Yazar "Ezgi, Cuneyt" seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Design and thermodynamic and thermoeconomic analysis of an organic Rankine cycle for naval surface ship applications(Pergamon-Elsevier Science Ltd, 2017) Girgin, Ibrahim; Ezgi, CuneytThis paper presents the thermodynamic modeling of an organic Rankine cycle (ORC) that uses waste exhaust energy of a 1000 kW diesel generator on a naval ship. Seven different working fluids have been selected as the ORC fluids. The commercial software (EES) has been used to predict the thermodynamic properties of the selected fluids. The efficiency of the ORC goes up to 32% with toluene. For the needed generator power of 500 kW on cruising, the ideal ORC can produce 118 kW power with the working fluid toluene. Assuming an isentropic efficiency for the turbine and the pump of the case ORC to be 0.75 and 0.20, respectively, and neglecting the losses at the ORC electric generator, the electric power output of the ORC cycle becomes 92 kW. The power of the diesel-ORC system becomes 592 kW while the combined efficiency is calculated as 0.349. The ORC saves 25,500 L of diesel fuel (US$24,870) and reduces 67.2 tons of CO2 emissions at the end of 1000 operating hours. ORC working fluids may result different efficiencies at different temperatures. Therefore, a combined ORC system is proposed to get higher efficiencies at different thermal loads. The exergy efficiencies and irreversibilities were calculated. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Experimental Analysis of a Laboratory-Scale Diesel Engine Exhaust Heat-Driven Absorption Refrigeration System as a Model for Naval Surface Ship Applications(Soc Naval Architects Marine Engineers, 2020) Ezgi, Cuneyt; Bayrak, SinemDecreasing industrial energy sources and major environmental problems caused by uncontrolled energy consumption have led to studies on alternative energy sources. This study presents a design and experimental analysis of an exhaust gas-driven absorption refrigeration system for the purpose of air conditioning by using the exhaust heat of a diesel engine, which is installed in the Naval Academy Mechanics Laboratory. The diesel engine is loaded with a dynamometer, and water and ammonia are used as an absorbent and refrigerant, respectively. At various diesel engine loads, cooling capacity and coefficient of performance (COP) of the absorption refrigeration system are calculated. Experimental results have indicated the cooling capacity as 1.098 kW at a maximum engine power of 4.9 HP. The highest COP value in the designed system has been calculated to be .3022 for the generator temperature of 160 degrees C. Although the COP of refrigeration is low, the absorption refrigeration system can be provided a great cooling load from the exhaust heat of diesel engines and can be used in naval surface ships. In addition to energy efficiency of naval surface ships, infrared and acoustic signature can be minimized and a ship's susceptibility can be dramatically reduced.Öğe Numerical Modeling of Hydrogen-Rich Gas Production From Gasoline Autothermal Reforming in a Plug Flow Reactor for Electric Vehicles(Asme, 2021) Kosa, Ergin; Ezgi, CuneytDue to the increase in the greenhouse effect, lowering emissions is becoming a certain issue all over the world. It is a concern to develop alternative options to minimize the spread of exhaust gases. For this purpose, in this study, the plug flow reactor in the system consisting of solid oxide fuel cell, reactor, electric motor, battery, burner, and the heat exchanger is considered. Numerical modeling of hydrogen gas generation in a plug flow reactor is studied. The reactor indicated on-board hydrogen gas generation for an electric motor automobile has not been modeled in the literature yet. Autothermal reforming of isooctane is simulated in the comsol multiphysics software program in the reactor particularly. Conversion of isooctane and H2O is examined at different overall heat transfer coefficients, input temperatures, and steam/carbon ratios. Also, there are certain differences between adiabatic and non-adiabatic conditions. The produced synthesis gas of hydrogen drastically increases in the non-adiabatic case. The obtained results from the model are compared with experimental data obtained from the literature. H-2 production at the end of the autothermal reforming process indicates that the power provided from the reactor can operate a motor of an automobile. In this study, the achieved power is 65.8 kW (88 HP) and is sufficient for an automobile. Simulation results show that the reactor volume of 75 L supplies 0.18 mol(-1) of H-2 and 0.08 mol(-1) of CO in the non-adiabatic case.Öğe Thermal Design of Double Pipe Heat Exchanger Used as an Oil Cooler in Ships: A Comparative Case Study(Soc Naval Architects Marine Engineers, 2019) Ezgi, Cuneyt; Akyol, OzgurDouble-pipe heat exchangers are devices that provide the transfer of thermal energy between two fluids at different temperatures. The major use of these heat exchangers is the sensible heating or cooling process of fluids where small heat transfer areas are required. The oil cooler is an example of these processes. In this study, fouled finned, clean finned, fouled unfinned, and clean unfinned double-pipe heat exchangers used as an oil cooler in ships have been compared. In thermal design, suggested different Nusselt number equations have been used, and the results of these equations have been shown in tables and figures. As a result, it is evaluated that using fouled finned double-pipe heat exchanger as oil cooler in ships is the most appropriate selection.Öğe Three-dimensional CFD modeling of a steam ejector(Taylor & Francis Inc, 2022) Atmaca, Mustafa; Ezgi, CuneytSteam ejectors are one of the key components of steam ejector refrigeration/heat pump systems. Steam ejector is required to compress low-pressure stream to a higher pressure. Steam ejectors have no moving part, a simple structure, low cost, reliability, easy installation, high vacuum performance, corrosion resistance, and no consumption of electrical energy. In this study, steam ejector design was modeled using finite volume techniques, and Mach number and pressure in constant cross-section have been compared with analytical data reported in the literature. In this work, numerical calculations were performed with ANSYS Fluent(ANSYS FLUENT Theory Guide, ANSYS, Inc. Release 17.2, 2016, Canonsburg, PA, USA), a computational fluid dynamic code. In the turbulent flow, heat transfer-based analyses were performed using energy equations.
