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Öğe Chaotic quantum behaved particle swarm optimization algorithm for solving nonlinear system of equations(Pergamon-Elsevier Science Ltd, 2014) Turgut, Oguz Emrah; Turgut, Mert Sinan; Coban, Mustafa TurhanThis study proposes a novel chaotic quantum behaved particle swarm optimization algorithm for solving nonlinear system of equations. Different chaotic maps are introduced to enhance the effectiveness and robustness of the algorithm. Several benchmark studies are carried out. Logistic map gives the best results and is utilized in solving nonlinear equation sets. Nine well known problems are solved with our algorithm and results are compared with Quantum Behaved Particle Swarm Optimization, Intelligent Tuned Harmony Search, Gravitational Search Algorithm and literature studies. Comparison results reveal that the proposed algorithm can cope with the highly non-linear problems and outperforms many algorithms which exist in the literature. (C) 2014 Elsevier Ltd. All rights reserved.Öğe Comparison of Flow Boiling Pressure Drop Correlations for Smooth Macrotubes(Taylor & Francis Inc, 2016) Turgut, Oguz Emrah; Coban, Mustafa Turhan; Asker, MustafaThis paper investigates two-phase pressure-drop correlations available in the literature and compares them with the experimental data in order to assess their performances in terms of prediction accuracy. Pressure drops for pure refrigerants and mixtures are predicted by comparing 1714 experimental data points with eight two-phase pressure drop correlations. In this context, R22, R407C, R410A, R744, R717, R404A, and R134a are selected as test refrigerants. A flow-pattern-based pressure-drop correlation developed by Moreno Quiben and Thome is also discussed. The Moreno Quiben and Thome model takes the effect of annular to dryout transition, and therefore maximum pressure drop occurs at the end of the annular flow regime. Results refer to experimental works in circular smooth tubes between 3.25 and 14.0mm, for saturation temperatures between -30.0 and 50.0 degrees C, mass fluxes between 100.0 and 1082.0kg/m(2)-s, and heat fluxes from adiabatic to 36.8 kW/m(2). The Muller-Steinhagen and Heck correlation shows better performance, predicting 61.7% of experimental data within a +/- 30.0% error band. It is also seen that the Chawla and Gronnerud correlations agree with experimental results only for R134a and R717.Öğe Experimental and numerical investigation on the performance of an internally cooled dehumidifier(Springer, 2016) Turgut, Oguz Emrah; Coban, Mustafa TurhanLiquid desiccant based dehumidifiers are important components of the air conditioning applications. Internally cooled dehumidifiers with liquid desiccants are deemed to be superior to the adiabatic types, thanks to the cooling medium which takes away the latent heat of vaporization occured when moist air contacts with liquid desiccant. However, its utilization in industrial applications is restricted due to the inherent corrosive characteristics of the liquid desiccants. In this study, an experimental chamber is built for epoxy coated plate fin type dehumidifier which is used in order to diminish the corrosive effect of the lithium chloride aqueous solution. Dehumidification effectiveness and moisture removal rate, two parameter indices, are adopted to measure the performance of the air conditioning system. The effect of inlet operating parameters on moisture removal rates is extensively analyzed. Two dimensional numerical model adapted from the conservation principles is utilized for obtainment of output parameters. Experimental results are compared with the numerical model and comparisons show that numerical outputs agrees with the experimental results. And also, dehumidification performance of lithium chloride and lithium bromide aqueous solutions are evaluated and compared against each other.Öğe Modeling of the drying process of apple slices: Application with a solar dryer and the thermal energy storage system(Pergamon-Elsevier Science Ltd, 2017) Atalay, Halil; Coban, Mustafa Turhan; Kincay, OlcayIn this study a solar air heater was developed to determine the drying rate of apple (Golden Delicious). In order to provide the drying process continuously a packed bed thermal energy storage system was designed and manufactured. Also, a recuperator unit was used for waste heat recovery. In the recuperator unit, it is provided the mixing of the fresh air with the drying air whose moisture content increases, at a specified rate. So at the rate of 50-60% waste heat is recovered and reutilized in the drying system. The advantage of the system is that it consumes less energy at the rate of 76.8% than other drying technologies. Experinients on the drying system were repeated twice a day. In the experiments the drying kinetics of apple slices (5 +/- 2 mm thick) was determined at constant temperatures ranging from 50-60 degrees C. Also, Diffusion Approximation model was used for drying of apple slices in constant temperature. A mathematical model was developed to calculate the prediction of the moisture ratio during time and it is observed that the model is complied with the studies in the literature. