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Öğe A NOVEL MACHINE LEARNING STUDY: MAXIMIZING THE EFFICIENCY OF PARABOLIC TROUGH SOLAR COLLECTORS WITH ENGINE OIL-BASED COPPER AND SILVER NANOFLUIDS(Begell House Inc, 2024) Colak, Andac Batur; Bayrak, MustafaEstimating the heat transfer parameters of parabolic trough solar collectors with machine learning is crucial for improving the efficiency and performance of these renewable energy systems, optimizing their design and operation, and reducing costs while increasing the use of solar energy as a sustainable power source. In this study, the heat transfer characteristics of two different nanofluids flowing through the porous media in a straight plane underneath thermal jump conditions were investigated by machine learning methods. For the flow in the parabolic trough solar collector, two different nanofluids obtained from silver- and copper-based motor oil are considered. Flow characteristics were obtained by nonlinear surface tension, thermal radiation, and Cattaneo-Christov heat flow, which was used to calculate the heat flow in the thermal boundary layer. A neural network structure was established to estimate the skin friction and Nusselt number determined for the analysis of the flow characteristic. The data used in the multilayer neural network, which was developed using a total of 30 data sets, were divided into three groups as training, validation, and testing. In the input layer of the network model with 15 neurons in the hidden layer, 10 parameters were defined and four different results were obtained for two different nanofluids in the output layer. The prediction performance of the established neural network model has been comprehensively studied by means of several performance parameters. The study findings presented that the established artificial neural network can predict the heat transfer characteristics of two different nanofluids obtained from silver- and copper-based motor oil with deviation rates less than 0.06%.Öğe Analysis of tempering treatment on material properties of DIN 41Cr4 and DIN 42CrMo4 steels(ASM INT, 2007) Bayrak, Mustafa; Ozturk, Fahrettin; Demirezen, Mehmet; Evis, ZaferDIN 41Cr4 and DIN 42CrMo4 materials have been widely used in automotive driving elements. Although 42CrMo4 is more expensive than 41Cr4, it is more preferable in terms of material properties. In this study, these two materials were heat treated by austenitizing in a continuous furnace at 850 degrees C and quenched in oil at 90 degrees C. After they were tempered at various temperatures, mechanical properties were determined for each tempering temperature. The material properties for both materials were compared with each other. Results indicated that same mechanical properties for 41Cr4 and 42CrMo4 can be achieved by tempering 41Cr4 about 50 degrees C lower temperature than for 42CrMo4. In addition to the mechanical tests, fatigue tests were performed for both materials. Weibull distributions were plotted. Results indicated that 42CrMo4 had a longer life than 41Cr4 material.Öğe Comparison of experimental thermal conductivity of water-based Al2O3-Cu hybrid nanofluid with theoretical models and artificial neural network output(Springer, 2024) Colak, Andac Batur; Bayrak, MustafaThe research aimed to experimentally test the thermal conductivity of five distinct Al2O3-Cu/water hybrid nanofluids. These nanofluids were generated at volumetric concentrations of 0.0125, 0.025, 0.05, 0.1, and 0.2. The measurements were conducted within a temperature range of 10-65 degrees C. The primary objective of this research is to tackle the insufficient empirical data on hybrid nanofluids and establish a dependable artificial neural network model for forecasting their thermal conductivity. A multilayer perceptron feed forward back propagation artificial neural network has been created using the acquired experimental thermal conductivity data. The experimental thermal conductivity data have been compared with four commonly used mathematical correlations and the outputs of an artificial neural network. The findings demonstrated that the constructed artificial neural network accurately forecasted the thermal conductivity of the Al2O3-Cu/water hybrid nanofluid, with an average deviation of just 0.4%. Nevertheless, Maxwell's mathematical correlation proved to be the most accurate model in predicting the experimental findings, with an average error margin of just 0.08%.Öğe EFFECTS OF VARIATIONS IN ALLOY CONTENT AND MACHINING PARAMETERS ON THE STRENGTH OF THE INTERMETALLIC BONDING BETWEEN A DIESEL PISTON AND A RING CARRIER(INST ZA KOVINSKE MATERIALE I IN TEHNOLOGIE, 2010) Acar, Ahu Fahriye; Ozturk, Fahrettin; Bayrak, MustafaThe intermetallic bonding between an aluminium alloy piston and a cast-iron ring carrier must be able to withstand prolonged exposure to the high-pressure and high-temperature environment of a diesel engine. Weak cohesion may result in the debonding of the ring carrier. Such debonding causes devastating damage to the piston while the engine is in service. Thus, the quality and strength of the intermetallic bonding is very important in piston manufacturing. In the present study, the effects of variations in the alloy content and the machining parameters on the overall strength of the intermetallic bonding are investigated. The defects are determined by ultrasonic inspection. The results indicate that the variation in the alloy content and graphite flakes affects the bond quality adversely. It was determined that the graphite size is a very important parameter. If the graphite size gets smaller, then stronger intermetallic bonding is observed. The graphite accumulation can be resolved by choosing the right amount of alloying elements. The machining process parameters were found to be ineffective for the formation of defects on the intermetallic bonding.