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Energy, exergy and thermoeconomic analysis of a combined cooling, heating and power (CCHP) system with gas turbine prime mover
, Article International Journal of Energy Research ; Volume 35, Issue 8 , June , 2011 , Pages 697-709 ; 0363907X (ISSN) ; Amidpour, M ; Karimkashi, S ; Rezayan, O ; Sharif University of Technology
2011
Abstract
In this paper energy, exergy and thermoeconomic analysis of a combined cooling, heating and power (CCHP) system has been performed. Applying the first and second laws of thermodynamics and economic analysis, simultaneously, has made a powerful tool for the analysis of energy systems such as CCHP systems. The system integrates air compressor, combustion chamber, gas turbine, dual pressure heat recovery steam generator (HRSG) and absorption chiller to produce cooling, heating and power. In fact, the first and second laws of thermodynamics are combined with thermoeconomic approaches. Next, computational analysis is performed to investigate the effects of below items on the fuel consumption,...
New turbulence modeling for simulation of Direct Contact Condensation in two-phase pressurized thermal shock
, Article Progress in Nuclear Energy ; Volume 108 , 2018 , Pages 358-371 ; 01491970 (ISSN) ; Ghofrani, M. B ; D'Auria, F ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Injection of Emergency Core Cooling System (ECCS) water into the primary loops of the Pressurized Water Reactors (PWRs) leads to rapid cooling of Reactor Pressure Vessel (RPV) inside wall after Loss Of Coolant Accident (LOCA). This condition, known as Pressurized Thermal Shock (PTS) intensifies the propagation of the RPV structural defects and would be considered as an ageing mechanism. For structural and fracture analysis of RPV wall, thermal-hydraulic analysis of PTS should be accomplished to obtain the steam/water flow characteristics in the downcomer. For this purpose, simulation of steam/water stratified flow (due to density difference) after the injection point should be done by...
Synthesis of a new self-supported Mgy(CuxNi0.6-xMn0.4)1-yFe2O4 oxygen carrier for chemical looping steam methane reforming process
, Article International Journal of Hydrogen Energy ; Volume 46, Issue 37 , 2021 , Pages 19397-19420 ; 03603199 (ISSN) ; Soltanieh, M ; Heydarinasab, A ; Maddah, B ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Novel self-supported Mgy(CuxNi0.6-xMn0.4)1-yFe2O4 with (y = 0, 0.05, 0.1, 0.15, and x = 0, 0.15, 0.3, 0.45, 0.6) oxygen carriers (OCs) are synthesized through the co-precipitation method. The synthesized OCs’ properties are characterized by X-ray powder diffraction (XRD), Raman spectra, transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and Thermogravimetric Analysis (TGA). The synthesized OCs are assessed in Chemical Looping Steam Methane Reforming (CL-SMR) process subject to different mesh sizes, reaction temperatures, Steam/Carbon...
Prediction of steam/water stratified flow characteristics in NPPs transients using SVM learning algorithm with combination of thermal-hydraulic model and new data mapping technique
, Article Annals of Nuclear Energy ; Volume 166 , 2022 ; 03064549 (ISSN) ; Ghafari, M ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Steam/water stratified flow would occur in transient condition (e.g. LOCA) in light water Nuclear Power Plants (NPPs). Due to high gradient of flow characteristics at the interface of steam/water flow, the prediction of flow characteristics (e.g. temperature, pressure, velocity, and Turbulent Kinetic Energy (TKE)) requires further attention and special interfacial models. Also, accurate simulation of these mentioned characteristics needs fine spatial mesh and very small time steps based on Computational Fluid Dynamics (CFD) standard criteria. In order to reduce the computational cost, the combination of thermal–hydraulic modelling and soft computing is considered as a new strategy in this...
Fabrication and Characterization of Graphene Oxide-based Flexible Humidity Sensor
, M.Sc. Thesis Sharif University of Technology ; Iraji Zad, Azam (Supervisor)
Abstract
In this research, room-temperature flexible humidity sensors using graphene oxide (GO) and partially reduced grapheme oxide (PRGO) are reported. Sensing layer was deposited onto Kapton substrate by spin coating method. Topography of the sensing layer was observed by Optical Microscopy, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). Partial reduction of the GO was confirmed by X-ray Diffraction (XRD) data. Humidity sensing properties of the samples that were annealed in different temperatures in the range of 125-200 were measured at room temperature. The sample which was reduced at 125 presented higher response about 106% and shorter recovery time of about 65 s....
