Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Icier, Filiz(4)
- Kahraman, Gökhan(4)
- Sabanci, Serdal(3)
- Cevik, Mutlu(2)
- Cokgezme, Omer Faruk(2)
- Döner, Deniz(2)
- Taşgın, Yahya(2)
- Çevik, Mutlu(2)
- Çokgezme, Ömer Faruk(2)
- İçier, Filiz(2)
- Atalar, Aydın(1)
- Doner, Deniz(1)
- Halime Okyay(1)
- Işık, Erdem(1)
- Kemahlıoğlu, Ali Varsın(1)
- Sabancı, Serdal(1)
- Tezcan, Derya(1)
- Tuba Şahin(1)
Yayınlar
- MakaleAçık Erişim2026Scopus SJRQ2Examination of the thermal and metallographic characteristics at high temperatures of natural stones (andesite) extracted from different elevations
Işık, Erdem; Kahraman, Gökhan; Atalar, Aydın
This study examines the high‑temperature thermal response of andesite stones extracted from two different elevations of Mount Ağrı (Türkiye) in order to improve material selection strategies for engineering applications. Thermal conductivity and density values of the samples were first measured under laboratory conditions. The specimens were then heated to 850 °C and cooled by natural convection while surface temperatures were recorded at fixed time intervals using a thermal camera. Based on these measurements, convective heat transfer coefficients were determined, and the time‑dependent thermal diffusivity and Biot numbers were subsequently calculated using the first-term approximation of the Fourier series. Metallographic examinations were conducted to correlate the thermal behavior with microstructural characteristics. Results indicate a pronounced effect of elevation on thermal performance. The sample obtained from the higher elevation exhibited substantially greater thermal diffusivity, reaching 2.93 × 10⁻5 m2 s−1 at 360 s and decreasing to 8.96 × 10⁻6 m2 s−1 at 1300 s. In contrast, the lower‑elevation andesite showed lower diffusivity values (1.83 × 10⁻5 m2 s−1 at 360 s and 5.9 × 10⁻6 m2 s−1 at 1300 s). Conversely, Biot numbers were consistently higher for the lower‑elevation sample, decreasing from 0.60 to 0.29 during the cooling process, whereas the high‑elevation sample displayed values from 0.314 to 0.165. Metallographic analysis confirmed that variations in microstructure—linked to different geological formation conditions—directly influenced these thermophysical properties. Overall, the findings demonstrate that andesite sourced at higher elevations possesses superior thermal diffusivity and more favorable heat‑transfer characteristics at elevated temperatures. These results highlight the importance of geological origin in the design, assessment, and selection of natural stone materials for high‑temperature engineering applications.
- MakaleAçık Erişim2025Scopus SJRQ2Investigation of the effect of the metallographic properties of vertical and horizontal cylinders made of ferrochrome with different contents on heat transfer by natural convection
Kahraman, Gökhan; Taşgın, Yahya
In this study, ferrochrome materials containing elements with different content ratios were manufactured into six-cylinder specimens, 13 mm in diameter and 16 mm in length, and heated in a furnace up to 500 °C. The heated cylinders were removed and left to cool in vertical and horizontal positions in a 16 °C environment. The temperatures were recorded using thermal cameras at certain intervals while the materials cooled down. The six specimens, whose metallographic differences were identified using SEM and XRD analysis devices, were placed vertically and horizontally, and their heat transfer by natural conviction was noted. In the calculations, each specimen’s Nusselt and Rayleigh numbers were identified based on time and then compared. The fastest cooling among the specimens occurred in the ferrochromium material with 55.93% Cr, 31.11% Fe, 11.56% C, 0.48% Si, 0.83% O, and 0.09% Al compound ratios, both in vertical and horizontal positions. Additionally, since the Nusselt number of the horizontal cylinders remained below one based on their position, their natural convection flows were not initiated. The cooling in the horizontal cylinders occurred via conduction.
