Tez Yöneticisi: Prof. Dr. Melda Ö. ÇARPINLIOĞLU
Yardımcı Tez Yöneticisi: Prof. Dr. M. Yaşar GÜNDOĞDU
Ekim 2011
Bu çalışmada, sinüzoidal darbeli boru akımında türbülansa geçişin tespiti ve geçiş başlangıcındaki akım dinamiği incelenmiştir. Deneysel çalışma 1019≤Reta≤4817 ve 107≤Reos≤4261 zaman ortalamalı Reynolds sayısı ve salınımlı Reynolds sayısı aralıklarında yapılmıştır. 0.05≤A1≤0.96 aralığındaki hız genliği oranı ve 2.72≤√ω´≤32.21 aralığındaki Womersley sayısına denk düşen 0.1 Hz≤ f≤14 Hz aralığındaki salınım frekansı darbeli akışın “intermediate” bölgesini kapsamaktadır. Darbeli akışın üretimi ve kontrolü, ölçülen verinin toplanması ve işlenmesi, ve akım dinamiğinin analizleri LabView 2009-SP1 yazılım programı içerisinde tasarlanmış program, TDFC.vi ile gerçekleştirilmiştir.
Literatürde bahsedilen hız dalga profilleri üzerinden görsel gözlemler ile türbülansa geçişin tespiti yerine özgün bir türbülansa geçiş tespit metodu TDFC.vi içerisinde tasarlanmıştır. İki boyutsuz, dinamik türbülans tespit parametresi, , f ≤ 1 Hz için R(dU(r,t)/dt)2 /(Utav ω2) ve f > 1 Hz için (dU(r,t)/dt)2/(Uta2ω2) tanımlanmıştır. Bundan başka, iki boyutsuz, dinamik eşik değişkeni, , f ≤1 Hz için (1/√ω´)n (n=| f |) ve f > 1 Hz için (1/√ω´)4, √ω´ parametresinin fonksiyonu şeklinde tanımlanmıştır. Türbülansa geçişin başlangıcının tespiti ve değişkenlerinin kıyaslanması esasına dayalıdır.
√ω´≤8.61 ve √ω´>8.61 için akım dinamiklerinde belirgin bir farkın olduğu sonucu çıkarılmıştır. Şöyle ki, türbülansa geçişin başlangıcında, √ω´≤8.61 için A1’in Reta üzerinde fark edilir etkisinin olmasına rağmen, √ω´>8.61 için A1’in Reta üzerinde etkisi gözlemlenmemiştir. Türbülansa geçiş başlangıcında A1>0.30 için √ω´’nın Reta üzerinde kayda değer etkisinin gözlemlenmesine rağmen, A1=0.10 ve A1=0.20 için Reta üzerinde √ω´’nın etkisi yoktur.
Anahtar Kelimeler: Darbeli akış, laminardan türbülansa geçiş, zaman ortalamalı Reynolds sayısı, salınımlı Reynolds sayısı, Womersley sayısı, hız genliği oranı, salınım frekansı.
Tez Yöneticisi: Prof. Dr. Melda Ö. ÇARPINLIOĞLU
Kasım 2006
Bu tezde, farklı geometrik ve fiziksel özelliklere sahip olan paketli yataklar üzerinde akım dinamiğine yönelik sistematik bir deneysel çalışma sunulmaktadır.
Geometrik paket özelliklerinin etkilerini belirlemek için 16 farklı paketli yatak kullanılmıştır. Uygulanan paket uzunluğunun paket çapına olan oranı L/D, 0.242≤L/D≤1.456 arasındadır. Uygulanan paket çapının paket malzemesi ortalama çapına oranı D/d, 5.72≤D/d≤17.16 arasındadır. Paket malzemesi ortalama çapının paket uzunluğuna oranı d/L, 0.040035≤d/L≤0.722378 arasında ve paketli yatak boşluk kesit oranı;ε, 0.36≤ε≤0.56 arasında kalmıştır.
Deneysel çalışmada, kullanılan paket malzemeleri nohut, iki farklı ölçüde zeolite taşı ve cam bilyedir. Bu paket malzemeleri paketli yatağın içerisine rasgele şekilde yerleştirilmiştir. 6 mm≤d≤18 mm aralığını içeren paket malzeme ortalama çapı, 640 kg/m3≤ρ≤2675 kg/m3 aralığını içeren paket malzeme yoğunluğu, 0.55≤Φ≤1.0 aralığını içeren küresellik şeklinde geometrik ve fiziksel özellikleri içeren paket malzemeleri kullanılmıştır.
