Browsing by Author "Nil, M"

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    Experimental and numerical studies on improvement of heat transfer of OLED TVs
    Nil, M; Öztürk, Y; Akgül, MB; Sari, G
    In this study, the thermal behaviors of organic light emitting diodes (OLED) televisions are investigated experimentally and numerically. Organic light emitting diodes are very sensitive to temperature. For this reason, the heat emitted from the diodes must be removed quickly from the environment. The study consists of two parts. In the first part, the use of an effective heat spreader between the screen and the metal casing is proposed as a mechanism for improving the temperature distributions for heat transfer. Pyrolytic graphite plate and tempered pyrolytic graphite plate were used as heat spreader. The graphical heat transfer coefficients of the graphite plates are considerably higher than in the normal direction. The effectiveness of these proposed mechanisms is demonstrated by simulation. As an example model, OLED TV was selected in 15 dimensions and both experimental and numerical thermal analyzes were performed. The temperature distributions of the OLED were obtained with the help of the ANSYS ICEPAK program, a commercial code that uses the finite volume method. Simulation and test results are obtained very close to each other. The thermal management contributions of OLED TVs using different thicknesses of pyrolytic and tempered pyrolytic graphite plates are presented experimentally and numerically. In the second part, a dual action piezo fan design is proposed. The design parameters of the piezo fan were determined and the numerical analyzes for these parameters were made with the Comsol Multiphysics program. Experimental measurements were made for design dimensions determined by numerical analysis. The result is that the use of a dual-acting piezo provides more efficient cooling than the existing synthetic jets.
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    A review on bismuth telluride (Bi2Te3) nanostructure for thermoelectric applications
    Mamur, H; Bhuiyan, MRA; Korkmaz, F; Nil, M
    Bismuth Telluride (Bi2Te3) is basically known as an efficient thermoelectric material. Nowadays, it has been attracted a great deal of interest in energy harvesting, chip cooling, chip sensing and other field of material science because of its potential applications. In order to produce Bi2Te3 nanostructure, a number of methods such as solvo and hydro thermal, refluxing, straight forward arc-melting and polyol methods have been employed. Among of them, the solvothermal method has been one of the most common methods to fabricate Bi2Te3 nanostructure in thermoelectric applications. But the development of device-quality material has been a challenging task for the researchers, yet. For this reason, this paper provides a review of current research activities on Bi2Te3 nanostructure growth by several methods and its characterization through theoretical and analytical aspects. Moreover, the paper handles a systematic and intensive research work to develop and understand the materials in nanostructure forms.
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    Effects of slot-pole combinations on vibration and performance in fractional slot permanent magnet synchronous machines
    Kurtoglu, A; Bakbak, A; Nil, M; Ayaz, M
    Unbalanced Magnetic Force (UMF) is a critical factor that significantly impacts vibration and overall performance in Permanent Magnet Synchronous Machines (PMSMs). This study investigates the influence of different fractional slot combinations on UMF behavior in PMSMs using finite element analysis (FEA). The focus is on the canceling and additive effects of UMFs generated by radial and circumferential stresses. Two PMSM configurations with slot and pole numbers differing by one-26 poles/27 slots and 28 poles/27 slots-are analyzed to evaluate the effect of varying pole configurations while keeping the slot count constant. The analysis employed the Maxwell stress tensor method to quantify the UMFs in these designs. The results underscore the critical role of the magnet configuration in determining UMF characteristics, providing essential insights for optimizing machine design to minimize vibration and enhance performance. These findings serve as a valuable reference for designing and operating high-performance fractional slot PMSMs, particularly for industrial and automotive applications.
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    Life performance prediction of natural gas combined cycle power plant with intelligent algorithms
    Karaçor, M; Uysal, A; Mamur, H; Sen, G; Nil, M; Bilgin, MZ; Dogan, H; Sahin, C
    The efficient use of a system is enabled with the life performance estimations. Thus, the effective use of underground resources is realized especially natural gas. Based on this, life performance models were generated to aim of improving the efficient use of energy for a combined cycle power plant (CCPP) of 243 MW installed in Izmir, Turkey by using fuzzy logic (FL) and artificial neural network (ANN) in this study. Therefore, output power estimations were carried out. Depending on the developed models, an estimation of the energy that the CCPP can produce and provide to the interconnected system in the following years has been made. According to the obtained results, the error prediction rates of FL and ANN models were determined. It was found that while the energy relative error estimation value that can be produced between the years calculated in modeling using FL varies between 0.59% and 3.54%, this value was found to vary between 0.001% and 0.84% in modeling using ANN. This result shows that the ANN model is more suitable for the life performance estimations of such a nonlinear system.
