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exergy-analysis
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, M.Sc. Thesis Sharif University of Technology ; Farhanieh, Bijan (Supervisor)
Abstract
Development of cities as well as population growth causes to development of public transportation especially subway lines. Fire is the one of the most important issues that may occur in subways. The difference in flame size, emission heat, smoke and pollutants generation of subway fires attracts an especial attention of fire investigators. The emergency ventilation of subways in the case of fire should have the ability of discharging heat, smoke and pollutants from passenger escape route and preparing a safe place for a specific duration. The aim of this research is simulating fire in subway stations and defining proper regional fire scenarios to prepare a safe route for passengers escape....
Exergy and Thermoeconomic Analysis of Hybrid Desalination Unit (RO+MED) Coupled with a Combined Cycle Power Plant (Case study: Mapna standard design for Combined Cycle Power Plants)
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor) ; Abbaspor, Majid (Co-Supervisor)
Abstract
In recent years, providing sustainable water supplies in dry and low water areas in the south of country is one of the important problems in the country. In addition to advantages of using cogeneration systems (power plant and desalination unit), using hybrid technologies causes productivity and reduction in energy consumption and water supplies. The target of this thesis is studying different thermal coupling scenarios to find optimum and constraint design in specific conditions in terms of cost and production. So in this conceptual study, by using thermoflow software, the hybrid unit coupled with a back pressure and condensing combined cycle power plant was studied based on thermodynamic...
Thermodynamic Analysis of a Combined Ejector-assisted System for Electric Equipment Cooling and Air Conditioning in Electric Vehicles
, M.Sc. Thesis Sharif University of Technology ; Morad, Mohammad Reza (Supervisor)
Abstract
Transportation is one of the essential parts of human life and at the same time one of the main sources of greenhouse gases emissions that are harmful to the environment. Therefore, the use of electric vehicles have become widespread in recent years due to limited capacity of natural resources and environmental issues. As a result, attention to climate control systems for electric vehicles and electric aircrafts is growing rapidly. According to multiple studies, the integrated air conditioning-heat pump system is a suitable option as the climate control system.In this research, an air conditioning-heat pump system has been proposed and studied, which works based on the vapor compression...
Energy and exergy analyses of a spark-ignition engine
, Article International Journal of Exergy ; Volume 7, Issue 5 , 2010 , Pages 547-563 ; 17428297 (ISSN) ; Kiaahmadi, F ; Khanaki, M ; Nazoktabar, M ; Sharif University of Technology
2010
Abstract
In this paper, the performance of an internal combustion engine is evaluated at the steady-state condition by application of energy and exergy analysis using the experimental test results. The energy and exergy balances are calculated at different engine speeds. The results show that the heat rejection of energy and exergy flow increases with increasing engine speed. The exergy efficiencies are slightly higher than the corresponding energy efficiencies. The results of this study have revealed that the most important source of the system inefficiency is the destruction of exergy by irreversible processes, mostly by the combustion. One can conclude that the use of a combined energy and exergy...
Investigation of effective parameters on the performance of the helium liquefaction cycle
, Article International Journal of Heat and Technology ; Volume 37, Issue 4 , 2019 , Pages 1009-1018 ; 03928764 (ISSN) ; Eslami, M ; Afshin, H ; Sharif University of Technology
International Information and Engineering Technology Association
2019
Abstract
Due to its unique properties, helium has wide application in different industries and scientific fields, which has turned it into a strategic material. Helium liquefaction plants include wide temperature range from 300 k to 4.2 k, so these plants have high energy consumption. A lot of studies have done to optimize the operation of these cycles. In this research, an exergy analysis is performed for a liquid helium production plant. The optimal performance of 3 and 4 stage cycles is extracted using parametric study and the results are compared with those of Collins dual-expander cycle. The results show that by increasing the number of cooling stages, not only the compressor optimum discharge...