Gerçekleştirilen 64 ayrı testte, 15000≤Re≤33000 aralığındaki akım Reynolds sayısı ve 708.2≤Rep≤7772.73 aralığındaki parçacık Reynolds sayısı için basınç kaybı ölçümleri, kesit çıkış hızı dağılımı ölçümleri ve sürtünme katsayısı hesaplamaları yapılmıştır. Ölçülen basınç kayıpları, ΔPBed, Ergun denklemi, ΔPErgun ile kıyaslanmıştır. ΔPBed/ΔPErgun oranı 0.8≤ΔPBed/ΔPErgun≤1.25 aralığında bulunmuştur. Deneysel veriler ayrıca eş ilişkiler halinde tanımlanan orijinal boyutsuz parametreler cinsinden sunulmuştur. Bu doğrultuda, ΔP*, ΔPBed/ΔPEmpty, Reexit parametreleri tanımlanmıştır. ͞u
Deneysel veriler ΔP* ile d/L, ΔP* ile Rep(d/L), ΔP* ile εRep(d/L), ΔPBed/ΔPEmpty ile Rep(d/L) ve son olarak Rep ile Reexit içeren birimsiz parametrelerle de verilmiştir. Bu eş ilişkiler deneysel çalışmanın kapsadığı paketli yatak değişkenleri ve özellikle Rep aralıklarında geçerli olup pratikte kolaylık sağlamaktadır.
Anahtar Kelimeler; Paketli Yataklar, Basınç Kaybı, Ergun Denklemi, Akım Reynolds Sayısı, Partikül Reynolds Sayısı, Çıkış Reynolds Sayısı, Sürtünme Katsayısı, Boşluk Kesit Oranı, Küresellik, Paket Malzeme Yoğunluğu, Paket Malzeme Ortalama Çapı.
Tez Konusu: An Investigation of Renewable Energy Potential of Municipal Biodegradable Solid Waste Plants in Frame of Thermodynamic, Thermoeconomic Analysis and Optimization and Developing Sustainable Models Using Zero Waste Approach
Başlangıç/Bitiş: 2014/-
The main aim of this thesis is to be able to figure out a sustainable and environmentally friendly waste management policy which can be applied to all solid waste storage, biogas and cogeneration plants in Turkey, by determining the optimum energy recovery strategies that can be integrated to current facilities. In the scope of the proposed models, increasing the energy recovery potentials of current solid waste storage facilities and reducing the environmental emissions are aimed to contribute to health of both human and environment by means of a rational zero waste management strategy.
Zero waste approach is based on reassessment of wastes and in this way, minimization of damage of wastes on the environment by increasing energy recovery potential of current systems. The first step of zero waste management is to be able to figure out all waste constituents in waste elimination facility and also how to eliminate these wastes in order to perform an adequate environmental management. The second step is to integrate the appropriate proposed energy recovery models to current systems according to the present waste elimination techniques. At last step, recovered energy is provided for usage in waste storage plants and/or in energy dense sectors. Zero waste approach can be evaluated as a management style which provides a favorable cost gain with low payback period and increases the current operational efficiency of the facility in long term.
In accordance with the modeling, analyses and assessments to be performed in this study, the energy recovery potential from solid waste in Turkey are presented; the place and importance of energy from waste among other renewable energy sources are emphasized; and lastly, a rational strategy is developed by means of the proposed models in order to apply zero waste approach to current facilities.
In this thesis, first, thermodynamic and thermoeconomic analyses and optimization of Gaziantep Metropolitan Municipality Solid Waste Storage, Biogas and Cogeneration Plant are performed using its operational and economic data. Then, energy recovery models in the frame of zero waste approach are proposed using available waste heat sources of the current plant. After the detailed simulation studies of the proposed models, comparative thermodynamic and thermoeconomic analyses and optimization are done. Simulation and optimization studies to be performed in this thesis are done by using ASPEN One-Tech 8.4 Pro Program and Genetic Algorithm in Matlab.
Tez Konusu: An experimental study on drying of food materials in a fluidized bed dryer
Başlangıç/Bitiş: 2011/2013
The aim of the thesis is to design, product and automatically control of a fluidized bed dryer which operates under both atmospheric and vacuum pressures optionally. Therefore the drying performance and efficiency are investigated in terms of the experimental data such as air velocity, temperature, moisture content, drying time and rate.