Design of Steam Turbine Control Valves Seat on Site Machinning Robot
, M.Sc. Thesis Sharif University of Technology ; Durali, Mohammad (Supervisor)
Abstract
Designing a part of an on site repair system for refurbishing steam turbine high pressure control valve has been done in this project. The main role of this control valve is to control the input flow to the turbine in different working condition . However, due to high temperature and pressure, the seat is exposed to erosion. R epairing this part in workshop requires great amount of time and cost, because the valve is a part of the turbine body and must be cut and rewelded to the turbine body. S o using an on-site repair method is highly needed. In addition, due to the limited visibility and access to the valve seat, and accurate...
Reliability Evaluation of Heat Recovery Steam Generator of Combined Cycle Thermal Power Plants
, M.Sc. Thesis Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor) ; Kazemzadeh Hannani, Siamak (Supervisor)
Abstract
Combined cycle power plants consist of three main sections, namely gas turbine, Heat Recovery Steam Generator (HRSG) and steam turbine. Occurring failure in HRSG causes the steam turbine trip, so the reliability assessment of HRSG has a great importance for forecasting the probability of occurring failure and also reducing failure causes. In this project, the reliability of HRSG considering effects of aging phenomenon, maintenance and, environmental and operational conditions on reliability is modeled. Afterward a method to estimate the model parameters is introduced. Using present method, failure data of six HRSGs of a plant each with a capacity of 50 MW is analyzed and the model parameters...
Axial Turbine Performance Improvement Under Steam Injection
,
M.Sc. Thesis
Sharif University of Technology
;
Ghorbanian, Kaveh
(Supervisor)
Abstract
Steam Injection is one of the most effective methods to improve performance and emission reduction of a gas turbine engine. In this study, the effect of using steam injection on the performance of a mechanical drive gas turbine engine is simulated and power output, thermal efficiency, compressor surge margin, velocity field in axial turbine and turbine isentropic efficiency are examined. In the two-shaft configuration, turbine inlet temperature and gas generator spool speed are the two parameters limiting the output power. On the other hand, matching of compressor turbine and power turbine is an important task that affects the performance of engine under steam injection condition. Based on...
Preparation, Evaluation and Investigation of NiO-MgO-SiO2 Catalyst Deactivation in Propane Reforming
, Ph.D. Dissertation Sharif University of Technology ; Frahadi, Fathollah (Supervisor) ; Kazemeini, Mohammad (Supervisor) ; Rezaei, Mehran (Supervisor) ; Keshavarz, Ahmad Reza (Co-Supervisor)
Abstract
Synthesis gas (H2, CO) is widely used in chemical and petrochemical industries, utilized for methanol and ammonia production. Hydrogen is the main component of syngas which is considered as an appropriate alternative for fossil fuels. Catalytic steam reforming is one of the most common and economical pathway for syngas production. Light hydrocarbons such as propane which can easily be transported, stored and distributed, is a promising feed candidate for steam reforming. Catalyst deactivation along with low stability resulting from carbon formation and sintering is one of the main crucial problems in this process, leading to much research on the preparation of stable and coke resistant...
Simultaneous Analysis of Steam and Power Cogeneration in Tehran Refinery
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fatollah (Supervisor)
Abstract
Due to the increasing cost of energy, we want in this study to increase energy efficiency and reduce waste of system energy. Oil, gas and petrochemical sector is a widespeard part in Iran, so the study of energy systems in the industry have a paramount importance. The study focused on the Tehran refinery steam and power systems, seeking the most economical system of power and steam for the Tehran refinery. To achieve this goal, with the help of simulation of power and steam system for Tehran refinery with Aspen Utility software, a superstructure obtained. Then, using a sensitivity analysis, we were able to achieve economic arrangment of utility system. In this study by increasing the...