Investigation of effective parameters on the performance of the helium liquefaction cycle
, Article International Journal of Heat and Technology ; Volume 37, Issue 4 , 2019 , Pages 1009-1018 ; 03928764 (ISSN) ; Eslami, M ; Afshin, H ; Sharif University of Technology
International Information and Engineering Technology Association
2019
Abstract
Due to its unique properties, helium has wide application in different industries and scientific fields, which has turned it into a strategic material. Helium liquefaction plants include wide temperature range from 300 k to 4.2 k, so these plants have high energy consumption. A lot of studies have done to optimize the operation of these cycles. In this research, an exergy analysis is performed for a liquid helium production plant. The optimal performance of 3 and 4 stage cycles is extracted using parametric study and the results are compared with those of Collins dual-expander cycle. The results show that by increasing the number of cooling stages, not only the compressor optimum discharge...
An updated review of the performance of nanofluid-based photovoltaic thermal systems from energy, exergy, economic, and environmental (4E) approaches
, Article Journal of Cleaner Production ; Volume 282 , 2021 ; 09596526 (ISSN) ; Taheri, A ; Farzanehnia, A ; Passandideh fard, M ; Sardarabadi, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
One of the most prominent hybrid solar devices is the photovoltaic thermal system (PVTS), which is able to provide simultaneous electricity and thermal energy. The thermal energy is the heat absorbed by the photovoltaic (PV) module and transferred to the attached thermal collector and finally to the heat transfer fluid. Utilizing a proper heat transfer fluid is an effective means to increase in obtained thermal and electrical powers and enhance PV thermal management. Over the past decade, employing nanofluids thanks to their superior thermophysical properties became a proved strategy to improve the efficiency of the PVTS. This paper covers cutting-edge researches on nanofluid-based PVTS via...
Optimization of a combined heat and power PEFC by exergy analysis
, Article Journal of Power Sources ; Volume 143, Issue 1-2 , 2005 , Pages 179-184 ; 03787753 (ISSN) ; Ehyaei, M. A ; Abbasi, A ; Sharif University of Technology
2005
Abstract
In this paper, design and exergy method optimization of a 5 kW power output polymer electrolyte fuel cell (PEFC) fuel cell with cogeneration application has been investigated. It is assumed that cooling water is passed through the fuel cell cooling channel, warmed up and supplied for space heating applications. The performance of the proposed system has been optimized by the second law based on exergy analysis. Results show that for maximum system efficiency and minimum entropy generation, fuel cell temperature and voltage should be as high as possible in the range of application. Also, the fuel cell pressure and stoichiometric air:fuel ratio should be as low as possible in the range of...
Optimization of operating parameters in a hybrid wind-hydrogen system using energy and exergy analysis: Modeling and case study
, Article Energy Conversion and Management ; Volume 106 , December , 2015 , Pages 1318-1326 ; 01968904 (ISSN) ; Ahmadi, S ; Mirghaed, M. R ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In this study, hybrid renewable energy system based on wind/electrolyzer/PEM fuel cell are conceptually modeled, and also, exergy and energy analysis are performed. The energy and exergy flows are investigated by the proposed model for Khaf region-Iran with high average wind speed and monsoon. Exergy and energy analysis framework is made based on thermodynamic, electro-chemical and mechanical model of the different component of hybrid system. Also, the effects of various operating parameters in exergy efficiency are calculated. The results show an optimum wind speed where the exergy efficiency and power coefficient is at maximum level, and also, when the ambient temperature start to be...
Modeling the Solar Heat Pump with an Energy Storage System
, M.Sc. Thesis Sharif University of Technology ; Samimi , Jalal (Supervisor) ; Vesaghi, Mohammad Ali (Supervisor)
Abstract
Purpose of ongoing thesis is providing a tool for suitable modeling, increase efficiency and decrease construction cost of solar absorption heat pump. At first, the solar absorption heat pump is modeled by the thermodynamic laws. Then, this model is converted to the new standard mathematical programming model using exergy and thermodynamic Analysis with considering all technical and economic constrains. This mathematical model is optimized by Genetic algorithm (GA). Because of the nonlinear objective function and the constraint, GA is used as optimization algorithm. After applying GA, optimized parameters of cycle heat exchanger designing and its electricity consumption are calculated....
