Browsing by Author "Karakoc, T. Hikmet"

Now showing 1 - 11 of 11

Citation - WoS: 18
Citation - Scopus: 18
A Parametric Study of a Piston-Prop Aircraft Engine Using Exergy and Exergoeconomic Analysis Methods
(TAYLOR & FRANCIS INC, 2015) Onder Altuntas; T. Hikmet Karakoc; Arif Hepbasli; Altuntas, Onder; Hepbasli, Arif; Karakoc, T. Hikmet
In this study exergetic and exergoeconomic analysis methods are applied to a four-cylinder spark ignition (SI) naturally aspirated and air-cooled piston-prop aircraft engine in the cruise phase of flight operations. The duration of cruise is selected to be 1 h. Three parameters altitude rated power setting (PS) and air-to-fuel ratio (AF) are varied by the calculation of the max-min values of exergy analysis. Based on the results of energy analysis the values for the maximum energy efficiency and fuel consumption flow rate are calculated to be 21.73% and 28.02 kg/h respectively at 1000-m altitude and 75% PS. The results of exergy analysis indicate that all exergetic values vary from 65% to 75% PS while this increase is not seen in exergoeconomic analysis. While the maximum exergy input rate is obtained to be 405.60 kW exergy efficiency has the minimum value with 14.43% and exergy destruction rate has the maximum value with 168.48 kW. These values are achieved at 3000-m altitude and 18 AFs. The maximum average exergy cost of the fuel is calculated to be 130.77 $/GJ at 1000-m altitude 13 AF ratios and 65% PS. At this point while the minimum cost rate associated with the exergy destruction is obtained to be 40.29 $/h the maximum exergoeconomic factor is found to be 19.98%.
Citation - WoS: 19
Citation - Scopus: 24
Advanced exergoenvironmental assessment of a building from the primary energy transformation to the environment
(ELSEVIER SCIENCE SA, 2015) Emin Acikkalp; Arif Hepbasli; Cem Tahsin Yucer; T. Hikmet Karakoc; Açikkalp, Emin; Yucer, Cem Tahsin; Karakoc, T. Hikmet; Hepbasli, Arif
Buildings are of great importance in terms of consumption of energy all over the world. Building sector has a significant influence over the total natural resource consumption and is significant contributors of greenhouse gases. Exergy-based methods in assessing the performance of buildings have become very popular in recent years. In this context conventional exergoenvironmental methods include exergy and life cycle analysis and are considered to be very reliable to evaluate environmental impacts of any system. Advanced exergoenvironmental analysis is a combination of advanced exergy analysis and life cycle assessment. This study deals with determining the environmental effects of a building heating system at various stages. Advanced exergoenvironmental method is applied to the system from the primary energy transformation to the environment. Using advanced exergoenvironmental analysis relations between the components and the stages (endogenous exogenous parts) the improvement potentials (avoidable and unavoidable parts) and the advanced exergoenvironmental rates for the system stages are determined. A parametric study is undertaken to investigate effects of the environment temperature on exergy destruction rates and the environment temperature on efficiencies. Based on the environmental temperature a sensitivity analysis is also performed for exergy destruction rates and efficiencies. Results show that the exogenous environmental impact of the system is 68.6% while the avoidable exergoenvironmental impact is only 7%. (C) 2014 Elsevier B.V. All rights reserved.
Citation - WoS: 85
Citation - Scopus: 100
Advanced exergy analysis of an aircraft gas turbine engine: Splitting exergy destructions into parts
(Elsevier Ltd, 2015) Yasin Şöhret; Emin Açıkkalp; A. Hepbasli; Hikmet Tahir Karakoc; Acikkalp, Emin; Sohret, Yasin; Karakoc, T. Hikmet; Hepbasli, Arif
Advanced exergy analysis of an aircraft gas turbine engine is presented in this paper. In this framework the main exergy parameters of the engine components are introduced while the exergy destruction rates within the engine components are split into endogenous/exogenous and avoidable/unavoidable parts. Also the mutual interdependencies among the components of the engine and realistic improvement potentials depending on operating conditions are acquired through the analysis. As a result of the study the exergy efficiency values of the engine components are determined to be 89% 86% 60.6% and 98.6% of the low pressure compressor the high pressure compressor the combustion chamber and the gas turbine respectively. The system has low improvement potential because the unavoidable exergy destruction rate is 93.55%. The relationships between the components are weak since 81.83% of the exergy destruction is endogenous. Finally it may be concluded that the combustion chamber component of the engine should be focused on according to the results obtained. © 2017 Elsevier B.V. All rights reserved.
