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Impacts of fault diagnosis schemes on distribution system reliability
, Article IEEE Transactions on Smart Grid ; Vol. 3, issue. 2 , 2012 , p. 720-727 ; ISSN: 19493053 ; Lehtonen, M ; Fotuhi-Firuzabad, M ; Sharif University of Technology
Abstract
Design and development of fault diagnosis schemes (FDS) for electric power distribution systems are major steps in realizing the self-healing function of a smart distribution grid. The application of the FDS in the electric power distribution systems is mainly aimed at precise detecting and locating of the deteriorated components, thereby enhancing the quality and reliability of the electric power delivered to the customers. The impacts of two types of the FDS on distribution system reliability are compared and presented in this paper. The first type is a representative of the FDS which diagnoses the deteriorated components after their failing. However, the second type is a representative of...
Impacts of fault diagnosis schemes on distribution system reliability
, Article IEEE Transactions on Smart Grid ; Volume 3, Issue 2 , February , 2012 , Pages 720-727 ; 19493053 (ISSN) ; Lehtonen, M ; Fotuhi Firuzabad, M ; Sharif University of Technology
2012
Abstract
Design and development of fault diagnosis schemes (FDS) for electric power distribution systems are major steps in realizing the self-healing function of a smart distribution grid. The application of the FDS in the electric power distribution systems is mainly aimed at precise detecting and locating of the deteriorated components, thereby enhancing the quality and reliability of the electric power delivered to the customers. The impacts of two types of the FDS on distribution system reliability are compared and presented in this paper. The first type is a representative of the FDS which diagnoses the deteriorated components after their failing. However, the second type is a representative of...
Introducing film cooling uniformity coefficient
, Article Heat Transfer Engineering ; Volume 39, Issue 2 , 2018 , Pages 180-193 ; 01457632 (ISSN) ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
An optimal performance film cooling implies a high cooling effectiveness along with a wide surface cooling coverage. During the past decades, film cooling effectiveness has been well defined with a specific formula to evaluate the quality of a cooling system. However, despite numerous research on film cooling, there is still no explicit parameter to quantify how well a coolant film is spread over a hot surface. This work introduces a new coefficient namely cooling uniformity coefficient (CUC) to evaluate how well a coolant film is spread over a surface that is being cooled. Four different cases at two blowing ratios of 0.5 and 1.5 are studied. Three cases are ordinary single jets with...
Improving direct load control implementation by an inititative load control method
, Article EPDC 2013 - 18th Electric Power Distribution Network Conference ; 2013 ; ISBN: 9781480000000 ; Fotuhi-Firuzabad, M ; Moeini-Aghtaie, M ; Sharif University of Technology
Abstract
Demand response (DR) as a state-of-the-art program is accommodated in the energy efficiency contexts of the smart grid. Lack of the customer knowledge about how to respond to the time-differentiated tariffs and offered controlling signals is the major obstacle in the way of broad DR implementing. As a solution, an optimization method, namely load control (LC), is proposed to automatically control the on/off status of the responsive appliances in a smart home. This paper focuses on the direct load control (DLC) program in the category of incentive-based DR programs. LC is extended to consider inconvenience cost of the DLC implementation for DLC program participants. Outputs of the extended LC...
The study of air-cooled condenser in high wind velocity and environmental temperature conditions
, Article 52nd AIAA Aerospace Sciences Meeting - AIAA Science and Technology Forum and Exposition, SciTech 2014 ; 2014 ; ISBN: 9781624102561 ; Behrouzifar, A ; Salemkar, H ; Schneider, G. E ; Sharif University of Technology
Abstract
The use of air-cooled condenser (ACC) has become very popular in erecting thermal powerplants around the world since two or three decades ago. The advantages of forced convection heat cooling system, instead of the classical natural draught convection heat transfer cooling systems, promote the thermal powerplant designers and users to benefit more from such systems in their thermodynamics cycles. However, such forced convection heat transfer mechanisms, can lose their cooling efficiency in off-design ambient conditions, i.e., in high wind velocity and high ambient temperature conditions. There have already been some efforts to analyze the reduction of ACC System performance in some critical...
