Browsing by Author "Karabey, A."

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Analyzing the Heat and Flow Characteristics in Spray Cooling by Using an Optimized Rectangular Finned Heat Sink
(Begell House Inc., 2024) Karabey, A.; Yakut, K.
Rapid advancements in technology constantly keep the need for thermal systems, which have high performance, on the agenda and direct the attention of researcher-engineers to the studies on improving the heat transfer. Spray cooling process depends on many parameters including nozzle diameter, surface area, surface geometry, critical heat flux, mass flow, gravity, spraying angle, and surface slope. One would need results from many experiments to better analyze the spray structure. In the present study, by using the rectangular-finned heat sinks optimized for spray cooling and those called “general,” the heat and flow characteristics in spray cooling were analyzed. Water was used as the cooling fluid and the cooling fluid was atomized by using an air-supported atomized. The experiments were conducted with six air-to-liquid ratio (ALR) values, three different jet heights, three different spraying times, three different fin heights, and three different fin widths. The results are presented in the Nusselt number–air-to-liquid ratio (Nu–ALR) and jet thickness–jet velocity (tjet–Ujet) diagrams. It was determined that the ALR value tended to decrease with increasing Nusselt numbers. For the determined ALR values, Nusselt numbers decreased as the fin height increased. It was concluded that Nusselt numbers tended to decrease at all fin widths as the ALR value increased. In addition, considering the parameters examined for the rectangular-finned heat sink, separate correlations were developed for the Nusselt number, spray angle, and jet thickness. © 2024 by Begell House, Inc.
Experimental and Numerical Investigation of Flow and Heat Transfer Characteristics Using Jet Impinging on Optimized Rectangular Finned Heat Sinks
(Begell House Inc., 2022) Karabey, A.; Abdulrazzaq Al-Ani, R.A.; Bozdoğan, D.
Potential application of the impingement jet technique in various situations has gained the attention of researchers in recent times for its large heat transfer rate characteristics. In the present study, the heat transfer and flow characteristics of a heat sink having rectangular fins and being optimized for impingement jet by making use of the Taguchi experimental L18(21*37) design method were analyzed both experimentally and numerically. The heat transfer and flow characteristics of a heat sink with rectangular fins and optimized for impingement jet cooling were analyzed both experimentally and numerically by making use of six different jet speeds (4, 5, 6, 7, 8, and 9 m/s), four different nozzle diameters (D = 40, 50, 63, and 75 mm), and three different dimensionless nozzle-to-target distances (h/d = 1, 2, and 3). The changes in average target surface temperature were measured and the Nusselt numbers were calculated, as well as the changes in the Reynolds number. These results were also simulated numerically by making use of the Ansys Fluent software. To compare the results to the experimental research data, the k–ε realizable turbulence model was selected to be the most suitable one. Experimental and numerical results were compared using the Nu–Re diagrams. The numerical results show that the average Nusselt number is directly proportional to the increase in the Reynolds number. The Nusselt number was also found to decrease with increase in the distance between the nozzle and the heat sink. The peak value of the local Nusselt number was found to be the stagnation point. It was determined that experimental and numerical findings were consistent. © 2022 by Begell House, Inc.
Effect of Insulation Thickness on Energy Saving in Cold Regions of Türkiye
(Gumushane University, 2022) Karabey, A.
In the countries procuring a major amount of their energy from abroad, using of the energy effectively and ensuring the energy-saving become gradually more important. In this study, considering the climatic and meteorological conditions of Van province, optimum insulation thickness, payback period, and energy-saving values were analyzed for three insulation materials (rock wool, polyurethane, XPS) and five energy sources (imported coal, fuel oil, LPG, natural gas and electricity) on wall models built with pumice and aerated concrete. The optimum insulation thickness was calculated using the interest and inflation rates. The calculations were made by making use of the lifecycle cost analysis (LCCA). Insulation thickness that should be applied depending on the wall elements used in buildings can vary. Thus, examining the wall models, insulation materials and energy sources were examined, and the optimum insulation thicknesses, annual savings, and payback periods were found to be 3-15.6 mm, 30-63%, and 1.4-5.8 years, respectively, in the present study. © 2025, Gumushane University. All rights reserved.
Optimization of the Design Parameters Using the Taguchi Method in Inclined Impingement Multijet Heat Transfer With Rectangular Finned Heat Sink
(Begell House Inc., 2023) Karabey, A.; Arvasi, S.
Thanks to the rapid advancement in technology, especially for the systems having high temperatures and high heat fluxes, the interest in studies on impingement jets to improve the cooling efficiency increased in recent years. The current study focuses on determining the optimization of the inclined multijet array to reduce the temperature of electronic devices. In this study, the cooling was performed on the inclined surfaces by making use of impingement multijets via heat sinks consisting of rectangular fins modeled in different geometries and optimum cooling conditions were achieved. In achieving the optimum cooling conditions, the Taguchi method was used since it was thought to offer a reduction in time and costs in industrial applications. In this study, 11 different parameters were examined at three different levels in order to determine the optimum conditions for impingement multijet applications. The Nusselt number was set as the performance characteristic and the L27(311) orthogonal sequence was used as the experiment plan for 11 parameters that were determined. When calculating the Nusselt number by using nozzle diameter, the optimum results were achieved using the following parameters: 40 mm of nozzle diameter, 9 m/s of air velocity, 20 mm of vertical distance between slices, 4444 W/m2 of heat flux, 20 mm of vertical distance between fins, 15 mm of fin width, 30° of fin angle, 15 mm of horizontal distance between slices, 10° of heat sink angle, 20 mm of horizontal distance between fins, and 8 of nozzle diameter/heat sink dimensionless distance ratio. The flat plate and optimum heat sink established using the data obtained were compared under the optimum conditions obtained from the analysis and to the optimum conditions obtained using the finned optimum heat sink and it was determined that, under the optimum conditions, the finned heat sink improved the heat transfer by 28.61% when compared to the flat plate. © 2023 by Begell House, Inc.