Yazarlar
- Can, Erol(25)
- Uzun, Sinem(20)
- Yilmaz, Harun(18)
- Ting, Naim Suleyman(16)
- Kalkan, Orhan(15)
- Yesilbag, Yasar Ozkan(15)
- Sahin, Yakup(13)
- Yilmaz, Ilker(13)
- Cam, Omer(12)
- Celen, Ali(11)
- Ertugrul, Mehmet(11)
- Genç, Yasin(11)
- Huseyin, Ahmad(11)
- Salih, Ahmed Jalal Salih(10)
- Ganjehsarabi, Hadi(9)
- Tuzluca Yesilbag, Fatma Nur(8)
- Bakirci, Kadir(7)
- Ozgenel, Mehmet Cihat(6)
- Çırak, Çağrı(6)
- Acir, Adem(5)
- Acır, Adem(5)
- Amsil, Hamid(5)
- Astam, Aykut(5)
- Caglar, Bulent(5)
- Chakir, El Mahjoub(5)
- Demirci, Oğuz Kürşat(5)
- Kabach, Ouadie(5)
- Yesilbag, Fatma Nur Tuzluca(5)
- Akın, Fatih(4)
- Asgin, Mansur(4)
- Balli, Esra(4)
- Demir, Fatih(4)
- Demir, Zeynep(4)
- Dogan, Ahmet(4)
- Ekici, Selcuk(4)
- Karakoc, T. Hikmet(4)
- Katipoğlu, Okan Mert(4)
- Kilic, Bayram(4)
- Kılınç, Tuba(4)
- Manga, Müge(4)
Yayınlar
- ArticleAçık Erişim2025Innovative thorium-based fuel assemblies for LW-SMR: In-depth assembly-level neutronic analysis and safety considerations in solid and annular configurations
Rifai, Hanan; Kabach, Ouadie; Sadoune, Zouhair; Chakir, El Mahjoub; Uzun, Sinem; Amsil, Hamid; Banni, Fadi El
This study presents a comprehensive neutronic and safety evaluation of different thorium-based fuel compositions (Th-235U)O2, (Th-233U)O2, and a new proposed composition, namely, (Th-233U-235U)O2 fuel, compared to conventional UO2 in solid and dual-cooled annular assembly configurations in the context of Small Modular Reactors (SMR) applications. Results demonstrate that (Th-233U)O2 achieves the highest cycle length in both solid configurations, significantly exceeding UO2 performance. The proposed, however, (Th-233U-235U)O2 composition exhibits favorable safety characteristics, including enhanced negative temperature reactivity coefficients and favorable kinetic parameters. Annular fuel configurations also demonstrate superior thermal performance with centerline temperature reductions of approximately 50 °C compared to solid configurations and consistently lower power peaking factors throughout burnup. The findings indicate that thorium-based fuels, particularly (Th-233U-235U)O2 in dual-cooled annular configuration, offer compelling advantages for SMR applications, including extended fuel cycles, improved safety characteristics, enhanced proliferation resistance, and superior thermal performance, supporting their viability as sustainable alternatives to conventional uranium-based fuels.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2025Fully Insulated Dual Output DC-DC Converter Battery Charging System with Single Dynamo Input at the Electric Vehicle
Can, Erol; Kürşat Demirci, Oğuz
Battery charging and regulation for the electrical system of electric cars or fuel cars are of great importance for the efficient operation and comfort of the vehicles. In this study, a DC-DC boost converter system that can charge two batteries isolated from each other with the same dynamo for a car is presented. With this system, it is possible to charge two different batteries at their nominal voltages at the same time by increasing the voltage of the system at the low voltage inputs that will occur. First, the circuit model and mathematical expansions that give the operating logic of the circuit are given. Then, the designed circuit model is operated between the modulation indexes of 0.2-0.5 and two different batteries are fed at their nominal voltages in isolation from each other. After the simulation studies, the current and voltage values of the circuit elements and the charging parameters of the battery are measured and the system application is carried out. According to the obtained results, although the charging circuit receives low voltage from the alternator, the two batteries can be charged to the requested level with the proposed system.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2025Enhanced thermal performance of a flat-plate solar water heating system using nanofluids: a TRNSYS-based analysis
Uzun, Sinem; Seyhan, Aslıhan Kurnuç
This study examines the potential of nanofluids to enhance the thermal efficiency of flat-plate solar water heating systems (SDHW) through numerical modeling using TRNSYS software. Improving the efficiency of such systems is critical for increasing the viability and sustainability of solar thermal technologies, particularly in regions with high solar potential like Türkiye. Three different nanofluids (Al2O3, TiO2, and CuO) were evaluated for their ability to improve heat transfer and system performance. Simulation results revealed that incorporating 0.1% Al2O3 into the working fluid increased the collector outlet temperature from 97 °C (with pure water) to 120 °C, indicating a 23% improvement. Comparable enhancements were observed with TiO2 and CuO nanofluids. Furthermore, collector efficiency, which typically ranges between 35 and 40% under peak solar conditions, was elevated to approximately 45% with the use of nanofluids. These findings suggest that nanofluids significantly improve thermal performance and energy conversion efficiency in SDHW systems. The results highlight the practical potential of nanofluids in advancing solar thermal technology and promoting cleaner, more efficient renewable energy solutions.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024Synthesis of Tungsten Disulfide on B-N-Doped Carbon Nanotubes to Enhance the Electrochemical Performance of Supercapacitors
