DSpace Arşivi :: by Yazar "Utlu, Zafer" değerine göre listeleniyor

Yazar "Utlu, Zafer" seçeneğine göre listele

Listeleniyor 1 - 18 / 18

Advanced exergy analysis of cryogenic liquefaction system
(Institute of Thermal Technology, 2019) Karabuğa, Arif; Utlu, Zafer; Selbaş, Reşat
The elements in the air are separated by different methods and these elements are basically liquefied by three different methods (cryogenic, pressure swing adsorption and membrane). In this study, advanced exergy analysis of the nitrogen liquefaction unit was performed using the cryogenic liquefaction method. Advanced exergy analysis consists of four different splitting. These; endogenous/exogenous and avoidable/unavoidable exergy destruction. In the study, forward exergy analysis was performed for each component and endogenous, exogenous, unavoidable and avoidable values of these components were calculated. In the result of the study, the highest endogenous exergy degradation was found in the CM1 compressor with 32.56 kW, the highest exogenous exergy destruction was in the HE3 heat exchanger with 25.8 kW, the highest unavoidable exergy destruction was in the CM1 compressor with 22.55 kW and the highest avoidable value was in the HE1 heat exchanger with a value of 17.76 kW. Total exergy destruction of system were calculated as 755.08 kW.
Applicability of thermophotovoltaic technologies in the iron and steel sectors
(Wiley-V C H Verlag Gmbh, 2018) Utlu, Zafer; Paralı, Ufuk; Gültekin, Çağrı
The theoretical potential for converting excess heat from the iron and steel sectors in Turkey into electricity by the use of thermophotovoltaic (TPV) systems is investigated and analyzed. The TPV usage in this industry is numerically investigated because this sector is in the leading position in terms of energy consumption in industrial sectors. Using the iron and steel industry waste heat energy data, it is shown that the energy conversion efficiencies of the TPV systems with the photovoltaic (PV) cell modules of In0.2Ga0.8As0.18Sb0.82 and GaSb are 7.31% and 2.04%, respectively. When using TPV systems in the Turkish iron and steel sectors for waste heat energy potential, it is calculated that 29.88MJ per year can be generated with GaSb cells, and 1.076PJ per year can be generated with In0.2Ga0.8As0.18Sb0.82 cells. Based on the results obtained from the numerical model in this study, some specific advice for the applicability and the development of the high efficiency TPV conversion systems is proposed.
Application of artificial neural network model for forecast energy efficiency of the cryogenic liquefaction system in the meaning of sustainability
(Inderscience Enterprises Ltd, 2021) Altıntaş, Elif; Tolon, Mert; Karabuğa, Arif; Utlu, Zafer
Sustainable engineering approaches are a necessity for improving efficiency. For this reason, the artificial neural network (ANN) model is used to forecast different types of energy efficiency problems. In this paper, a comparison is made between a simple model based on ANN which gives meaningful findings in terms of thermodynamics and a model that is based on thermodynamic principles as auditing and predicting tool to forecast exergy efficiency of the system by applying different ANN architecture types with 441 data of experimental measurements obtained from liquefied nitrogen and analysed the Engineering Equation Solver (EES) program to make an exergy analysis.
Assessment of occupational health and safety issues in geothermal energy systems
(ECOS 2020 Local Organizing Committee, 2020) Erten, Begüm; Oral, Bülent; Utlu, Zafer
Geothermal energy is a sustainable, low cost, inexhaustible, environmentally friendly energy source. On the other hand, the fact that it can be used in many ways, such as electricity generation, heating, and cooling in the health sector, makes geothermal energy important in the world. For this reason, occupational health and safety (OHS) is of great importance in the success of geothermal energy projects, system efficiency, assessment of environmental impacts, protection of human health and prevention of economic losses. In this study, a holistic approach to geothermal energy plants with OHS issues has investigated. Accordingly, a literature survey has conducted on the dangers encountered or may be encountered in geothermal power plants, occupational health, and safety issues. Also, national and international legal regulations were researched. In this regard, Turkey, as well as legal regulations applied in areas where Iceland and the Philippines in geothermal energy production in the world, have shared first place. To analyze the functioning of field application is made observations in a geothermal power plant in Turkey. In this regard, it has been determined that national and international labors in geothermal energy should be supported with a common language, scientific infrastructure, applicability, and legal regulations that will form a basis in terms of OHS. By defining the environmental effects, dangers, and risks of geothermal systems, the emphasis has been placed on the work to be done in the field of OHS. In conclusion, when the legal regulations and literature on geothermal power plants are examined, it is seen that there is a need for guidance studies on the location and importance of OHS issues.
