Energy Systems Engineering / Enerji Sistemleri Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4752
Browse
11 results
Search Results
Article Citation - WoS: 9Citation - Scopus: 11Experimental Investigation of Spray Characteristics of Ethyl Esters in a Constant Volume Chamber(Springer, 2024) Ulu, A.; Yildiz, G.; Özkol, Ü.; Rodriguez, A.D.Abstract: Biodiesels are mainly produced via the utilization of methanol in transesterification, which is the widespread biodiesel production process. The majority of this methanol is currently obtained from fossil resources, i.e. coal and natural gas. However, in contrast with methanol, biomass-based ethanol can also be used to produce biodiesels; this could allow the production line to become fully renewable. This study aimed to investigate the spray characteristics of various ethyl ester type biodiesels derived from sunflower and corn oils in comparison to methyl esters based on the same feedstocks and reference petroleum-based diesel. Spray penetration length (SPL) and spray cone angle (SCA) were experimentally evaluated in a constant volume chamber allowing optical access, under chamber pressures of 0, 5, 10 and 15 bar and injection pressures of 600 and 800 bar. Sauter mean diameter (SMD) values were estimated by using an analytical correlation. Consequently, ethyl esters performed longer SPL (2.8–20%) and narrower SCA (5.1–19%) than diesel under ambient pressures of 5 and 10 bar. Although the SMD values of ethyl esters were 48% higher than diesel on average, their macroscopic spray characteristics were very similar to those of diesel under 15 bar chamber pressure. Moreover, ethyl esters were found to be very similar to methyl esters in terms of spray characteristics. The differences in SPL, SCA and SMD values for both types of biodiesels were lower than 4%. When considering the uncertainty (± 0.84%) and repeatability (±5%) ratios, the difference between the spray characteristics of methyl and ethyl esters was not major. Graphical abstract: [Figure not available: see fulltext.] © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Article Citation - WoS: 1Citation - Scopus: 1Experimental Investigation of Naca 4415 Airfoil Using Vibration Data for Stall Detection(Emerald Group Publishing, 2023) Ayaz Ümütlü, Hatice Cansu; Kıral, Zeki; Karadeniz, Ziya HaktanPurposeThe purpose of this study is to identify the possible relation between the vibration and the stall by using the vibration response of the airfoil. For this purpose, the root mean square values of the acceleration signals are evaluated to demonstrate the compatibility between the stall angles and the vibration levels. Design/methodology/approachAn experimental study is conducted on NACA 4415 airfoil at Reynolds numbers 69e3, 77e3 and 85e3. Experiments are performed from 0 & DEG; to 25 & DEG; of the angles of attack (AoA) for each Reynolds number condition. To observe the change of the vibration values at the stall region clearly, experiments are performed with the AoA ranging from 10 & DEG; to 25 & DEG; in 1 & DEG; increments. Three acceleration sensors are used to obtain the vibration data. FindingsThe results show that the increase in the amplitude of the vibration is directly related to the decrease in lift. These findings indicate that this approach could be beneficial in detecting stall on airfoil-type structures. Originality/valueThis study proposes a new approach for detecting stall over the airfoil using the vibration data.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: 4Küçük ve Mikro Ölçekli Enerji Yatırımı için Hibrit Enerji Modeli(Pamukkale Üniversitesi, 2019) Yıldız, Mustafa; Bingöl, FerhatTürkiye çatı üstü güneş ve küçük ölçekli rüzgâr türbinleri gibi farklı olasılıklarda yeni düzenlemelere 2017 yılında gitmiştir. Her iki teknoloji için de ayrı çalışmalar yapılmış olmasına rağmen henüz hibrit sistem değerlendirme metodolojisi ve sonuçları ülke çapında yaygın değildir. Bu çalışma, verilen tesis alanın mikro ölçekli rüzgâr ve güneş esaslı toplam enerji kapasitesine göre iki kaynaktan üretilen enerjiyi azami noktaya ulaştırmak için önerilmiş, Hibrit Optimizasyon Aracı (Hybrid Otpimization Tool)-HOT-olarak isimlendirilmiş bir model içerir. Son kullanıcının basit aylık bilgileri girerek yıllık üretim tahmini yapmasına olanak verir. Modelin karşılaştırılması yaygınca kullanılan ve ticari yazılım HOMER ile yapılmıştır. Sonuçta yapılan tahminlerin mikro sistemlerin ekonomik modelini tehlikeye atmayacak belirsizlikte çalışarak fizibilite çalışmalarında ön-analiz için kullanılabileceği sonucuna ulaşılmıştır.Article Citation - WoS: 5Rüzgar Enerji Sistemleri için Hava Yoğunluğunun Hesaplanması(Gazi Üniversitesi, 2018) Bingöl, FerhatRüzgar tarlaları son yıllarda dünyada ve Türkiye’de deniz seviyesindeki alanların yanı sıra yüksek rüzgar hızı kapasitesine sahip dağlık bölgelerde de kurulmaya başlamıştır. Ancak, dikkat edilmesi gereken en önemli nokta bu konumlarda hava yoğunluğunun azaldığı ve bunun da rüzgar türbinlerinden üretim gücüne doğrudan etkilediğidir. Küçük görünen farklar eğer fizibilite aşamasında yanlış hesaplanırsa uzun yıllar üretim göz önüne alındığında önemli farklar yaratabilirler. Bu çalışmada Türkiye'de 126 ölçüm yapılmış nokta için temelde iki farklı yöntem kullanılarak yoğunluk hesabı yapılmış ve karşılaştırılmıştır. Genel itibariyle, sonuçlar