Yeşilbağ, Yaşar Özkan; Yesilbag, Fatma Nur Tuzluca; Huseyin, Ahmad; Salih, Ahmed Jalal Salih
In this research, boron and nitrogen-doped carbon nanotubes (B-N-CNTs) were synthesized at 900°C using the FCCVD method. Carbon, nitrogen, and boron as source materials were simultaneously introduced using a batch- mode droplet reactor and ferrocene as a catalyst. B-N-CNTs were obtained with diameters ranging from 10 - 50 nm and lengths around 30 – 80 μm. These B-N-CNTs were thoroughly characterized and structurally analyzed. Subsequently, tungsten disulfide (WS2) nanosheets on B-N-CNTs were synthesized using the hydrothermal method to design a composite material and were investigated as electrodes for supercapacitors. The morphological properties of B-N-CNT@WS2 were determined by various analytical techniques such as XRD, FESEM, XPS, and EDS. B-N-CNT@WS2 was investigated as an electrode for supercapacitors in two- and three-electrode cells. In the three-electrode cell, B-N-CNT@WS2 exhibited a specific capacitance of 320 F g−1 at a current density of 0.5 A g−1, while the two-electrode cell showed a capacitance of 41 F g−1. The symmetric supercapacitor at a current density of 5 A g−1 exhibited excellent structural stability by preserving 90% of its specific capacitance after 9000 cycles in the 1 V potential range.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024The Effect of Nanofluid Coolant and Thorium-added Fuel on Burnup Dependent Isotopic Compositions in VVER-1000 Reactor
Acır, Adem; Genç, Yasin; Uzun, Sinem
Recently, the use of nanofluids has gained importance in studies aimed at increasing reactor efficiency while also addressing safety concerns in nuclear technology. Various studies have investigated the effects of adding nanoparticles of different types and proportions to the coolant water on the thermal and neutronic characteristics of power reactors using conventional UO2 fuels. Given the abundance of thorium compared to uranium, research on thorium-based fuels has become increasingly significant. In this study, the criticality and isotope changes in a VVER-1000 reactor loaded with 5% ThO2 and 95% UO2 by mass as fuel, and 0.1% by volume of Al2O3, CuO, and TiO2 nanoparticles as the coolant, were investigated. Neutronic analysis was performed using the MCNP5 and MONTEBURNS2.0 codes. The analysis results indicated that the operational lifespan of the reactor with only water coolant and thorium-based fuel was shortened due to the presence of nanoparticles. Furthermore, it was observed that while there was no significant change in the amount of fissile 235U and fertile 238U isotopes, the consumption of fertile 232Th isotope in the reactor increased with the insertion of nanoparticles into the coolant.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024A COMMERCIAL TURBOFAN ENGINE MODELING AND EXERGY ANALYSIS
Kalkan, Orhan
Turbofan engines are one of the most common types of engines used in modern commercial and military aircraft due to their efficiency and performance characteristics. In this study, a thermodynamic model is generated using GasTurb 14 software for a commercial two-spool, unmixed flow, and booster turbofan engine (CFM56-5A3) used in Boeing A320-212. Besides, an exergy analysis of the modeled turbofan engine is performed. Exergy performance criteria such as exergy efficiency, exergy development potential, exergy destruction ratio, productivity lack ratio, and fuel depletion ratio are evaluated for the engine components. In addition, how bypass ratio (BPR) affects net thrust and specific fuel consumption (SFC) for the modeled turbofan engine is investigated. As a result, the net thrust and SFC values of the modeled engine and the actual engine are overlapped with 14.0% and 7.2% deviation, respectively. The maximum exergy efficiency occurs at the high-pressure turbine as 0.992. When the bypass ratio is minimum, the maximum net thrust and SFC occur as 62.24 kN and 24.08 g kN(-1) s(-1) , respectively. High pressure turbine has the minimum exergy development potential of 1528.5 kW.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024Impact of virtual inertia and damping control on stability delay margins of load frequency control systems with renewable energy sources
Hasen, Suud Ademnur; Aydın, Ömer; Ayasun, Saffet; Sönmez, Şahin
