Yazar "Karaali, Rabi" seçeneğine göre listele
Listeleniyor 1 - 6 / 6
Sayfa Başına Sonuç
Sıralama seçenekleri
Yayın Development of apparatus for increasing efficiency and savings in radiation and convection heat transfer in stovetops(Prof. Dr. İskender AKKURT, 2026) Karaali, Rabi; Akçay, Enes; Keven, ArzuA new apparatus is designed to increase the efficiency and save fuel in electric and gas stoves used in kitchens. Through analyses and experiments, improvements are made to this apparatus to utilize a larger amount of heat lost through convection and radiation, thus saving electricity and gas fuel used in stoves. Initial and final heat values and cooking energies is compared. A test unit is prepared for this purpose, using an electric and gas stove, a pot with a diameter of approximately 17 cm, and a specific amount of water. Equipment used will include a thermometer, a stopwatch, and a thermal camera. Different diameter and thickness designs of the apparatus is created. These are incorporated heat insulation material to facilitate heat transfer to the outside environment: radiant heat transfer via a bright inner surface, conductive heat transfer via the insulation material, and convective heat transfer by lowering the outer surface temperature with the insulation material. The apparatus is designed with lower openings for air intake to improve gas combustion and upper openings for exhaust outlet. In the experiments, the time it takes for water in a steel pot to reach 80°C is determined for various designs of the appliance on a natural gas stovetop, and the efficiency increases and results are shown graphically. Lots of experiments done and the figures show for electric stove that uninsulated round without sheet metal plates the best performance with 9 minutes obtained for electric stove. For gas stove, with the device developed from 0.5 mm steel the temperature rises from 20°C to 80°C in 9 minutes, which is the best performance among all of the other alternatives.Yayın Exergy analysis and optimization of combined brayton and rankine cycles(Prof. Dr. İskender AKKURT, 2026) Bozkurt, Ali; Keven, Arzu; Karaali, RabiThere are many energy sources on the World that can be classified as renewable and non-renewable energies. The non-renewable energies which are exhaustible and often harmful to the environment. The usage of all these renewable and non-renewable energies efficiently is very important in technology and industry. The concept of exergy and exergy analysis is very important methods to show the inefficiencies and the irreversibility’s in a system and its devices. In this study, exergy analysis methods are applied to efficient combine cycle and cogeneration systems. The destruction of exergy has been examined for combined cycles and cogeneration system to find the optimum working conditions. It is found that as the pump pressure of the Rankine cycle increases from 400 kPa to 7600 kPa, the exergy efficiency increases from 76% to 85%, and as the compression pressure of the Brayton cycle increases from 400 kPa to 2200 kPa, the exergy efficiency increases from 72% to 79%. When these operating conditions, where the two cycles will operate at their optimum, are applied together, the exergy efficiency of the all cycle exceeds 86%. When the operating conditions, where the Brayton and Rankine cycles are at their maximum efficiency, are applied together, the optimum operating conditions of the system are obtained.Yayın Performance and exergy analyses of GT-MHR nuclear cycles(Prof. Dr. İskender AKKURT, 2026) Akçay, Enes; Keven, Arzu; Karaali, RabiIn this study, the performance and exergy analyses of the GT-MHR type nuclear power plants with high thermal energy were analysed. The GT-MHR(GasTurbine-Modular HeliumReactor), produces electricitybyusing helium gas inthe Brayton cycle, and utilizes the waste heat of the system with the Rankine cycle. The Brayton cycle allows helium gas to be heated to high temperatures in the reactor core, then converted into mechanical energy by usinga gas turbine. This hybrid structuresin the designsof GT-MHRsallow the combined use of nuclear and renewable energy sources.It was foundthat exergy efficiency reached its maximum level between approximately 