Person: SEVİLGEN, GÖKHAN
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SEVİLGEN
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GÖKHAN
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Publication A comparative study on conventional and hybrid quenching hot forming methods of 22mnb5 steel for mechanical properties and microstructure(Springer, 2022-08-01) Eşiyok, Ferdi; Ertan, Rukiye; Sevilgen, Gökhan; Bulut, Emre; Özturk, Ferruh; Alyay, İlhan; Abi, Tuğçe Turan; ERTAN, RUKİYE; SEVİLGEN, GÖKHAN; BULUT, EMRE; ÖZTÜRK, FERRUH; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014; 0000-0001-9159-5000; KIH-2391-2024; JIW-7185-2023; JCO-2416-2023; ABG-3444-2020In this paper, the conventional hot forming and hybrid quenching hot forming processes of Al-Si-coated 22MnB5 steel sheet were investigated and compared at 0.5 s-15 s holding times in the press tool related to the mechanical properties, microstructure, and dimensional accuracy. The conventional hot forming method is classified as a direct method and an indirect method. Both methods have limitations due to processing time and cooling of the press tool. To speed up the process, an alternative cooling method based on spray or jet cooling was used outside of the die tool. The hybrid quenching method involves hot forming and spray cooling process. This method, using spray parameters, provides more effective control in mechanical properties and microstructure compared to the conventional method by using spray parameters. Vickers hardness tests and tensile tests were carried out to compare mechanical properties. Changes in the microstructure of the materials were investigated using an optical microscope. The results show that spray cooling can be used as part of quenching in the hot forming process by reducing the holding time in the press tool by 97%. However, the microstructure, mechanical properties, and geometry deviations of the stamped parts are still below tolerances after the hybrid quenching hot forming process. The use of the hybrid quenching method with multi-point nozzles in the hot forming process resulted in sheet hardness up to 470 HV1 and 8% elongation with tensile strength of 1500 MPa.Publication Liquid cooling performance of the single and multi led circuit boards used in automotive lighting systems(Ieee, 2019-01-01) Kılıç, Muhsin; Aktaş, Mehmet; Sevilgen, Gökhan; Perkovic, T.; Vukojevic, K.; Rodrigues, J. J. P. C.; Nizetic, S.; Patrono, L.; Solic, P.; KILIÇ, MUHSİN; SEVİLGEN, GÖKHAN; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; Perkovic, T; Vukojevic, K; Rodrigues, JJPC; Nizetic, S; Patrono, L; Solic, P; 0000-0003-2113-4510 ; 0000-0002-7746-2014; O-2253-2015; ABG-3444-2020In this paper, the thermal performance of a liquid cooling block designed for automotive lighting components integrated with high power Light Emitting Diode (LED) was investigated, numerically and experimentally. Single and multi-chip on the printed circuit board (PCB) were selected to get comparative numerical results in view of temperature differences on PCB surfaces for automotive lighting systems. In the numerical simulations, three-dimensional Computational Fluid Dynamics (CFD) model with natural convection effects was developed for predicting temperature distributions of PCB surfaces. For this purpose, the single and multi 5-cell high power LED lighting system with cooling block design were modeled. On the other hand, the effect of the aspect ratio of cooling channel and block material on the thermal performance of circuit boards with single and multi-chip was also investigated numerically due to needing for weight reduction for automotive lighting applications. From the results, higher temperature gradients were measured and predicted near the LED chip due to the heat production of LEDs. Block material had little impact on the LED temperature but using different materials aid to reduce block weight for automotive application. From the comparison of the numerical data obtained for each PCB, the LED junction temperature was similar therefore same cooling block design can also be used for multi-LED chip applications for Automotive Lighting Systems. This Multi LED design using with liquid cooling block gives more opportunities for future head and rear lamp applications of vehicles.Publication Experimental and numerical investigations on the thermal performance of three different cold plates designed for the electrical vehicle battery module(MDPI, 2023-10-01) Sevilgen, Gökhan; Dursun, Harun; Kılıç, Muhsin; SEVİLGEN, GÖKHAN; Dursun, Harun; KILIÇ, MUHSİN; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014; 0000-0003-2113-4510; O-2253-2015; JPA-3189-2023; ABG-3444-2020The thermal performance of battery modules has a crucial role