The utilization of communication linkages generates delays that degrade system dynamic performance and cause fluctuations in the system frequency while the extensive integration of renewable energy sources may cause further increase in the frequency oscillations owing to low inertia. By considering the inclusion of the virtual inertia and damping (VID) control in load frequency control (LFC) systems with time delays, this article investigates the impacts of the VID control on the stability delay margins (SDMs) of two-area LFC systems. For this purpose, an exact method, which is based on recursively removing exponential terms from the characteristic equation, is first implemented to compute SDMs of the two-area LFC system enhanced by VID control for a wide range of controller gains. Secondly, the effect of the VID parameters on the SDMs is investigated by employing the exact method. Theoretical results clearly illustrate that SDMs significantly increase as VID parameters increase. Furthermore, simulation analysis elucidates that with the VID incorporation, the performance of the LFC system with low inertia is enhanced and the rate of change of the frequency and frequency nadir are remarkably decreased, improving the stability of time-delayed LFC systems.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024PID Control of Hybrid DC-DC Converter System in Complex Load with Double Reference Time
Can, Erol; Gülnahar, Murat
DC-DC converters are circuits that are widely used in energy distribution systems, in industry and technology applications, as well as in household appliances such as computers and televisions, and in uninterruptible power supplies used to feed all these systems. For the design and optimization of DC-DC converter circuits, it is important to create and analyze mathematical models according to the load it is connected to. Simple load structures and circuit structures have been examined and control units have been designed in studies carried out to date. In this study, while the DC-DC converter with a more complex load structure is discussed, mathematical analysis and PID control of DC-DC converters with Buck-Boost feature are performed with the same modulation index in different time periods. In the results obtained, it is shown how to create the mathematical models of a system that provides DC-DC energy conversion with a complex load structure and how to formulate the PID control in a system with this complex load structure.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Examining the Effects of Renewable Energy and Economic Growth on Carbon Emission in Canada: Evidence from the Nonlinear ARDL Approaches
Erdoğan, Esma; Serin Oktay, Duygu; Manga, Müge; Bal, Harun; Algan, Neşe
Increasing industrial activities trigger the intense use of fossil fuels and increase the number of carbon emissions in the atmosphere. Countries with a high share in current carbon emissions need to expand their use of renewable energy sources. Canada is an important energy producer and consumer globally. In this regard, its decisions are important for the future development of global emissions. This study examines the asymmetric effects of economic growth, renewable energy, and non-renewable energy consumption on carbon emissions in Canada from 1965 to 2017. In the first stage of the analysis, unit root testing was performed for the variables. For this, Lee-Strazicich (2003), ADF and PP unit root tests were used. The nonlinear ARDL method was used to analyze the relationship between variables. and Measures: In order to analyze the relationship between the variables in the established model, renewable energy consumption (%), non-renewable energy consumption (%), and carbon emissions (per capita-Mt). In addition, the economic growth (constant price 2010- US$) parameter was added to the model as a control variable. The findings support that energy consumption, economic growth, and renewable energy have an asymmetric effect on carbon emissions in the long run. The positive shock in renewable energy reduces carbon emissions, and a unit increase in renewable energy reduces carbon emissions by 1.29%. Besides, the negative shock in economic growth greatly deteriorates the quality of the environment; that is, a 1% reduction in economic growth causes emissions to increase by 0.74% in the long run. On the other hand, positive shocks in energy consumption have a positive and significant effect on carbon emissions. A 1% increase in energy consumption causes 1.69% carbon emissions. There are important policy implications for Canada to eliminate carbon emissions, increase the share of renewable energy sources and achieve its economic growth targets. In addition, Canada needs to reduce its consumption of non-renewable energy (such as gasoline coal, diesel, and natural gas).