Comparison of real and theoretical data in high temperature GaSb cell thermophotovoltaic systems
(Institute of Thermal Technology, 2019) Utlu, Zafer
In this study, it is aimed to compare real and theoretical data in high temperature GaSb cell thermophotovoltaic systems. The thermophotovoltaic system can be defined as a system that converts the waste heat energy emitted from the heat sources into electrical energy at high temperature. The thermophotovoltaic energy conversion system consists of heat source, selective emitter, filter and photovoltaic cell module.The temperature parameters used are cell temperature and source temperature. With these graphs, energy efficiency, fill factor, effect of open circuit voltage and short circuit current values have been determined. While the efficiency value of the GaSb thermophotovoltaic cell systems was calculated, the radiation source temperature values have been taken in increments of 300 K between 1300 K and 3100 K. The theoretical and real datas obtained from the analysis have been compared. In the theoretical (lossless) analysis, the optimum energy conversion efficiency value of GaSb solar cell structure was found to be 33.14% while it was found to be 21.5763% in real (lossy) analysis. As a result of the obtained results, opinions about the feasibility, efficiency and development of thermophotovoltaic energy conversion systems have been stated and suggestions are presented.
Energetic and exergetic analysis of thermophotovoltaic systems
(Institute of Thermal Technology, 2019) Utlu, Zafer; Karabuğa, Arif
Thermodynamic analysis of the thermophotovoltaic system was carried out in our research and the results are presented. Firstly, the thermophotovoltaic system was analyzed in three different regions. In the analysis, each part of the system is taken separately, while the whole system is handled separately. In the system, the first analysis was resolved following the first law of thermodynamics and the second according to the second law.The first region is the thermodynamic analysis of the heat source of energy that occurs with radiation until it reaches the filter. The second region is where the filter, selective-emitter and photovoltaic cells, considered as photovoltaic systems, take place. The heat radiating from the heat source is evaluated within the scope of the thermodynamic analysis of the heat generated by the electrospinning and the electromotive force of each element. The third region, which is expressed as the last region, is considered to be the part where electric energy is stored. Within the thermodynamic analysis of each region, energy and exergy analysis were carried out and the system was analyzed from part to part. As a result of this induction method, a general energy and exergy efficiency of the whole thermophotovoltaic system is determined. Our results are supported by formulas. It is aimed that the work done will be an alternative to the existing electricity generation and will form a resource for future Works.
Energy usage in electric production sector in terms of environmental impacts and energy planning with fuzzy TOPSIS method & game theory
(ECOS 2020 Local Organizing Committee, 2020) Altıntaş, Elif; Utlu, Zafer
In recent years, fuzzy multi-criteria decision making (FMCDM) was introduced as a promising and important field of energy supply systems. The aim of this study is that to develop the multi-criteria decision support framework and determine optimal options for energy management in terms of energy used in the electric production sector (EPS) by taking into account the interactions of energy and environment used in production sector. Energy management of the EPS and the environment are investigated in care of game theory approach in decision-making process. The players of game theory approach are the EPS and the environment. Both the EPS and the environment try to find optimal strategies in terms of managing energy policy, the players also have conflicting objectives. The objectives of the EPS player are to ensure sustainability using fossil energy, renewable energy, waste energy recovery and nuclear energy use, while the objectives of the environment player are to ensure the sustainability of the environment. Fuzzy multiple criteria decision making (FMCDM) problem with the Technique for Order Performance by Similarity to Ideal Solution (TOPSIS) is employed for the analysis of the strategies' performance efficiency values and select the best. The rating of each alternative and the weight of each criterion are described by linguistic variables which can be expressed in triangular fuzzy numbers. Then, a vertex method is proposed to calculate the distance between two triangular fuzzy numbers. the concept of the TOPSIS is developed for solving MCDM problems with the basic principle to choose the alternative which has the shortest distance from the fuzzy positive-ideal solution (FPIS) and the farthest distance from fuzzy negative-ideal solution (FNIS). Consequently the most appropriate strategies that determine energy policies for the electric production sector and environment players are found and analyzed with a numerical example. According to results of the pay-off matrix, the equilibrium point is found. An application of this method demonstrates that the EPSs' use of energy triggers the environment's strategy. First and foremost, the environment creates its protection reflex.