- MakaleAçık Erişim2024Scopus SJRQ1Design of Ohmic Thawing Cell with Hydrostatic Pressure Units: Application in Minced Beef
Döner, Deniz; Çokgezme, Ömer Faruk; Çevik, Mutlu; İçier, Filiz
The thawing process is a common processing method used in the meat industry. To ensure provide food safety and protect meat quality, the thawing process should be carried out carefully. Ohmic thawing (OT) is one of the novel thawing methods. In this study, a custom-designed ohmic thawing prototype was set up and used to thaw frozen minced beef samples in different shapes (X: 13 × 4 × 3 cm3; Y: 13 × 6 × 2 cm3; Z: 13 cm height × 3.91 cm diameter) at 3 different voltage gradients (10–13-16 V/cm) by using 3 different electrode designs (E1, titanium foil; E2, needle type titanium electrode; E3, titanium embossed). The optimum OT condition resulting in a high-quality product with the highest process efficiency was determined. As an optimization procedure, a three-level general factorial design was performed. Thawing time, drip loss, thawing ratio, maximum temperature, ohmic power consumption, energy efficiency, and exergy efficiency values were used as responses. The cylindrical sample shape resulted in higher changes in quality and decreased performance of the process. The optimum ohmic thawing condition was a 16 V/cm voltage gradient for Y-shaped samples by using an E2 electrode design. The thawing time for the optimum condition was 2074s corresponding ohmic power consumption of 15.84 W. The drip loss during thawing was measured at 1.20%. The maximum temperature reached during the thawing process was recorded as 15.90 °C. Energy efficiency and exergy efficiency values were greater than 35%. Based on these results, the overall desirability of the ohmic thawing method was evaluated as 0.755. The obtained desirability value indicated the ohmic thawing method to be highly efficient and effective in achieving optimal thawing outcomes. The results of this study could give valuable information on the design of industrial-scale ohmic heating units to be used with solid foods, especially for thawing purposes.
AtıfScopus13WoS11
İncele - Kitap BölümüAçık Erişim2024Recent trends in evaporation techniques
Icier, Filiz; Doner, Deniz; Cokgezme, Omer Faruk; Sabanci, Serdal; Cevik, Mutlu
Increasing energy costs of the food industry and the necessity to reduce emissions of greenhouse gases orient the researchers to find alternative solutions to increase energy efficiency, and to decrease waste and environmental damage. Hence, the use of novel technologies comes to the fore. Since volumetric heating could be provided by Ohmic and microwave heating methods, a heating medium is not required. Thus it is possible to reduce undesirable changes in quality attributes by eliminating contact with hot surfaces and providing rapid heating. The negative effects on the environment could also be reduced owing to both utilization of efficient energy for the heating process and the elimination of wastewater. Alternative nonthermal methods including ultrasound, membrane filtration, pulsed electric field, and electroplasmolysis techniques could also be applied. In this chapter, recent studies on the evaporation techniques, regarding their system setups, effects on the quality characteristics, and performance evaluations are reviewed.
- MakaleYalnız künye2024Scopus SJRQ2Evaluating the metallographic properties and performance of heat transfer by natural convection of graphene-coated glass used for heating
Kahraman, Gökhan; Taşgın, Yahya
In this study, a decorative electric heater was manufactured to reduce carbon emissions related to residential and office heating, and this heater was metallographically evaluated. In addition, the heating performance of the manufactured plate was investigated by examining its heat transfer capacity by natural convection. For this purpose, the surface of the tempered glass plate was coated with graphene by spraying to improve its electrical and heat conduction properties. Copper strips were attached to both sides of the plate to allow for an electric current. The plate was connected to mains electricity, and its change in surface temperature over time was measured. Using the measured temperature values, the heat transfer rate by natural convection on the plate surface was calculated. As a result of the calculations, it was determined that the graphene-coated tempered glass plate reached a heating performance of 40 watts after 2400 s of electrical energy supply. This value can be increased by increasing the heat transfer surface area. This study, taking advantage of the excellent thermophysical properties of graphene, will contribute to other studies conducted in this field.
