Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1247
  Examination 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.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1209
  Synergistic Effect of Cylindrical Fins and Phase Change Material on the Thermal and Economic Performance of a Double-Slope Solar Distillation Device Under Tunceli Climatic Conditions

  Tuğan, Volkan; Işık, Erdem; İnallı, Mustafa

  Global water scarcity driven by population growth, climate variability, and rising freshwater demand increases the need for more efficient solar desalination systems. In this study, a double-slope solar distillation device supported by a phase change material pool was developed to improve freshwater production. The phase change material layer was placed directly beneath the absorber plate to store excess thermal energy during peak solar radiation and release it during low-radiation periods. To strengthen thermal interaction between the absorber surface and the storage medium, cylindrical fins were embedded within the phase change material pool. The development of a double-slope solar distillation device integrated with a finned phase change material pool, and the simultaneous comparison of the thermal efficiency and economic analyses of single-slope and double-slope solar distillation devices under the same climatic conditions, are the prominent features of this study. Additionally, the performance of solar distillation devices has not previously been investigated under the climatic conditions of Tunceli, which further motivates this research. The developed system reached a peak freshwater productivity of 2459.2 g/m2/day, providing a 21.4% enhancement over the conventional configuration. In addition, the thermal efficiency increased from 17.7% in the conventional unit to 21.4% in the phase change material-assisted design. The economic analysis showed that the cost of distilled water was $0.097/kg for the conventional system and $0.105/kg for the proposed system, with the corresponding payback periods being approximately 11 and 12 months, respectively.

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  AtıfScopus2·WoS2·OpenAlex2

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• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/752
  Numerical analysis of PCM integrated in solar dryers for thermal efficiency

  Bakır Gür, Eda; Işık, Erdem; Uçar, Aynur

  Solar dryers using phase change materials buffer heat, yet the combined influence of airflow regime and PCM placement on melting remains underexplored. A controlled like-for-like study fixed geometry and PCM properties while varying placement and operating conditions. A 3D transient CFD model simulated a forced-convection dryer with RT28HC over Re = 3000–9000 and inlet temperatures Ti = 50–60 °C. Raising either Re or Ti shortened melt time, and three-wall coverage melted faster and more uniformly than a rear-wall-only layout. For three walls, melt time dropped from 13 h (50 °C, Re = 3000) to 7 h (60 °C, Re = 9000) (−46 %) for the rear wall it fell from 19 h to 11 h (−42 %). A 10 °C increase in Ti reduced overall melt time by 4 h across Re. Practically, three wall PCM with Re ≥ 6000 at Ti = 60 °C achieved reliably 7–9 h melting, enabling late afternoon heat release without auxiliary heating.

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  AtıfScopus17·WoS16·OpenAlex12

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• MakaleYayıncıda açık erişim2025Scopus SJRQ1/r/munzur/1427
  Experimental analysis of a double-slope solar still integrated with parabolic trough solar collector using nanofluid

  Tuğan, Volkan; İnallı, Mustafa; Işık, Erdem

  The use of solar energy in the treatment of saline water offers a sustainable and low-cost solution to the increasing global fresh water demand. In this direction, solar still systems separate water vapor from saline water by directly using solar radiation and then condense it to obtain pure water. However, their fresh water productivity is relatively low. Therefore, in this study, the fresh water productivity and thermal efficiency of the double slope solar distillation unit integrated with parabolic trough solar collector, which operates completely on solar energy, were investigated experimentally. In addition, the effect of water-based nanofluid containing multi-walled carbon nanotubes on the performance of the solar still was investigated. All the stills produced were compared in terms of fresh water productivity and thermal efficiency. According to the results obtained from the study, the highest daily productivity was found to be 1963.8 g/m2/day, 2008.5 g/m2/day, 2592.0 g/m2/day and 2937.6 g/m2/day for SSSS, DSSS, PTSC integrated DSSS and both NF and PTSC integrated DSSS, respectively. It was observed that the daily productivity of DSSS, DSSS with integrated PTSC, and DSSS with both PTSC and NF were 6.6 %, 42.2 %, and 49.6 % higher than SSSS, respectively. Additionally, it was observed that the thermal efficiency of DSSS using PTSC and NF was lower compared to SSSS due to its larger system area.