Improving direct load control implementation by an inititative load control method
, Article EPDC 2013 - 18th Electric Power Distribution Network Conference ; 2013 , Pages 1-5 ; 9781479900923 (ISBN) ; Fotuhi Firuzabad, M ; Moeini Aghtaie, M ; Sharif University of Technology
2013
Abstract
Demand response (DR) as a state-of-the-art program is accommodated in the energy efficiency contexts of the smart grid. Lack of the customer knowledge about how to respond to the time-differentiated tariffs and offered controlling signals is the major obstacle in the way of broad DR implementing. As a solution, an optimization method, namely load control (LC), is proposed to automatically control the on/off status of the responsive appliances in a smart home. This paper focuses on the direct load control (DLC) program in the category of incentive-based DR programs. LC is extended to consider inconvenience cost of the DLC implementation for DLC program participants. Outputs of the extended LC...
Geometrical effects on the thermoelectric properties of ballistic graphene antidot lattices
, Article Journal of Applied Physics ; Volume 110, Issue 5 , 2011 ; 00218979 (ISSN) ; Pourfath, M ; Faez, R ; Kosina, H ; Sharif University of Technology
2011
Abstract
The thermoelectric properties of graphene-based antidot lattices are theoretically investigated. A third nearest-neighbor tight-binding model and a fourth nearest-neighbor force constant model are employed to study the electronic and phononic band structures of graphene antidot lattices with circular, rectangular, hexagonal, and triangular antidot shapes. Ballistic transport models are used to evaluate transport coefficients. Methods to reduce the thermal conductance and to increase the thermoelectric power factor of such structures are studied. Our results indicate that triangular antidot lattices have the smallest thermal conductance due to longer boundaries and the smallest distance...
Energy and exergy analysis of a gas turbine power plant with inlet evaporating cooling systems
, Article 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, 14 June 2010 through 17 June 2010 ; Volume 4 , 2010 , Pages 203-210 ; 9781456303181 (ISBN) ; Karimi, M ; Ahmadi, P ; Ecole Polytechnique Federale de Lausanne; Schweizerische Eidgenossenschaft ; Sharif University of Technology
Aabo Akademi University
Abstract
The gas turbine (GT) is known to feature low capital cost to power ratio, high flexibility, high reliability without complexity, short delivery time, early commissioning and commercial operation and fast starting-accelerating. Hence, researchers all over the world are working to increase the output power and efficiency of gas turbine cycle. One of the important techniques to increase the output power of such cycles is the compressor inlet air cooling method. The objective of this paper is to analysis the gas turbine cycle from both energy and exergy point of view. Thus, two important methods for increasing the output power, i.e. fog and media inlet air cooling systems are discussed....
Performance evaluation of a modular design ofwind tower withwetted surfaces
, Article Energies ; Volume 10, Issue 7 , 2017 ; 19961073 (ISSN) ; Bahadori, M. N ; Dehghani Sanij, A ; Nourbakhsh, A ; Sharif University of Technology
MDPI AG
2017
Abstract
Wind towers or wind catchers, as passive cooling systems, can provide natural ventilation in buildings located in hot, arid regions. These natural cooling systems can provide thermal comfort for the building inhabitants throughout the warm months. In this paper, a modular design of a wind tower is introduced. The design, called a modular wind tower with wetted surfaces, was investigated experimentally and analytically. To determine the performance of the wind tower, air temperature, relative humidity (RH) and air velocity were measured at different points. Measurements were carried out when the wind speed was zero. The experimental results were compared with the analytical ones. The results...
Exhaust soot investigation in a JP combustor working at various wall temperatures
, Article AIAA Aerospace Sciences Meeting, 2018, 8 January 2018 through 12 January 2018 ; Issue 210059 , 2018 ; 9781624105241 (ISBN) ; Ghafourizadeh, M ; Darbandi, M ; Saidi, M. H ; Sharif University of Technology
American Institute of Aeronautics and Astronautics Inc, AIAA
2018
Abstract
In this study, a jet propulsion JP combustor is studied numerically to investigate the combustor wall temperature influences on the soot characteristics emitted at its exhaust. There are a number of ways to control the combustor wall temperatures benefiting from different wall cooling technologies. Irrespective of using different high technology cooling systems, it is important to recognize how the wall temperature can affect the soot emission from one specific JP engine. Before examining the main combustor, it is important to assess the accuracy of the computational fluids dynamics (CFD) tool via solving a benchmark problem. In this regard, the predicted flame structure for the benchmark...