yıllık ortalamalar dikkate alındığında iki metotta da birbirine yakın çıkmakta ama aylık ortalamalarda %2 seviyelerine ulaşan üretim tahmininde hatalara yol açacak farklılıklar göstermektedir.Article Omega type solar charge station(Croation Union of Mech. Engineers and Naval Architects, 2002) Atagündüz, GürbüzAcid rains, greenhouse effect, smog and depletion of ozone layer arc some of the factors, which lead to the air pollution in big cities all over in the world. One of ways to reduce the air pollution in big cities is the introduction of electro or hybrid cars. The present work deals with a photovoltaic charge station, which could be installed on a garage roof with the dimensions about three meters by six meters in order to charge the battery of an electro car. The present work consists of two parts. First part deals with the theoretical design of the charge station, which has been started during a research stay of the author* in Germany. The second part is an experimental work, completed at Izmir Institute of Technology as a MS-Thesis. The present work bases on the original idea of the author, used in a previous work for the field of heliostats of the Solar Thermal Power Plant in the University Ege. The idea is to create a fix mirror area, which should acts as if it were a sun-tracking array. The theoretical design work and the results of the experiments have shown that the idea is applicable also to photovoltaic fields.Conference Object Citation - WoS: 1Citation - Scopus: 3Green Smart Cities: Living Healthily With Every Breath(Institute of Electrical and Electronics Engineers Inc., 2019) Turhan, Cihan; Atalay, Ali Serdar; Gökçen Akkurt, GüldenFifty-four percent of the world's population lives in big cities and it is projected to increase to nearly 70% by 2050s. Rapid and dense urbanization leads to smart cities which improve the quality of lives of the citizens. Therefore, development of smart cities is becoming vital. The quality of the citizens is affected by many factors including poor air quality, increased pollutants and microclimates called urban heat islands. The URBAN GreenUP project, initiated in June 2017, is a project funded under the European Union's Horizon 2020 programme. The main objective of the project is the development, application and replication of re-naturing Urban Plans in a number of European cities. In this study, measurement of nature-based solutions for mitigation of urban heat island effect and improvement of air quality for Urban GreenUP project in Izmir, will be introduced.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.Conference Object Citation - WoS: 14Citation - Scopus: 16Drying of Olive Leaves in a Geothermal Dryer and Determination of Quality Parameters of Dried Product(Elsevier, 2019) Helvacı, Hüseyin Utku; Menon, Abhay; Aydemir, Levent Yurdaer; Korel, Figen; Gökçen Akkurt, GüldenIn this study, a cabinet type geothermal dryer was designed, operated and tested for drying olive leaves with minimum losses of phenolic content and antioxidant capacity by optimization of drying conditions. Two factors; face centered central composite design was applied and response surface methodology was used to optimize the drying conditions of olive leaves. The results indicate that phenolic content stability were mainly affected by air temperature, whereas antioxidant capacity is affected by both air temperature and velocity (p<0.05). The optimal drying conditions were found to be at 50°C of air temperature and 1 m/s of air velocity for the minimum losses of determined quality parameters, where 88.8% of phenolic content and 95.3% of antioxidant capacity were recovered.Conference Object Citation - WoS: 6Citation - Scopus: 8The Effect of Spatial Interventions on Historic Buildings' Indoor Climate (case Study: Tire Necip Paşa Library, Izmir-Turkey)(Elsevier Ltd., 2017) Coşkun, Turgay; Gülhan, Özcan; Şahin, Cem Doğan; Durmuş Arsan, Zeynep; Gökçen Akkurt, GüldenThe indoor climate of historic libraries should meet rigorous requirements related to human thermal comfort and conservation of books, manuscripts and cultural proper-ties. Paper based collections in historic libraries can be deteriorated chemically, mechanically and biologically because of inadequate indoor climate conditions. In this paper, Necip Paşa Library, the historic library located in Tire-Izmir, Turkey, was selected as a case study. The chemical, mechanical and biological degradation risks on the manuscripts were evaluated based on the indoor climate parameters measured for one year period. The Library, consisting of a main hall, a manuscript zone and an entrance hall, was modelled via the dynamic simulation software, Design Builder. Calibration of the model was conducted with respect to the measured indoor temperature and relative humidity values. The portico/Revak at the south facade of Library was converted into the entrance hall by wooden framed windows in 1930. To be able to see the effect of that intervention on the indoor climate (correspondingly on degradation risk of the manuscripts), a new model, namely semi-open model, was created and simulated. A remarkable change has not been observed on chemical degradation risk when the results of semi-open and existing library models were compared, while mechanical and biological degradation risks were less in semi-open model.