Impacts of Ground Slope on Main Performance Figures of Solar Chimney Power Plants: A Comprehensive CFD Research with Experimental Validation

Geometric parameters in solar chimney power plants are numerically optimised for the purpose of better power output figures. Several parameters have been investigated in the pilot plant such as chimney height and diameter, collector diameter and slope, and slenderness. However, ground slope has not been studied to date despite its perspicuous impact on turbulent flow. In this study, the impacts of the different slope angles of the ground, where the solar radiation is absorbed through the collector, on the main performance parameters of the system are numerically analysed through a reliable CFD software ANSYS FLUENT. By considering the actual geometric figures of the pilot plant, a 3D model is constructed through DO (discrete ordinates) solar ray tracing algorithm and RNG k-epsilon turbulence model. For the solar intensity of 1000 W/m(2), the maximum velocity inside the system is found to be 14.2 m/s, which is in good accordance with the experimental data of 15.0 m/s. Starting from 5 m inside the collector, the chimney inlet heights are reconfigured 0.209, 0.419, 0.625, 0.838, and 1.04 m, respectively, and when the ground slope is 0.1, 0.2, 0.3, 0.4, and 0.5 degrees, the changes in the performance output of the system are investigated. For the reference case which refers to the horizontal ground, the maximum air velocity is determined to be 14.2 m/s and the power output is 54.3 kW. However, when the ground slope is made 0.5 degrees, it is observed that the maximum velocity increases by 37% to 19.51 m/s, and the power output is enhanced to 63.95 kW with a rise of 17.7%. Sloping ground is found a key solution to improve the turbulent effects inside the plant, thus to enhance the electrical power output

Doğu Karadeniz Bölgesindeki küçük akarsuların hidroelektrik potansiyellerinin analizi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Anahtar kelimeler: Hidroelektrik Enerji, Küçük Hidroelektrik Santralleri, Enerjihtiyaç ve Potansiyel DengesiBu çalısmada, Türkiye'nin küçük hidroelektrik potansiyeline genel bir bakısyapılarak Türkiye'nin küçük Hidrolik potansiyelde çok önemli bir yere sahip olanDogu Karadeniz Bölgesine agırlık verilmistir. Bu bölgede mevcut su potansiyelidiger illere göre daha fazla miktarda olan Trabzon, Rize ve Giresun illerindekiderelerin çesitli kurumlardan alınan bilgiler ve yaptıgımız çalısmalarda eldeettigimiz kot ve debi degerleri incelenerek enerji potansiyelleri üzerinde çalısmayapılmıstır. Bu tezdeki:Birinci bölümde; Türkiye'nin hidroelektrik potansiyel gelisimi genel olarakincelenmis, küçük hidroelektrik santrallerin avantaj ve dezavantajlarıirdelenmistir.kinci bölümde; Dogu Karadeniz Bölgesi'ndeki iller içerisinde mevcut supotansiyeli diger illere göre daha fazla miktarda olan Trabzon, Rize ve Giresunillerindeki akarsuların hidrolik ve hidrolojik özellikleri üzerinde arastırmalaryapılmıs olup daha sonra elde edilen verilerden bu illerdeki küçük akarsularınhidroelektrik potansiyelleri hesaplanmıstır.Üçüncü bölümde; Dogu Karadeniz Bölgesi'nde bulunan Trabzon, Rize veGiresun llerinin bir önceki bölümde hesaplanmıs olan küçük akarsuların brüthidroelektrik potansiyelleri ile bulunan toplam potansiyelin degisik oranlardakullanılabilmesi halinde Trabzon, Rize ve Giresun illerinin ihtiyaç duyulanelektrik enerjisinin karsılanabilirligi arastırılmıstır.Dördüncü bölümde; yapılan çalısmaların sonuçları özetlenerek ileride alınmasıgereken önlemler konusunda bilimsel yaklasımlar sunulmustur. Sonuç olarak,çalısılan illerde yalnızca küçük hidroelektrik potansiyeli bu illerin simdiki vegelecekteki elektrik enerjisi ihtiyaçlarını karsılayamayacaktır. Bunun için elektrikihtiyaçlarının karsılanması amacıyla hibrit enerji kaynakları kullanılmalıdır.Key words: Hydroelectric energy; small hydropower; energy requirement andpotential balanceAmong 26 hydrological basins in Turkey, the Eastern Black Sea Basin (EBSB)has great advantages from the view point of small hydropower (SHP) potential.So, in this study, the SHP potential of Turkey and especially EBSB areinvestigated. In this basin, rivers in the province of Trabzon, Rize and Giresunwas selected as a research basin due to their higher SHP potential than the otherprovinces in this basin. In the present study, the SHP potential of these rivers arecalculated by using some measured data and obtained SHP potential values fromvarious local governmental offices. In the present thesis, there are four sectionssuch as:In the first section; Turkey?s hydroelectric power potential discussed as anoverview and the advantage and disadvantages of SHP plants are discusseddetailed.In the second section; the small rivers in the province of Trabzon, Rize andGiresun at the EBSB was selected as a research area due to their higher SHPpotential than the other provinces in the EBSB. So, the SHP potential of thesesmall rivers was calculated by using obtained measured data for these rivers.In the third section; the calculated SHP values for the small rivers in the provinceof Trabzon, Rize and Giresun and the total potential of the other provinces in theEBSB are discussed for meeting the electric energy demand of the basin.In the fourth section; the studied and obtained results are summarized and somescientific results was presented for future studies in the EBSB. As a result; in thestudied provinces, the SHP potential will not meet the present and future electricenergy demand of these provinces with alone. So, in order to meet the electricenergy demand, the hybride energy sources must be used