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  AtıfScopus13·WoS8·OpenAlex10

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/956
  Heat transfer and condensation analysis of the walls of a house built with natural andesite stone

  Işik, Erdem; Kahraman, Gökhan; Atalar, Aydın

  The use of natural stones in buildings is increasingly popular due to both their decorative appearance and their thermal performance. Proper use of these stones in buildings is crucial for energy conservation and preventing condensation within structural components. This study investigated heat transfer and condensation in the wall of a house made from natural andesite stone in Iğdır, Turkey, under steady-state conditions and different wall combinations. Samples were created from natural stones extracted from two different elevations in the foothills of Mount Ararat, with measured thermal conductivity values of 1.73 W/m·K (higher elevation– Haverage) and 1.31 W/m·K (lower elevation– Laverage). In the wall model using a 3-cm thick insulation board between two natural stones from the higher elevation, condensation occurred on the outer surface of the insulation layer. This can negatively impact the durability and thermal performance of the structure, and such design should be avoided. The highest heat flux of 18.27 W/m² was observed in the non-insulated wall made of higher elevation stones, while the lowest heat flux of 6.68 W/m² occurred in the model using a 3-cm insulation board between two lower elevation stones. No condensation risk was found in this configuration. The difference between the worst and best cases in terms of heat flux was approximately threefold, emphasizing the importance of proper material selection and insulation design. These findings provide guidance for energy-efficient building design using natural stone.

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• MakaleAçık Erişim2025Scopus SJRQ3/r/munzur/823
  Experimental and Theoretical Study on the Freshwater Productivity of a Single-Slope Solar Still

  Tuğan, Volkan; Işık, Erdem; İnallı, Mustafa

  Converting saline water into freshwater using renewable energy resources is crucial to address global shortages of freshwater. This study aims to investigate the freshwater productivity of a single-slope solar still (SSS) operating with solar energy, one of the renewable energy sources. The main motivation of this study is to evaluate the experimental, theoretical, and economic performance of the solar still under climate conditions that have not been sufficiently studied before. Experimental analyses were conducted under the climatic conditions of Tunceli, a city located in the Eastern Anatolia Region of Türkiye. In addition, a comprehensive theoretical analysis was carried out using energy equations, and the experimental and theoretical results were compared with each other. Finally, the economic feasibility of the system was evaluated through a cost analysis. The SSS's experimental and theoretical productivity were found to be 1883.9 and 2458.7 g/m2/day, respectively. The experimental thermal efficiency for this still was 15.1%, whereas the theoretical thermal efficiency was 19.7%. It was concluded that the theoretical productivity and efficiency values were close to the experimental values and the difference between them originated from the assumptions of theoretical calculations. The cost of water distilled by the single-slope solar distillation unit was found to be $0.077/kg, and the payback period was found to be 9 months.

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  AtıfScopus2·WoS3·OpenAlex2

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• MakaleAçık Erişim2024/r/munzur/6308
  Modeling changes in the quality attributes of couscous cooked with ohmic heating

  Sabanci, Serdal; Işık, Erdem; Goksu, Ali; Omaç, Basrı

  Kinetic studies on the quality alters of couscous are crucial to the suitable design of ohmic heating treatment. Hence, it was targeted to build mathematical models to forecast the changes in quality attributes of couscous cooked using ohmic heating (OH) in the present study. In addition, the average power and total energy for cooking couscous with OH at a voltage gradient of 17 V/cm were determined. Three dissimilar kinetic models—zero, first, and second—were fitted to the data. Our findings showed that, for the ohmic heating system, as cooking time increased, energy consumption increased while heating system efficacy declined. The best model to reflect the changes in color parameters was the second-order model, while the zero-order model best fit the experimental data observed for the cooking loss, moisture content, and weight increase (%). For all TPA parameters, however, neither model yielded the greatest fit.