Modeling a Solar Refrigerator Powered by Energy Storage System
,
M.Sc. Thesis
Sharif University of Technology
;
Samimi, Jalal
(Supervisor)
;
Vesaghi, Mohamd Ali
(Supervisor)
Abstract
Considering high potential of solar energy and exhaustibility of fossil fuels in Iran, using solar energy seems to be inevitable. But one of the main problems in the application of these systems is high investment and maintenance costs. So, in this thesis, suitable solution is presented for decreasing cost and optimizing of a solar absorption refrigerator based on developed energy model. This system consists of two CPC solar collectors and a thermal energy storage system using phase change materials that provides input energy to the generator of absorption refrigerator. The exergy efficiency of system components is calculated by relations of energy model and exergy analysis. Then...
Gas sweetening process optimization with economic, Exergy and Environmental criteria
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor) ; Bozorg Mehri, Ramin (Supervisor)
Abstract
In the present work, a comprehensive economic, environmental and exergy analysis and multi-objective optimization for gas sweetening plant are provided and the interaction between decision variables in these criterions is discussed. In the first part, potentials of three environmental features (global warming, acid rain, smog formation) of the operational plant are quantified and normalized using life cycle assessment (LCA) for both process waste and utility environmental impacts.Acid rain index is determined as the most important environmental impactindex in this unit. By choosing proper decision variables based on sensitivity analysis, LCA and EA results, optimization is performed to...
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
In the present work, a comprehensive economic, environmental and exergy analysis and multi-objective optimization for world’s largest aromatic plant are provided and the interaction between decision variables in these criterions is discussed. In the first part, potentials of seven environmental features of the operational plant are quantified and normalized using life cycle assessment (LCA) for both process waste and utility environmental impacts. Exergy analysis (EA) is also used to determine the lowest eco-efficiency equipment. By choosing proper decision variables based on sensitivity analysis, LCA and EA results, optimization is performed to determine the best design variables based on...
Energy and Economic Analysis of Micro CHP Systems in Buildings
, M.Sc. Thesis Sharif University of Technology ; Sattari, Sourena (Supervisor)
Abstract
In recent decades, due to economic, political and environmental issues, tend to use of the CHP systems (combined heating and power) have increased. CHP systems not only increase energy efficiency, but also decrease fuel consumption and emission levels of systems. The use of CHP technology in the industry has a long history, but the use of these systems in the commercial and residential sector, is considered, recently. As to the residential buildings, both electricity and thermal energy demands fluctuate seasonally and hourly, so it is necessary to take account of the plant’s annual operational strategies for the variations of load demands. In this paper, a nonlinear programming model is...
Energy and Exergy Analysis of a Turbocharged Three-Cylinder Spark Ignition Engine and the Use of a Vortex Tube to Recover the Exhaust
, M.Sc. Thesis Sharif University of Technology ; Kazemzadeh Hanani, Siamak (Supervisor) ; Chitsaz, Eiman (Supervisor)
Abstract
In this research energy and exergy Balance has been studied for a turbocharged three-cylinder engine. Energy balance is a method based on the first law of thermodynamics and based on this method the control volume is selected on the engine and the input and output energies of the control volume are calculated. Exergy balance is also a method based on the second law of thermodynamics which achieves the amount of irreversibility and ability to convert useful work for different energies in the control volume. In the tests performed, the net output power, output exhaust energy, energy transferred to the cooling fluid and other energies, including convection and radiation heat transfer from the...
Feasibility Study and Modelling of Using Absorption Refrigeration System for Recovering Heat in Oil and Gas Industry
, M.Sc. Thesis Sharif University of Technology ; Sattari, Sorena (Supervisor)
Abstract
By growing the global demand for energy and use the fosil fuel for it by knowing the issue of increase in their resourses؛ it’s important to use new technologies for these energies in an optimum way.
Most of industrial process uses a lot of thermal energy by burning fossil fuel to produce steam or heat for the purpose. One of the most important processes that use energy is refrigeration. After these processes, heat is rejected to the surrounding as waste. This waste heat can be converted to a useful refrigeration by using a heat operated refrigeration system, such as an absorption refrigeration cycle. This can be a useful pattern to improve thermal efficiency of process and reduce its...