Wind quality designation concept and application

Generally, wind energy production is based on the average wind speed without any classification. This article proposes a classification system on the basis of wind speed durations greater than a given threshold value. For this purpose, the wind quality designation (WQD) concept is defined based on the wind potential duration, amount, and intensity on a threshold level. Its classifications are depicted on five risk percentage classes as excellent, very good, good, fair, and weak. Apart from the classification, the change of WQD with wind speed threshold provides qualitative and quantitative wind speed energy production assessment. The specific objective of the article is to present theoretical WQD explanations on the basis of the most frequently employed two-parameter Weibull probability distribution function (PDF). The application is provided for Adiyaman City, Kahta meteorology station wind speed records from the Southeastern province of Turkey. It is noticed that there is no Weak category at this station and the most effective quality class is Excellent from 14 m/s to almost 27 m/s wind speeds. The average wind speed corresponds to about 62% WQD. Finally, the wind speed potential durations PDF abides by the logarithmic-normal PDF, whereas amount and intensity accord with the Weibull PDFs

Wind quality designation concept and application

Generally, wind energy production is based on the average wind speed without any classification. This article proposes a classification system on the basis of wind speed durations greater than a given threshold value. For this purpose, the wind quality designation (WQD) concept is defined based on the wind potential duration, amount, and intensity on a threshold level. Its classifications are depicted on five risk percentage classes as "excellent," "very good," "good," "fair," and "weak. Apart from the classification, the change of WQD with wind speed threshold provides qualitative and quantitative wind speed energy production assessment. The specific objective of the article is to present theoretical WQD explanations on the basis of the most frequently employed two-parameter Weibull probability distribution function (PDF). The application is provided for Adiyaman City, Kahta meteorology station wind speed records from the Southeastern province of Turkey. It is noticed that there is no "Weak" category at this station and the most effective quality class is "Excellent" from 14 m/s to almost 27 m/s wind speeds. The average wind speed corresponds to about 62% WQD. Finally, the wind speed potential durations PDF abides by the logarithmic-normal PDF, whereas amount and intensity accord with the Weibull PDFs

Impacts of Ground Slope on Main Performance Figures of Solar Chimney Power Plants: A Comprehensive CFD Research with Experimental Validation

Geometric parameters in solar chimney power plants are numerically optimised for the purpose of better power output figures. Several parameters have been investigated in the pilot plant such as chimney height and diameter, collector diameter and slope, and slenderness. However, ground slope has not been studied to date despite its perspicuous impact on turbulent flow. In this study, the impacts of the different slope angles of the ground, where the solar radiation is absorbed through the collector, on the main performance parameters of the system are numerically analysed through a reliable CFD software ANSYS FLUENT. By considering the actual geometric figures of the pilot plant, a 3D model is constructed through DO (discrete ordinates) solar ray tracing algorithm and RNG k-epsilon turbulence model. For the solar intensity of 1000 W/m(2), the maximum velocity inside the system is found to be 14.2 m/s, which is in good accordance with the experimental data of 15.0 m/s. Starting from 5 m inside the collector, the chimney inlet heights are reconfigured 0.209, 0.419, 0.625, 0.838, and 1.04 m, respectively, and when the ground slope is 0.1, 0.2, 0.3, 0.4, and 0.5 degrees, the changes in the performance output of the system are investigated. For the reference case which refers to the horizontal ground, the maximum air velocity is determined to be 14.2 m/s and the power output is 54.3 kW. However, when the ground slope is made 0.5 degrees, it is observed that the maximum velocity increases by 37% to 19.51 m/s, and the power output is enhanced to 63.95 kW with a rise of 17.7%. Sloping ground is found a key solution to improve the turbulent effects inside the plant, thus to enhance the electrical power output