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    Evaluation of municipal solid waste characterization and landfill gas power plant electrical energy production efficiency during COVID-19 pandemic
    Alboga, B; Nil, M; Bhuiyan, MRA; Mamur, H
    Due to the COVID-19 pandemic, the amount and types of municipal solid waste (MSW) have dramatically changed. This study focuses on characterizing the MSWs in the regular waste storage facility (RWSF) in Izmir, Turkey, and determining the electrical energy that can be produced by the landfill gas power plant (LFGPP) established to convert the waste to energy (WtE). Therefore, firstly the MSWs were characterized. After, the amount of produced methane (CH4) 4 ) gas was determined using Landfill Gas Emissions Modeling (LandGEM). The amount of generated electricity, the dependent variable in the LandGEM model, was most influenced by the quantity of MSW, garbage disposal processes, and maintenance times of gas generators, while other factors remained relatively weak. This situation has also been confirmed in the field. During the COVID-19 pandemic, the increase in MSW was 9.8% in 2020 and 10.3% in 2021. Kitchen waste containing the highest CH4, 4 , accounted for 38% of the MSW characterization. The amount of generated electricity in the LandGEM model was 237 GWh in 2020 and 245 GWh in 2021. While these values could be achieved by 11.25% in 2020 due to various system and field failures, they reached 79.73% in 2021 due to system and field improvements.
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    Half bridge LLC resonance converter reliability analysis for OLED TV
    Nil, M; Öztürk, Y; Özdemir, S; Sözen, H; Nil, M
    In this study, half-bridge LLC resonant DC-DC converter design was realized for 65 AMOLED TV. The main objective of the design is to achieve the optimum level of reliability and to reach the appropriate life cycle of MTBF (Mean-time between failure). Reliability tests were carried out which cover the thermal, electromagnetic compatibility (EMC) and electrical tests of the designed power board and critical circuit components of this power board. Moreover, in order to analyze the operating characteristics of the circuit at different switching frequencies, simulation analyses were carried out by PSIM Program. As a result of the, all these simulations and empirical studies, a high level of reliability conditions have been achieved with a 120.215 hours MTBF value.
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    Passive thermal management of an OLED TV display
    Nil, M; Öztürk, Y; Akgül, MB; Çatalbas, MC; Nil, M
    In this study, passive thermal management of a 15 '' OLED TV display is studied. In addition to the OLED display, the effect of other heat generating electronic components on the device is taken into account. Experimental temperature measurements are conducted on the OLED display. The CFD model of the device is developed in order to be able to predict the temperatures and validated with experimental results. A good agreement is obtained between CFD simulation and experimental measurements. To eliminate hot spots and homogenize the temperature distribution, heat spreaders like copper and graphite are used and the effects of them are discussed in detail.
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    An Anomaly Detection Study on Automotive Sensor Data Time Series for Vehicle Applications
    Derse, C; el Baghdadi, M; Hegazy, O; Sensoz, U; Gezer, HN; Nil, M
    Anomaly detection in automotive systems has been a strong challenge: first, during the development phase, then after the manufacturing approval in ramp-up production and finally during the vehicles life cycle management. The numerous sensors positioned inside a vehicle generate more than a gigabyte of data at each second timeframe. These sensors are connected through the vehicle network, which comprises Electronic Control Units (ECUs) and Controller Area Network (CAN) buses. Each ECU gets input from its sensors, executes specific instructions and aims to monitor the vehicle's normal state detecting any irregular action corresponding to its observed behavior. The aggregator of all sensor data and control actions detects the anomalies in vehicle systems, which poses a multi-source big data problem. Detecting anomalies during manufacturing has turned out to be another research challenge after the introduction of Industry 4.0. This paper presents a performance comparison of different anomaly detection algorithms on time series originating from automotive sensor data. Interquartile range, isolation forest, particle swarm optimization and k-means clustering algorithms are used to detect outlier data in the study.