Citation - WoS: 15
Citation - Scopus: 18
Advanced life cycle integrated exergoeconomic analysis of building heating systems: An application and proposing new indices
(Elsevier Ltd, 2018) Emin Açıkkalp; A. Hepbasli; Cem Tahsin Yucer; Hikmet Tahir Karakoc; Açıkkalp, Emin; Yucer, Cem Tahsin; Karakoc, T. Hikmet; Hepbasli, Arif
Advanced exergy-based analysis and assessment tools have been considered very useful tools for detecting the interactions among components of energy-conversion systems and the real potential for improving each component in any system. In this study a building heating system is analyzed using advanced life cycle integrated (LCI)exergoeconomic analysis method which combines cost and environmental impacts. Some new indices (metrics) such as advanced exergy destruction ratio advanced LCIexergoeconomic ratio advanced LCIexergoeconomic sustainability index and advanced indices are presented. These metrics are also applied to the main components of the system. The boiler has the maximum LCI endogenous exergy destruction cost ratio while the maximum LCI exogenous destruction ratio is due to the water heater. The advanced LCIexergoeconomic depletion ratios are 0.187 0.599 0.414 and 0.371 for the endogenous exogenous unavoidable and avoidable parts respectively. © 2018 Elsevier B.V. All rights reserved.
Citation - WoS: 14
Citation - Scopus: 16
Advanced low exergoeconomic (ALEXERGO) assessment of a building along with its heating system at various stages
(ELSEVIER SCIENCE SA, 2015) Emin Acikkalp; Cem Tahsin Yucer; Arif Hepbasli; T. Hikmet Karakoc; Açikkalp, Emin; Yucer, Cem Tahsin; Karakoc, T. Hikmet; Hepbasli, Arif
The present study deals with evaluating the performance of a building heating system along with its main components using advanced low exergoeconomic analysis method. This method combines advanced exergoeconomic with low exergy (LowEx) and is shortly called ALEXERGO. A building heating system is investigated from the energy production to the building envelope stage by stage through the ALEXERGO for the first time by the authors. Based on the results the generation and distribution stages are found to have bigger exogenous exergy destruction cost rates meaning that the components in these stages have strong interconnections. The emission (heating) stage has however a bigger endogenous exergy destruction cost rate. The generation and emission stages have low improvement potentials while the distribution stage has a big improvement potential. A sensitivity analysis is also made based on the environmental temperature for exergy destruction rates and efficiencies. (C) 2014 Elsevier B.V. All rights reserved.
Citation - WoS: 19
Citation - Scopus: 24
Advanced low exergy (ADLOWEX) modeling and analysis of a building from the primary energy transformation to the environment
(ELSEVIER SCIENCE SA, 2014) Emin Acikkalp; Cern Tahsin Yucer; Arif Hepbasli; T. Hikmet Karakoc; Acikkalp, Emin; Yucer, Cern Tahsin; Karakoc, T. Hikmet; Hepbasli, Arif
The main objective of the present study is to model analyze and assess a building heating system along with its main components through advanced low exergy method. This method is shortly called ADLOWEX and combines advanced exergy (AD) with low exergy (LOWEX) for the first time by the authors. In the ADLOWEX analysis method a building heating system is investigated from the energy production to the building envelope by dividing exergy destructions into four basic parts namely endogenous exogenous avoidable and unavoidable exergy destruction rates first. The mexogenous exergy destructions for all components are determined. The endogenous and exogenous exergy destructions of the system are 27% and 73% while the avoidable and unavoidable exergy destructions are 26.2% and 73.8% respectively. (C) 2014 Elsevier B.V. All rights reserved.
Citation - WoS: 33
Citation - Scopus: 37
EXERGETIC EXERGOECONOMIC AND SUSTAINABILITY ASSESSMENTS OF PISTON-PROP AIRCRAFT ENGINES
(TURKISH SOC THERMAL SCIENCES TECHNOLOGY, 2012) Onder Altuntas; T. Hikmet Karakoc; Arif Hepbasli; Altuntas, Onder; Hepbasli, Arif; Karakoc, T. Hikmet
In this study the exergetic exergoeconomic and sustainability aspects of piston-prop aircraft engines are comprehensively reviewed. These analysis and assessment tools are applied to a four-cylinder spark ignition naturally aspirated and air-cooled piston-prop aircraft engine in the landing and takeoff (LTO) phases of flight operations. LTO consists of four parts: takeoff climb out approach and taxi. The results of energy analysis indicate that takeoff is a phase requiring high power with a maximum work rate of 111.90 kW. Maximum fuel energy and exergy rates are calculated to be 444.30 kW and 476.51 kW respectively. The minimum total loss is found in the taxi phase while maximum energy and exergy efficiency values are 26.76% and 24.95% in the climb out phase respectively. Based on the results of the cost analysis the taxi has the maximum exergy destruction cost rate with 23.41 $/h at a fixed production and 2.96 $/h at a fixed fuel. Maximum sustainability index (SI) is found to be 1.332 at the climb out phase.
