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Öğe Assessment of a solar-assisted infrared timber drying system(Wiley, 2017) Aktas, Mustafa; Ceylan, Ilhan; Ergun, Alper; Gurel, Ali Etem; Atar, MusaThis study investigates convective-infrared drying characteristics of timber. The biggest disadvantage of infrared heating systems is the uncontrollable rise of the surface temperature up to extremely high values, which causes damage to the product. In this study, the power of an infrared system was controlled and adjusted according to the surface temperature of the product. In doing so, the surface temperature of the infrared heater was prevented from reaching up to values that could damage the product. During the analysis, the surface temperature of the timbers was kept at an average of 65 degrees C, while the bottom temperature was kept at an average of 45 degrees C. The air collector used in the system was found to be 50% efficient. At the end of a 13-h drying period, the moisture content of pine timbers could be reduced from 1.42 to 0.0948 g water/g dry matter. During the system analysis, parameters such as moisture content, mass diffusion coefficient, and useful energy rate were taken into consideration. (c) 2017 American Institute of Chemical Engineers Environ Prog, 36: 1875-1881, 2017Öğe Comparison of DC link current and stator phase current in inverter switching faults detection of PMSM drives in HEVs(Elsevier - Division Reed Elsevier India Pvt Ltd, 2018) Aktas, Mustafa; Aygun, HilmiIn this paper, a robust method for detection of inverter short circuit faults in field oriented control (FOC) of permanent magnet synchronous motor (PMSM) drive that is used frequently in hybrid electric vehicles (HEV) thanks to high power density and high efficiency is introduced. In the proposed method, a fault diagnostic and protection technique is developed by using discrete wavelet transform (DWT) and artificial neural network (ANN). The Symlet2 wavelet is selected to perform stator current analysis and the DWT coefficients of the motor currents are used as inputs of ANN for detecting inverter faults in PMSM drives. In HEVs, motor faults can cause permanent damage and accidents. So the early detection of PMSM drive faults in HEV will be provided by the proposed method. For implementing this method, the Matlab program is used to process DWT of signals. DC link and phase currents are compared in inverter switch faults detection and the results show that the proposed technique is very effective for fault diagnostic. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.Öğe Decreasing the Cooking Time of the Dry Beans Without Lowering the Quality(Gazi Univ, 2015) Aktas, Mustafa; Ceylan, Ilhan; Sevik, Seyfi; Dogan, HikmetThe aim of this study is to decrease the cooking time of the dry beans without lowering the quality. A second soaking was applied to the dry beans after drying, which were cooked for 2 hours following the first cooking. The dry beans were dried at 40 degrees C drying air temperature after the soaking. The volume of the beans was increased by about 16% through these procedures. Cooking period after the second drying was decreased by 1 hour. Results also showed that there was no split skin on the outer layers of the dry beans, which is a notable quality criterion, owing to the method used while soaking and, soaking and drying operations on the dry beans before packaging decreased the pre-cooking soaking and cooking period. Thus, energy and time saving can be obtained during cooking.Öğe DESIGNING, MANUFACTURING AND PERFORMANCE EXPERIMENTS OF HEAT PUMP RED PEPPER DRYER ASSISTED SOLAR ENERGY(Turkish Soc Thermal Sciences Technology, 2010) Aktas, Mustafa; Ceylan, Ilhan; Dogan, Hikmet; Aktekeli, ZuelfikarIn this study, redpeppers were dried in a heat pump dryer assisted solar energy. Redpeppers have been dried from initial moisture content (10.81 g water/g dry matter) to final moisture content (0.16 g water/g dry matter) by using heat pipe solar collector and air to air heat pump system. In the drying system, 24 h drying period was provided heat pump support. In PID controlled dryer, air velocity changed according to the temperature value which is set in process control device. Redpeppers were dried at 50 degrees C dry bulb temperature and average 0.4 m/s air velocity in a period of 210 min. According to experiment results, average heating coefficient performance (COPwh) and specific moisture extraction rate (SMERws) were calculated for whole system as 2.24 and 0.209 kg/kWh respectively.