Evaluation of electrical field effects of façade type a PV panel with occupational health and safety perspective, a case study
(ECOS 2020 Local Organizing Committee, 2020) Erten, Begüm; Karabuğa, Arif; Utlu, Zafer
In this study, the trend towards sustainable building concept has increased considerably in recent years. For this reason, the environmental impacts of photovoltaic (PV) systems integrated into the building have been examined in terms of occupational health and safety (OHS) for buildings that produce their own energy. In addition, the efficiency of the integrated PV systems outside the building is discussed. Therefore, the study is based on two main factors such as environmental effects and system efficiency. We measured the electrical field (electric, magnetic and electromagnetic) of the façade type PV system that building-integrated in Turkey for investigating the environmental effect. The measurements are carried out using the relevant standards, legal regulations and measurement methods at a total of 16 points in the front, top, back and in the inverter room of the panel one day per month for one year. The measurements include the electrical field values of the PV system area, the indoor areas covered by the PV area and the inverter room where the electrical systems are located. The measurements made in the inverter room are evaluated separately, since people are not intense and are located in a separate room. There are specific situations in terms of danger and risks due to the different functioning in this area. Measurement results are interpreted in accordance with OHS rules and legal regulations in terms of human, environment and workplace. While this study highlights the effects of electrical field effects occurring in façade type PV systems in terms of the OHS, it contributes to the proactive approach, which is the main purpose of the OHS. In result of this study, we have obtained during the measurement period, electric field values vary between 0.053 and 0.096 V/m. In addition, we have measure electromagnetic flux values are between 0.154 and 0.242 Gauss.
Evaluation of thermodynamic analysis of solar energy systems integrated into sustainable buildings with artificial neural network: a case study
(Elsevier B.V., 2019) Tolon, Fahriye Enda; Karabuga, Arif; Tolon, Mert; Utlu, Zafer
With the increasing concern on the environment and climate change, scientists focused on the way in which new structures, especially in the field of energy. In this sense, the concept of sustainable buildings is developing day by day in terms of energy efficiency. The sustainable building concept identifies five objectives which are resource efficiency, energy efficiency, prevention of pollution, harmonization with the environment; and also using integrated and systemic approaches. To increase energy efficiency in buildings, the integration of Solar Energy Systems into buildings attaches importance in terms of sustainable engineering designs. Evacuated Tube Heat Pipe (ETHP) solar energy systems are also noteworthy in this regard. This paper presents the results of an experimental study that is an ETHP solar collector system. ETHP systems are an alternative solar energy system to low-efficiency planary collectors. Only water was used to avoid losses in the heat transfer from the fluid to the fluid. Water is inserted in the vacuum tube in order to improve the rate of heat transfer, such that the mode of heat transfer from the inner surface of the vacuum tube to the heat pipe becomes convection via the water, as well as conduction through the installed. The exergy efficiency of the ETHP system was calculated as 32.94%. For a long time, artificial neural networks (ANN) have been widely applied in energy efficiency for modeling and optimization of various processes. In the field of processing, recent studies confirm the validity and effectiveness of using ANNs as promising and most powerful computer modeling techniques. Within the scope of this study, exergy efficiency was evaluated on the developed Artificial Neural Network algorithm. The effect rates of parameters such as pressure, temperature, and ambient temperature affecting exergy efficiency were calculated. Finally, significant findings obtained were evaluated in terms of thermodynamics rules.
