Energy Systems Engineering / Enerji Sistemleri Mühendisliği

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Now showing 1 - 6 of 6
  • Article
    Citation - WoS: 9
    Citation - Scopus: 11
    Experimental 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: 5
    Rüzgar Enerji Sistemleri için Hava Yoğunluğunun Hesaplanması
    (Gazi Üniversitesi, 2018) Bingöl, Ferhat
    Rüzgar 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.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 3
    Green Smart Cities: Living Healthily With Every Breath
    (Institute of Electrical and Electronics Engineers Inc., 2019) Turhan, Cihan; Atalay, Ali Serdar; Gökçen Akkurt, Gülden
    Fifty-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.
  • Conference Object
    Citation - WoS: 14
    Citation - Scopus: 16
    Drying 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, Gülden
    In 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: 6
    Citation - Scopus: 8
    The 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, Gülden
    The 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.
  • Conference Object
    Citation - WoS: 21
    Citation - Scopus: 27
    Applying Underfloor Heating System for Improvement of Thermal Comfort in Historic Mosques: the Case Study of Salepçioglu Mosque, Izmir, Turkey
    (Elsevier Ltd., 2017) Bughrara, Khaled S. M.; Durmuş Arsan, Zeynep; Gökçen Akkurt, Gülden
    Mosques differ from other types of buildings by having an intermittent operation schedule. Due to five prayer times per day throughout the year, mosques are fully or partially, yet periodically, occupied. This paper examines the potential of using an underfloor heating system for improvement of indoor thermal comfort in a historic mosque, which is naturally ventilated, heated and cooled, based on adaptive thermal comfort method. The selected Salepçioǧlu Mosque, housing valuable wall paintings, was built in 1905 in KemeraltI, Izmir, Turkey. It requires specific attention with its cultural heritage value. Firstly, indoor microclimate of the Mosque was monitored for one-year period of 2014-15. Then, dynamic simulation modelling tool, DesignBuilder v.4.2 was used to create the physical model of the Mosque. The ASHRAE Guideline 14 indices were utilized to calibrate the model, by comparing simulated and measured indoor air temperature to achieve hourly errors within defined ranges. The results of calibrated baseline model indicate that the Mosque does not satisfy acceptable thermal comfort levels for winter months that provided by the adaptive method. Then, the effect of underfloor heating was examined in the second model by the.