14,000 -16,000 kPa. At this point, the exergy losses of thissystem approach itslowest level and the components reach the most ideal operating conditions. If the system is operated below or above of this value, the total exergy efficiency will decrease. The exergy efficiency, which is initially approximately 74.5% at 500 kPa pump pressure, increases to 75.1% at 1000 kPa pressure level. While the pump pressure at 500 kPa produces a work of approximately 532,000 kW, at 1000 kPa it increases to 560,000 kW. Thus, GT-MHR pioneers the energy technologies of the future by combining both high efficiency and environmental sustainability.Yayın Performance and exergy analysis of cryogenic cycles(Prof. Dr. İskender AKKURT, 2026) Çeker, Hüsniye; Öztekin, Erman Kadir; Keven, Arzu; Karaali, RabiThis study examines and demonstrates the concepts of thermodynamics, exergy, and exergy analysis, and shows how these principles are applied to cryogenic cycles using equations. Furthermore, an energy, exergy, and performance analyses of the two-stage vapor compression cascade cryogenic cycle for natural gas liquefaction is conducted, and optimum operating conditions are presented in tables. Based on the data obtained from these equations, exergy analysis of cryogenic cycles was performed, and performance analysis and curves were plotted. When the compressor outlet pressures of the first sub cycle is increased from 3300 kPa to 4590 kPa, the exergy loss of the devices decreases, the exergy efficiencies of the increases, and the COP values increase. When the cooling amount in heat exchangers 1 and 2 is increased from 9 °C to 17 °C, i.e., when cooling is increased, it leads to a slight improvement in the performance of the system. The optimum total compressor consumption according to inlet/outlet temperature difference in heat exchangers 1 and 2 are obtained at about 14-15 °C. When these two improvement methods are applied together, optimum performance values of the system are obtained. The COP value increases from 0.078 to 0.1164. The system is affected by the compressor outlet pressure of the first sub cycle. Increasing the cooling level from 9°C to 17°C in heat exchangers 1 and 2 has a minor impact on system performance.Yayın Set üstü ocaklarında ışınım ve taşınımla ısı geçişinde verim artışı ve tasarruf için aparat geliştirilmesi(Serüven Yayınevi, 2026) Karaali, Rabi; Akçay, Enes; Keven, Arzu; Zenk, HilmiEnerji talebindeki hızlı artış ve fosil yakıt rezervlerinin tükenme tehli kesi, küresel ölçekte enerji verimliliği politikalarının yeniden şekillenmesine neden olmaktadır. Uluslararası Enerji Ajansı (IEA) raporlarına göre, konut sektörü dünya genelindeki toplam nihai enerji tüketiminin yaklaşık %30’un dan sorumludur [1]. Bu tüketim kalemleri arasında ısıtma ve soğutmadan sonra en büyük payı pişirme faaliyetleri almaktadır. Özellikle gelişmekte olan ülkelerde evsel enerjinin önemli bir kısmının pişirme eylemi için harcandığı ve bu süreçteki verimsizliğin karbon emisyonlarını doğrudan artırdığı bilin mektedir [2]. Bu bağlamda, pişirici cihazların termodinamik verimliliğinin artırılması, küresel sürdürülebilirlik hedefleri için kritik bir adımdır.Yayın Tepsili bir kurutucuda deveci ve santa maria armut dilimlerinin kurutma performansları ve enerji ekserji analizi(Serüven Yayınevi, 2026) Karaali, Rabi; Keven, Arzu; Cimşit, Canan; Zenk, HilmiDünyada enerji talebindeki artış, sınırlı fosil kaynaklar ve çevre kirliliği gibi faktörler nedeniyle temiz ve verimli enerjinin önemini artırmış ve dikkatleri üzerine çekmiştir. Gıdaları muhafaza etmenin en eski ve en iyi yöntemlerinden biri kurutma işlemidir. Bu işlem temel olarak ısı enerjisini kullanarak katı gıdadaki nemin uzaklaştırılması olarak tanımlanabilir. Gıda kurutma işleme tesislerinde gıdanın nem içeriğini azaltmak amacıyla yapı lan işlemlerde akışkan yataklı, kesikli, tepsili ve güneş enerjisiyle kurutma yöntemleri yaygın olarak kullanılmaktadır. İşlemin temel amaçları su aktivitesinin azaltılması, bozulmanın önlenmesi ve gıdanın hacim ve ağırlığının en aza indirilmesi olarak vurgulanabilir. Bu yönüyle kurutma işlemi tarım alanları için raf ömrünü uzatması, paketleme maliyetini düşürmesi, lezzetini ve besin değerini koruması nedeniyle bir zorunluluktur.
