Sürdürülebilir Kalkınma Amaçları

• 2
• 2
• 1

• MakaleAçık Erişim2024Scopus SJRQ4/r/gumushane/12716
  OUTDOOR DEGRADATION ANALYSES OF SIX DIFFERENT AGED PHOTOVOLTAIC MODULE TECHNOLOGIES UNDER THE ARID-STEPPE CLIMATE CONDITION

  Cantürk, Zeynep; Özden, Talat; Akinoglu, Bulent G.

  Outdoor tests of photovoltaics module are crucial both for marketing and for research and technological developments. The electric generation performance and their degradation rates and lifetime are also related to different climatic conditions of the regions. In this work, the outdoor tests are carried out for six different photovoltaic (PV) modules under Arid-steppe Climate condition of Ankara, Türkiye. Their degradation rates are calculated by using linear regression (LR) and year on year (YOY) methods. The comparison between LR and YOY are carried out and with the other performed studies of different regions of world. In addition, it is investigated that how effective the climatic conditions on daily degradation rates. The results obtained are as follows: Mono-Si and Hetero-junction Silicon (HIT) cell modules degradation rates of 0.71/1.56 %/year and 0.84 %/year are respectively obtained by LR method and 0.57/0.90 %/year and 0.85%/year are respectively by YOY method. The degradation rates for Cupper Indium Selenide (CIS), Cupper Indium Gallium Selenide (CIGS) and microcrystalline Silicon/Amorphous Silicon (µc-Si/a-Si) modules have 1.73/1.49 %/year, 11.55/9.52 %/year and 1.48 %/year for LR method and 1.28/1.12 %/year, 9.94/9.53 %/year and 0.99 %/year for YOY method are obtained respectively. It is also obtained for the Polycrystalline Silicon Modules as 1.20/1.86 %/year degradation rates by LR method and 0.79/1.88 %/year degradation rates by YOY method.

  • 
  • 
  AtıfScopus1·WoS1·OpenAlex1

  İncele
• MakaleAçık Erişim2022Scopus SJRQ4/r/gumushane/13266
  Analysis and assessment of daily and seasonal photovoltaic heat island effect on Sekbandemirli rural region by local weather data records; [YEREL METEOROLOJIK VERI KAYITLARI ILE SEKBANDEMIRLI KIRSAL BÖLGESINDE GÜNLÜK VE MEVSIMSEL FOTOVOLTAIK ISI ADASININ INCELENMESI VE DEǦERLENDIRILMESI]

  Demirezen, Emre; Ozden, Talat; Akinoglu, Bulent G.

  Photovoltaic Power Plants have a considerable share among solar energy conversion technologies toward environmentally sustainable and economically feasible electricity production. However, when a rural region's land surface formed by natural soil types is covered by a Photovoltaic Power Plant (PVPP)'s dark-colored solar modules in large numbers, an artificial albedo (reflectivity) change is expected on that surface. Because of the heat exchange between these modules and the air surrounding them due to albedo alteration, the region's natural weather conditions may experience Photovoltaic Heat Island Effect (PVHIE) as a result of external and time-dependent air temperature oscillations caused by the warming-cooling cycles of solar modules. To observe and analyze a possible PVHIE trend, it has been conducting a field study project since October 2017 for a PVPP near the Sekbandemirli rural region in the Kutahya city of Turkey. The weather data, including air temperature and wind (direction and speed) at every 10-minute and hourly intervals, are collected by the three weather monitoring stations installed at the specific locations inside and outside the PVPP field. The plant's hourly average power output and module temperature data can also be monitored. After conducting statistical, correlational, and graphical analyses, the results show some temporal PVHI formations at the PVPP field center daily and on a seasonal basis. The plant center's air temperature tends to be warmer (up to the 6°C difference) during daytimes and colder (up to the (-3)°C difference) during nighttimes.

  • 
  • 
  • 
  AtıfScopus1

  İncele
• MakaleYalnız künye2017Scopus SJRQ3/r/gumushane/18397
  Dizel yakıtına etanol ve dietil eter katılmasının motor performansı ve emisyonlara etkilerinin deneysel incelenmesi

