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transient-model
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Transient modeling of dual fuel catalytic converter
, Article Iranian Journal of Science and Technology, Transaction B: Technology ; Volume 27, Issue 2 , 2003 , Pages 291-298 ; 03601307 (ISSN) ; Kazemeini, M ; Badakhshan, A ; Soltanieh, M ; Estiri, M ; Sharif University of Technology
2003
Abstract
Exhaust gas emissions from mobile sources and its importance in urban pollution have currently attracted lots of interests towards studying on alternative fuel systems for road vehicles usage. One of the best replacements is the natural gas/diesel dual fuel, which offers an alternative to standard compression-ignition diesel engines. In the dual fuel system the primary fuel is natural gas, which may replace as much as 90% of the diesel fuel with a small amount of diesel fuel required ensuring effective ignition. Methane, the main constituent of natural gas, has high combustion efficiency. Dual fuel engines produce lower NOx emissions and fewer particulates. However, at moderate engine loads,...
Numerical Modeling of Fuel Droplet Vaporization in Gas Phase at Supercritical Conditions
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
The study of evaporation of fuel droplet and determination of the rate of vaporization are important in designing combustion chambers. For achieving high performance of a combustor, the evaporation of fuel droplets takes place within a high pressure environment. At these conditions, the use of low-pressure models is not appropriate and many effects that are assumed negligible at low ambient pressures become very important. For example, the solubility of the ambient gas into the liquid phase is increased by increasing the ambient pressure. In addition, the ideal gas assumption is not valid for these conditions and one should use an appropriate equation of state (EOS) that can predict the...
Gas Turbine Simulator Design for Dynamic Modeling
, M.Sc. Thesis Sharif University of Technology ;
Abstract
In order to observe natural gas turbine phenomena and predicting engine behavior, we need to have a comprehensive simulator in every engine phase of design and analysis. Because of the high cost of manufacturing and prototype experimental tests, it's beneficial to access a gas turbine engine simulator. As well it's hard to make change in a manufactured engine, while we can change a simulator easily.Gas turbine is simulating in zero, one, two and three dimensions. In this project, we have studied previous researches and according to problem, among all simulations, we have studied the ATEC simulation and its assumptions in this thesis. Of these, zero and one dimensional simulations are simpler...
Modeling of Liquid-Vapor Two Phase Flow through Nozzle
, M.Sc. Thesis Sharif University of Technology ; Nouri Borujerdi, Ali (Supervisor)
Abstract
This thesis is about modeling of liquid-vapor two phase flows through nozzle. Liquid-vapor two phase flow is very applicable in industries such as boilers, expansion valves, refrigeration and sudden failures in pipelines. Two models are used for modeling of fluid flow through nozzle, transient and steady state. In Both model the solution field is considered as saturated liquid and vapor and the mass, momentum and energy equations as well as equation of state is used for describing of fluid flow properties. Homogeneous equilibrium model is used and for complete modeling of fluid flow heat transfer and friction force is also considered.
Numerical solutions are used for solving of the...
Numerical solutions are used for solving of the...
Dme direct synthesis from syngas in a large-scale three-phase slurry bubble column reactor: transient modeling
, Article Chemical Engineering Communications ; Vol. 201, issue. 5 , Nov , 2014 , pp. 612-634 ; ISSN: 00986445 ; Kazemeini, M ; Fattahi, M ; Fatahi, M ; Sharif University of Technology
Abstract
In this research, a new transient mathematical model based upon tanks-in-series configuration was developed to simulate the direct synthesis of dimethyl ether (DME) from syngas in a commercial-scale slurry bubble column reactor. A comparison between the simulation results and experimental data showed that the applied model might acceptably describe the behavior of the slurry reactor. Furthermore, simulation results in the heterogeneous bubble flow regime indicated that the proposed model with 10 tanks-in-series provided the optimum condition. Utilizing this transient model and considering catalyst deactivation, the effect of operating conditions on DME productivity and CO conversion were...
A transient model of vanadium redox flow battery
, Article Mechanics and Industry ; Volume 17, Issue 4 , 2016 ; 22577777 (ISSN) ; Elyasi, S ; Sharif University of Technology
EDP Sciences
2016
Abstract
It has been attempted to gain a new viewpoint in transient cell modeling of vanadium redox flow battery. This has been achieved by considering electrochemical relations along with conceptual electrical circuit of this kind of battery. The redox flow battery is one of the best rechargeable batteries because of its capability to average loads and output power sources. A model of transient behavior is presented in this paper. The transient features are considered as the most remarkable characteristics of the battery. The chemical reactions, fluid flow, and electrical circuit of the structure govern the dynamics. The transient behavior of the redox flow battery based on chemical reactions is...
Evaluation of a transient borehole heat exchanger model in dynamic simulation of a ground source heat pump system
, Article Energy ; Volume 147 , March , 2018 , Pages 81-93 ; 03605442 (ISSN) ; Abbaspour, M ; Saidi, M. H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The performance of a vertical ground source heat pump system (GSHPS) largely depends on the fluid temperature leaving the borehole heat exchanger (BHE) that may be affected by the short-term behavior of the BHE. Although considerable research has been carried out to analyze the short-term transient response of the BHEs, few studies have investigated its impact on dynamic simulation of GSHPS. Therefore, this paper presents a numerical approach based on a transient BHE model to evaluate the performance of a residential GSHPS over short and long timescales. The numerical results are compared with the results of EnergyPlus software. It is shown that the proposed model can appropriately predict...
A year-round study of a photovoltaic thermal system integrated with phase change material in Shanghai using transient model
, Article Energy Conversion and Management ; Volume 210 , 2020 ; Salari, A ; Ma, T ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In the study, the daily and monthly performance of a photovoltaic thermal system integrated with phase change material is investigated in Shanghai, China. A three-dimensional model of photovoltaic thermal system integrated with phase change material system is developed and numerically simulated. Water is considered as working fluid, and the fluid flow regime is laminar and incompressible. Both quasi-steady and transient models are compared together, and the transient model is selected because of its higher accuracy. Validation analysis is performed on the numerical model to show the reasonable agreement of current research compared to some other research. After obtaining the suitable...
A non-isothermal, transient model of a non-catalytic reaction in a packed bed with a multi-component high-temperature gas mixture
, Article 3rd M.I.T. Conference on Computational Fluid and Solid Mechanics, Boston, MA, 14 June 2005 through 17 June 2005 ; 2005 , Pages 1023-1025 ; 0080444814 (ISBN); 9780080444819 (ISBN) ; Saboohi, Y ; Sharif University of Technology
2005
Abstract
A mathematical model has been developed to simulate heterogeneous reactions with a complex set of physicochemical and thermal phenomena in a packed bed. These include the chemical reaction itself, the transport of gaseous species in the pores, the generation or consumption of heat by the reactions, and the transport of heat in the porous domain. Solution of complicated sets of governing equations is based upon the concept of a finite volume fully implicit approach. The model has then been applied to analyze the reduction of a hematite pellet in a moving packed bed reactor. © 2005 Elsevier Ltd