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exergy-efficiency
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Optimal Model of Energy and Exergy of Iran’s Economic Activities and their Impact on the Environment
, M.Sc. Thesis Sharif University of Technology ; Saboohi, Yadollah (Supervisor)
Abstract
The economic activities in a country involved with depletion of natural resources and emission of pollutants and gases to the environment. Depletion of exhaustible resources and environmental pollutions are two determinants of sustainability of development. The present research work is aimed at studying the sustainability of Iranian economy in 2009. The analysis of sustainable development of economy is based the concept of exergy, exergy efficiency and ecological exergy efficiency. Exergy efficiency is the ratio of the exergy of a product in economic activity to the exergy of input streams to that section of economy. Ecological exergy efficiency is defined as the ratio of exergy of product...
Performance analysis and multi-objective optimization of an organic Rankine cycle with binary zeotropic working fluid employing modified artificial bee colony algorithm
, Article Journal of Thermal Analysis and Calorimetry ; 2018 ; 13886150 (ISSN) ; Maghsoudi, P ; Shabani, B ; Gorgani, H. H ; Shabani, N ; Sharif University of Technology
Springer Netherlands
2018
Abstract
From a thermal point of view, zeotropic mixtures are likely to be more efficient than azeotropic fluids in low-temperature power cycles for reduction in exergy destruction occurring during heat absorption/rejection processes due to their suitable boiling characteristics. In this study, comprehensive energetic and exergetic analyses are mathematically performed for an organic Rankine cycle (ORC) system employing a potential binary zeotropic working fluid, namely R717/water. For this purpose, initially mass, energy, and exergy balance equations are derived. With regard to the similarity in molar mass of R717 (17.03 g mol−1) and water (18.01 g mol−1), there is no need to alter the size of the...
Performance analysis and multi-objective optimization of an organic Rankine cycle with binary zeotropic working fluid employing modified artificial bee colony algorithm
, Article Journal of Thermal Analysis and Calorimetry ; Volume 136, Issue 4 , 2019 , Pages 1645-1665 ; 13886150 (ISSN) ; Maghsoudi, P ; Shabani, B ; Gorgani, H. H ; Shabani, N ; Sharif University of Technology
Springer Netherlands
2019
Abstract
From a thermal point of view, zeotropic mixtures are likely to be more efficient than azeotropic fluids in low-temperature power cycles for reduction in exergy destruction occurring during heat absorption/rejection processes due to their suitable boiling characteristics. In this study, comprehensive energetic and exergetic analyses are mathematically performed for an organic Rankine cycle (ORC) system employing a potential binary zeotropic working fluid, namely R717/water. For this purpose, initially mass, energy, and exergy balance equations are derived. With regard to the similarity in molar mass of R717 (17.03 g mol −1 ) and water (18.01 g mol −1 ), there is no need to alter the size of...
Exergy analysis and thermodynamic optimisation of a steam power plant-based Rankine cycle system using intelligent optimisation algorithms
, Article Australian Journal of Mechanical Engineering ; 2019 ; 14484846 (ISSN) ; Assareh, E ; Moltames, R ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
In this paper, exergy analysis of a steam power plant located in southern Iran named Zarand power plant has been studied. In order to optimize the performance of the Rankine cycle and achieve higher exergy efficiency, several parameters have been considered as decision variables. Knowing that there is the ability to change some of the parameters in the specific range in the process of electricity production in power plant, temperature and output pressure of the boiler and output pressure of four steps of extraction turbine have been selected as six decision variables. Also, exergy efficiency has been considered as the objective function. For this purpose, the exergy efficiency of the system...