  Sezer, İsmet

  Bu çalışmada, etanol ve dietil eterin dizel yakıtına katılmasının motor performansı ve egzoz emisyonlarına etkileri deneyselolarak incelenmiştir. Deneylerde %15 etanol, %15 etanol ile %2 dietil eter ve %15 etanol ile %4 dietil eter içeren üç farklı yakıtkarışımı ve dizel yakıtı kullanılmıştır. Deneyler tek silindirli direkt püskürtmeli bir dizel motoru kullanılarak 1500 d/dk sabitdevir sayısında ve farklı yükleme durumlarında gerçekleştirilmiştir. Dizel yakıtı ve yakıt karışımları için püskürtme, yanma,performans ve emisyon parametreleri değerlendirilmiştir. Çalışma sonuçları, etanol ve dietil eter yakıt karışımlarının püskürtmebasıncında düşüşe ve dietil eter katkısının püskürtme zamanında gecikmeye neden olduğunu göstermiştir. Yanmanın ilkaşamasında kütlesel yanma oranı etanol ve dietil eter karışımları için düşük değerler alırken yanmanın ilerleyen aşamasındakütlesel yanma oranı dietil eter içeren karışımlar için artış göstermiştir. Ayrıca, etanol ve dietil eter yakıt karışımları silindirbasıncı ve sıcaklığında azalmaya neden olmuştur. Etanol ve dietil eter yakıt karışımları kullanıldığında hava fazlalık katsayısı%9,310,4 oranında artarken egzoz gazı sıcaklığı %4,8-5,5 oranında azalmıştır. Etanol karışımı motor gücünde %1,4 oranındadüşüşe neden olurken, dietil eter karışımları için güçteki azalma %0,3-1,1 arasında kalmıştır. Etanol ve dietil eter karışımlarıefektif verimde %14,7-17,2 oranında artış ve özgül yakıt tüketiminde %8,5 oranında azalma sağlamıştır. Yakıt karışımlarıkullanıldığında NOx emisyonunda %6,8-18,2 ve CO2 emisyonunda %10,313,8 oranında azalma sağlanmıştır. Yakıt karışımlarıHC emisyonunda %5-12,5 artışa neden olurken, CO emisyonu motor yüküne bağlı olarak dalgalanmalar göstermiştir.

  AtıfTR Dizin2

  İncele
• MakaleYalnız künye2017Scopus SJRQ3/r/gumushane/16521
  EXPERIMENTAL INVESTIGATION THE EFFECTS OF ETHANOL AND DIETHYL ETHER ADDITION INTO DIESEL FUEL ON ENGINE PERFORMANCE AND EXHAUST EMISSIONS

  Sezer, Ismet

  In this study, effects of ethanol and diethyl ether addition into diesel fuel on the performance and emissions of a diesel engine were experimentally investigated. A commercial diesel fuel and three different blends prepared with 15% ethanol, 15% ethanol and 2% diethyl ether and 15% ethanol and 4% diethyl ether were used in the tests. The experiments were performed at an engine speed of 1500 rpm and under various loads by using a single cylinder direct injection diesel engine. The injection, combustion, performance and emissions parameters were evaluated for baseline fuel and blends. The results show that, the injection pressure decreases for all blends, and diethyl ether addition causes a delay in the injection timing. The burnt mass fraction is lower for ethanol and diethyl ether blends during early combustion phase, while it increases for diethyl ether blends during the progressive combustion phase. Ethanol and diethyl ether blends also give the reductions in the cylinder pressure and temperature. Air excess coefficient increases the rate by 9.3-10.4%, but exhaust gas temperature decreases the rate by 4.8-5.5% when using ethanol and diethyl ether blends. Although ethanol blend causes a decrement of 1.4% in engine power, reductions in engine power are between 0.3% and 1.1% for diethyl ether blends. Both ethanol and diethyl ether blends yield increments the rate by 14.7-17.2% in brake thermal efficiency and a reduction of 8.5% in brake specific fuel consumption. The reductions were obtained the rate by 6.8-18.2% for NOx and 10.3-13.8% for CO2 emissions, when using the blended fuels. Ethanol and diethyl ether blends cause the increments the rate by 5-12.5% for HC emission, while CO emission fluctuates depending on the engine load.

  AtıfWoS5

  İncele
• MakaleYalnız künye2015Scopus SJRQ2/r/gumushane/16037
  PRESSURE-DRIVEN LAMINAR PULSATING FLOW IN A PIPE: EFFECT OF THE AMPLITUDE

  Aygün, Cemalettin; Aydin, Orhan

  In this study, pressure-driven laminar pulsating flow in a pipe is examined numerically. Both the hydrodynamically developing flow and fully developed conditions are considered. A commercially available CFD package, FLUENT, is used in the simulations. A constant value of the time-averaged Reynolds number is considered, Re=1000. Six different values of the dimensionless frequency (F=0.01, 0.1, 1, 10, 100, 1000) and three different values of the dimensionless amplitude (A=0.1, 0.5 and 0.95) are considered. Both the hydrodynamically developing and fully developed flows are analyzed. Effects of the amplitude and frequency of the pulsating inlet velocity on the friction coefficient as well as velocity field are predicted.