AtıfScopus2WoS2OpenAlex2İncele - Yüksek Lisans TeziAçık Erişim2023Enerji diplomasisi çerçevesinde Türkiye-Azerbaycan ilişkileri
Tuba Şahin
Sanayi Devrimi ile önemi ve kullanım alanı gittikçe artan enerji, günümüzde devletlerin ekonomik alanda kalkınabilmelerinin temel araçlarındandır. Enerji, son yıllarda diplomatik alanda en etkili güç kaynağı olarak karşımıza çıkmaktadır. Güney Kafkasya'da yer alan Azerbaycan devleti 1991 yılında bağımsızlığını kazanmıştır. Türkiye, köklü bir geçmişi bulunan Azerbaycan'ın en büyük destekçisi olarak bağımsızlığını tanıyan ilk devlet olmuştur. Bu doğrultuda iki devlet arasında diplomatik ilişkiler kurulmuştur. Çalışma, enerji diplomasisi çerçevesinde Türkiye-Azerbaycan ilişkilerini ele almıştır. Enerji konusunda dışa bağımlı olan Türkiye ve zengin enerji kaynaklarına sahip olan Azerbaycan arasındaki ilişkilerin enerji boyutu, iki ülkeye katkılarından dolayı önemlidir. Tarihi ve kültürel geçmişe sahip olan iki devletin ortak işbirliği sonucu enerji projeleri hayata geçirilmiştir. Türkiye ve Azerbaycan arasında enerji alanında yatırımlar, anlaşmalar ve diplomatik alanda ilişkiler enerji işbirliğine dayanarak olumlu yönde şekillenmiştir. Böylece Türkiye, enerji ihtiyacını karşılarken Azerbaycan da sahip olduğu enerji kaynaklarını dünya pazarlarına ulaştırmış ve ekonomisini güçlendirmiştir. Enerji alanında karşılıklı fayda sağlama potansiyellerine dayanarak gelişen diplomatik ilişkiler iki ülke ilişkilerini tanımlamada önem arz etmektedir. Enerji, insan hayatının vazgeçilmez unsuru ve kalkınmanın devamı için en önemli araçlardan biridir. Türkiye-Azerbaycan ilişkileri ve enerji, iki ülkenin dış politikasına yön veren en önemli konudur. Bu doğrultuda enerji diplomasisi, enerjinin dünyadaki görünümü, Türkiye ve Azerbaycan arasında enerjiye dayalı gelişen boru hatları projeleri hakkında analiz yapılmıştır. Türkiye ve Azerbaycan arasındaki diplomatik ilişkileri, enerji çerçevesinde değerlendirmek amaçlanmıştır. Araştırmada nitel araştırma yönteminin doküman inceleme tekniği kullanılmış, elde edilen verilerin yorumlanmasında betimsel araştırma yönteminden yararlanılmıştır. Araştırma konusu ile ilgili yabancı ve Türkçe literatür taranmıştır. Taranan kaynakların sonucunda dolaylı ve alıntısal araştırma yöntemi kullanılarak çalışma yazılmıştır. Anahtar Kelimeler: Diplomasi, Enerji, Enerji Diplomasisi, Türkiye Azerbaycan İlişkileri.
- Yüksek Lisans TeziAçık Erişim2022Ohmik ısıtma işlemi kullanılarak portakal kabuğu tozundan fenolik madde ekstraksiyonunun incelenmesi
Halime Okyay
Bu tez çalışmasında ohmik ısıtma destekli ekstraksiyon (OIDE) yöntemin kullanılarak farklı üretim koşullarında portakal kabuğu tozu örneğinden toplam fenolik madde (TFM) ekstrakte edilmiştir. Maksimum TFM ekstraksiyonu belirlemek amacıyla maserasyon (MS) uygulanmış ve OIDE yöntemiyle elde edilen toplam fenolik madde miktarının verimi belirlenmiştir. OIDE işlemi kullanılarak portakal kabuğu örneğinden TFM ekstraksiyon işlemi süresince elektriksel ve performans özellikleri (enerji, akım, zaman, sıcaklık) belirlenmiş ve istatiksel olarak incelenmiştir. OIDE yöntemi üç farklı katı: sıvı oranında, üç ayrı voltaj gradyanında (20, 25 ve 30 V/cm) ve dört ayrı sıcaklık (45, 60, 75 ve 90˚C) aralığında uygulanmıştır. Ohmik ısıtma destekli ekstraksiyon işlemi, güç ünitesi, test hücresi, mikroişlemci, bağlantı elemanları ve bilgisayardan oluşmaktadır. OIDE işleminde tüm katı sıvı oranları için 3 farklı voltaj gradyanı için 20 °C'den hedef ekstraksiyon sıcaklıklarına kadar (45, 60, 75 ve 90˚C) sıcaklık zaman ilişkisinin doğrusal bir artış olduğu tespit edilmiştir. Bütün katı: sıvı oranlarında ve voltaj gradyanlarında hedef ekstraksiyon sıcaklığı arttıkça işlem süreleri artmıştır (p<0.05). En kısa işlem süresi 1:20 konsantrasyonda, 90˚C sıcaklıktaki 30 V/cm voltaj gradyanında elde edilmiştir. Isınma süresinin üzerinde hedef ekstraksiyon sıcaklığının ve voltaj gradyanın olumlu etkisinin olduğu fakat katı: sıvı oranın etken olmadığı belirlenmiştir (p>0.05). Ayrıca akım ve sıcaklık ilişkisinde 20˚C ile 90˚C doğrusal bir artış olduğu, R² değerinin 0.98 üzerinde olduğu belirlenmiştir. OIDE işleminde toplam harcanan enerji ve ortalama güç değerleri üzerinde ekstraksiyon sıcaklığının, voltaj gradyanının ve kat: sıvı oranın etkisi olduğu belirlenmiştir. Özellikle voltaj gradyanı değeri arttıkça harcanan enerji miktarının da azaldığı belirlenmiştir (p<0.05). Ayrıca aynı voltaj gradyanlarında tüm katı: sıvı oranları için artan ekstraksiyon sıcaklığına bağlı olarak ortalama güç değerinin arttığı tespit edilmiştir (p<0.05). OIDE işlemini portakal kabuğunun toplam fenolik madde miktarı üzerine ilişkisi incelendiğinde tüm voltaj gradyanı ve ekstraksiyon sıcaklıkları ile katı: sıvı oranları arasında en yüksek TFM miktarının 1:20 katı: sıvı oranında bulunması ve en düşük 1:60 katı: sıvı oranında bulunmuştur. Farklı üretim koşulları kullanılarak ohmik ısıtma destekli ekstraksiyon işlemi ile TFM miktarının değişimi incelendiğinde, istatiksel olarak katı: sıvı oranı ve ekstraksiyon sıcaklığının bireysel etkisi olduğu (p<0.05), ancak voltaj gradyanının etkisi olmadığı (p>0.05) tespit edilmiştir. OIDE yöntem kullanılarak yapılan ekstraksiyon işlemi için ekstraksiyon verimi tüm katı: sıvı oranlarında (1:20, 1:40 ve 1:60 g/ml), 25 V/cm voltaj gradyanı değerlerinde daha yüksek ekstraksiyon verimi tespit edilmiştir. Ayrıca dört farklı sıcaklık (45, 60, 75 ve 90˚C) değerleri arasında ve tüm koşullar içinde en yüksek ekstraksiyon verimine 90˚C' de ulaşılmıştır. En yüksek sıcaklık değerlerinde en fazla ekstraksiyon verimi elde edildiği tespit edilmiştir. Sonuç olarak ohmik ısıtma destekli ekstraksiyon işleminde TFM elde edilmesi için sıcaklığın önemli bir etken olduğu, işlem süresi ve performans değerleri üzerine ise hem uygulanan voltaj gradyanın hem de uygulanan sıcaklık değerinin önemli bir etken olduğu tespit edilmiştir. Ayrıca kullanılan katı: sıvı oranın ekstraksiyon işlemi için önemli bir koşul olduğu bu yüzden çalışmalarda dikkate alınması gereken önemli bir uygulama olduğu tespit edilmiştir.
- MakaleYalnız künye2022Scopus SJRQ1Evaluation of an ohmic assisted vacuum evaporation process for orange juice pulp
Sabanci, Serdal; Icier, Filiz
An ohmic assisted vacuum evaporation (OAVE) processes was used to concentrate orange juice from 11.4% total soluble solid content (TSSC) to 42% TSSC by applying 13 V/cm constant voltage gradient at different temperatures. The evaporation temperatures were adjusted to 100 °C, 85 °C, 75 °C and 65 °C by setting absolute system pressures of 101.32 kPa, 58 kPa, 39 kPa and 25 kPa, respectively. The total time for the processes, including heating and evaporation, was 34, 40, 48, and 54 min for 100, 85, 75, and 65 °C, respectively. As the evaporation temperature increased, the applied energy required for phase change decreased while maximum current values increased from 0.6 A at 65 °C to 2.52 A at 100 °C. During any given run, the current value increased as the orange juice pulp heated up, but then decreased after it began to boil, leading to a reduction in the rate of heat generation. Increasing evaporation temperature has a positive effect on evaporation rates, energy efficiency, specific water removal ratio (SWRR), exergy efficiency, and Improvement Potential (IP) (p < 0.05). The reduced energy requirement with higher temperature is partially due to reduced work from the vacuum pump at the higher absolute pressure.
AtıfScopus19WoS11OpenAlex16İncele - MakaleYalnız künye2021Scopus SJRQ2Infrared drying of dill leaves: Drying characteristics, temperature distributions, performance analyses and colour changes
Tezcan, Derya; Sabancı, Serdal; Cevik, Mutlu; Cokgezme, Omer Faruk; Icier, Filiz
Thin-layer drying behaviour of dill leaves samples under three different infrared radiation power intensities was investigated. Diffusion Approach was found to be the best model that describes the drying behaviour of dill leaves. Effective diffusivity values were 6.97 × 10−9, 6.84 × 10−9 and 8.96 × 10−9 m2/s for power intensities of 1790, 1970 and 2070 W/m2, respectively. According to the first and second law efficiencies, the infrared drying system was more efficient at higher power intensities (p < 0.05). However, the total colour change was maximum at the highest power intensity. For the investigated infrared drying conditions, 1970 W/m2 was recommended as the best-infrared power intensity applied for drying of dill leaves by taking into account both performance analyses and quality changes.
