society ; Volume 64 , 2021 ; 22106707 (ISSN) ; Habibifar, R ; Moradi, M ; Khoshjahan, M ; Nojavan, S ; Jermsittiparsert, K ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
This paper presents a new model for optimal scheduling of renewable-based multi-energy microgrid (MEM) systems incorporated with emerging high-efficient technologies such as electric vehicle (EVs) parking lots, power-to-gas (P2G) facility, and demand response programs. The proposed MEM is equipped with wind energy, multi-carrier energy storage technologies, boiler, combined heat and power unit, P2G, EVs, and demand response with the aim of total operational cost minimization. Meanwhile, the system operator can participate in three electricity, heat, and gas market to meet local demands as well as achieve desired profits through energy exchanges. The proposed MEM is exposed to high-level...
Numerical investigation of transient thermo-fluid processes in a Ranque-Hilsch vortex tube
, Article International Journal of Refrigeration ; Volume 131 , 2021 , Pages 746-755 ; 01407007 (ISSN) ; Ghorbanian, K ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
A 2D numerical investigation is performed to better understand the transient thermo-fluid processes in a vortex tube for a cold mass fraction equal to0.44. The results along the Ranque-Hilsch vortex tube reveal a close agreement with past numerical and experimental data. The distribution of axial, radial, and tangential velocities as well as the stagnation pressure and temperature are examined at different positions for different time steps. The results indicate that the tangential velocity is the most significant velocity component and dominates the heat transfer and energy conversion processes. In addition, it is evident that the core of the cold end experiences the highest pressure...
Thermal and electrical conductivity of a graphene-based hybrid filler epoxy composite
, Article Journal of Materials Science ; Volume 56, Issue 27 , 2021 , Pages 15151-15161 ; 00222461 (ISSN) ; Kazemi Ranjbar, S ; Sharif University of Technology
Springer
2021
Abstract
The development of polymer-based composites with thermal transport capability has now become essential in response to the efficient thermal management required in electronic and energy conversion devices. In this work, a novel hybrid filler consisting of graphene nanoplatelet (GNP) and boron nitride microparticles (micro-BN) is used to improve the thermal conductivity of epoxy composite. The GNPs with an average lateral size of 8 µm and an average thickness of 5 nm are in the same volume range with the 1 µm size micro-BN particles. According to the results, the thermal conductivity of the composites changes abruptly with increasing micro-BN loading at fixed GNP loading, which is attributed...
Design and simulation studies of hybrid power systems based on photovoltaic, wind, electrolyzer, and pem fuel cells
, Article Energies ; Volume 14, Issue 9 , 2021 ; 19961073 (ISSN) ; Alshukri, M. J ; Mikhaeel, L. M ; Al-Sawaf, N. N ; Nesrine, K ; Reddy, M. V ; Zaghib, K ; Sharif University of Technology
MDPI AG
2021
Abstract
In recent years, the need to reduce environmental impacts and increase flexibility in the energy sector has led to increased penetration of renewable energy sources and the shift from concentrated to decentralized generation. A fuel cell is an instrument that produces electricity by chemical reaction. Fuel cells are a promising technology for ultimate energy conversion and energy generation. We see that this system is integrated, where we find that the wind and photovoltaic energy system is complementary between them, because not all days are sunny, windy, or night, so we see that this system has higher reliability to provide continuous generation. At low load hours, PV and electrolysis...
Multi-objective optimization of regenerative ORC system integrated with thermoelectric generators for low-temperature waste heat recovery
, Article Energy Reports ; Volume 7 , 2021 , Pages 300-313 ; 23524847 (ISSN) ; Moosavi, A ; Sadrhosseini, H ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Three novel geothermal-based organic Rankine cycle (ORC) systems are proposed to enhance the efficiency and for waste heat recovery purpose. The proposed systems are modeled based on a basic ORC system (concept 1), an ORC system with an internal heat exchanger (concept 2), and a regenerative ORC system (concept 3). Accordingly, two thermoelectric generators (TEG) are introduced into the systems to exploit the waste heat of the system. The condenser is replaced with a TEG unit while the other TEG unit is used to recover the waste heat of the reinjected geothermal fluid. A comprehensive numerical investigation is conducted to compare the proposed systems from the thermodynamic and...