Exergy analysis of a flat plate solar collector in combination with heat pipe
, Article International Journal of Environmental Research ; Vol. 8, Issue. 1 , 2014 , Pages 39-48 ; ISSN: 17356865 ; Shafii, M. B ; Rahni, M. T ; Abbaspour, M ; Sharif University of Technology
Abstract
The use of solar collectors in combination with heat pipes is rapidly growing in recent years. Heat pipes, as heat transfer components, have undeniable advantages in comparison with other alternatives. The most important advantage is their high rate of heat transfer at minor temperature differences. Although there have been numerous studies on the heat analysis or first thermodynamic analysis of flat plate solar collectors in combination with heat pipes, the exergy analysis of these collectors is needed to be investigated. In this work, energy and exergy analysis of a flat plate solar collector with a heat pipe is conducted theoretically. Next, the exergy efficiency of pulsating heat pipe...
Investigation of the performance of modified organic Rankine cycles (ORCs) and modified trilateral flash cycles (TFCs) assisted by a solar pond
, Article Solar Energy ; Volume 182 , 2019 , Pages 361-381 ; 0038092X (ISSN) ; Akbari, A ; Khalilian, M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Solar pond is a type of solar collector that stores solar energy in the form of heat. The solar pond can be used as a low-temperature heat source for electricity generation. In this paper, to find the most suitable power cycle for power generation from the solar pond, the performance of the Organic Rankine Cycle (ORC), Trilateral Flash Cycle (TFC) and their modified forms with an open feed liquid heater and an internal heat exchanger for different working fluids was investigated. Water was considered as the heat transfer fluid which transfers the stored heat from the solar pond to the working fluid of the cycle. The results indicate that in all cases, the energy and exergy efficiency of the...
An Economic Approach To Study & Optimization of Helium liquefier
, M.Sc. Thesis Sharif University of Technology ; Afshin, Hossein (Supervisor)
Abstract
Gas liquefaction is one of the main applications of Cryogenics science. Due to the unique properties of Helium, it is a strategic product in the world. Therefore, appropriate and applicable analysis should be used to investigate and optimize the Helium liquefaction cycles. In the current study, the goal is to find the optimal point with the help of energy and exergy analysis based on economic criterion, for the various parameters of Collins’ cycle. In order to simulate the cycle, a computer code is developed. First, sensitivity analysis of different parameters affecting the exergy efficiency and liquid fraction of the cycle has been done. Then, Artificial Neural Network and Genetic Algorithm...
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...
Multi-objective thermoeconomic optimisation for combined-cycle power plant using particle swarm optimisation and compared with two approaches: An application
, Article International Journal of Exergy ; Volume 16, Issue 4 , 2015 , Pages 430-463 ; 17428297 (ISSN) ; Fani, M ; Farhanieh, B ; Abbaspour, M ; Sharif University of Technology
Inderscience Enterprises Ltd
2015
Abstract
This paper shows a new possible way with particle swarm optimisation (PSO) to achieve an exergoeconomic optimisation of combinedcycle power plants. The optimisation has been done using a classic exergoeconomic and genetic algorithm, and the effects of using three methods are investigated and compared. The design data of an existing plant is used for the present analysis. Two different objective functions are proposed: One minimises the total cost of production per unit of output, and maximises the total exergetic efficiency. The analysis shows that the total cost of production per unit of output is 2%, 3%and 5% lower and exergy efficiency is 4%, 8% and 6% higher with respect to the base case...
Exergy analysis of parabolic trough solar collectors using Al2O3/synthetic oil nanofluid
, Article Solar Energy ; Volume 173 , 2018 , Pages 1236-1247 ; 0038092X (ISSN) ; Shamloo, A ; Kazemzadeh Hannani, S ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Parabolic trough solar collector (PTC) is one of the most mature and widely used type of solar energy harnessing devices. Therefore, investigation of the effect of various operational conditions on the overall efficiency of these devices has been topic of substantial interest in the recent decade. Moreover, utilization of nanoparticles as a useful additive to the working fluid should be examined thoroughly to optimize the collector's outputs. To do so, in the present study, energy and exergy efficiencies of a typical PTC as a function of several involving parameters are numerically calculated. These parameters are nanoparticle volume fraction (from 0 to 5 percent), environment wind speed...