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Neural Network Predictive Control of a Vapor Compression Cycle(Springer Heidelberg, 2020) Turgut, Mert Sinan; Coban, Mustafa TurhanThis study investigates the Neural Network Predictive Control of a vapor compression cycle (VCC). VCC consists of four components, namely the compressor, electronic expansion valve (EEV), evaporator and condenser. Modeling of the compressor and EEV is carried out with the static relationships, while modeling of the evaporator and condenser is performed with the lumped parameter moving boundary method. the established thermodynamic model is validated against the ASPEN model with the same design specifications. the neural network is trained off-line with the input and output signal data of the established model. the solution of the optimization problem for the each time step is achieved with the metaheuristic method called Whale Optimization Algorithm in the predictive controller. Ultimately, performances of the four different controllers, namely the cooling load, first law efficiency, entropy generation and second law efficiency, are compared with each other. the results show that the entropy generation controller achieves the most favorable exergy destruction performance with 0.2% lower than the worst performer cooling load controller. It is also observed that the second law efficiency controller is the best performer in terms of the overall second law efficiency through the simulation time.Öğe A New Saturated Two-Phase Flow Boiling Correlation Based on Propane (R290) Data(Springer Heidelberg, 2021) Turgut, Oguz Emrah; Coban, Mustafa TurhanThere are plenty of literature research studies investigating two-phase heat transfer characteristics of propane under varying operational conditions. Based on the collected data retrieved from the experimental measurements, several flow boiling heat transfer correlations have been proposed up to now. However, the prediction accuracy of the proposed correlations for propane refrigerant is still in question as most of the correlation is developed for their measurements or derived for a limited range of operational conditions. To conquer this drawback, this study proposes a new flow boiling heat transfer model for smooth tubes based on a propane experimental database compiled of 2179 points obtained from different eighteen laboratories around the world. Operational conditions of the database cover mass fluxes between 50 and 600 kg/m(2)s, saturation temperatures between - 35.0 and 43.0 degrees C, heat fluxes between 2.5 and 227.0 kW/m(2), hydraulic diameters between 0.3 and 7.7 mm, and thermodynamic qualities 0.01 to 0.99. Estimations performed by the new flow boiling model have been compared to those obtained by the literature correlations, and comparative results indicate that the proposed model surpasses the existing flow boiling in terms of prediction accuracy with a mean absolute error of 19.1% and mean relative error of 1.7%.Öğe Novel Saturated Flow Boiling Correlations for R600a and R717 Refrigerants(Taylor & Francis Inc, 2022) Turgut, Oguz Emrah; Genceli, Hadi; Asker, Mustafa; Coban, Mustafa TurhanThis research study provides a detailed analysis of the two-phase flow boiling heat transfer coefficients of R600a and R717. In addition, it proposes novel saturated flow boiling heat transfer correlations for these two refrigerants. In this context, 1306 experimental data points for R600a and 885 data samples for R717 are extracted from the literature works to develop new flow boiling models. Two different correlations are constructed under different forms of baseline frameworks for each refrigerant. The proposed flow boiling model for R600a utilizes the dimensionless numbers and operational parameters of the best performing literature correlations for this refrigerant while the model developed for R717 takes the advantage of piecewise continuous correlation form which successfully trace the tendencies of heat transfer coefficient with varying vapor qualities. It is found that the new model for R600a has a mean absolute error of 12.4% and mean relative error of 0.1, predicting 78.5% of the entire database within +/- 20.0% error band whereas the proposed correlation for R717 has an absolute error value of 17.3% having 65.3% of the data within +/- 20.0% error band, which are much better and accurate estimations compared to those obtained by the existing flow boiling models for R717 refrigerant.Öğe Novel Saturated Flow Boiling Heat Transfer Correlation for R32 Refrigerant(Amer Inst Aeronautics Astronautics, 2022) Turgut, Oguz Emrah; Asker, Mustafa; Genceli, Hadi; Coban, Mustafa Turhan[No Abstract Available]Öğe Optimal proton exchange membrane fuel cell modelling based on hybrid Teaching Learning Based Optimization - Differential Evolution algorithm(Elsevier Science Bv, 2016) Turgut, Oguz Emrah; Coban, Mustafa TurhanSimulation proton exchange membrane fuel cell (PEMFC) performance accurately is a challenging process. Many mathematical models have been existed, yet due to lack of accurate parameter estimations, considerable errors might occur. Nowadays, meta-heuristic optimization algorithms have been successfully applied for parameter identification of PEMFC models. In this study, Teaching Learning Based Optimization method (TLBO) is hybridized with Differential Evolution (DE) algorithm for successful estimation of unknown PEMFC model parameters. Efficiency of the proposed algorithm is tested with several benchmark problems. A case study taken from the literature has been performed by hybrid TLBO-DE algorithm and other optimization methods such as Melody Search (MS), Backtracking Search (BS), Artificial Cooperative Search (ACS), Quantum behaved Particle Swarm Optimization (QPSO), Bat algorithm (BAT), Intelligent Tuned Harmony Search (ITHS) and Cuckoo Search (CS). TLBO-DE algorithm surpasses all these optimizers in terms of solution quality and accuracy. (C) 2015 Faculty of Engineering, Ain Shams University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Öğe