An innovative solar assisted desiccant-based evaporative cooling system for co-production of water and cooling in hot and humid climates
, Article Energy Conversion and Management ; Volume 185 , 2019 , Pages 396-409 ; 01968904 (ISSN) ; Roshandel, R ; Vakiloroaya, V ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Although evaporative coolers consume much lower electricity than the vapor compression systems, they are not applicable in humid climates. Combination of desiccant wheels and evaporative coolers, known as desiccant-based evaporative cooling systems, allows evaporative coolers to be used in humid climates, which provide significant energy and environmental advantages with respect to vapor compression systems. However, one of the main disadvantages of evaporative cooling is the high water. Regarding the global water crisis, a cooling system which saves both water and energy will be an attractive alternative to the current cooling systems. To this aim, this paper presents a novel...
Optimal placement of protective and controlling devices in electric power distribution systems: a MIP model
, Article IEEE Access ; Volume 7 , 2019 , Pages 122827-122837 ; 21693536 (ISSN) ; Safdarian, A ; Moeini Aghtaie, M ; Lehtonen, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper presents a mathematical model for simultaneous deployment of protective devices (PDs) and controlling devices (CDs) in distribution networks. The PDs include fuses and reclosers and the CDs are remote controlled switches (RCSs) and manual switches (MSs). The model is to minimize equipment costs as well as sustained and momentary interruption costs. It considers the coordination of fuses and reclosers during temporary faults involving fuse saving and fuse blowing schemes. The model is in mixed integer programming (MIP) fashion which can be effectively solved with available solvers. The performance of the proposed model is verified through applying it to Bus 4 of Roy Billinton test...
Optimal placement of protective and controlling devices in electric power distribution systems: A MIP Model
, Article IEEE Access ; Volume 7 , 2019 , Pages 122827-122837 ; 21693536 (ISSN) ; Safdarian, A ; Moeini Aghtaie, M ; Lehtonen, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
This paper presents a mathematical model for simultaneous deployment of protective devices (PDs) and controlling devices (CDs) in distribution networks. The PDs include fuses and reclosers and the CDs are remote controlled switches (RCSs) and manual switches (MSs). The model is to minimize equipment costs as well as sustained and momentary interruption costs. It considers the coordination of fuses and reclosers during temporary faults involving fuse saving and fuse blowing schemes. The model is in mixed integer programming (MIP) fashion which can be effectively solved with available solvers. The performance of the proposed model is verified through applying it to Bus 4 of Roy Billinton test...
A comprehensive comparative investigation on solar heating and cooling technologies from a thermo-economic viewpoint—A dynamic simulation
, Article Energy Science and Engineering ; Volume 9, Issue 5 , 2021 , Pages 724-742 ; 20500505 (ISSN) ; Behnam, P ; Abbasi Kamazani, M ; Mohammadi, O ; Kavian, S ; Ahmadi, P ; Rosen, M. A ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
The yearly thermo-economic performance is dynamically investigated for three solar heating and cooling systems: solar heating and absorption cooling (SHAC), solar heating and ejector cooling (SHEC), and heating and solar vapor compression cooling (HSVC). First, the effects of important design parameters on the thermo-economic performance of the systems to supply the heating and cooling loads of the building are evaluated. The systems are parametrically analyzed with the weather conditions of Tehran, Iran. The results show that the life cycle costs (LCC) of the SHAC and HSVC systems are alike and much lower than those of the SHEC system. The HSVC system exhibits the best performance from...
Evaluation of a cooling system integrated with different phase change materials and its effect on peak load shaving
, Article International Journal of Energy Research ; Volume 45, Issue 7 , 2021 , Pages 10425-10449 ; 0363907X (ISSN) ; Kavian, S ; Jafari Mosleh, H ; Shafii, M. B ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
In this study, a vapor-compression cooling system utilizing different phase change materials (PCMs) has been studied whereby the electricity consumption peak load is shifted. More specifically, the dynamic performance of cooling systems with and without using PCM is evaluated for the hottest day of the year. The proposed system uses the cooling energy to freeze, or “discharge” the PCM during nighttime when the cooling load is minimally needed and uses the stored thermal energy during the peak load hours by melting, or “charging” the PCM. This leads to better performance during peak load hours when higher cooling loads are needed. Different PCMs including oleic acid, SP224A, CL, CaCl2·6H2O...