Examination of the liquefaction system for the use of different cryogenics in terms of thermodynamic analysis
(Inderscience Enterprises Ltd, 2019) Karabuğa, Arif; Utlu, Zafer; Selbaş, Reşat
Energy consumption in the world is increasing day by day. In addition to diversifying energy resources, it is also important to reduce energy consumption. In order to find the actual consumption of a thermodynamic system, energy efficiency as well as exergy efficiency should be done. The purpose of this study is to determine the parameters affecting the exergy efficiency of the cryogenic liquefaction unit integrated into a real cryogenic air separation unit. Cryogenic liquefaction is one of the basic processes between liquefaction methods. In addition to this process, absorption and membrane are used in methods. The main difference in the selection of these methods is the desired purity rates. Cryogenes are defined as fluids used in cryogenic cooling. In this study, five different cryogenes in the air are investigated. The energy and exergy analysis of the liquefaction unit for each cryogen is made. As a result of the study, the highest COPactual value is obtained with 0.3105 hydrogen fluid and the highest COPrev value with 0.8551 oxygen. Exergy of the system is found as 0.48 with hydrogen.
Examination of thermophotovoltaic GaSb cell technology in low and medium temperatures waste heat
(Institute of Physics Publishing Ltd, 2018) Utlu, Zafer; Önal, Büşra Selenay
In this study, waste heat was evaluated and examined by means of thermophotovoltaic systems with the application of energy production potential GaSb cells. The aim of our study is to examine GaSb cell technology at low and medium temperature waste heat. The evaluation of the waste heat to be used in the system is designed to be used in the electricity, industry and iron and steel industry. Our work is research. Graphic analysis is done with Matlab program. The low and medium temperature waste heat graphs applied on the GaSb cell are in the results section. Our study aims to provide a source for future studies.
Investigation of performance of thermal power plants in terms of advanced exergy analysis approach
(ECOS 2020 Local Organizing Committee, 2020) Karabuğa, Arif; Utlu, Zafer; Yıldız, Oğuzhan
In this study, the conventional and advanced exergy analysis of a thermal power plant is carried out in Turkey. Energy and exergy balances are established for each component in the system and exergy destruction rates of the system and components are determined. The results obtained are assessment with a new concept, advanced exergy analysis, and the causes of exergy destruction are determined by a detailed examination of the exergy destruction. The system examined is a 1034 MW power generation system. In order to perform traditional and advanced exergy analysis on the system, thermophysical values are measured by determining twenty seven points at the inputs and outputs of each component. As a result, the total exergy destruction of the system is calculated to be approximately 382.3 MW. In addition, the highest exergy destruction among the components is found in the combustion chamber. Therefore, it is predicted that the component with the highest improvement potential is the combustion chamber.
İstanbul metro istasyonlarında iş güvenlik uygulamaları
(Demiryolu Mühendisleri Derneği, 2018) Damat, Arif; Utlu, Zafer
Metropol kentlerde şehir içi yaşamın getirdiği kalabalık trafik sorununuda beraber getirmektedir. Trafikten kurtulmak, işe vaktinde ve konforlu gitmek isteyen insanlar şehir içi ulaşımda metro kullanmaktadır. İstanbul’da hergün 2 milyondan fazla insan metro yolculuğu yapmaktadır. Bu tercih edilme beraberinde iş kazalarını da getirebilmektedir. Düşme, çarpma, çarpışma, tren ile peron boşluğuna ayak sıkışması, yürüyen merdivene ayak sıkışması, vb. kazalar metro istasyonlarında yaşanmaktadır. Bu çalışma da metro istasyonlarında , istasyon girişlerinden, perona inip trene binene kadar alınan iş güvenlik uygulamalarından bahsedilmiştir. Havalandırma sistemi, yangın ihbar ve kontrol sistemleri, yangından korunma sistemleri, PESB/CESB (Platform ve Merkezi Acil Durdurma Butonu), PAKS (Peron Ayırıcı Kapı Sistemi), Drenaj sistemi, Acil durum eylem planı, acil çıkış kapıları ve uyarı levhaları bu uygulamalardan bazılarıdır. Alınan bütün önlemlere rağmen işletme esnasında farklı tehlikeli durumların ortaya çıktığı görülmüş ve işletmeci firmanın bu problemlerin giderilmesine karşı aldığı iş güvenlik uygulamaları anlatılmıştır. Bu riskler risk değerlendirme yöntemlerinden fine-kinney ve 5x5 matris yöntemleri ile değerlendirilmektedir. Değerlendirme sonucu fine-kinney metodunun 5x5 matris yöntemine göre daha hassas sonuçlar verdiği görülmüştür.