  AtıfWoS1

  İncele
• MakaleYalnız künye2013Scopus SJRQ3/r/gumushane/15885
  COMPARATIVE INVESTIGATION THE USE OF METHANOL AND METHYL TERTIARY BUTYL ETHER IN GASOLINE ON ENGINE PERFORMANCE, CO EMISSIONS AND FUEL COST

  Sezer, Ismet; Bilgin, Atilla

  This study is concerned with investigating experimentally the effects of methanol and Methyl tert-Butyl Ether (MTBE) blending to base gasoline on the performance CO emissions and fuel cost of a spark ignition (SI) engine. The fuel blends were prepared by addition 5, 10, 15, and 20 vol % of methanol and MTBE with a specified amount of base gasoline. The methanol- and MTBE-gasoline blends were designated as M5, M10, M15, M20, and MTBE5, MTBE10, MTBE15, MTBE20, respectively. Experiments were conducted under various engine speeds, spark timings (STs), and compression ratios (CRs). The engine was operated under wide-open throttle conditions. The results of the study showed that the M5 and MTBE10 blends yield the best engine performance in terms of the brake mean effective pressure (bmep), while the M20 and MTBE15 blends are the best performers in terms of brake thermal efficiency (bte). Moreover, M20 and MTBE10 blends give the minimum CO emission values. The economical analysis performed in the study is based on both the current blending fuel prices in Turkey and brake specific fuel consumption (bsfc) of the engine while using gasoline, methanol-gasoline, and MTBE-gasoline blends. It was obtained that, in contrast to the improvement of engine performance, efficiency and CO emissions, methanol and MTBE blends caused increases in fuel costs because of the expensive methanol and MTBE prices in Turkey. Uncertainty analysis was also performed in this study, and it was found that; the uncertainties in the measurement devices do not have noticeable influences on the variations of engine characteristics.

  AtıfWoS3

  İncele
• MakaleYalnız künye2011Scopus SJRQ2/r/gumushane/13091
  The effect of fin pitch on heat transfer and fluid flow characteristics in the entrance region of a finned concentric passage

  Kuvvet, Kemal; Yavuz, Tahir

  In this study, the heat transfer and fluid flow characteristics in the unfinned and internally finned concentric passage (smooth and finned annulus) are investigated experimentally. The turbulence characteristics, mean flow, pressure drop and heat-transfer parameters in the entrance region of a concentric passage of diameter ratio 0.2 are measured. The hot-wire anemometer and the liquid-crystal technique are used for the turbulence and mean flow and the heat transfer measurements, respectively. The finned passage is designed as the fin width (W) of 2 mm, the fin height (H) of 2, 4, 6 and 8 mm and the fin pitch (P) of 20, 30 and 40 mm. Reynolds number ranges from 1.8 .104 to 1.24.105 and from 1.65.104 to 7.65.104 for flow and pressure drop and heat transfer measurements, respectively. Experiments are performed for the smooth and finned concentric passages by varying flow and fin parameters and the effects of the fin pitch are investigated. The developing of fluid flow is analyzed and the variation of turbulence intensity, friction factors, local and mean convective heat transfer coefficients in the smooth and finned concentric passages are obtained. Results obtained in the finned concentric passages are compared with the results of the smooth passage. For the average Nusselt numbers and friction factor, empirical equations are developed. As a result, it is seen that the friction factor in the finned passage increases between 3.61 and 18.05 times while the average Nusselt number augments between 1.36 and 5.23 times on the inner surface and between 1.03 and 1.80 times on the outer surface.

  AtıfScopus4·WoS4·TR Dizin1

  İncele
• MakaleYalnız künye2010Scopus SJRQ3/r/gumushane/19310
  Gündüz şartlarında üçgen kesitli çatıda doğal taşınım

  Küçük, Haydar; Gedikli, Hasan

  The natural convection is numerically investigated in a roof of triangular cross section under constant heat flux with seven different values depending on daylight on the inclined wall, constant wall temperature on the bottom wall and adiabatic on the vertical wall boundary conditions. Continuity, momentum and energy equations are solved by using finite volume method for laminar, two-dimensional and steady-state regime. Streamlines, isotherms, local and mean Nusselt numbers are presented for AR=0.25, 0.5, 0.75 and 1.0 and Ra=10³, 10⁴, 10⁵, 10⁶. The amount of heat flux ranges from 163 W/m² to 808 W/m² depending on daylight and the Prandtl number is chosen as 0.7. It is found out that the aspect ratio and Rayleigh number highly affect the heat transfer on the bottom and inclined walls while heat flux slightly affects.

  İncele
• MakaleYalnız künye2010Scopus SJRQ3/r/gumushane/15506
  Natural convection in a triangular cross section roof under daylight conditions

  Küçük, Haydar; Gedikli, Hasan

  The natural convection is numerically investigated in a roof of triangular cross section under constant heat flux with seven different values depending on daylight on the inclined wall, constant wall temperature on the bottom wall and adiabatic on the vertical wall boundary conditions. Continuity, momentum and energy equations are solved by using fmite volume method for laminar, two-dimensional and steady-state regime. Streamlines, isothenns, local and mean Nusselt numbers are p̧resented for AR=0.25, 0.5, 0.75 and 1.0 and Ra=103, 104, 105, 106. The amount of heat flux ranges from 163 W/m2 to 808 W/m2 depending on daylight and the Prandtl number is chosen as 0.7. It is found out that the aspect ratio and Rayleigh number highly affect the heat transfer on the bottom and inclined walls while heat flux slightly affects.

  AtıfScopus1·WoS1

  İncele