Browsing by Author "Altuntas, Onder"

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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: 22
Citation - Scopus: 22
Dynamic performance and sustainability assessment of a PV driven Carnot battery
(Elsevier Ltd, 2023) Demet Canpolat Tosun; Emin Açıkkalp; Onder Altuntas; A. Hepbasli; Ana I. Palmero-Marrero; David Borge-Diez; Altuntas, Onder; Açıkkalp, Emin; Tosun, Demet Canpolat; Borge-Diez, David; Hepbasli, Arif; Palmero-Marrero, Ana I.; Canpolat Tosun, Demet
This study investigates the performance of a Carnot Battery and performs a thermodynamic-based sustainability analysis using different methods. Carnot batteries have two different operational processes charge and discharge. Electricity generated from a renewable source is used to operate a heat pump and the heat rejected by the heat pump is stored in the battery which is then used to generate electricity in the Organic Rankine Cycle (ORC) at night and called as the discharge process. Climatic data from the city of Izmir the third largest city by population in Turkey has been chosen for the dynamic analysis. Exergy-based sustainability and thermo-ecological cost analyses are performed. The results show that the maximum Coefficient of Performance (COP) of the heat pump system is 4.5 the exergy efficiency can reach 0.78 and its the maximum sustainability index is 4.5. For the discharge process energy efficiency of the ORC is 0.118 while the exergy efficiency is around 0.49 with a sustainability value of about 2.0. © 2023 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.
Investigating the Sectional Thrust and Exergy Efficiency of a Turbojet Engine
(Inderscience Enterprises Ltd, 2026) Akbas, Mustafa; Altuntas, Onder; Hepbasli, Arif
This study delves into the performance characteristics of a turbojet engine, focusing on the impact of varying compressor pressure ratios and component geometries on thrust and exergy efficiency. The effects of Mach number and compressor pressure ratio on exergy utilisation efficiency at varying altitude values are also examined. Utilising the MATLAB, the analysis was conducted within a range of sea level to 12,000 m altitude. The results obtained provide valuable insights into the potential for optimising turbojet engine performance through strategic adjustments to pressure ratios and component geometries.
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: 23
Citation - Scopus: 24
Novel combined extended-advanced exergy analysis methodology as a new tool to assess thermodynamic systems
(PERGAMON-ELSEVIER SCIENCE LTD, 2021) Emin Acikkalp; Hakan Caliskan; Onder Altuntas; Arif Hepbasli; Altuntas, Onder; Acikkalp, Emin; Hepbasli, Arif; Caliskan, Hakan
In this study a novel combined extended-advanced exergy analysis method is developed for assessing thermodynamic systems. The method is established by combining extended exergy analysis with advanced exergy analysis and the so-called extended-advanced exergy analysis. The methodology used in the novel analysis method is different from only extended exergy analysis and only advanced exergy analysis but the criteria are the same to reach the goal. This proposed method is applied to a gas turbine system as a case study to show its variability. The gas turbine system considered consists of a combustion chamber a compressor and turbine units. The conventional (Fuel-Product approach) advanced and extended exergy analyses are separately applied to the case study system for the comparison with the novel combined extended-advanced exergy analysis. It is seen that the combined extended-advanced exergy analysis results of the case study are not exactly the same with the advanced and extended exergy analyses? results. The reason for this is its comprehensive joint of various thermodynamic analysis methodologies integrating all materials capital labor energy and environmental effect instead of the relation between components and their improvement potentials in one analysis. But it is assessed that the novel analysis tool is able to apply all of those analyses into one simple methodology. The exergy efficiencies of the case study are 28% and 31% by considering the conventional and extended exergy analyses respectively. This means that all input parameters including labor capital and environment are used with better efficiency. Also the exogenous exergy destruction rate (159 kW) is higher for the combined extended-advanced exergy analysis (384 kW). This shows that the relations between other components are increased for the turbine. Another important change is shown in avoidable exogenous exergy destruction rate for the turbine increasing from 374 kW to 833 kW. This new combined method is useful to those who wish to apply advanced and extended exergy analyses through a new practical assessment way.
Citation - WoS: 15
Citation - Scopus: 16
Proposal of novel exergy-based sustainability indices and case study for a biomass gasification combine cycle integrated with liquid metal magnetohydrodynamics
(Institution of Chemical Engineers, 2023) Demet Canpolat Tosun; Emin Açıkkalp; Başar Ca̧ǧlar; Onder Altuntas; A. Hepbasli; Altuntas, Onder; Açıkkalp, Emin; Tosun, Demet Canpolat; Hepbasli, Arif; Caglar, Basar
Exergy is considered a way to sustainability. Exergy-based analyses have been recently widely used for performance assessment and comparison purposes of energy systems from production to end-user while different sustainability related indices or indicators including exergetic concepts have been developed in the literature. In this regard the present study proposed five different indices: (i) Exergetic Fuel Based Environmental Remediation Index (χ) (ii) Exergetic Product Based Environmental Remediation Index (δ) (iii) Exergetic Fuel Based Total Environmental Remediation Index (β) (iv) Exergetic Product Based Total Environmental Remediation Index (α) and (v) Improved Sustainability Index (ISI). These indices were applied to a novel Biomass-integrated Gasification Combine Cycle (BIGCC) integrated with Liquid Metal Magnetohydrodynamics (LMMHD). They allowed to perform a more complete environmental analysis by considering the exergetic cost of environmental remediation of the process. The average exergy efficiency values for the BIGCC LMMHD and the overall system were determined as 0.491 0.222 and 0.688 under daily ambient temperatures for a year and different air to fuel ratio (AFR) conditions respectively. The average values for χ β δ α and ISI were 1.636 2.389 1.949 2.848 and 0.513 respectively. © 2023 Elsevier B.V. All rights reserved.