Kitap Bölümü Koleksiyonu
https://hdl.handle.net/11421/18339
2024-03-29T04:36:31ZSecond law analysis of an experimental micro turbojet engine
https://hdl.handle.net/11421/22306
Second law analysis of an experimental micro turbojet engine
Kahraman, C.; Yasin, S.; Özgür, C. C.; Hikmet, K. T.
Mini class gas turbine engines are today used for small UAVs, cogeneration applications, and hybrid electric vehicle applications. In this paper, exergetic assessment of an indigenous mini class gas turbine engine is investigated. This engine is classified as mini class gas turbine where it differs from similar class engines in two ways, including closed loop lubrication system and bearing damping. A great amount of bench testing studies with required extensive instrumentation were also performed to demonstrate the suitability of this technology. Consequently, an approach in order to evaluate test data parameters for the exergetic performance is presented for mini class gas turbine engines used for small experimental planes and small-scale UAVs by applying the energy and exergy analyses to the engine. Hence, exergetic efficiency, improvement potentials, exergy destruction rates, relative exergy destructions, fuel depletion ratios, productivity lacks, and fuel and product exergy factors are calculated for the engine taking into account only dry air. This study shows that main exergy destruction for a typical gas turbine occurs in the combustion chamber. Exergetic efficiencies for centrifugal compressor, combustion chamber, and high-pressure turbine are found to be as 74.04%, 56.06%, and 98.98%, respectively. Finally, it was flight tested several times on small-scale UAVs and small experimental aircrafts with success
2018-01-01T00:00:00ZSustainability Assessment of a Turboprop Engine: Exergy-Based Method
https://hdl.handle.net/11421/22305
Sustainability Assessment of a Turboprop Engine: Exergy-Based Method
Şöhret, Yasin; Sögüt, M. Ziya; Turan, Önder; Karakoç, Tahir Hikmet
Zhang, XR; Dincer, I
Sustainable energy utilization is a necessary to reduce environmental impact and combat global warming in twenty-first century. For this purpose, sustainability parameters of a turboprop engine are presented with exergetic approach in this study. At first, commonly used sustainability assessment methods are summarized. Then, fundamentals of exergy analysis and sustainability terms are explained in details. After all, a turboprop engine is evaluated from this viewpoint to exemplify the explained methodology. As a result of the component based exergy analysis, exergy efficiency of the air compressor, combustion chamber, gas turbine and power turbine are found to be 87.04 %, 74.50 %, 89.0 % and 92.23 %, respectively, whereas exergy efficiency of the overall engine is 38.09 %. In the sustainable framework; waste exergy ratio, recoverable exergy rate, exergy destruction factor, environmental effect factor and exergetic sustainability index of the overall engine are found to be in order of 0.43, 0.00, 0.20, 4.38 and 0.23.
WOS: 000401831300023
2017-01-01T00:00:00ZExergy Approach to Evaluate Performance of a Mini Class Turboprop Engine
https://hdl.handle.net/11421/22302
Exergy Approach to Evaluate Performance of a Mini Class Turboprop Engine
Çoban, Kahraman; Şöhret, Yasin; Söğüt, Mehmet Ziya; Turan, Önder; Karakoç, Tahir Hikmet
Zhang, XR; Dincer, I
In this chapter, performance assessment of a mini class turboprop engine is presented. Exergy analysis is used for this purpose on the basis of applicability on thermal systems. As a result of the component-based exergy analysis, relative irreversibility of the combustion chamber is higher relatively. Exergy destruction rates within the air compressor, combustion chamber and gas turbine components are 24.08 kW, 100.76 kW and 15.80 kW respectively. Additionally, exergy efficiencies of the components are 74.11, 69.68 and 98.99 % in order of air compressor, combustion chamber and gas turbine.
WOS: 000401831300024
2017-01-01T00:00:00ZExergy and energy analysis of an aircraft air cycle machine at designated altitude
https://hdl.handle.net/11421/18679
Exergy and energy analysis of an aircraft air cycle machine at designated altitude
Ayaz, Süleyman Kagan; Altuntaş, Önder; Açıkkalp, E.; Karakoç, Tahir Hikmet
In this paper, energy and exergy analyses are performed on an aircraft air cycle machine. Air cycle machine is essential to ventilate aircraft cabin during commercial flights. Exergy destruction rates and energy parameters of each component are investigated at a designated aircraft cruise altitude which is 10,789 meters and ambient air that is -55, °C. The thermodynamic parameters used here to obtain the results are real ones from actual devices. Exergy flow supplied to the air cycle machine is found as 235.392, kW. Exergy destruction rate of primary heat exchanger is calculated as 33.839, kW. Exergy destruction rate of turbine, compressor, and secondary heat exchanger section is calculated to be 55.65, kW
2018-01-01T00:00:00Z