Isıl sistemlerde mevcut atık ısı potansiyelinden yararlanarak termofotovoltaik yöntemlerle elektrik enerjisi üretim teknolojilerinin geliştirilmesi
(2018) Utlu, Zafer
Günümüzde enerji tüketiminin giderek artması, yenilenebilir enerji kaynaklarının hızla tükenmesi ve minimum girdi ile maksimum verim elde etme talebi yeni teknoloji arayışlarına hız kazandırmıştır. Atık ısıların değerlendirilmesi enerji yönünden tasarruf sağlamaktadır. Atık ısılardan elektrik üretimi gerçekleştirilerek temiz ve yenilenebilir enerji olarak mevcut elektrik üretimine katkı sağlanmaktadır. Bu yöntem, maliyet, atık ısının etkin kullanımı ve enerji tasarrufu açısından alternatif sunarken aynı zamanda sera etkisini azaltarak çevre dostu bir üretim modeli olarak kabul edilmektedir. Bu çalışmada mevcut atık ısı potansiyelinden yararlanarak termofotovoltaik enerji dönüşümü ile elektrik üretim teknolojisinin geliştirilmesi amaçlanmıştır. Literatürde termofotovoltaik enerji dönüşümü ile endüstriyel sistemlerde ve merkezi ısıtma sistemlerinde kullanılabilirliği araştırılmış ve endüstriyel sistemlerde teorik bir model geliştirilmiştir. Bu modelde, endüstriyel sistemlerdeki atık ısılar, sisteme ısı geçişi yöntemlerinden biri olan ışınım yolu ile incelenmiştir. Üretim aşamasından sonra meydana gelen atık ısı, sisteme termofotovoltaik dönüşüm ile elektrik üretimi sağlanarak geri kazandırılmıştır. Yapılan çalışmada endüstriyel ve merkezi ısıtma sistemlerinde termofotovoltaik sistemin analizi yapılmıştır. GaSb hücre yapısının tabaka kalınlıkları optimize edilmiş ve nihai örnek tasarımı Matlab programı kullanılarak hesaplanmıştır. Yapılan analizde, TPV sıcaklık grafikleri GaSb hücresi kullanılarak elde edilmiştir. Kullanılan sıcaklık parametreleri hücre sıcaklığı ve kaynak sıcaklığıdır. Bu grafiklerle enerji verimliliği, dolum faktörü, açık devre voltajının etkisi ve kısa devre akım değerleri belirlenmiştir. Ayrıca termofotovoltaik sistemin termodinamik analizi yapılarak sonuçlar sunulmuştur. Öncelikli olarak termofotovoltaik sistem üç ayrı bölgeye ayrılarak analizi yapılmıştır. Analizde sistemin her bir parçası ayrı ayrı yapılırken sistemin bütünü ayrıca ele alınmıştır. Sistem öncelikle birinci kanun analizi yapılarak değerlendirilmiştir daha sonra ikinci kanun analizi yapılmıştır. Birinci bölge ısı kaynağının ışınım ile filtrelere ulaşana kadar meydana gelen enerjinin termodinamik analizidir. İkinci bölge ise fotovoltaik sistem olarak değerlendirilen filtre, seçici- yayıcı ve fotovoltaik hücrelerin yer aldığı bölümdür. Son bölge olarak ifade edilen üçüncü bölge ise elektrik enerjisinin depolandığı kısım olarak değerlendirilmiştir. Sonuçlar formüller ve grafikler ile desteklenmiştir. Yapılan çalışmanın mevcut elektrik üretimine alternatif olması ve ileride yapılacak çalışmalara bir kaynak oluşturması amaçlanmıştır.