in the performance, safety, and lifetime of battery cells. Commonly, battery models are validated through experimental data to ensure the correctness of model behavior; however, the influences of experimental setups are often not considered in the laboratory environment, especially for prismatic cells such as lithium titanate oxide (LTO) battery cells used in electric vehicles. For this purpose, both experimental and numerical studies of the thermal performance of the battery module consisting of LTO cells was investigated using different cold plates used in electrical and hybrid vehicles. Three different discharging rates were applied to the battery module to obtain comparative results of the cooling performance. In the numerical simulations, heat generation models are typically used to observe the thermal behavior of the battery module; however, in the numerical study, dual potential multi-scale multi-domain (MSMD) battery models were used, with transient flow and heat transfer calculations performed. The numerical results were in good agreement with the experimental data. A new high-performance cold plate was developed for the thermal management of LTO battery cells. In comparison with the other two cold plate configurations, the proposed cold plate configuration dropped the maximum temperature up to 45% for the same operating conditions.Publication Experimental investigation of the cavitation erosion of a flat aluminum part using a sonotrode test device(Inst Za Kovinske Materiale I in Tehnologie, 2019-01-01) Dursun, Harun; Sevilgen, Gökhan; Karamangil, Mehmet İhsan; SEVİLGEN, GÖKHAN; KARAMANGİL, MEHMET İHSAN; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014; ABG-3444-2020; AAH-8619-2019In this paper we aimed to determine the gap distance between a horn and an aluminum part that ensures the highest cavitation erosion rate in a homogeneous delaminated area and provides the minimum energy consumption. For this purpose, a sonotrode device, which is capable of generating cavitation bubbles in the laboratory and enabling the evaluation of the cavitation resistance of parts with different parameters, was used in experiments. An optical microscope was used to visualize the surface delamination area where the cavitation erosion occurs, and a high-precision scale was used for measuring the total mass loss due to the cavitation erosion for each test. A high-speed camera was used to visualize the shape and behavior of the flow characteristics below the sonotrode. From the experimental results it is clear that the delamination area decreased with the increasing gap distance due to the impact region of bubble structures on the part surface. The gap distance clearly had a great effect on the cavitation erosion rate that must be determined while considering the energy consumption, test time and maximum homogeneous delaminated area in a specific cavitation test. The optimum distance was obtained as 3.5 mm, by considering the maximum cavitation erosion rate and using minimum power.Publication A new approach for battery thermal management system design based on grey relational analysis and latin hypercube sampling(Elsevier, 2021-09-16) Bulut, Emre; BULUT, EMRE; Sevilgen, Gökhan; SEVİLGEN, GÖKHAN; Öztürk, Ferruh; ÖZTÜRK, FERRUH; Albak, Emre İsa; ALBAK, EMRE İSA; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0001-9159-5000; 0000-0001-9215-0775; 0000-0002-7746-2014; ABG-3444-2020; AAG-8907-2021; I-9483-2017A liquid cooling system is an effective type of battery cooling system on which many studies are presented nowadays. In this research, the effects of the mass flow rate and number of channels on the maximum temperature and pressure drop are investigated for multi-channel serpentine cooling plates. A new approach with LHS and GRA is used to obtain the optimum ranges of design parameters to minimize the pressure drop, maximum temperature and to maximize the convective heat transfer coefficient. In this study, the values of the parameters for the numerical modeling are obtained by the experiments. The width and height of the serpentine channel and mass flow rate are chosen as input parameters and the pressure drop, convective heat transfer coefficient and maximum temperature are selected as output parameters. Comparing with the base design, the optimized design provided up to 40.3% decrease in the pressure drop with a penalty of 11.3% decrease in the convective heat transfer coefficient with a slight decrease in the maximum temperature. The proposed approach can be used to design better cooling plates to keep the batteries in safe temperature ranges and to reduce the power consumption by optimizing the pressure drop and maximum temperature values.Publication The investigation of the effects