Citation - WoS: 11
Citation - Scopus: 11
Exergoeconomic environmental optimization of piston-prop aircraft engines
(Taylor and Francis Inc. 325 Chestnut St Suite 800 Philadelphia PA 19106, 2015) Onder Altuntas; Hikmet Tahir Karakoc; A. Hepbasli; Altuntas, Onder; Hepbasli, Arif; Karakoc, T. Hikmet
In this study exergy exergoeconomic exergoenvironmental analyses and exergoeconomic environmental optimization are applied to a four-cylinder spark ignition naturally aspirated and air-cooled piston-prop aircraft engine in the cruise phase of flight for the first time to the best of the authors' knowledge. Here three piston-prop aircraft engine parameters (altitude air-fuel ratio (AF) and rated power setting (PS)) are selected for optimization purposes. All exergy exergoeconomic and exergoenvironmental values are calculated first. These values are then optimized to find the best results of all analyses. The best altitude AF ratio and PS values are finally found while the maximum exergy efficiency the minimum product specific environmental impact and the minimum average unit fuel exergy cost are obtained. The best results of optimization indicated that the maximum exergy efficiency varied between 19.54% and 19.80% the minimum unit fuel exergy cost ranged from 126.30 $/GJ to 127.23 $/GJ and the minimum specific environmental impact of production was in the range of 8.70-9.59 mPts/MJ. Based on the results obtained for ensuring the optimum conditions the low AF ratios and the low-altitude flight at high rated power settings have to be selected. © 2014 Elsevier B.V. All rights reserved.
Citation - WoS: 1
Citation - Scopus: 1
Investigating the effect of turbine inlet temperature on the exergetic improvement potential of a small turbojet engine
(Institute of Electrical and Electronics Engineers Inc., 2017) Onder Turan; A. Hepbasli; Hikmet Tahir Karakoc; Turan, Onder; Hepbasli, Arif; Karakoc, T. Hikmet
This paper analyzes and evaluates exergetic improvement rate (IPex) of the components of a small turbojet engine with various turbine inlet temperatures. The engine consists of an inlet starter generator a centrifugal compressor a reverse flow combustion chamber an axial-flow turbine and an exhaust nozzle. IPex analysis is performed on this turbomachinery utilizing kerosene as a fuel. Exergetic analysis is applied to the turbojet to investigate the turbine inlet temperature effects (i.e. turbine material improvement) on the IPex of each component in the engine using different turbine inlet temperatures at a constant reference environment. © 2017 Elsevier B.V. All rights reserved.
Citation - WoS: 6
Citation - Scopus: 6
Investigation of environmental impact caused by aircraft engines
(Inderscience Publishers, 2013) Onder Altuntas; Hikmet Tahir Karakoc; A. Hepbasli; Altuntas, Onder; Karakoc, T. Hikmet; Hepbasli, Arif; Hikmet Karakoc, T.
The environmental effects of exhaust gas emissions from different types of spark ignitions (SIs) - naturally aspirated and air-cooled from piston-prop aircraft engines - at the landing and take-off (LTO) phase of flight-based operations are investigated in this study. The minimum natural resources effect was determined to be 1.37 MJ surplus energy/LTO in 320 in three cylinder displacement and carburetor engine at the takeoff (TO) phase (one of the LTO phases). Besides this the minimum human health effect was obtained to be 3.49E-07 DALY/LTO and the minimum ecosystem quality effect was calculated to be 0.00805 PDF*m2yr/LTO in 320 in3 cylinder displacement and injected fuel system at the TO phase. © 2013 Inderscience Enterprises Ltd. © 2020 Elsevier B.V. All rights reserved.
Citation - WoS: 20
Milestone of Greening the Flight Path: Alternative Fuels
(PALGRAVE, 2020) Selcuk Ekici; Ilkay Orhan; T. Hikmet Karakoc; Arif Hepbasli; Ekici, Selcuk; Karakoc, T. Hikmet; Hepbasli, Arif; Orhan, Ilkay; T Walker; AS Bergantino; N SprungMuch; L Loiacono