Modelling of energy and exergy analysis of ORC integrated systems in terms of sustainability by applying artificial neural network
(Oxford University Press, 2021) Utlu, Zafer; Tolon, Mert; Karabuğa, Arif
The present study focuses on the organic Rankine cycle (ORC) integrated into an evacuated tube heat pipe (ETHP), whose systems are an alternative solar energy system to low-efficiency planary collectors. In this work, a detailed thermodynamic and artificial neural network (ANN) analysis was conducted to evaluate the solar energy system. One of the key parameters of sustainable approaches focused on exergy efficiency is application of thermal engineering. In addition to this, sustainable engineering approaches nowadays are a necessity for improving the efficiency of all of the engineering research areas. For this reason, the ANN model is used to forecast different types of energy efficiency problems in thermodynamic literature. The examined system consists of two main parts such as the ETHP system and the ORC system used for thermal energy production. With this system, it is aimed to evaluate energy and exergy analysis results by the ANN method in the case of integrating the ORC system to ETHP, which is one of the planar collectors suitable for the roofs of the buildings. Within the scope of this study, the exergy efficiency was evaluated on the developed ANN algorithm. The effect rates of parameters such as pressure, temperature and ambient temperature affecting the exergy efficiency of ORC integrated ETHP were calculated. Ambient temperature was found to be the most influential parameter on exergy efficiency. The exergy efficiency of the whole system has been calculated as similar to 23.39%. The most suitable BPNN architecture for this case study is recurrent networks with dampened feedback (Jordan-Elman nets). The success rate of the developed BPNN model is 95.4%.
Performance evaluation of thermophotovoltaic GaSb cell technology in high temperature waste heat
(IOP Publishing Ltd, 2018) Utlu, Zafer; Önal, Büşra Selenay
In this study, waste heat was evaluated and examined by means of thermophotovoltaic systems with the application of energy production potential GaSb cells. The aim of our study is to examine GaSb cell technology at high temperature waste heat. The evaluation of the waste heat to be used in the system is designed to be used in the electricity, industry and iron and steel industry. Our work is research. Graphic analysis is done with Matlab program. The high temperature waste heat graphs applied on the GaSb cell are in the results section. Our study aims to provide a source for future studies.
Photovoltaic system configurations: an occupational health and safety assessment
(Wiley Periodicals, Inc, 2020) Erten, Begüm; Utlu, Zafer
There is an attempt to reduce CO(2)emissions caused by the use of fossil fuel worldwide and the negative consequences of global warming. Thus, renewable energy systems (RES) are an alternative for reducing fossil fuel use. In addition to being environmentally friendly, it is also important to ensure safety, reliability, and sustainability in the resources and systems used to achieve targets to reduce CO(2)emissions by increasing RES use. Solar energy systems have an important share in RES investments and their scope of use is becoming widespread. However, employment rates are also increasing. Hence, the issue of protecting employees also gains importance. Moreover, photovoltaic (PV) systems require an accurate risk management process with a holistic approach since the design phase. Therefore, occupational health and safety (OHS) studies should be seen as an integral part of the whole. In this study, regulations and standards related to OHS in PV systems have been investigated. Studies have been evaluated in terms of human health, environmental, and economic effects. Regulations vary according to countries' energy policies. Therefore, solutions are offered with national approaches to global problems. In this respect, the arrangements made at the national level have been investigated in Turkey and field observations have been made from an OHS perspective. The aim of this study is to support a holistic approach to the hazards and risks in PV systems and the sustainability of the systems. In this regard, the need for an inclusive basic guide is emphasized and a contribution is made to proactive approaches.
Synthesis and characterization of salt-impregnated anodic aluminum oxide composites for low-grade heat storage
(Springer, 2020) Yılmaz, Bengisu; Yüksel, Behiye; Orhan, Gökhan; Aydın, Devrim; Utlu, Zafer
Thermochemical heat storage (THS) systems have recently attracted a lot of attention in research and development. In this study, an anodic aluminum oxide (AAO) template, fabricated by a two-step anodization method, was used for the first time as the matrix material for a THS system. Different salts were studied as thermochemical materials for their suitability in low-grade heat storage application driven by solar energy for an open system. Compositions were prepared by absorbing CaCl2, MgCl2, LiCl, LiNO3 and mixtures of these salts under a vacuum in an AAO matrix. Field Emission Scanning Electron Microscopy was used to examine the morphology of the produced AAO composites. Thermal energy storage capacities of the composites were characterized using a differential scanning calorimeter. Characterization analysis showed that anodized Al plates were suitable matrix materials for THS systems, and composite sorbent prepared with a 1:1 ratio LiCl/LiNO3 salt mixture had the highest energy value among all composites, with an energy density of 468.1 kJ center dot kg(-1).

Yazar "Utlu, Zafer" seçeneğine göre listele

Sayfa Başına Sonuç

Sıralama seçenekleri