of spray parameters on the thermal and mechanical properties of 22MnB5 steel during hybrid quenching process(Begell House, 2021-01-01) Sevilgen, Gökhan; Ertan, Rukiye; Bulut, Emre; Öztürk, Ferruh; Eşiyok, Ferdi; Abi, Tuğçe Turan; Alyay, İlhan; SEVİLGEN, GÖKHAN; ERTAN, RUKİYE; BULUT, EMRE; ÖZTÜRK, FERRUH; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014; 0000-0001-9159-5000; ABG-3444-2020; KIH-2391-2024; AAG-8907-2021; JIW-7185-2023In this paper, the investigation of the effects of spray parameters on the thermal and mechanical properties of 22MnB5 steel during the hybrid quenching (HQ) process was performed. The HQ method presented in this study includes early removal of hot-stamped parts from the die and transfer to an external multinozzle spray cooling device. The proposed method was developed due to the need for improving disadvantages of the traditional hot stamping process such as complexity of controlling the cooling rate during die quenching by using cooling channels and of providing the reduced tool contact surface temperature after a certain cycle of the hot stamping process. This paper focuses on the temperature distribution and mechanical characteristics of high-strength 22MnB5 steel during the HQ process. Moreover, the methodology developed in this paper can be used to get tailored parts where the cooling rates are locally chosen to achieve structures with graded properties, i.e., to allow local modification of final mechanical properties in order to provide high energy absorption to enhance the crashworthiness of the whole component and thus to improve the vehicle safety performance. The three-dimensional numerical model of spray cooling was also developed by using the computational fluid dynamics (CFD) method to get the suitable process parameters such as spray height and initial blank temperature and to present the detailed heat transfer analysis of hot-stamped parts during the hybrid quenching process.Publication Multi-objective optimization of liquid cooling system for a twelve-cell battery module(Begell House Inc, 2022-01-01) Bulut, Emre; Albak, Emre İsa; Sevilgen, Gökhan; Öztürk, Ferruh; BULUT, EMRE; ALBAK, EMRE İSA; SEVİLGEN, GÖKHAN; ÖZTÜRK, FERRUH; Mühendislik Fakültesi; Hibrit ve Elektrikli Araç Teknolojisi Bölümü; 0000-0001-9159-5000; 0000-0001-9215-0775; 0000-0002-7746-2014; I-9483-2017; AAG-8907-2021; JCO-2416-2023; FRD-1816-2022In this research, two cooling plates with six parallel channels are designed for a twelve-cell battery module. The heat generated by a Li-ion battery cell is numerically modeled, and the numerical model is validated with the experimental data. The temperature difference of the battery cells in the battery module is an important factor for the capacity usage and cycle life of a battery module. The aim of this study is to design an optimum cooling system that will increase the cycle life of the batteries by decreasing the temperature difference and reducing the parasitic power consumption of the pump by reducing the pressure drop. The channel height, channel width, and the ratio of the outlet height to the inlet height are selected as design variables. In recent years, several evolutionary multi-objective optimization techniques have been presented to improve the performance of thermal management systems. In this study, CMOPSO is used for the optimization of the liquid cooling system. The results of the NSGA-II, NSGA-III, MOPSO, and CMOPSO techniques are evaluated to compare the efficiency of different optimization techniques. The results of four different multi-objective optimization methods are close to each other and have good agreement with the CFD results to reduce the temperature difference and pressure drop. A 30.3% decrease in the temperature difference and a 5.3% decrease in the total pressure drop are achieved with CMOPSO as the optimization technique. The results show the effectiveness of CMOPSO as the optimization technique for the design of battery cooling systems.Publication Experimental and numerical investigation of the windshield deicing analysis of a commercial vehicle(Begell House Inc, 2022-01-01) Bayram, Halil; Aydın, Abdulmecit; Sevilgen, Gokhan; SEVİLGEN, GÖKHAN; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; ABG-3444-2020In this study, the windshield deicing analysis of a light commercial vehicle was investigated in a transient manner both numerically and experimentally. In the numerical study, the more realistic three-dimensional (3D) computational fluid dynamics (CFD) models with three different inlet vent configurations, including steady and unsteady calculations, were developed by using the enthalpy-porosity technique in which the liquid form of a cell was defined as a liquid fraction. The