Öğe Effects of variations in alloy content and machining parameters on the strength of the intermetallic bonding between a diesel piston and a ring carrier(2010) Acar, Ahu Fahriye; Ozturk, Fahrettin; Bayrak, MustafaThe intermetallic bonding between an aluminium alloy piston and a cast-iron ring carrier must be able to withstand prolonged exposure to the high-pressure and high-temperature environment of a diesel engine. Weak cohesion may result in the debonding of the ring carrier. Such debonding causes devastating damage to the piston while the engine is in service. Thus, the quality and strength of the intermetallic bonding is very important in piston manufacturing. In the present study, the effects of variations in the alloy content and the machining parameters on the overall strength of the intermetallic bonding are investigated. The defects are determined by ultrasonic inspection. The results indicate that the variation in the alloy content and graphite flakes affects the bond quality adversely. It was determined that the graphite size is a very important parameter. If the graphite size gets smaller, then stronger intermetallic bonding is observed. The graphite accumulation can be resolved by choosing the right amount of alloying elements. The machining process parameters were found to be ineffective for the formation of defects on the intermetallic bonding.Öğe Exergy analysis of Eregli sugar factory(EMERALD GROUP PUBLISHING LTD, 2015) Sahin, Necmettin; Kaplan, Erkan; Bayrak, Mustafa; Yaka, I. Faruk; Gungor, AfsinProgressive decline in world energy resources, rising costs, on behalf of the various studies has led businesses to use energy resources efficiently. This work is at the top of the exergy analysis. In this study, using data from Eregli Sugar Factory 2010-2011 campaign year for sugar production processes, the first law of thermodynamics (energy analysis) and analysis of these condlaw (exergy analysis) were conducted. Depending on there sults of this analysis of the sugar production process yields the first and these cond law is calculated. Obtained in the light of the secalculation stoin crease theen ergy efficiency of the plant, was tetoprovide energy to gainth embackand give direction to the development of new technologies Eregli Sugar Factory recommendations were made.Öğe Experimental study for predicting the specific heat of water based Cu-Al2O3 hybrid nanofluid using artificial neural network and proposing new correlation(Wiley-Hindawi, 2020) Colak, A. Batur; Yildiz, Oguzhan; Bayrak, Mustafa; Tezekici, Bekir S.In this study, an artificial neural network model has been created in order to estimate the specific heat of Cu-Al2O3/water hybrid nanofluid based on temperature (T) and volume concentration (phi). Specific heat values of the Cu-Al2O3/water hybrid nanofluid prepared in five-volume concentration were measured experimentally in the 20 degrees C to 65 degrees C temperature range. The dataset was reserved into three primary parts, with the inclusion of 901 (70%) for the training, 257 (20%) for the test and 129 (10%) for the validation. As a result of comparison with experimental values, it is concluded that this model predicts specific heat with R-value of 0.99994 and an average relative error of approximately 5.84e-9. In addition, a mathematical correlation has been developed to estimate the specific heat of the Cu-Al2O3/water hybrid nanofluid. The data acquired from the mathematical correlation, developed, were in great correlation with all the experimental values with an average deviation of -0.005%. This result has revealed that the developed mathematical correlation is an ideal design for estimating the specific heat of the Cu-Al2O3/water hybrid nanofluid.Öğe Experimental Study on the Specific Heat Capacity Measurement of Water-Based Al2O3-Cu Hybrid Nanofluid by using Differential Thermal Analysis Method(Bentham Science Publ Ltd, 2020) Colak, Andac Batur; Yildiz, Oguzhan; Bayrak, Mustafa; Celen, Ali; Dalkilic, Ahmet Selim; Wongwises, SomchaiBackground: Researchers working in the field of nanofluid have done many studies on the thermophysical properties of nanofluids. Among these studies, the number of studies on specific heat is rather limited. In the study of the heat transfer performance of nanofluids, it is essential to raise the number of specific heat studies, whose subject is one of the important thermophysical properties. Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids and Al2O3-Cu/water hybrid nanofluids using the DTA procedure, and compare the results with those frequently used in the literature. In addition, this study focuses on the effect of temperature and volume concentration on specific heat. Methods: The two-step method was tried to have nanofluids. The pure water selected as the base fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer. Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared and the temperature and volume concentration of specific heat were investigated. Then, the experimental results obtained for all three fluids were compared with the two frequently used correlations in the literature. Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity among all tested fluids. Experimental specific heat capacity measurement results are compared by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental results, these correlations can predict experimental results within the range of +/- 1%.Öğe Fossil fuel sustainability: Exergy assessment of a cogeneration system(JOHN WILEY & SONS LTD, 2011) Bayrak, Mustafa; Gungor, AfsinThermodynamics plays an important role to perform the energy and exergy analyses of the industrial processes. The first law is widely used in engineering practice and is the basis of the heat-balance method of analysis that is commonly used in energy systems performance analysis. However, the second law involves the reversibility or irreversibility of processes and is a very important aspect in the exergy method of energy systems analysis. From the viewpoints of energy conservation and environmental benefits, cogeneration system can be considered as one of sustainable energies. The exergy analysis allows for improvements not necessarily attainable via energy methods, like increased efficiency, reduced fuel use, and reduced environmental emissions. From this point of view, in this study, exergy analysis of an actual Diesel engine-based cogeneration plant with a total capacity of 11.52 MW electrical powers, 9 t h (-1) of steam and 140 t h (-1) of hot water is carried out by analyzing the components of the system separately. The results show that 39.86% of the exergy entering the plant is converted to electrical power. The net steam production of the plant constitutes 8% of the total exergy input and the hot water production of the plant constitutes only 1.26% of the total exergy input. The remaining 50.88% of the exergy input is lost. Total exergy destruction in the engine is mostly due to the highly irreversible combustion process in the engine, heat losses from engine and friction. Small improvements in engine design and operation can provide better utilization of plant performance compared to large and expensive improvements in other components. Copyright (C) 2010 John Wiley & Sons, Ltd.Öğe In view of sustainable future energetic-exergetic and economic analysis of a natural gas cogeneration plant(INDERSCIENCE ENTERPRISES LTD, 2013) Gungor, Afsin; Bayrak, Mustafa; Beylergil, BertanThermodynamics plays an important role in performing energy and exergy analyses of industrial processes. The first law is widely used in engineering practice, and is the basis of the heat-balance method of analysis that is commonly used in energy systems performance analysis. However, the second law involves the reversibility or irreversibility of processes, and is a very important aspect of the exergy method of energy systems analysis. For a sustainable future, exergy analysis allows for improvements not necessarily attainable via energy methods, like increased efficiency, reduced fuel use and reduced environmental emissions. From the viewpoints of energy conservation and environmental benefits, cogeneration systems can be considered as systems of sustainable energies. From this point of view, in this study, the energy, exergy and economic analysis of an actual natural gas cogeneration plant with a total capacity of 121.5 MWh electrical powers is carried out. The first and second law efficiency of the cogeneration plant is calculated as 40.8% and 90.2%, respectively. The pay-back period of the cogeneration plant is calculated as three years, which means this plant runs quite efficiency and economically.Öğe Metal-hidrit yataklarda hidrojen şarj/deşarj işlemine etki eden proses parametrelerinin incelenmesi(2008) Kaplan, Yüksel; Bayrak, Mustafa; Demiralp, Mehmet[Abstract Not Available]Öğe Niğde Bölgesinde Tarımsal Sulama Amaçlı Güneş Enerjisi Potansiyelinin Teorik ve Deneysel İncelenmesi(2019) Şen, Burak; Gözyuman, Remzi; Bayrak, Mustafa; Yıldız, OğuzhanYenilenebilir enerji kaynaklarına olan yönelme son yıllarda giderek artmaktadır. Bu yöneliş,öncelikle potansiyel hesaplamalarıyla başlamış, zamanla teknolojilerin uygulamasına geçilmiştir.Teknolojik anlamda güneş enerjisi uygulamaları; genelde ısıtma, elektrik üretme ve tarımsal sulamaamaçlı olmaktadır. Elektrik üretmede fotovoltaik pil (PV) uygulamaları, dünya çapında büyük ivmekazanmıştır. Fotovoltaik sulama sistemlerinde boyut analizi yapılırken, kullanılan eski metotlar,sadece üretilen hidrolik enerjinin gereksinimlerini dikkate alırdı. Bu metotların aksine bu çalışmadaproblem, sistematik olarak ele alınıp, sistemin bütün elemanlarının ve bileşenlerinin analizleriyapılmıştır. Bu çalışmada, öncelikle Niğde’nin tarımsal yapısına uygun olarak, patates üretimiyapılan işletmenin enerji ihtiyacı belirlenmiştir. Söz konusu çalışmalar göstermiştir ki; tarımsalamaçlı sulamada, çok büyük bir enerji ihtiyacı bulunmaktadır. Bu enerji ihtiyacının güneş enerjisiile karşılanmasının ekonomik boyutu sistemin projelendirilmesi, uygulanması ve üretilen elektriğindeğerlendirilmesine göre çok değişkenlik göstermektedir. Çalışmada, bu sorunlar uygulama ve farklısenaryolar dahilinde irdelenmiştir.Öğe Single phase flow of nanofluid including graphite and water in a microchannel (vol 56, 1, 2020)(Springer, 2020) Yildiz, Oguzhan; Acikgoz, Ozgen; Yildiz, Guldem; Bayrak, Mustafa; Dalkilic, Ahmet Selim; Wongwises, Somchai[Abstract Not Available]
