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Öğe An Investigation of Thermal Comfort for Mold, Welding and Turning Technicians and the Effects on Performance in Naturally Ventilated Area(2019) Sökmen, Kemal FürkanIn this study, thermal comfort measurements were made for mold, welding, and turning technicians in naturally ventilated industrial establishments. Metabolic rates were determined as 100 W/m2 for welding and turning and 190 W/m2 for mold technicians. The clothing insulation factor was calculated as 0.68 clo. The measurements were done in three different companies on 17-19 July 2017 during working hours without stop working. In terms of PMV findings, it was determined that the thermal comfort conditions are not met according to the ASHRAE standard. As for the WBGT value, it was determined that there was heat pressure on 17.07.2017 and there was no heat pressure on 18.07.2018 on all the employees. On 19.07.2017, it was determined that there was a heat pressure after 13:00 for mold technicians and after 17:00 for welding and turning technicians. Calculated PMV values were compared with the survey results and ıt was determined that results were compatible with values. It was made firm that people who were overweight and obese felt their working environment warmer than normal weight worker. The performance loss ratios which are dependent on ambient temperature were calculated and compared with the literature and was determined that they are compatible.Öğe Computational thermal analysis of cylindrical fin design parameters and a new methodology for defining fin structure in LED automobile headlamp cooling applications(Pergamon-Elsevier Science Ltd, 2016) Sökmen, Kemal Fürkan; Yuruklu, Emrah; Yamankaradeniz, NurettinIn this study, the effects of fin design, fin material, and free and forced convection on junction temperature in automotive headlamp cooling applications of LED lights are researched by using ANSYS CFX 14 software. Furthermore a new methodology is presented for defining the optimum cylindrical fin structure within the given limits. For measuring the performance of methodology, analyses are carried out for various ambient temperatures (25 degrees C, 50 degrees C and 80 degrees C) and different LED power dissipations (0.5 W, 0.75 W, 1 W and 1.25 W). Then, analyses are repeated at different heat transfer coefficients and different fin materials in order to calculate LED junction temperature in order to see if the fin structure proposed by the methodology is appropriate for staying below the given safety temperature limit. As a result, the suggested method has always proposed proper fin structures with optimum characteristics for given LED designs. As another result, for safe junction temperature ranges, it is seen that for all LED power dissipations, adding aluminum or copper plate behind the printed circuit board at low ambient temperatures is sufficient. Also, as the ambient temperature increases, especially in high powered LED lights, addition of aluminum is not sufficient and fin usage becomes essential. High heat transfer coefficient and using copper fin affect the junction temperature positively. (C) 2015 Elsevier Ltd. All rights reserved.Öğe DOĞAL YOL İLE HAVALANDIRILAN BİR SANAYİ KURULUŞUNDA ISIL KONFOR İNCELEMESİ VE GİYSİ FAKTÖRÜ, METABOLİK ORAN, ÇALIŞAN AĞIRLIĞININ KONFORA ETKİLERİNİN ARAŞTIRILMASI(2018) Sökmen, Kemal FürkanBu çalışmada otomotiv sektöründeki firmanın termal konfor şartları ve çalışan kilosu, giysi yalıtım faktörü, metabolik oranın termal konfor üzerinde etkilerini incelenmiştir. Konfor ölçümleri 6 bölümde yapılmıştır. Ölçümlerin yapıldığı bölümler kalıphane, kaynak, pres, boya, montaj ve boyahane bölümleridir. Ölçümler DELTA OHM 52.1 marka ekipmanlar ve yazılımı ile yapılmıştır. Giysi faktörü ölçümlerde 0,8 clo olarak alınmıştır. Metabolik oran değerleri bölümlerine bağlı olarak düşük 100 W/m2 ve orta 135 W/m2 değerler olarak kabul edilmiştir. Giysi faktörü etkisinin incelenmesinde değerler 0,5, 0,6, 0,7, 0,8, 0,9, 1 clo olarak seçilmiştir. Çalışma sonucunda fabrika içinde termal konfor bakımından en iyi ve kötü bölümün sırasıyla lojistik ve kalıphane olduğu tespit edilmiştir. Çalışanların düşük giysi faktörü değerlerinde özellikle iş yoğunluğunun yüksek olmadığı sabah saatlerinde ortamı daha konforlu hissettikleri görülmüştür. Çalışmada dikkate değer bir sonuç olarak ağırlığı 80 kg’ın üzerindeki kişilerin ortamı daha sıcak hissettikleri yapılan anket sonucu belirlenmiştir. Yüksek metabolik oranda çalışan kişilerin düşük metabolik oran gerektiren işlerle değişimli çalışmasının konfor hissi bakımından önemli olduğu tespit edilmiştir.