Öğe Determination of drying characteristics of apples in a heat pump and solar dryer(Elsevier, 2009) Aktas, Mustafa; Ceylan, Ilhan; Yilmaz, SezayiBoth a heat pump and solar dryer were designed and manufactured. They were experimentally analyzed by drying apples, and a comparison was made between the two. Apples were sliced 4 mm thick, and dried from 4.8 (g water/g dry matter) moisture content to 0.18 (g water/g dry matter) at 3.3 kg/m(2)s-2.4 kg/m(2)s mass air velocity for 15 h in a heat pump dryer. Apples were also dried at the range of 3.3 kg/m(2)s and 2.9 kg/m(2)s mass air velocity from 4.8 (g water/dry matter) moisture content to 1 (g water/g dry matter) moisture content in the same period in a solar dryer. Effective moisture diffusivity was found to be 2.36 x 10(-8) m(2)/s in the heat pump dryer, and 1.03 x 10(-8) m(2)/s in the solar dryer. For both systems, the moisture ratio was analyzed with the Statgraphic program by using semi-theoretical models and compared to the empirical values. Correlation coefficients of the equations were calculated and standard error of estimation (SEE) and R-2 values were obtained.Öğe Development and Analysis of a Multi-evaporator Cooling System with Electronic Expansion Valves(Springer Heidelberg, 2017) Atas, Safak; Aktas, Mustafa; Ceylan, Ilhan; Dogan, HikmetIn this study, a vapor compression cooling system with three evaporators and electronic expansion valves was designed, manufactured and tested experimentally. Compressor of this system was converted to be inverter driven which enabled it to run at variable speeds. Temperature values of cold rooms were controlled more sensitive by using electronic expansion valves. Energy analysis was done by comparing the operating parameters of the system with constant and variable speeds. Programmable logic control (PLC) and cold room controls were used to control the system. The PLC device provided the variable operation of the system by determining the required operation frequency of the compressor according to the changes at the suction line. Using this program, the desired values are set on the PLC screen and the multi-evaporator cooling system was tested at various conditions. The desired conditions are determined for the system at 0,+5 and -5 degrees C temperatures. Calculations on the experimental results revealed that the cooling coefficient of performance is 1.86 for the constant frequency operation and 2.22 for the variable frequency operation. Besides, it was determined experimentally that the system running on variable frequency consumed 20% less electrical energy than the constant frequency system.Öğe Direct torque control versus indirect field-oriented control of induction motors for electric vehicle applications(Elsevier - Division Reed Elsevier India Pvt Ltd, 2020) Aktas, Mustafa; Awaili, Khaled; Ehsani, Mehrdad; Arisoy, AydemirPerformance and energy efficiency of induction motors (IM) used in electric vehicle (EV), by applying two control methods, namely the indirect field-oriented control (IFOC) method and the direct torque control (DTC) method, are compared. The tracking accuracy under changing vehicle speed circumstances for different speed controllers (classical PI, fuzzy logic, and sliding mode speed controllers) is studied. The EV including IM and battery is considered a nonlinear system. For modelling and simulation of EV components and for evaluating the controller performances, a Matlab m-file code package based only m-file coding is developed. The simulations reveal the advantage of DTC over IFOC and the superiority of the proposed sliding mode controller, in terms of improved tracking accuracy and increasing energy efficiency, and motivate the use of the proposed sliding mode controller for EV applications. (c) 2020 Karabuk University. Publishing services 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 Drying of Kanlıca Mushroom by the Hot Air Drying Method and the Investigations of Its Effects on Its Quality(Gazi Univ, 2023) Ongun, Goknur Kayatas; Aktas, Mustafa; Acar, Bahadir; Ozkaymak, MehmetIn this study, by providing the hot air drying of Kanlica mushroom collected from Karabuk city; prevention of aflatoxin occurrence, shelf life extension, taking precaution against early putrefaction and decomposition, protection of the beneficent aromas in its content have been ensured. As the dried product, Kanlica mushroom, the most consumed endemic