The experimental data are used for prediction of minimum fluidization velocity, pressure drop, etc. by proposing the empirical correlations. The obtained experimental data are compared with some available data in the literature and also with the mathematical expressions.
In this thesis, a fluidized bed dryer system also under the vacuum pressure is utilized to eliminate above mentioned problems. The advantages and disadvantages of the fluidized bed dryer optionally operated under both atmospheric and vacuum pressures are researched by taking into consideration of their performances. As a result of the comprehensive literature survey, it can be deduced that there are still many gaps in the research study on fluidized bed dryer at both atmospheric and especially vacuum (reduced pressure) pressures.
Until now, many studies are related with the fluidized bed dryers operated under atmospheric pressures. However, there are many difficulties for the usage of this type of dryers especially in the food and pharmaceutical industries due to the need of high operating temperature. By means of investigation on the dryers operating under vacuum pressure, the positive contribution is satisfied to minimize these difficulties in the applications, and also minimizing the health problems. In this respect, the experimental study gives a contribution to the literature filling gap in this field. The aim is to reduce the energy consumption which is resulted in contribution to the economy. On the other hand, the thesis encourages the student, giving theoretical and industrial insights together.
The performances of both drying techniques are compared with each other in terms of the drying rate, moisture content, drying time air velocity and temperature. The data acquisition, control and flow generation are controlled automatically by means of LabView 2009SP1® environment. The study includes experimental working. In this study, batch fluidized bed dryer is used under both high and vacuum pressure ranges. Theoretical and experimental results are examined using with literature which is about fluidized bed drying systems. The calculations which depend on the air velocity, moisture content, drying time, drying rate are performed.
Tez Konusu: Thermodynamic and economic analyses and assessment of HVAC applications in buildings for the optimization of energy consumption
Başlangıç/Bitiş: 2012/2015
In this study, the optimization of energy consumption in a specified building is performed analyzing and optimizing the variable parameters thermodynamically and economically. Also, different heating and cooling systems are investigated for the same building. The optimum conditions and system are determined as a result of the study.
The optimization of energy consumption is a leading concept in the world due to its decreasing and scarce amount. The efforts for decreasing energy consumption turn into economic recovery. It also provides benefits for health of people and cleaner environment. The thermodynamic and economic analyses are applied for the case study. The variables are controlled for different working conditions. Therefore the optimization of HVAC system is performed. In the analyses, the statistical procedures and techniques are also used in the computer environment.
Tez Konusu: Thermodynamic and economic analyses and assessment of a coal-fired power plant
Başlangıç/Bitiş: 2017/Devam Ediyor
In this thesis, a coal-fired thermal power plant is analyzed thermodynamically and economically utilizing real operating data taken from the plant in order to give its updated portrait in terms of energetic and exergetic efficiencies. New models as an energy recovery system are proposed if the efficiencies are found to be less than the nominal expected values. The overall energetic and exergetic efficiencies of the power plant are examined considering all factors that influence the system. Suggestions and developments are outlined in order to increase the overall performances of the existing coal-fired power plants.
The existing coal-fired power plant is analyzed thermodynamically and economically. Therefore, new improvements in terms of energy recovery or waste-to-energy are developed. Besides, the economic analysis of such systems is so important as well as thermodynamic analyses in order to define its exergetic cost rate. Some developments are recommended for further studies. As another M.Sc. study, the thermoeconomic analysis is carried out. In this way, any faults that affect the system thermodynamically, maybe economically are realized and tolerated before constructing of other similar plants by assessing the most exergy destructive sub-components. This thesis also encourages the M.Sc. student to get an ability to analyze an existing system in a power plant thermodynamically and economically.
The energetic and exergetic analyses are performed during this thesis. The actual operating data are taken for different working conditions. EES (Energy Equation Solver) software program is used for these analyses. Therefore the optimization of the system is performed using genetic algorithm (GA) optimization method of MATLAB software.
Tez Konusu: Aeroelastic Modeling and Analysis of Multi-Aileron Flexible Wings Aircraft
Başlangıç/Bitiş: 2014/2016
Tez Konusu: Thermodynamic Analysis and Energy Optimization on a VRF System
Başlangıç/Bitiş: 2020/
Tez Konusu: Lean Energy Approach on Energy Efficiency in a Learning Factory
Başlangıç/Bitiş: 2020/