experimental study was also performed in a standard test room and the comparative results were presented and discussed. The temperature values were suddenly increased especially close to the inlet vents. The deicing process was initiated nearly at the 10th min for both numerical and experimental studies and the liquid fraction values increased rapidly after 15 min when the temperature value of the air inlet vents was about 30 degrees C. The highest values of temperature on the windshield were 33 degrees C and 80% of the A-zone was defrosted in 20 min and 95% of the B-zone was defrosted in 40 min from the beginning of the test period which is compatible with the international automotive test standards. The defrosted regions obtained from the numerical and experimental studies were quite similar during all stages of the deicing process. The largest homogeneous defrosted zone was achieved for Case-1 which had defroster inlet vents with equal surface areas and space between these inlet vents. The presented method and numerical results can be used as a reference study for further similar studies to improve the defrosting performance of light commercial vehicles.Publication Dual-separated cooling channel performance evaluation for high-power led Pcb in automotive headlight(Elsevier, 2021-06) Sevilgen, Gökhan; Kılıç, Muhsin; Aktaş, Mehmet; SEVİLGEN, GÖKHAN; KILIÇ, MUHSİN; Mühendislik Fakültesi; Otomotiv Mühendisliği Bölümü; 0000-0002-7746-2014; 0000-0003-2113-4510; O-2253-2015; ABG-3444-2020In this paper, thermal and hydraulic analysis of a dual-separated cooling channel was performed for the cooling applications of different automotive lighting systems. A single LED and multi-LEDs were considered to evaluate the thermal and hydraulic performance as well as the lighting properties of automotive headlights. The detailed hydraulic analysis was theoretically evaluated for developing laminar flow to get higher thermal performance with less pumping power. The theoretical and simulation results for the dual-separated cooling channel were compared and discussed. Unlike the constant properties were used in the current literature, thermal analysis with temperature-dependent properties was performed to estimate Nusselt number preciously for dual-separated cooling channels. The temperature measurements were also performed in the experimental study to compare the numerical results. The light output parameter of the LEDs depends on junction temperature, it was found that the increase in light output by using a dualseparated cooling channel was about 10% for all cases. Otherwise, higher junction temperature values lead to a reduction in operating efficiency. The top copper surface temperature drop was higher than 50%, and the junction temperature had been reduced by 36% to ensure the desired operating conditions of the automotive lighting system.Publication Prediction and optimization of the design decisions of liquid cooling systems of battery modules using artificial neural networks(Wiley-Hindawi, 2022-01-03) Bulut, Emre; Albak, Emre İsa; Sevilgen, Gökhan; Öztürk, Ferruh; BULUT, EMRE; ALBAK, EMRE İSA; SEVİLGEN, GÖKHAN; ÖZTÜRK, FERRUH; Gemlik Asım Kocabıyık Meslek Yüksekokulu; Otomotiv Mühendisliği Bölümü; 0000-0001-9159-5000; 0000-0001-9215-0775; 0000-0002-7746-2014; I-9483-2017; ABG-3444-2020; AAG-8907-2021; FRD-1816-2022Liquid cooling systems are effective for keeping the battery modules in the safe temperature range. This study focuses on decreasing the power consumption of the pump without compromising the cooling performance. Artificial neural network (ANN) models are created to predict the effects of the height and width of the cooling channel and the mass flow rate on the maximum temperature, convective heat transfer coefficient, and pressure drop. The ANN models are used as surrogate models for the design and optimization of the liquid cooling battery system. Particle swarm optimization (PSO) and genetic algorithm (GA), which are commonly utilized optimization methods in many areas, and chaos game optimization (CGO) and coot optimization algorithm (COOT) methods, which are recently presented methods, are adopted to minimize the power consumption of the pump. The results are compared in terms of computational performance and best, worst, average, and SD values. Despite all of the optimization methods used giving similar results, the CGO method comes forward due to fast converging, SD, and finding the minimum power consumption of the pump among other optimization methods. A 22.4% decrease in the power consumption of the pump is achieved with the use of the ANN-based CGO method while conserving the cooling performance. When comparing the ANN predicted and CFD results, the relative errors are less than 1%.