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Self-Powered Quasi-Solid-State Photoelectrochemical Photodetectors Based on MXene Paper Modified by ZnO Nanostructured Architecture
Karagoz, Emine; Tuc Altaf, Cigdem; Tuzluca Yesilbag, Fatma Nur; Yesilbag, Yasar Ozkan; Erdem, Emre; Bakan Misirlioglu, Feray; Demirci Sankir, Nurdan; Sankir, Mehmet
In this work, we report a self-powered quasi-solid-state photodetector (PD) device prepared from flexible two-dimensional (2D) nanocomposites of a zinc oxide nanowire (ZnO-NW) in various weight percents (5, 10, 30, 50%) and Ti3C2Tx (MXene) paper, constructed with manganese (Mn)-doped zinc oxide nanorods (ZnO NRs) using an ionic gel electrolyte and carbon paper. All PD performance tests revealed that 5% ZnO-MXene-based devices were superior to the other samples. The maximum detectivity of 1.44 × 1013 Jones at 367 nm (0.1 mW cm-2) and zero bias was calculated for the 5% ZnO-MXene-based device. Additionally, a very high on/off ratio of nearly 106, which is approximately 35-fold higher than that of the 50% ZnO-MXene-based PDs, was achieved for 5% ZnO-MXene PD at a zero bias under 367 nm (2.52 mW cm-2) illumination. The rise time for this device was 9.25 ms. Furthermore, the PD device exhibited excellent stability by enduring 1000 s of light on/off cycles. As a result, a simple, compact, and cost-effective self-powered ZnO-NW:MXene-based PD configuration showed fast photoresponse and excellent detecting performance.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Torques and the speed vibrations reducing and optimization of asynchronous motor with ECCA-PID controlling in power system
CAN, EROL
In renewable energy-sourced power systems, asynchronous motors serve as elements that both produce and consume electricity. The stability and efficiency of the asynchronous motor in renewable energy system should be considered. Although performance optimization studies have been carried out using power circuits that control the asynchronous motor fed with solar energy and control units such as proportional, integral, derivation (PID), and Fuzzy logic; They may be insufficient to eliminate and reduce vibrations in the output values of an induction motor fed with a renewable energy source. Losses occur as the system performance decreases constantly due to oscillations. In this study, an induction motor power system is optimized with the extra control coefficient (ECCA)-PID, which provides semi-linear control for the first time, unlike the power systems controlled by other linear controllers used so far to reduce oscillations, and the vibration losses are eliminated. The speed oscillations, torque oscillations, and oscillation losses of the induction motor in the system are controlled by conventional PID, and Fuzzy logic controllers in order to demonstrate the effectiveness of the proposed method in simulation and experimentation. Then, the results are compared after the proposed method are examined. As a result of the comparisons, while the motor oscillations and losses in the power system continue throughout the control period in traditional control methods, the proposed method reduces the losses to zero in a large part of the control period.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Photo-supercapacitors based on zinc oxide/MXene paper dual acting electrodes
Colak, Tuluhan Olcayto; Altaf, Cigdem Tuc; Yesilbag, Fatma Nur Tuzluca; Yesilbag, Yasar Ozkan; Yildirim, Ipek Deniz; Erdem, Emre; Misirlioglu, Feray Bakan; Sankir, Nurdan Demirci; Sankir, Mehmet
Photo-supercapacitors (PSCs) have great potential as devices that enable both the conversion and storage of solar energy. However, it remains challenging to design new dual-acting electrodes providing high energy density and capacitance with self-powering capacity. Herein, we successfully prepared dual electrodes using ZnO-nanoflake and Ti3C2Tx-based MXene paper. By utilization of the MXene to the PSC device, capacitive contribution to the total capacitance increased ∼4 times compared to the bare ZnO-nanoflake-based PSC due to the surface redox reactions and electrically double layer formation. Maximum energy and power density of 57.3 μWhcm−2 and 11.1 mWcm−2, respectively were obtained for ZnO/MXene//MXene-PSC@UV irradiation and at a 2.5 V. Areal capacitance of this device calculated from CV was as high as 151.5 mFcm−2. Moreover, the ZnO/MXene//MXene-PSC device was highly stable over 10,000 GCD cycles with 100 % CE and 98 % Cp-retention under daylight.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Designing CuO@MnCo2O4 nanowire arrays electrode on copper foam and foil substrates via chemical synthesis methods for asymmetric supercapacitor
Tuzluca Yesilbag, Fatma Nur; Huseyin, Ahmad