Most of industrial process uses a lot of thermal energy by burning fossil fuel to produce steam or heat for the purpose. One of the most important processes that use energy is refrigeration. After these processes, heat is rejected to the surrounding as waste. This waste heat can be converted to a useful refrigeration by using a heat operated refrigeration system, such as an absorption refrigeration cycle. This can be a useful pattern to improve thermal efficiency of process and reduce its...
Exergy analysis of Airlift Systems: Experimental approach
, Article International Journal of Exergy ; Volume 8, Issue 4 , 2011 , Pages 407-424 ; 17428297 (ISSN) ; Ghanbarzadeh, S ; Saidi, M. H ; Sharif University of Technology
Abstract
Airlift Systems (ALS) are widely used in various industrial applications. As the main part of the flow through ALS's upriser pipe, is formed by gas-liquid flow, the analysis of such systems will be accompanied by problems of two-phase flow modelling. Several effective variables are involved in ALS; thereupon comprehensive method is needed to consider these parameters. Exergy analysis can be considered as a simple solution for the realisation of the preferred domain of ALS's operation. Here, this method has been proposed to examine the performance of ALS. Based on thermodynamic principles, an analytical model has been implemented in each phase and the respective experimental data have been...
Improvement of airlift pump performance based on the exergy analysis
, Article Proceedings of the 23rd International Conference on Efficiency, Cost, Optimization, Simulation, and Environmental Impact of Energy Systems, ECOS 2010, 14 June 2010 through 17 June 2010, Lausanne ; Volume 1 , 2010 , Pages 489-497 ; 9781456303006 (ISBN) ; Hanafizadeh, P ; Gholampour, P ; Shams, H ; Saidi, M. H ; Sharif University of Technology
Aabo Akademi University
2010
Abstract
Airlift systems (ALS) are widely used in various fields such as petroleum and oil extracting industries. As gas-liquid two phase flow is the main part of the flow through these systems, the analysis of such systems accompanies with problems of two phase flow modeling. However, exergy analysis could be a simple method for modeling of airlift systems. In the present study, an analytical model based on thermodynamic principles has been implemented on each phase to analyze the performance of airlift systems. The experimental data were collected at a large scale multiphase flow test rig for the airlift pump with 6m height and diameter of 50 mm. Finally, irreversibility terms, energy destruction,...
Optimal power generation from low concentration coal bed methane in Iran
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 38, Issue 4 , 2016 , Pages 590-596 ; 15567036 (ISSN) ; Fahimi, M ; Saboohi, Y ; Sharif University of Technology
Taylor and Francis Inc
2016
Abstract
Development of a model for optimal power generation from the thermal oxidation of a low concentration coal bed mine has been considered as the main objective of this investigation. The model has been applied to identify the optimal thermodynamic characteristics of the power generation system through using a mixture with 1.6% methane concentration in a recuperative lean-burn gas turbine and coupling a gas engine to the system for more power generation from the remaining coal bed methane. The implementation of the model based on the real site condition would lead to the generation of 6.97 MW electricity in Tabas coal mine of Iran. © 2016 Taylor & Francis
Energy and exergy analysis of intensified condensate stabilization unit with water draw pan
, Article Applied Thermal Engineering ; Volume 155 , 2019 , Pages 49-58 ; 13594311 (ISSN) ; Hosseini, S. H ; Ahmadi, G ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
An industrial condensate stabilizer unit is simulated with HYSYS 3.1 software when the excessive water is present on the trays. Effects of reboiler temperature, excess water flow rate, and incoming stream temperature on the Reid vapor pressure (RVP), temperature distribution along the column and impurity concentrations along the stabilization column, as well as, energy usage are studied. In addition, the optimal location for the water draw tray for the condensate stabilizer column is found. It is observed that the presence of water draw pan in the column leads to about 15% and 28% reduction, respectively, in the reboiler and the compressor duties compared to the industrial case without water...