plant spicy in terms of the vitamin and the mineral that it contains among the mushroom groups, has been used. By means of hot air drying, drying has been done at five different (30 oC, 40 oC, 50 oC, 60 oC and 70 oC) temperatures. The best result in terms of water activity, colour changes, energy consumption and drying duration has been obtained in the experiments at 50 oC. The water activity values of products (fresh mushroom water activity: 0,983 aw) dried in hot air drying processes have been found in 0,429 and 0,173 interval (in literature lower than 0,6) and according to the colour analysis experiments result, L*, a*, b*, C*, Ho, increment E, BI values of Kanlica mushroom dried at different temperatures have been calculated. According to the result of the analyses, it has been detected that the preservation of mushrooms hot air drying is appropriate.Öğe Energy analysis of hazelnut drying system-assisted heat pump(Wiley, 2008) Ceylan, Ilhan; Aktas, MustafaIn this experimental study, it proportional integral derivative (PID) controlled heat pump dryer wits designed and manufactured. Heat pump dryer was tested drying of hazelnut and energy analyses were made. Drying air temperatures were changed as 50,45 and 40 degrees C in the drying system. Drying air velocities were changed as 0.25 m s(-1) for 50 degrees C, 0.32 m s(-1) for 45 degrees C and 0.38 m s(-1) for 40 degrees C. Heating coefficient of performance of whole system (COPws) of the heat pump dryer was calculated its 1.70 for 50 degrees C, 1.58 for 45 degrees C and 1.40 for 40 degrees C drying air temperatures. Energy utilization ratio changed between 24 and 65% for 50 degrees C, 17 and 63% for 45 degrees C and 14 and 43% for 40 degrees C drying air temperatures in the heat pump dryer. Copyright (C) 2008 John Wiley & Sons, Ltd.Öğe Experimental Investigation of Freeze-Dried of Kanlica Mushroom (Lactarius Salmoncolor)(Gazi Univ, 2023) Ongun, Goknur Kayatas; Ozkaymak, Mehmet; Acar, Bahadir; Aktas, Mustafa; Dagdeviren, AbdullahIn this study, it is examined to prevent the formation of toxins by providing drying of the kanlica mushroom, which is unique to Karabuk, by freezing, to extend the shelf life, to take measures against early decay and spoilage. As the dried product, kanlica mushroom, which is an endemic plant, contains high amounts of protein and amino acids. In this study, the 5 mm thick cut kanlica mushroom was placed in a freeze-drying device and the drying process was initiated. Weight losses during drying were recorded and kinetic models were created. In the experiment lasting 14 hours in total, 100 gr. The weights of the canlica mushrooms were measured every two hours and MR (Moisture rates) were calculated. According to our results, the lowest chi-square (X-2) was 1.851 x10(-4) and the estimated standard error (RMSE) value was 0.01358. The correlation value (R-2) was calculated as 0.9988, close to one. The best Page model gave these results from the kinetic models. The effective diffusivity for the Kanlica Mushroom with 5 mm thicknesses can be calculated at about 3.2035x10(-10) m(2)/s. It was confirmed that the calculated effective diffusivity value was within the reference range mentioned in the literature (10(-12) m(2)/s - 10(-8) m(2)/s) for food products.Öğe HAZELNUT DRYING IN A DRYER ASSISTED HEAT PUMP(Gazi Univ, Fac Engineering Architecture, 2008) Ceylan, Ilhan; Aktas, MustafaIn this study, hazelnut drying was examined experimentally at kiln assisted heat pump. After the drying hazelnuts were analyzed emotionally, moisture change was observed with mass measurement method. After the drying increasing of the quality of hazelnuts were provided by applying necessary first preparation and last control operations with this drying kiln which has been required by producers, has low first investment and energy expense.