Energy Systems Engineering / Enerji Sistemleri Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4752
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Article Stochastic 1-D Reactive Transport Simulations To Assess Silica and Carbonate Phases During the $co_2$ Reinjection Process in Metasediments(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2024) Erol, SelçukOne proposed method to mitigate carbon emission is to mineralize the $CO_2$ in deep geothermal reservoirs while mixing the coproduced CO2 with the effluent fluid for reinjection. The injection fluid temperature fluctuates due to the mixing process between CO2-charged water and the effluent fluid, and compressor interruptions change the thermodynamic conditions that influence the fluid- rock interaction in the reservoir. Mineral dissolution or precipitations are associated with changes in permeability and porosity that affect the flow and, eventually, the lifespan of the reservoir. A combined stochastic–reactive transport simulation approach is useful for inspection purposes. Moreover, the stochastic algorithm validates the deterministic reactive transport simulation and demonstrates the time evolution of a chemically reacting system in the reservoir. This study examines a range of injection temperatures between 80 °C and 120 °C to evaluate silica and calcite precipitation along a flow path. One-dimensional (1-D) reactive transport and compartment- based stochastic reaction-diffusion-advection Gillespie algorithms are carried out. The 1-D model represents a reservoir feed zone of around 2300 m. Two common metasediment rock types are evaluated for inspection. The first one is the muscovite schist, which has approximately 60% quartz, and the second is the quartz schist, consisting of roughly 90% quartz. The stochastic method can be applied more effectively if the chemical system is completely defined with proper reaction rates as a function of temperature. The mixing ratio of the coproduced $CO_2$ over the effluent fluid is around 0.0028. Simulation results show that $CO_2$ is partially sequestrated as calcite within the first 10 m of the entrance to the reservoir and plugs the pores completely in the muscovite schist scenario. Chalcedony and α-cristobalite precipitate as secondary minerals evenly along the flow path. $CO_2$ injection into a quartz schist layer is more appropriate for geochemical interactions below 120 °C.Article Eşli çalışan düşey eksenli türbin performansının iki boyutlu benzetimi(2023) Akgül, Ufuk; Kökey, İskender; Turgut, Alpaslan; Karadeniz, Ziya HaktanRüzgar enerji santralindeki (RES) türbinlerin birbirine göre konumları oldukça önemlidir. Bu açıdan önemli hususlardan biri de, birbirine yakın konumda çalışan iki düşey eksenli türbinin (DERT) birbirlerinin performansına olan etkisidir. Literatürde gösterilmiş olan, birlikte çalışan DERT’lerin performansındaki yükselişin nedenlerinin araştırılması gerekmektedir. Saha testlerinde rüzgâr hızlarının tam olarak kontrol edilememesi ve düşey eksenli türbinin kanat dışındaki yapısal elemanlarının akış bozucu etkisi olması, problemin daha basit haliyle, iki boyutlu bilgisayar benzetimi yöntemiyle incelenmesini zorunlu kılmıştır. Bu amaçla çalışma kapsamında, düşey eksenli türbinin akışı bozacak parçalarını ihmal ederek, farklı merkezler arası uzaklığa (1,5, 2, 2,5 ve 4) sahip eşli çalışan iki türbinin performansının farklı uç hız oranlarında (0,5, 1, 1,5, 2, 2,5 ve 3 uç hız oranı) tek çalışan türbine göre nasıl değiştiği iki boyutlu bilgisayar benzetimleriyle incelenmiştir. Eşli çalışma durumunda türbin performansının tek çalışmaya göre %26 yükseldiği görülmüştür. Bu yükselişin ana etkeninin blokaj etkisi olduğu, yanal hızların ve iki türbin ara bölgesinde hızlanan akış gibi etkilerin ise daha az olduğu saptanmıştır.Article Citation - WoS: 7Citation - Scopus: 8Update for Reactive Transport Modeling of the Kızıldere Geothermal Field To Reduce Uncertainties in the Early Inspections(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2023) Erol, Selçuk; Akın, Taylan; Akın, SerhatThe development of carbon capture and storage techniques has become essential to reduce and mitigating CO2 emissions to the atmosphere. CarbFix1 and CarbFix2 projects carried out in Iceland demonstrated that the emissions of waste CO2 gas from geothermal power plants can be captured and mixed with the effluent geofluid and subsequently injected back into the geothermal reservoir. This experience gained in the CarbFix projects expanded into other geothermal fields around Europe, and one of the demonstration sites is the geothermal field in Turkey, Kızıldere. This paper focuses on the results of an updated study on early field evaluations with reactive transport simulations. In the new three-dimensional numerical model, the geological formations and fault zones were updated according to the well-logs data. Based on the tracer tests performed in the field, the anisotropic permeabilities between the wells were evaluated and imposed into the model. Geofluid chemistry, mineral components, and the volume fractions used as input in the simulations are modified depending on the performed laboratory experiments on the metamorphic schists taken from the geothermal site (i.e. X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning-electron microscope (SEM), and batch reactor tests). Different thermodynamic databases such as Lawrance Livermore National Laboratory (LLNL) and Thermoddem databases were tested using PHREEQC and TOUGHREACT programs for consistency with experiments. The thermodynamic conditions and the geofluid-rock-CO2 interactions prevent the mineralization of CO2 in the reservoir. This outcome differs from CarbFix