Magnetic-induced nanoparticles and rotary tubes for energetic and exergetic performance improvement of compact heat exchangers
, Article Powder Technology ; Volume 377 , 2021 , Pages 396-414 ; 00325910 (ISSN) ; Rostamzadeh, H ; Bezaatpour, J ; Ebadollahi, M ; Sharif University of Technology
Elsevier B.V
2021
Abstract
In the present study, the effects of rotary tubes and magnetic-induced nanofluid on heat transfer characteristics of a compact heat exchanger are individually investigated. Two-phase Eulerian model is employed to predict the hydrothermal and entropic characteristics of Fe3O4/water ferrofluid in the heat exchanger. Results indicate that utilizing each rotary tubes and magnetic field method can improve the energy and exergy efficiencies of the compact heat exchanger under specific circumstances by forming different types of secondary flow. It is found that employing each method individually can increase the maximum heat transfer rate by more than 60%. In comparison with methods like passive...
Exergy analysis of waste heat recovery section in steam-natural gas reforming process
, Article Energy and Fuels ; Volume 29, Issue 5 , April , 2015 , Pages 3322-3327 ; 08870624 (ISSN) ; Farhadi, F ; Sharif University of Technology
American Chemical Society
2015
Abstract
In this work, an exergy analysis is performed for the waste heat recovery section (WHRS) of the steam-natural gas reforming (SNGR) process as a major energy intensive process. Two alternate conditions are investigated to evaluate the required thermodynamic parameters: normal operating condition and increase of C2 + components in the process feed stream. At normal operating condition, the exergy efficiency of WHRS amounts to 0.58 while some 17.2 kJ energy is destructed for each mole of H2 produced. If heavier than methane components are increased in the feed up to 8.5 mole %, despite the increase of H2 production, the exergy efficiency decreases down to 0.54...
A new biogas-fueled bi-evaporator electricity/cooling cogeneration system: Exergoeconomic optimization
, Article Energy Conversion and Management ; Volume 196 , 2019 , Pages 1193-1207 ; 01968904 (ISSN) ; Vajdi, M ; Rostamzadeh, H ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
An innovative bi-evaporator electricity/cooling cogeneration system fueled by biogas is introduced. The plausibility of the introduced integrated power plant is examined from thermodynamic and economic vantage points. Later, single- and multi-objective optimization of the reckoned system are achieved by selecting appropriate parameters as decision variables and thermal and exergy efficiencies and total unit product cost (TUPC) of the system as objective functions. Four optimum modes of thermal efficiency optimum design (TEOD), exergy efficiency optimum design (EEOD), cost optimum design (COD), and multi-objective optimum design (MOOD) are selected for optimization and the attained results...
Multi-objective optimal design of gas-fired heater based on modified design model of fired heater taking into account exergy, economic and environmental factors
, Article International Journal of Engineering, Transactions A: Basics ; Volume 34, Issue 7 , 2021 , Pages 1785-1798 ; 17281431 (ISSN) ; Rezaei, F ; Saboohi, Y ; Sassani, F ; Sharif University of Technology
Materials and Energy Research Center
2021
Abstract
Heaters are one of the central parts of natural gas reduction stations using turboexpanders to prevent the formation of hydrate and corrosion failure. This study intends to design a fired heater by applying a combustion sub-model to derive an optimal model for this kind of application. This model is developed to accurately consider all subsections of the fired heater namely radiation, convection, and shield sections, as well as flue gas composition, and its volume. Within this context, a multi-objective optimization is employed to identify the optimal design of the gas-fired heater in the natural gas reduction station for the Ramin power plant case study. The total economic and environmental...