Öğe Experimental and Numerical Analysis of the Effect of Components on a Double-Sided PCB on LED Junction Temperature and Light Output Using CFD(Springer Heidelberg, 2020) Sökmen, Kemal Fürkan; Karatas, Osman BedrettinIn today's lighting industry, with developing technology and a widened usage area, LEDs have become very popular due to their higher energy efficiency and longer life. In the present study, the effect of electronic components on printed circuits and the radiation level on light output was studied. The performed analysis was validated with an experimental method. For the finite volume method, FloEFD 2019, commercial software, was used. The ambient temperature was assumed to be 23 degrees C. The value of solar irradiance was taken as 1009 W/cm(2). LEDs on a PCB were driven at 70 mA at first and then at 50 mA, and, by exerting power on all electronic components, analyses were performed. Both sides of the PCB were examined, and, in order to achieve efficient heat conduction, the power and distribution of the electronic components on the back side of the LEDs were optimized. With a new electronic circuit design, analyses were performed at 50, 55, 60, 65, and 70 mA. It was determined that the highest light output was achieved at 65 mA and that the distribution of electronic components on a PCB indirectly affects light output through junction temperature (T-j).Öğe Investigation of Air Flow Characteristics in Air Intake Hoses using CFD and Experimental Analysis based on Deformation of Rubber Hose Geometry(Isfahan Univ Technology, 2020) Sökmen, Kemal Fürkan; Karatas, O. BedrettinIn this study, the pressure loss value of air intake hose of FIAT 1.3 E6D type engine, located between intercooler and inlet manifold of the engine, was examined using computational fluid dynamics, considering geometrical deformation in a rubber material. The rubber material modelling was performed by the verification of the data - obtained through the experimental method- with ANSYS software using Mooney-Rivlin method. The rubber material modelling was performed with the aim of correctly determination of the increase in the hose diameter when subjected to pressure, since the material has the feature of elasticity. In this study, ANSYS Fluent v.18.0 software and a static pressure machine were used. The air intake into the hose took place at the pressure of 123,5 kPa and flow rate of 0,087 kg/s. A solution, independent of the number of element, was obtained in the analysis. The turbulence model used in the study is standard k-epsilon type. As a result, the deformation-oriented pressure loss in the last geometry was found 1,85 kPa. The analyses were repeated for non-deformed geometry, and a pressure loss of 2,04 kPa was determined. At the result of the test, the geometry was seen to become actually deformed, and the pressure loss was found 1,9 kPa. The lowness of pressure loss in the deformed geometry was seen as the removal of the sharp bends that would cause local losses with the effect of pressure forces. In this study, it was determined that geometrical deformation changes the geometrical features that causes pressure loss, and leads to less pressure loss.Öğe INVESTIGATION OF HEAT TRANSFER TYPES IN AN AUTOMOBILE FOG LAMP WITH COMPUTATIONAL FLUID DYNAMIC ANALYSIS(Znack Publishing House, 2016) Sökmen, Kemal Fürkan; Yaiviankaradeniz, Nurettin; Coskun, SalihThis study investigated the temperature distribution and heat transfer in an automobile fog lamp. First, a mesh independent solution was obtained. The results were compared with the literature and validated with test results. Measurements were taken from five different points by using thermocouple. Tests were applied for two hours at 24 degrees C. For thermal analysis, ANSYS CFX 12.1 was employed. Air flow inside the fog lamp was assumed as steady, incompressible, laminar and three-dimensional. Thermophysical property variations, buoyancy and radiation effects were taken into consideration. The radiation effect is an important heat transfer type to be considered in the temperature distribution on the lenses of automotive lighting systems. The radiation effect can have a negative influence on the lens due to the selection of unsuitable material. Despite the complexity of the bulb geometry and its non-isothermal surface conditions, general flow and heat transfer characteristics did not change.Öğe Research into the junction temperature and power of new led modules generation in dependence on variable parameters(LLC Editorial of Journal ""Light Technik"", 2020) Sökmen, Kemal Fürkan; Karatas, O.B.In this research, the change in the junction temperature and luminous flux of a new generation LED module depending on variables such as radiation, lens piece, ambient temperatures, currents, and quantity of elements had been studied. Commercial software FloEFD2019 was used in the finite volume analysis made during the study. The analyses were verified by experiments. On basis of the analysis, a solution was obtained that does not depend on the number of elements. The force of gravity was taken into account. While the ambient temperatures were taken as Ta = 23 °C and 40 °C, and the radiation value as 1009 W/m2, currents as 140 mA, 160 mA, 180 mA, 200 mA, 220 mA and 240 mA, meanwhile, samples numbers on PCB were taken as 101 and 202. In order to determine the effect of the lens piece located on the LED module, the analysis was repeated with and without using the lens. As a result of the study, it was found that the increase in ambient temperature and radiation has an adverse effect on the temperature Tj and luminous flux. It has been observed that changing samples number has a negligible effect on luminous flux and temperature Tj. It was found that the use of radiation and lenses are the most important factors affecting the luminous flux of the module. © 2020, LLC Editorial of Journal ""Light Technik"". All rights reserved.