projects in terms of the carbonization process, but the CO2 injection is still reliable with solubility-trapping in a geothermal reservoir to partially mitigate the emission. Roughly, 200 kt of CO2 in 10 years can be safely injected into the geothermal reservoir. According to the new analysis, the ratio of magnesium, sodium, and potassium varies in solid solution series of feldspars and clay minerals as albite end-member and montmorillonite/illite end-members, respectively. The evaluations of solid solution reactions are relatively limited in the law of mass action approach used by PHREEQC and TOUGHREACT. © TÜBİTAK.Article Determining Suitable Regions for Potential Offshore Wind Farms in Bandırma Bay Using Multi-Criteria Method(Bandırma Onyedi Eylül Üniversitesi, 2021) Karipoğlu, Fatih; Öztürk, Samet; Genç, Mustafa SerdarWind energy is an environmentally friendly, profitable, and renewable energy resource. Wind energy eployment is increasing in the last two decades. In this paper, Bandırma bay which has a potential for offshore wind deployment is studied to determine the most suitable area in it and eventually potential offshore power capacity of the location is estimated. This study combines applications of Geographical Information System and Multi-Criteria- Decision-Making Methodology to obtain fast results supported with visual documentation. In this scope, eight standard criteria such as wind speed, water depth, bird migration lines are applied and nvestigated in detail by using Geographical Information System. It is found that there is sufficient wind speed t the shallow level of the sea. Consequently, two locations are found to be suitable; one is on the northwest and the other one is on the north east of Bandırma, with capacities of 72 MW and 48 MW, respectively.Article Türkiye’nin Farklı İklim Koşullarında Isıl Konfor Sıcaklıklarına Bağlı Olarak Konutların Enerji Performanslarının Değerlendirilmesi(2021) Hancıoğlu Kuzgunkaya, Ebru; Yıldırım, Nurdan; Gökçen Akkurt, GüldenIsıl konfor, insanın yapısı, yaşı, cinsiyeti gibi kişisel parametrelerin yanı sıra çevresel parametrelere de bağlıdır. Isıtma, soğutma ve havalandırma sistemlerinin çalışma şekli ve dış hava sıcaklıkları ısıl konfor için önemli parametrelerdir. Fanger deneysel çalışmalar sonucu “tahmini ortalama oy (PMV)” olarak adlandırılan bir gösterge oluşturmuş ve PMV=0’ı konfor için en iyi değer olarak belirlemiştir. Bu çalışmada, farklı iklim bölgelerinden dört il seçilerek, her bir il için ısıl konfor sıcaklıkları belirlenmiş ve bu ısıl konfor sıcaklıklarındaki enerji performansları değerlendirilmiştir. Isıtma ve soğutma sistemi için kişisel kontrole izin verilmeyen tam mekanik kontrollü sistem seçilmiş, kesikli ve sürekli rejim için hesaplamalar yapılmıştır. Çalışmada, konfor koşullarının PMV=0 olması durumunda enerji tüketimleri incelenerek iller arasındaki ısıl konfor memnuniyeti ve enerji tüketiminindeki farklılıklar saptanmaya çalışılmıştır. PMV değerlerinin istatistiksel analizinde, İzmir ili için kesikli rejimde çalışmanın sürekli rejime göre daha iyi olmasına rağmen İstanbul için sürekli rejimde konfor koşulları açısından daha iyi sonuçlar alınmıştır. Tüm illerde sürekli rejim uygulandığında birim enerji tüketiminde artış olduğu belirlenmiştir. Sürekli rejim, kesikli rejime göre ısıtma enerji tüketiminde % 4,5-6,2, soğutma enerji tüketiminde ise % 9,1-23,2 daha yüksektir.Article Citation - WoS: 1Performance Analysis of Thermal Storage Assisted Cooling Tower With Night Cooling(Gazi Üniversitesi, 2020) Ouedraogo, Kiswendsida Elias; Toprak, KasımAs global warming and water scarcity issues continue to grow, it is essential to increase resources efficiency for air conditioners and power plants. In order to increase the efficiency, the systems need to be modified to take the advantages of the low night temperature and thermal storage tanks. In this study, the low night temperature and thermal storage tanks effects on the cooling tower is studied using TRNSYS. Using a chiller operating from 8:00 to 16:00 as a case study, hot water from the condenser is partially stored on daytime and cooled slowly during the night. The storage tank volume is optimized by considering two big tanks and five small tanks. The results show that night cooling reduces cooling water temperature by 5.8 degrees C or 21.8% while the cooling efficiency is increased by 36%. The thermal storage tanks enable to have the low continuous flow rate and help to reduce the fan power by 67.1%. On the storage side, compared to two tanks system, the tanks volume is reduced by 16.5% when 5 tanks are used. In theory this reduction can go up to 50% by increasing the number of tanks and reducing their individual size.Article Citation - WoS: 7Inertia and Droop Controller for a Modern Variable Speed Wind Turbine To Provide Frequency Control in a Microgrid(Gazi Üniversitesi, 2020) Hassan, Ali; Altın, Müfit; Bingöl, FerhatThe increasing penetration of modern Variable Speed Wind Turbines (VSWTs) in microgrids creates the problem of frequency stabilization due to reduced inertia of the power system. To emulate the Inertia Response of the conventional synchronous machines, wind turbines can be provided with an inertia emulation controller. The modeling presented in this paper aims at equipping the modern Type D wind turbine with inertia response and primary frequency control (PFC) capabilities. Two controllers - inertial and droop, are implemented and their frequency control capabilities are compared in an isolated power system which consists of a conventional steam turbine generator and a wind farm. The results suggest that proposed controllers help in better frequency control performance in the microgrid.