Saturated Flow Boiling Heat Transfer Correlation for Small Channels Based on R134a Experimental Data(Springer Heidelberg, 2016) Turgut, Oguz Emrah; Asker, Mustafa; Coban, Mustafa TurhanIn the literature, the modeling of saturated flow boiling heat transfer characteristics of R134a flowing through small channels is still questionable since it is based on very limited operational data. This study proposes a new evaporative heat transfer model based on R134a for micro-and macro-tubes. The proposed correlation is developed from 3594 data points, which are obtained from 19 different studies. Ranges of the database cover mass fluxes between 50.0 and 1500.0 kg/m(2) s, heat fluxes between 3.0 and 150.0 kW/m(2), hydraulic diameter between 0.5 and 13.84mm, saturation temperatures between -8.8 and 52.4 degrees C, and vapor qualities up to 1.0. Findings of the proposed method are compared with those of the most quoted flow boiling heat transfer correlations developed for micro- and macro-tubes. Results of the comparison indicate that new method, which has a mean absolute deviation of 19.1% and captures 66.7 and 83.2% of the experimental data within +/- 20 and +/- 30% error bands correspondingly, outperforms the available flow boiling correlations in the literature in terms of prediction accuracy.Öğe Thermal design of spiral heat exchangers and heat pipes through global best algorithm(Springer, 2017) Turgut, Oguz Emrah; Coban, Mustafa TurhanThis study deals with global best algorithm based thermal design of spiral heat exchangers and heat pipes. Spiral heat exchangers are devices which are highly efficient in extremely dirty and fouling process duties. Spirals inherent in design maintain high heat transfer coefficients while avoiding hazardous effects of fouling and uneven fluid distribution in the channels. Heat pipes have wide usage in industry. Thanks to the two phase cycle which takes part in operation, they can transfer high amount of heat with a negligible temperature gradient. In this work, a new stochastic based optimization method global best algorithm is applied for multi objective optimization of spiral heat exchangers as well as single objective optimization for heat pipes. Global best algorithm is easy-to-implement, free of derivatives and it can be reliably applied to any optimization problem. Case studies taken from the literature approaches are solved by the proposed algorithm and results obtained from the literature approaches are compared with thosed acquired by GBA. Comparisons reveal that GBA attains better results than literature studies in terms of solution accuracy and efficiency.Öğe Thermodynamic and Thermophysical Properties of Dry Air by Using Cubic Peng-Robinson EoS for Gas Mixtures(Int Center Applied Thermodynamics, 2020) Coban, Mustafa Turhan; Kavas, SuleymanDry air is widely used in industrial and technological applications. Ideal gas EoS is used in dry air thermodynamic property calculations. For most applications, it might be sufficient, but when applications with higher pressure zones are considered, error level will increase. Peng-Robinson cubic Eq. of states is considered for better accuracy of the thermodynamic properties for dry air in this paper. So, the objective of this study is to suggest a more accurate EoS for thermodynamic and heat transfer analyses. Set of computer programs were developed in java language to calculate thermodynamic properties like specific volume, internal energy, enthalpy, entropy, Gibbs energy, Helmholtz energy, specific heat, thermal conductivity, and viscosity of dry air. The results are compared with the perfect gas EoS and the Eq.s developed by The International Association for the Properties of Water and Steam (IAPWS).Öğe THERMODYNAMIC PERFORMANCE OF THE TRANSCRITICAL REFRIGERATION CYCLE WITH EJECTOR EXPANSION FOR R744, R170, AND R41(Turkish Soc Thermal Sciences Technology, 2018) Atmaca, Ayse Ugurcan; Erek, Aytunc; Ekren, Orhan; Coban, Mustafa TurhanFor more than a decade, there is a great demand for finding environmentally-friendly refrigerants obeying the global warming potential value restrictions of the tough environmental legislation. Among the candidate working fluids, R744 (carbon dioxide or CO2), R170 (ethane), and R41 (fluoromethane) are selected to be investigated parametrically in this paper. Performance comparison is made for these three working fluids individually in both transcritical (supercritical) refrigeration cycle and modification of this cycle with ejector expansion. As the first step, the effects of the gas cooler outlet temperature, evaporator temperature, and evaporator outlet superheat temperature difference on the overall performance and percentage expansion losses are investigated within a specific gas cooler pressure range. Evaporator outlet superheat temperature difference is found to be the least effective parameter on the performance; hence, secondly, the transcritical ejector expansion refrigeration cycle is analyzed considering only evaporator temperature and gas cooler outlet temperature based on the same gas cooler pressure ranges. Thermodynamic models are constructed in Matlab (R) and the ejector equations for the ejector expansion refrigeration cycle are established with reference to constant pressure mixing assumption. Comparisons of the performance, percentage expansion losses, and performance improvement potential through the implementation of the ejector instead of the expansion valve among these three refrigerants having low critical temperatures represent the main objective of the paper in order to make contributions to the previous researches in the literature.