Simulator Development for Thermal Operation (Pre-heating) of SAGD Techniques
, M.Sc. Thesis Sharif University of Technology ; Pishvaie, Mahmoud Reza (Supervisor) ; Bozorgmehri, Ramin (Supervisor)
Abstract
This work describes the use of a two-dimensional numerical simulator for Steam Assisted Gravity Drainage (SAGD) using the model proposed by Coats et al with some improvements. Despite the Coats model this developed model accounts for capillary and gravity effects in the energy equation with a variable thermal conductivity of the formation. First, a sensitivity analysis is performed for SAGD process. Then, the simulator is used to describe the pre-heating process preceding SAGD. We studied two methods of preheating process and found that there exists an optimum method of preheating for any reservoir. We concluded that longer preheating period does not necessarily yield a faster recovery
A study of enhanced heavy oil recovery by two well cyclical steam assisted gravity drainage (TWC-SAGD) in conventional and fractured reservoirs
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Vol. 36, issue. 10 , Dec , 2014 , pp. 1065-1076 ; ISSN: 15567036 ; Bolouri, S. H ; Sharif University of Technology
Abstract
Steam-assisted gravity drainage is one of the most promising strategies to develop huge heavy oil and bitumen accumulations. Like the other thermal processes, this method aims at reducing oil viscosity by increasing the temperature. But in an economical point of view, it requires a great volume of steam for injection. Moreover, early breakthrough of steam and high steam-oil ratio makes it uneconomical, especially in long production time. In this study, a new method, two wells cyclical steam-assisted gravity drainage is compared with a conventional steam-assisted gravity drainage process. Well configuration in two wells cyclical steam-assisted gravity drainage is the same as the...
Developing of constructal theory concept to the total site cogeneration heat and power retrofit
, Article International Journal of Exergy ; Volume 17, Issue 2 , 2015 , Pages 171-191 ; 17428297 (ISSN) ; Amidpour, M ; Abbaspour, M ; Farzaneh, H ; Sharif University of Technology
Inderscience Enterprises Ltd
2015
Abstract
In this paper, a novel method of retrofit design in total site cogeneration systems based on constructal theory is presented. In this regard, the total site cogeneration system is decomposed into three constructs: turbines, turbine arrays, and steam generators. The objective function to be minimised is the total annual cost of existing total site. Using constructal theory simplifies the optimisation procedure of total site in addition to reaching better conceptual design especially in more sophisticated systems. A case study from literatures has been taken up to examine the applicability of the algorithm and excellent agreement has been observed. Copyright
Adaptive critic-based neurofuzzy controller for the steam generator water level
, Article IEEE Transactions on Nuclear Science ; Volume 55, Issue 3 , 2008 , Pages 1678-1685 ; 00189499 (ISSN) ; Boroushaki, M ; Sharif University of Technology
2008
Abstract
In this paper, an adaptive critic-based neurofuzzy controller is presented for water level regulation of nuclear steam generators. The problem has been of great concern for many years as the steam generator is a highly nonlinear system showing inverse response dynamics especially at low operating power levels. Fuzzy critic-based learning is a reinforcement learning method based on dynamic programming. The only information available for the critic agent is the system feedback which is interpreted as the last action the controller has performed in the previous state. The signal produced by the critic agent is used alongside the backpropagation of error algorithm to tune online conclusion parts...
Energy and exergy analysis of internal reforming solid oxide fuel cell-gas turbine hybrid system
, Article International Journal of Hydrogen Energy ; Volume 32, Issue 17 , December , 2007 , Pages 4591-4599 ; 03603199 (ISSN) ; Sharif University of Technology
2007
Abstract
The aim of this work is to analyze methane-fed internal reforming solid oxide fuel cell-gas turbine (IRSOFC-GT) power generation system based on the first and second law of thermodynamics. Exergy analysis is used to indicate the thermodynamic losses in each unit and to assess the work potentials of the streams of matter and of heat interactions. The system consists of a prereformer, a SOFC stack, a combustor, a turbine, a fuel compressor and air compressor, recuperators and a heat recovery steam generator (HRSG). A parametric study is also performed to evaluate the effect of various parameters such as fuel flow rate, air flow rate, temperature and pressure on system performance. © 2007...