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  AtıfOpenAlex1

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• MakaleAçık Erişim2024/r/munzur/6257
  İklimlendirme Sistemlerinin (VRF-CHILLER KAZAN FCU) Seçimi ve Maliyet Analizi: Otel Örneği

  Işık, Erdem; Bingöl, Abdullah

  Mekanik sistemlerin tükettikleri enerjilerin, sistemlere bağlı yatırım maliyetlerinin ve işletme maliyetlerinin ekonomi üzerindeki etkisi tartışılmazdır. Özellikle Türkiye gibi enerji tüketimi yoğun olan ve iklim koşulları ülke genelinde sert olan ülkelerde yüksek maliyet kalemlerinden biri olan soğutma/ısıtma sistemlerine ayrılan maliyet önemli bir sorun olarak görülmektedir. Çözüme yönelik sistem seçimlerinde yatırım ve işletme maliyetleri öncelikli ölçüt olmaktadır. Teknolojinin gelişmesiyle birlikte çelik boruların, kazanların, chiller gruplarının ve vanaların yerini, paket halinde üretilmiş ve içerisinde soğutma çevrimini gerçekleştirerek ısı alan ve tersinir olarak çalışıp ısı veren VRF (değişken soğutucu akışkan akışı) sistemleri almıştır. Bu gelişme ekipmanları koruma altına almayı da kolaylaştırmıştır. Bu çalışmada Marmara bölgesinde yer alan 300 odalı bir otel esas alınarak, Kazan-Chiller-Fancoil sistemi ile VRF sistemi yatırım, yaz-kış işletme ve bakım maliyetleri ele alınarak kıyaslanmıştır. Sonuç olarak VRF sisteminin ilk yatırım maliyeti açısından yaklaşık olarak %16 daha dezavantajlıyken, yaz-kış işletme ve bakım maliyetleri ele alındığında yaklaşık olarak yıllık %14 daha avantajlıdır ve bu sayede bir yıl gibi kısa bir sürede yatırım maliyetini amorti ettiği hesaplanmıştır.

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• MakaleYalnız künye2024Scopus SJRQ2/r/munzur/2041
  Dynamic Analysis and Metallographic Examination of Linings with Different Composite Contents used in the Brakes of a Hydraulic Turbine

  Işık, Erdem; Kahraman, Gökhan

  The main aim of this study was to find ways to increase the performance and life of generator brake linings, which can lead to cost reduction and adequate downtime periods for hydroelectric power plants. First, the dynamic analysis of the linings used in hydraulic turbines was realized and their reactions were examined under different operating conditions. Second, two types of brake linings with different composite components produced in the market were examined metallographically and tested to determine both the stopping performance and durability time of the turbine-generator unit for a sufficient period of time in the vertical 150-megawatt Francis turbine with approximately 500 tons of rotary weight. As a result of these experiments, the lining with the boron component led to much better results than the other brake linings. It has been determined that the boron-containing lining makes 100 stops more than the other lining and stops 20 s earlier in one stop. Therefore, the use of a composite lining with boron content in the braking systems of hydroelectric power plants significantly reduces maintenance incidents and operation costs as it prolongs brake replacement periods in these plants. Graphical Abstract: (Figure presented.)

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  AtıfScopus1·WoS1·OpenAlex1

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• MakaleYalnız künye2024Scopus SJRQ4/r/munzur/2030
  How How Much Much CCondensation ondensation Occurs Occurs With With Various Various Insulation Insulation Thicknesses? Thicknesses?

  Kahraman, Gökhan; Isik, Erdem

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