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    The effect of ambient temperature on electric power generation in natural gas combined cycle power plant-A case study
    Sen, G; Nil, M; Mamur, H; Dogan, H; Karamolla, M; Karaçor, M; Kuyucuoglu, F; Yörükeren, N; Bhuiyan, MRA
    Natural gas combined cycle power plants (CCPPs) are widely used to meet peak loads in electric energy production. Continuous monitoring of the output electrical power of CCPPs is a requirement for power performance. In this study, the role of ambient temperature change having the greatest effect on electric production is experimentally investigated for a natural gas CCPP. The plant has generated electricity for fourteen years and setup at 240 MW in Aliaga, Izmir, Turkey. Depending on the seasonal temperature changes, the study data were obtained from each gas turbine (GT), steam turbine (ST) and combined cycle blocks (CCBs) in the ambient temperature range of 8-23 degrees C. In electric energy production, an important decrease was in the GTs because of the temperature increase. This decrease indirectly affected the electric energy production of the STs. As a result, the efficiency of each GT, ST and CCB decreased, although the quantity of fuel consumed by the controllers in the plant was reduced. As a result of this data, it has been recommended and applied that additional precautions have been taken in the power plant to bring the air entering the combustion chamber to ideal conditions and necessary air cooling systems have been installed. (C) 2018 The Authors. Published by Elsevier Ltd.
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    A Numerical Analysis of Thermal Management Schemes of a LED Array in TFT TV
    Mermer, O; Nil, M; Akgul, MB
    This paper aims to perform the numerical analysis and to investigate thermal characteristics of the LED backlight TFT TV according to thermal design parameters. Natural convective cooling of a LED array system used TFT TV is considered in this study. Numerical computations are carried out for horizontal and vertical orientations of the LED array. The effects of the PCB materials on the temperature distribution are discussed in detail. It is found that the maximum temperature of the LED packages significantly decreases by the horizontal orientation of the LED array in TFT based television. In addition, ceramic based PCB materials having high thermal conductivity such as A1N present better thermal performance than that of metal based PCB materials.
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    A new hybrid approach in selection of optimum establishment location of the biogas energy production plant
    Ceylan, AB; Aydin, L; Nil, M; Mamur, H; Polatoglu, I; Sözen, H
    In this study, a new hybrid modeling optimization approach is presented for choosing the best installation location of a biogas power plant. This approach was evaluated in a case study for Manisa province in Turkey. First, the animal waste potential in Manisa was determined. By examining the biogas potential in Manisa, the mathematical model of the process is identified with the neuro-regression approach. Comparisons were made with the traditional and hybrid models, and it was seen that the values of the hybrid model based on the introduced approach were at more acceptable levels. Depending on this model, the most appropriate district where the power plant can be installed was calculated by considering the potentials in the environment. The single-objective and multi-objective approaches were considered to acquire the optimum design for the system. The modified versions of the optimization methods differential evolution (MDE), Nelder-Mead (MNM), simulated annealing (MSA), and random search (MRS) algorithms were used to solve problems. Thanks to the calculations and optimizations, it was concluded that it would be more appropriate to establish a biogas plant around Golmarmara, Salihli, and Ahmetli triangle in Manisa. It was determined that when this installation takes place, 68 GWh of electrical energy can be produced annually. This study is a pioneering study for the installation locations of bioenergy power plants in terms of the methods and approaches.
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    Selection of Load Resistance for Boost Converters with Maximum Power Point Tracking Algorithm in Thermoelectric Generators
    Üstüner, MA; Mamur, H; Taskin, S; Nil, M; Bhuiyan, MRA; Kherkhar, A; Chiba, Y
    Thermoelectric generators (TEGs) face challenges in efficiently converting waste heat into electrical energy. To enhance their performance, converters are employed, with the crucial feature being the implementation of the maximum power point tracking (MPPT) algorithm. However, the efficiency of the MPPT software in tracking the maximum power point (MPP) is influenced by the load connected to the converter's output, necessitating the determination of an appropriate load range. The primary objective of this study is to identify an acceptable load range for an isolated DC-DC boost converter used in MPPT within an installed TEG system. The methodology includes building a Simulink/MATLAB model based on TEG manufacturer data, designing a DC-DC boost converter with embedded MPPT algorithms, and conducting simulations and experiments at various load range values. Simulations and experimental studies reveal that the effectiveness of algorithms in tracking the MPP is optimized when the load resistance is between the TEG's internal resistance and three times this value. Below the internal resistance, the MPP cannot be tracked, while at high load values, the MPP significantly decreases. This underscores the critical role of load resistance selection in optimizing TEG system performance during MPPT applications.