Multi objective optimization of an irreversible thermoelectric heat pump using evolutionary algorithms and response surface method
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; 2021 ; 15567036 (ISSN) ; Assareh, E ; Erfani, A ; Alirahmi, M ; Jafarinejad, T ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
In this study, modeling of an irreversible thermoelectric heat pump was conducted, and its performance was assessed in terms of exergy for 10, 20, 30 and 40 K difference in temperature (∆T) by changing the values of the design parameters. By employing this model, positive impact of increasing cross-section area, current and thermocouple’s length which in turn increases the exergy efficiency is realized. In addition, diminishing adverse impact of adding more thermocouples on the exergy efficiency of the system is illustrated. Afterward, exergoeconomic performance of the thermoelectric heat pump is evaluated. Then, exergoeconomic factor for each of the system’s components is diagnosed. The...
Indirect mechanical heat pump assisted humidification-dehumidification desalination systems
, Article International Journal of Energy Research ; Volume 45, Issue 11 , 2021 , Pages 15892-15920 ; 0363907X (ISSN) ; Sharif University of Technology
John Wiley and Sons Ltd
2021
Abstract
In this study, four new indirect heat pump assisted mechanical vapor compression humidification-dehumidification (HDH) systems are proposed and their superiorities over the reference system are demonstrated from thermodynamics and thermoeconomics viewpoints. The proposed models are configured based on an HDH unit and a simple cascade heat pump, an HDH unit and a heat pump with an ejector, an HDH unit and a cascade heat pump with an ejector, and an HDH unit and a vapor injection heat pump. Although employing a heat pump with cascade and ejector configurations improved gain-output-ratio (GOR) and specific power consumption (SPC) values in comparison with the base system, the performance...
Energy and exergy analyses of an integrated gas turbine thermoacoustic engine
, Article Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy ; Volume 225, Issue 4 , June , 2011 , Pages 389-402 ; 09576509 (ISSN) ; Ghorbanian, K ; Gholamrezaei, M ; Sharif University of Technology
2011
Abstract
In this article, an attempt is made to utilize the exhaust gases of a small gas turbine to augment power output through the employment of a thermoacoustic system. A simple gas turbine cycle is selected as the base cycle and it is assumed that the thermoacoustic system is powered only by the waste heat of the base gas turbine. A comprehensive cycle analysis of the integrated gas turbine thermoacoustic engine (IGTTE) is carried out from an energy and exergy point of view. Exergy efficiency and internal exergy efficiency are calculated for the different components of the base gas turbine engine as well as the IGTTE. Value and exergy flow diagrams are used to investigate the possible...
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...
Alternative biomass fuels consideration exergy and power analysis for hybrid system includes PSOFC and GT integration
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 37, Issue 18 , Sep , 2015 , Pages 1962-1970 ; 15567036 (ISSN) ; Ghadamian, H ; Roshandel, R ; Moghadasi, M ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
The present study aims to analyze a combined heat and power (CHP) system with an approach towards exergy analysis and employing biomass gasification. The cycle modeling was carried out using Cycle-Tempo and the main purpose was to achieve parametric analysis of the model. The systems function was studied by categorizing alternative biomass fuels, also qualitative and quantitative analyses of the biomass fuel samples were presented and considering the trade-off points, most appropriate biomass fuel with respect to exergy efficiency and delivered power were determined. The results indicated that the bagasse and wood chips had the total exergy efficiency of 54.5 and 57.1% in trade-off point,...
Exergic, economic and environmental impacts of natural gas and diesel in operation of combined cycle power plants
, Article Energy Conversion and Management ; Volume 109 , 2016 , Pages 103-112 ; 01968904 (ISSN) ; Joda, F ; Bozorgmehry Boozarjomehry, R ; Sharif University of Technology
Elsevier Ltd
Abstract
Combined cycle power plants (CCPPs) play an important role in electricity production throughout the world. Their energy efficiency is relatively high and their production rates of greenhouse gases are considerably low. In a country like Iran with huge oil and gas resources, most CCPP's use natural gas as primary fuel and diesel as secondary fuel. In this study, effect of using diesel instead of natural gas for a selected power plant will be investigated in terms of exergy, economic and environmental impacts. The environmental evaluation is performed using life cycle assessment (LCA). In the second step, the operation of the plant will be optimized using exergy and economic objective...