Öğe LMC-based DTC for efficiency improvement of IM drives and their electric vehicle applications(Springer Heidelberg, 2020) Aygun, Hilmi; Aktas, MustafaElectric vehicles (EVs) with induction motor (IM) drives require energy optimization due to their limited energy storage capacity. Among the energy optimization methods currently available, a loss model-based controller (LMC) is a satisfactory technique, since it converges rapidly to an optimal operating point. Some of the simplifications applied to LMCs, such as neglecting the core loss and leakage inductances, affect IM drive performance negatively in terms of loss minimization. To overcome this problem, this paper presents an efficient LMC combined with direct torque control (DTC). The proposed method is based on the idea that the magnetizing current is much higher than the core loss current. Using the sum of the stator current and the rotor current instead of the magnetizing current, modelling the losses is simplified and the optimal stator flux is determined easily. A simulation study is carried out to evaluate the performance of the proposed scheme with an EV application during an FTP-75 urban driving cycle. A prototype 3 kW IM drive with a TMS320F28335 digital signal processor (DSP) is built to validate the simulation results. A significant efficiency improvement is obtained at low loads. Both simulation and experimental results demonstrate that the proposed DTC improves efficiency and decreases torque ripple.Öğe Modeling of a hazelnut dryer assisted heat pump by using artificial neural networks(Elsevier Sci Ltd, 2008) Ceylan, Ilhan; Aktas, MustafaThe artificial neural network (ANN) approach is generic technique for mapping non-linear relationships between inputs and outputs without knowing the details of these relationships. In this paper, an application of the ANN has been presented for a PID controlled heat pump dryer. In PID controlled heat pump dryer, air velocity changed according to the temperature value which is set in process control device. Heat pump dryer was tested drying of hazelnut at 40 degrees C, 45 degrees C and 50 degrees C drying air temperatures. By training the experiment results with ANN, drying air velocities, moisture content of hazelnuts and total drying time were predicted for 42 degrees C,44 degrees C, 46 degrees C and 48 degrees C drying air temperatures. (c) 2008 Elsevier Ltd. All rights reserved.Öğe A Novel DTC Method with Efficiency Improvement of IM for EV Applications(Eos Assoc, 2018) Aygun, Hilmi; Aktas, MustafaInduction motor (IM) stator flux optimization is very important in order to get increasing running distance per battery charge of electric vehicles (EVs). This study introduces a new direct torque control (DTC) method for efficiency improvement of IM in EV applications. Also, it is proposed to decrease the torque ripple of DTC based IM. Generally, loss minimization algorithms can be simplified by neglecting the core loss or the effect of leakage inductance in the motor model. However, neglecting the core loss causes an error in torque control of DTC. Beside this, exact loss minimization cannot be achieved since a large voltage drop across leakage inductance occurs especially in high-speed region. In the proposed method, the motor model is simplified by neglecting the current in the core loss resistance branch instead of neglecting the core loss and the effect of leakage inductance. The proposed method is simulated in Matlab for variable speeds and loads. Results show that it provides a significant reduction of losses and decreases the torque ripple of IM drives.Öğe A Novel Method for Inverter Faults Detection and Diagnosis in PMSM Drives of HEVs based on Discrete Wavelet Transform(Univ Suceava, Fac Electrical Eng, 2012) Aktas, MustafaThe paper proposes a novel method, based on wavelet decomposition, for detection and diagnosis of faults (switch short-circuits and switch open-circuits) in the driving systems with Field Oriented Controlled Permanent Magnet Synchronous Motors (PMSM) of Hybrid Electric Vehicles. The fault behaviour of the analyzed system was simulated by Matlab/SIMULINK R2010a. The stator currents during transients were analysed up to the sixth level detail wavelet decomposition by Symlet2 wavelet. The results prove that the proposed fault diagnosis system have very good capabilities.Öğe A Novel Sensorless Field Oriented Controller for Permanent Magnet Synchronous Motors(Ieee, 2014) Aygun, Hilmi; Gokdag, Mustafa; Aktas, Mustafa; Cernat, MihaiIn this paper, a Particle Swarm Optimization based PI controller (PSO-PI) is used for control the speed and the torque of a Permanent Magnet Synchronous Motor (PMSM) while a Model Reference Adaptive System (MRAS) based on an Artificial Neural Network (ANN) estimation mechanism is applied to estimate sensorless the speed. In order to show the capability of the proposed PSO-PI controller, it is compared with a Fuzzy-Logic PI controller and with a classical PI controller. The simulation results prove the usefulness of the proposed PSO-PI controller.