Performance evaluation of the solar-driven multi-ejector refrigeration cycle without an auxiliary heat source
, Article Applied Thermal Engineering ; Volume 217 , 2022 ; 13594311 (ISSN) ; Hakkaki Fard, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Solar-driven ejector refrigeration (SER) systems have been granted special attention as a green and sustainable replacement for conventional vapor compression cooling systems. However, despite their significant advantages, SER systems suffer from a relatively low coefficient of performance and failure at high ambient temperatures and low solar radiations. Therefore, the need for an auxiliary heat source and cooling system has hindered their adoption in practice. In an attempt to eliminate the need for an auxiliary heat source and cooling system, this contribution puts forward a novel Solar-driven Multi-Ejector Refrigeration (SMER) system with an internal heat exchanger, a regenerator, and a...
Optimized design of water-saving system in-slab cooling plant of Mobarakeh steel complex
, Article Journal of Cleaner Production ; Volume 335 , 2022 ; 09596526 (ISSN) ; Bazofti, M. M ; Golkar, B ; Saboohi, Y ; Mokhtari, H ; Milani, B ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
The aim of this paper is to provide a solution to decrease water consumption in the slab-cooling unit of Mobarakeh Steel Complex in Iran. The plan should give an hourly decline in water consumption during a one-year operation period to calculate the annual reduction in water consumption of the proposed process. Recommended solutions for the conversion scheme of an existing wet cooling tower to a dry or hybrid cooling system require modeling of the slab cooling process. The curves of temperature drop in slabs are extracted in this paper by modeling the transient heat transfer of the slabs in the cooling process. This will reduce the computational volume. Then, the design and optimization of...
A validated numerical-experimental design methodology for a movable supersonic ejector compressor for waste-heat recovery
, Article Journal of Thermal Science and Engineering Applications ; Volume 6, Issue 2 , Oct , 2014 ; 19485085 (ISSN) ; Persoons, T ; Murray, D. B ; Tehrani, M. S ; Farhanieh, B ; Koehler, J ; Sharif University of Technology
Web Portal ASME (American Society of Mechanical Engineers)
2014
Abstract
The aim of this paper is to develop the technical knowledge, especially the optimum geometries, for the design and manufacturing of a supersonic gas-gas ejector for a wasteheat driven vehicle cooling system. Although several studies have been performed to investigate the effects of geometrical configurations of gas-gas ejectors, a progressive design methodology of an ejector compressor for application to a vehicle cooling system has not yet been described. First, an analytical model for calculation of the ejector optimum geometry for a wide range of operating conditions is developed, using R134a as the working fluid with a rated cooling capacity of 2.5 kW. The maximum values of entrainment...
Materials selection for electronic enclosures in space environment considering electromagnetic interference effect
, Article Advances in Space Research ; Volume 49, Issue 3 , February , 2012 , Pages 586-593 ; 02731177 (ISSN) ; Abedian, A ; Sharif University of Technology
2012
Abstract
Using low power electronic devices for space applications to reduce the mass and energy consumption has lead to electromagnetic interference (EMI) problem. Electronic enclosures are used to shield electronic devices against EMI. In the past, electromagnetic shielding has been mainly the only criteria considered in electronic enclosure design. However, there are several structural and thermal requirements for selection of shielding materials which should also be taken into account. In this research work, three quantitative materials selection methods, i.e. Digital Logic (DL), Modified Digital Logic (MDL), and Z-transformation, are employed to select the best material from among a list of...
Engineering enhanced thermoelectric properties in zigzag graphene nanoribbons
, Article Journal of Applied Physics ; Volume 111, Issue 5 , 2012 ; 00218979 (ISSN) ; Neophytou, N ; Pourfath, M ; Faez, R ; Kosina, H ; Sharif University of Technology
2012
Abstract
We theoretically investigate the thermoelectric properties of zigzag graphene nanoribbons in the presence of extended line defects, substrate impurities, and edge roughness along the nanoribbon's length. A nearest-neighbor tight-binding model for the electronic structure and a fourth nearest-neighbor force constant model for the phonon bandstructure are used. For transport, we employ quantum mechanical non-equilibrium Green's function simulations. Starting from the pristine zigzag nanoribbon structure that exhibits very poor thermoelectric performance, we demonstrate how after a series of engineering design steps the performance can be largely enhanced. Our results could be useful in the...