Coke formation possibility during production of reducing gas in large scale direct reduction plant
, Article Ironmaking and Steelmaking ; Volume 34, Issue 2 , 2007 , Pages 115-123 ; 03019233 (ISSN) ; Vakhshouri, K ; Hashemi, M. M. Y. M ; Sharif University of Technology
2007
Abstract
For the production of synthesis gas utilised in Midrex direct reduction plants, catalytic steam/CO2 hydrocarbon reforming in tubular reformer is the major process. Owing to the high heat input through the Midrex reformer tube wall, the endothermic nature of reforming reactions, low mass velocity of feed gas and large tube diameter, the catalyst bed is exposed to considerable axial and radial temperature gradients. These radial concentration and temperature gradients may create local areas with potential for carbon formation. To investigate this phenomenon, a rigorous two-dimensional model is developed for simulating the operation of a Midrex reformer which applies a dual catalyst loading...
Selection of prime mover to meet heating demand of a single effect absorption chiller based on laws of thermodynamics
, Article SN Applied Sciences ; Volume 3, Issue 1 , 2021 ; 25233971 (ISSN) ; Saidi, M. H ; Najafi, M ; Aghanajafi, C ; Sharif University of Technology
Springer Nature
2021
Abstract
In this study the first and the second laws of thermodynamics are evaluated for a single effect absorption chiller. Entropy generation and COP are selected as the objective functions and their variations are studied by varying the generator temperature for various condensing temperatures. For this purpose, the enthalpy and the entropy data of the super-heated steam, saturated steam and the saturated water are formulated in the mathematical equations. Also to provide the required steam of generator, prime mover in the form of internal combustion engine is applied and its partial load conditions are analyzed. A residential tower is considered as the case study for selecting the proper prime...
A fully implicit single phase T-H-M fracture model for modelling hydraulic fracturing in oil sands
, Article Journal of Canadian Petroleum Technology ; Volume 43, Issue 6 , 2004 , Pages 35-44 ; 00219487 (ISSN) ; Chan, D. H ; Sharif University of Technology
Society of Petroleum Engineers (SPE)
2004
Abstract
Enhancing oil extraction from oil sands with a hydraulic fracturing technique has been widely used in practice. Due to the complexity of the actual process, modelling of hydraulic fracturing is far behind its application. Reproducing the effects of high pore pressure and high temperature, combined with, complex stress changes in the oil sand reservoir, requires a comprehensive numerical model which is capable of simulating the fracturing phenomenon. To capture all of these aspects in the problem, three partial differential equations, i.e., equilibrium, flow, and heat transfer, should be solved simultaneously in a fully implicit (coupled) manner. A fully coupled thermo-hydro-mechanical...
Optimal Model of Integrated Water Network to Reduce the Freshwater and Energy Consumption and Produce Wastewater at Power plant
, M.Sc. Thesis Sharif University of Technology ; Avami, Akram (Supervisor)
Abstract
In recent years, there has been the extensive researches on energy and water efficiency due to the increasing stress on these resources. Therefore, the water-energy nexus in large industries, especially power plants, has become very important. In the present study, the water and energy nexus has been analyzed using energy analysis tools, exergy, economic and environmental in a combined cycle power plant. The nexus are observed in the boiler blow-downs, leakage of steam traps, cooling of the air entering the compressor and injection of steam into the combustion chamber, which have been studied in different scenarios to improve water and energy consumption and reduce environmental impact. In...
Solar generated steam injection in HAMCA, Venezuelan extra heavy oil reservoir; Simulation study for oil recovery performance, economical and environmental feasibilities
, Article EUROPEC 2015, 1 June 2015 through 4 June 2015 ; 2015 , Pages 1176-1202 ; 9781510811621 (ISBN) ; Ayatollahi, S ; Bashtani, F ; Romero, C ; Sharif University of Technology
Society of Petroleum Engineers
2015
Abstract
Application of solar energy compared to conventional gas-burning boilers for steam generation in thermal Enhanced Oil Recovery processes is a newly attended technology, which brings significant benefits to the petroleum industry through environmental and economical aspects. This technique is especially designed for the regions in which gas-burning steam generation is not viable in large scale. The objective of this study is to investigate about viability of using solar energy to generate steam instead of using conventional steam generators in a Venezuelan extra heavy oil reservoir. Limited gas production policy of the Venezuelan government is the major challenge for utilizing gas steam...