AtıfScopus40WoS34OpenAlex44
İncele - MakaleAçık Erişim2021Scopus SJRQ1Influences of sample shape, voltage gradient, and electrode surface form on the exergoeconomic performance characteristics of ohmic thawing of frozen minced beef
Çokgezme, Ömer Faruk; Döner, Deniz; Çevik, Mutlu; Kemahlıoğlu, Ali Varsın; İçier, Filiz
In the present study, it was aimed to investigate the exergoeconomic performance of ohmic thawing (OT) system during the thawing of frozen minced meat (lean beef). The effects of the sample shape (X: 13 × 4 × 3 cm, Y: 13 × 6 × 2 cm, Z: cylinder with a height of 13 cm and diameter of 3.91 cm), electrode surface form (titanium foil with smooth surface, titanium electrode with needle-type surface and titanium electrode with pyramid-type surface), and voltage gradients (10, 13, and 16 V/cm) were investigated. Lower exergoeconomic values were obtained for the cylindrical shape compared to the rectangular prism. The lowest exergy efficiency value (12.45 ± 0.42), is was obtained for the cylindrical shape at 10 V/cm voltage gradient with titanium foil electrode. The needle-type surface electrodes had higher performance values than other electrodes. The exergoeconomic performance increased as the voltage gradient increased. The lowest unit exergy cost (72.40 ± 2.8) was obtained for rectangular prism shape at 16 V/cm with needle-type electrode. The comprehensive exergoeconomic evaluation in this study exhibited the energy utilization effectiveness and unit exergy cost of OT.
AtıfScopus32WoS28OpenAlex30İncele - MakaleYalnız künye2021Scopus SJRQ3Comparison of heat transfer and condensation on the walls of buildings constructed with iron profiles versus other classic models
Kahraman, Gökhan
This study aims to present the evaluation of the thermal performance and the amount of condensation on the walls of a building with iron profiles under steady-state conditions. Elazig, situated in the east part of Turkey, was chosen for fieldwork. In this region, minimum average temperature is around 1°C during winter. Calculations are made in a real wall model and three different wall model scenarios. Estimated advantages and disadvantages of these have been investigated. Heat transfer and condensation amount are taken as variables. In four different building component models, the required amount of energy during the heating period is calculated month by month. Calculations reveal the resistance of the wall without application of insulation material with iron profile is higher than of the other three wall types. The wall built with betopen and iron profile saves 37.5% more energy than the wall with bricks. When the iron-profiled wall model is compared with the insulated brick wall, it is observed that energy savings are similar, but calculations show condensation begins on the iron profile wall. Iron profile buildings become popular increasingly in rural areas. As a result of this study, it is observed that iron profile buildings are advantageous in terms of energy saving compared to other building component models. However, condensation is inevitable in wall components of iron profile buildings and so the damage in the buildings is more than just a disadvantage, it is an irreversible result.
AtıfScopus2WoS3OpenAlex3İncele - MakaleYalnız künye2020Scopus SJRQ1ENHANCEMENT OF THE PERFORMANCE OF SOUR CHERRY JUICE CONCENTRATION PROCESS IN VACUUM EVAPORATOR BY ASSISTING OHMIC HEATING SOURCE
Sabanci, Serdal; Icier, Filiz
Sour cherry juice was concentrated to 65% TSS content by using ohmic heating assisted vacuum evaporation (OVE) at voltage gradients (10, 12, 14 V/cm) and vacuum evaporation (VE). The change of performance efficiencies (energy/exergy) of OVE process depending on the voltage gradient applied and the increase in TSS content during the process were investigated by taking into account of both process and system boundaries, and compared with those of VE process. During this process, total energy consumption decreased as the voltage gradient increased, but it increased as TSS content increased. System boundary based efficiencies were lower than process based ones. Maximum efficiency was obtained for 14 V/cm. Improvement potential values increased as TSS content increased but the voltage gradient increased. The assistance of ohmic heating to VE increased the performance of the evaporation process in terms of energy and exergy efficiencies, and decreased the improvement requirements of the system.
AtıfScopus31WoS24OpenAlex31İncele