In this study, CuO nanowires were grown on copper foam (Cufoam) and copper foil (Cufoil) substrate with a cost-effective anodization method as core, and then MnCo2O4 nanowires were grown by hydrothermal synthesis method and three-dimensional (3D) core-shell nanowire arrays (NWAs) were obtained. The synthesized CuO NWAs, which provide a high surface area, contribute to the capacitance with the faradaic redox reaction and act as a current collector for the MnCo2O4 NWAs. Therefore, the 3D electrode design can increase the redox reaction, shorten the ions diffusion pathway, and exhibit low intrinsic resistance. The areal capacitance values of Cufoil/CuO, Cufoam/CuO, and Cufoam/CuO@MnCo2O4 electrodes were obtained at a current density of 0.5 mA cm−2 as 0.21, 1.02, and 2.82 F cm−2, respectively. The Cufoam/CuO@MnCo2O4 NWAs electrode exhibits excellent cycling stability of 97.3 % retention after 5000 cycles. In addition, an asymmetric supercapacitor (ASC) device was assembled by using the Cufoam/CuO@MnCo2O4 electrode and active carbon (AC) as the positive and negative electrodes, respectively. The ASC device operates in a potential range of 0–1.5 V and an energy density of up to 7.1 × 10−2 mWh cm−2 at a power density of 1.56 mW cm−2. This work may contribute to developing low-cost materials for energy storage devices.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024A new high-frequency multilevel inverter effecting cables weight and energy efficiency of aircraft
Can, Erol; Kilic, Ugur
Purpose: Static inverters are very important for the emergency energy distribution system of aircraft and similar machines. At the same time, the electrical energy produced at high frequency for electrical devices is used to reduce the weight of the cables in the aircraft and spacecraft because of the skin effect. In the high-frequency system, a thinner cable cross-section is used, and a great weight reduction occurs in the aircraft. So, fuel economy, less and late wear of the materials (landing gear, etc.) can be obtained with decreasing weight. This paper aims to present the development of a functional multilevel inverter (FMLI) with fractional sinus pulse width modulation (FSPWM) and a reduced number of switches to provide high-frequency and quality electrical energy conversion. Design/methodology/approach: After the production of FSPWM for FMLI with a reduced component, which, to the best of the authors’ knowledge, is presented for the first time in this study, is explained step by step, and eight operating states are given according to different FSPWMs operating the circuit. The designed inverter and modulation technique are compared by testing the conventional modular multilevel inverter on different loads. Findings: According to application results, it is seen that there is a 50% reduction in cross-section from 100 Hz to 400 Hz with the skin effect. At 1000 Hz, there is a 90% cross-section reduction. The decrease can be in cable weights that may occur in aircraft from 10 kg to 100 kg according to different frequencies. It causes less harmonic distortion than conventional converters. This supports the safer operation of the system. Compared to the traditional system, the proposed system provides more amplitude in converting the source to alternating voltage and increases the efficiency. Practical implications: FSPWM is developed for multilevel inverters with reduced components at the high frequency and cascaded switching studies in the power electronics of aircraft. Social implications: Although the proposed system has less current and power loss as mentioned in the previous sections, it contains fewer power elements than conventional inverters that are equivalent for different hardware levels. This not only reduces the cost of the system but also provides ease of maintenance. To reduce the cable load in aircraft and create more efficient working conditions, 400 Hz alternative voltage is used. The proposed system causes less losses and lower harmonic distortions than traditional systems. This will reduce possible malfunctions and contribute to aircraft reliability for passengers and cargo. As technology develops, it is revealed that the proposed inverter system will be more efficient than traditional inverters when devices operating at frequencies higher than 400 Hz are used. With the proposed inverter, safer operation will be ensured, while there will be less energy loss, less fuel consumption and less carbon emissions to the environment. Originality/value: The proposed inverter structure shows that it can provide energy transmission for electrical devices in space and aircraft by using the skin effect. It also contains less power elements than the traditional inverters, which are equivalent for different levels of hardware.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Investigation of Mazidagi phosphate ore in wet flue gas desulphurization
Mazlumoglu, Hayrunnisa; Gulaboglu, M. Sahin