Öğe Performance analysis and modeling of a closed-loop heat pump dryer for bay leaves using artificial neural network(Pergamon-Elsevier Science Ltd, 2015) Aktas, Mustafa; Sevik, Seyfi; Ozdemir, M. Bahadir; Gonen, EmrahThis study discusses the performance analysis and modeling of bay leaves drying in a closed-loop heat pump dryer. To control relative humidity and temperatures, a controller has been designed, developed and tested to perform at low temperature drying applications (40 degrees C, 45 degrees C and 50 degrees C). New techniques are applied simultaneously such as control of relative humidity, drying air temperature and air velocity for the closed-loop heat pump dryer. A closed-loop heat pump dryer using water as a secondary fluid has been used to determine drying characteristics of bay leaves. Moreover, a Programmable Logic Control (PLC) has been used to control drying air temperature, air velocity, relative humidity and the mass obtained for the dried product. The performance of the facility has been carried out but several experimental tests under different psychrometric conditions from the test results. COPhp and COPws values were 2.8-3.7 and 2.4-3.2, respectively, while Energy Utilization Ratio (EUR) values were found to vary 0.22-0.75. From experimental data the system was analyzed and modeled by using Artificial Neural Network (ANN) and drying kinetics of bay leaf. The ANN model was used to predict the moisture content (MC, g water/g dry matter) and the total energy consumption (TEC, kWh) of the system. The back-propagation learning algorithm with Levenberg-Marquardt (LM) and Fermi transfer function were used in the network. The coefficient of determination (R-2), the root means square error (RMSE) and the mean absolute percentage error (MAPE) were calculated as 0.996, 0.0002053, 0.4161673 and 0.997, 0.0005013, 0.4280322, respectively. Accordingly, it can be concluded that predicted MC and TEC results are in good agreement with experimental results. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Soft Set-Based Switching Faults Decision Making in DTC Induction Motor Drives(World Scientific Publ Co Pte Ltd, 2015) Turkmenoglu, Veli; Aktas, Mustafa; Karatas, Serkan; Okumus, Halil IbrahimThis paper introduces a method for detection and identification of IGBT-based drive open-circuit fault of DTC induction motor drives. The detection mechanism is based on soft set theory and wavelet decomposition, if it is detailed, (Lambda) over bar -product decision making method and sym2 wavelet decomposition have been used in the detection mechanism. In this method, the stator currents have been used as an input to the system. The stator current has been used for the detection of the fault. The signal analysis has been performed up to the six level details wavelets decomposition. Faulty switch is detected by applying soft set theory to sixth level wavelets transformation. This is the first time applied to inverter in induction motor drives fault detection. The results demonstrate that the proposed fault detection and diagnosis system has very good capabilities.Öğe Testing of a Condensation-type Heat Pump System for Low-temperature Drying Applications(Walter De Gruyter Gmbh, 2014) Aktas, Mustafa; Ceylan, Ilhan; Gurel, Ali EtemA closed-type water source heat pump dryer integrated with a drying programme (DP) was designed and tested. The DP was developed using psychometric conditions of desired drying air and thermodynamic balance of heat pump. A drying algorithm was developed according to the technical specification of the dryer. Drying air temperature, relative humidity and drying air volumetric flow rate were entered from a programmable logic controller (PLC) screen. In this study, the drying of mint leaves was examined. Mint leaves were dried at different temperatures (35 degrees C, 40 degrees C and 45 degrees C) and at different volumetric flow rates 300 m(3)/h for a velocity of 0.75 m/s and 600 m(3)/h for a velocity of 1.5 m/s in the PLC-controlled heat pump dryer. The relative humidity of the drying air entering the dryer chamber was kept between 13.88% and 6.81% and the two air dampers were controlled according to predetermined value. The coefficient of performance (COPhp) values obtained were between 3.81 and 2.29. The specific moisture extraction rate for the whole system (SMERws) was between the 0.034 and 0.044 kg/kWh. The drying air temperatures were controlled with an accuracy of +/- 0.41 degrees C to +/- 0.76 degrees C depending on the mode of operation.