The employment of Mazidagi phosphate ore for wet flue gas desulphurization was investigated. The ore was exposed to sulfation processes in a three-phase double-stirred reactor to determine the effects of certain parameters on SO2 absorption. The absorption rate significantly increased with inlet SO2 concentration, gas flow rate, stirring speeds, and solid concentration but not with temperature. The absorption rate increases as the mass transfer coefficients and interface area value increase with stirring speeds. These parameters have also a prominent impact on the absorption rate depending on the dissolution rate of CaCO3. Based on these, the most effective parameters on SO2 absorption are liquid-phase stirring speed and suspension concentration, and the process is diffusion-controlled in the liquid phase. In addition, optimum conditions were determined, and then the ore was exposed to sulfation processes via a semi-batch operation mode. A comparison between raw and sulfated ore was examined for the changes in physical structure and chemical composition. Although the ratios of fluorapatite and carbonate-fluorapatite remained nearly constant, the ratio of calcite decreased significantly. It was determined from these investigations that the calcite in the phosphate ore has been converted into the CaSO3∙½H2O compound. Consequently, both the calcite in the phosphate ore was utilized effectively for wet flue gas desulphurization, and a phosphate-rich industrial product was obtained.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Determination of optimum insulation thickness of building walls according to four main directions by accounting for solar radiation: A case study of Erzincan, Türkiye
Köse Özturan, Merve; Kurnuç Seyhan, Aslıhan
Reducing heat transfer from the building will reduce the energy cost required to heat the building. Significant energy savings of 25 % to 50 % can be achieved when the appropriate thickness of thermal insulation is applied to the building walls. In this study, calculations were made to determine the optimum insulation thickness of some thermal insulation materials used to reduce the heat transfer from buildings in Erzincan, located in Türkiye's fourth climate zone. The optimum thickness of the thermal insulation to be applied to the external walls was determined using the heating degree day method, taking into account the effect of solar radiation according to the four main directions. Optimum insulation thicknesses and payback periods were calculated for combinations of two building materials (pumice and bricks), four fuels (fuel oil, LPG, natural gas, and coal), and three insulation materials (XPS, EPS, and Rock wool). The numbers of heating degree days were calculated as 2229 in the north, 1425 in the east and west, and 1118 in the south direction for the four main wall directions. The lowest optimum insulation thickness for these heating degree day values, which minimizes the total heating cost, was obtained for pumice/XPS/natural gas combination. The optimum insulation thicknesses for this combination were calculated as 0.037 m in the north, 0.025 m in the east and west, and 0.02 m in the south direction. The calculated payback periods for all combinations range from 0.9 to 4 years and the payback period of Pumice/XPS/Natural Gas combination is 4 years.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024Performance Analysis of Modulation Strategies in Single-Phase HBNPC Inverter Across Variable Operating Conditions
Cavli, Nazlican; Ozkop, Emre
This study investigates the performance of a single-phase 5-level H-Bridge Neutral Point Clamped (HBNPC) inverter across various operating conditions. These conditions encompass variations in output power, frequency, modulation index, and modulation techniques. To adapt modulation strategies typically employed in three-phase inverter structures, we apply them to a single-phase HBNPC inverter. The modulation strategies under consideration include level-shifted (LS) based on phase disposition pulse width modulation (PD-PWM), third harmonic injection pulse width modulation (THI-PWM), space vector pulse width modulation (SV-PWM), and modified PWM (MPWM). These strategies are developed using different types of reference signals (RS) and carrier signals (CS). Initially, we analyze the inverter's output voltage and current waveforms across various modulation strategy states. Subsequently, we explore the relationships between efficiency, total harmonic distortion (THD), and variable output power across different modulation strategy states. We uncover distinct patterns between modulation strategy-THD, efficiency, and output voltage for maximum inverter output power. Furthermore, we examine the relationship between the modulation index and THD for each modulation strategy state, considering different switching frequencies. Additionally, we investigate the relationship between switching frequency and THD across different modulation index values, approaching the analysis from multiple perspectives.
RDL Kalıcı Kaydıİncele - ArticleAçık Erişim2024Analyzing the load capacity curve hypothesis for the Turkiye: A perspective for the sustainable environment
Caglar, Abdullah Emre; Destek, Mehmet Akif; Manga, Muge
Although it takes time to achieve a sustainable environment, this goal can be possible with the Sustainable Development Goals. The transition from gray energy sources to green in the 21st century is among the important policy goals of global economies. Since this process is long, countries focus on energy efficiency as part of their carbon reduction policies. In this context, this study investigates the impact of clean energy technologies on environmental quality in Turkiye. Using the load capacity curve (LCC) hypothesis, human capital, income, and natural resources are theoretically added to the balance model. The novel Augmented ARDL with Fourier terms approach is used in the empirical analysis. As a result of the analysis, the LCC hypothesis is valid, and income will support environmental quality after a certain level. While human capital increases environmental quality, natural resources bring environmental pollution. Finally, it is determined that clean energy technologies have not yet reached the level that enables carbon reduction. The finding that clean energy technologies are insufficient for Turkiye, as a result of empirical analysis, shows the uniqueness of this study. With our new findings, policymakers can take action for a sustainable environment. Since Turkiye has to ensure energy security due to its regional characteristics, it should increase investments in clean energy technologies. Based on empirical findings, clean energy technologies will gain momentum as policymakers support human capital.
RDL Kalıcı Kaydıİncele - Book ChapterYalnız künye2024A Case Study on Investigating Probabilistic Characteristics of Wind Speed Data for Green Airport
Tatli, Ali; Suzer, Ahmet Esat; Filik, Tansu; Karakoc, Tahir Hikmet
Accurate estimation of wind distribution plays a vital role in modelling more efficiently and minimizing theoretical computation errors in terms of practical applications. This research strives to conduct elaborately an assessment of the wind behavior and features of an international airport based on various heights from the ground level. Wind speed at each height, composed of 10 m, 20 m, 30 m, 40 m, and 50 m, is computed by applying the power-law equation. After that, the wind profile at each height is comparatively estimated based on the graphical, empirical, and maximum-likelihood method. Several statistical tools, namely, root mean square (RMSE) and R-squared (R2), are performed to make a fair comparison among the methods that help estimate the Weibull parameters. The results of this study reveal that the empirical and maximum-likelihood methods exhibit better performance than the graphical method in estimating the shape and scale parameter, irrespective of heights. Moreover, the findings of the study imply that the airport has a moderate potential to make use of generating electricity and hydrogen from wind power.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2024Deep learning-based forecasting modeling of micro gas turbine performance projection: An experimental approach
Kilic, Ugur; Villareal-Valderrama, Francisco; Ayar, Murat; Ekici, Selcuk; Amezquita-Brooks, Luis; Karakoc, T. Hikmet
Performance forecasting of aeroengines is crucial for achieving better operational efficiency, ensuring safety, reducing costs, and minimizing environmental impact in the aviation industry. It enables engineers and researchers to make informed decisions, leading to advancements in technology and the overall evolution of aviation. This study is focused on the effects of flight conditions on the performance of a turbojet, which in consequence affects the environmental aspect of operation. By investigating the relationships between aeroengine efficiency and performance indicators such as thrust, shaft speed, and exhaust gas temperature (EGT), and flight characteristics expressed in terms of environmental and operational conditions, the study seeks to elucidate these connections. The article's significance lies in its successful application of Long Short-Term Memory (LSTM) networks to predict thrust, shaft speed, and EGT variations in turbojet engines under varying flight conditions. Experimental data from a turbojet test bench is processed with deep learning, specifically LSTM recurrent neural networks that are developed based on Matrix Laboratory (MATLAB). The model inputs are free stream air speed, compressor inlet pressure, combustor inlet temperature, combustor inlet pressure, turbine inlet temperature, turbine inlet pressure, nozzle inlet pressure and fuel flow, and the outputs are thrust, shaft speed and EGT. Predicted thrust closely aligns with actual thrust values, though with minor discrepancies. Shaft speed predictions exhibit a similar trend, while EGT predictions showcase a comparable pattern with slight variations. Despite the prediction errors, a thorough evaluation of median values, box plots, and probability density functions confirms that the models effectively capture available information, though discrepancies may arise from measurement inaccuracies and initial engine conditions. These results show that it is possible to accurately predict turbojet performance using LSTM recurrent neural network. This research paves the way for enhanced aeroengine performance prediction, particularly in scenarios requiring off-board or high-performance applications.
RDL Kalıcı Kaydıİncele
