Yazar "Balli, Ozgur" seçeneğine göre listele
Listeleniyor 1 - 11 / 11
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Comparative Performance Metric Assessment of A Military Turbojet Engine Utilizing Hydrogen and Kerosene Fuels Through Advanced Exergy Analysis Method(Mdpi, 2020) Yuksel, Burak; Balli, Ozgur; Gunerhan, Huseyin; Hepbasli, ArifThis study dealt with evaluating the (J85-GE-5H) military turbojet engine (TJE) in terms of exergetic and advanced exergetic analyses at Military (MIL) and Afterburner (AB) process modes by utilizing kerosene (JP-8) and hydrogen (H-2) fuels. First, exergy and advanced exergy analyses of the engine were performed using JP-8 fuel as per actual engine operating conditions. These analyses of the turbojet engine using hydrogen fuel were also examined parametrically. the performance evaluation of the engine was lastly executed by comparing the obtained results for both fuels. Based on the parametric studies undertaken, the entire engine's exergetic efficiency with JP-8 was reckoned 30.85% at the MIL process mode while it was calculated as 16.98% at the AB process mode. With the usage of H-2, the efficiencies of the engine decreased to 28.62% and 15.33% for the above mentioned two modes, respectively. As the supreme exergy destructions occurred in the combustion chamber (CC) and afterburner exhaust duct (ABED) segments, the new technological developments should be considered to design more efficient engines. As a result, the engine worked less efficiently with hydrogen fuel due to the enhancement in exergy destructions. Conversely, the greenhouse gas (GHG) emission parameters lessened with the utilization of H-2 fuel.Öğe Estimating and statistically analyzing the global solar radiation potential over big cities in Turkey(Multi Science Publ Co Ltd, 2007) Balli, Ozgur; Aras, Haydar; Aras, Nil; Hepbasli, ArifThis study develops empirical models in order to estimate the monthly average daily global solar radiation on a horizontal surface (H). The seven big cities considered in the model have 33.4% of Turkey's population and are as follows: Izmir in the Aegean Sea, Samsun in the Black Sea, Ankara in the Central Anatolia, Van in the East Anatolia, Istanbul in the Marmara, Antalya in the Mediterranen Sea, and Urfa in the Southeast Anatolia Region of Turkey. The developed models were analyzed using the seven statistical analyzing methods such as the mean percentage error (MPE), mean absulate percentage error (MAPE), sum of squares of relative error (SSRE), relative standard error (RSE), mean bias error (MBE), root mean square error (RMSE) and correlation coefficient (R). It may be concluded that the present models estimate the values of H, reasonably well for the cities studied and possibly elsewhere with similar climatic conditions.Öğe Estimating the horizontal diffuse solar radiation over the Central Anatolia Region of Turkey(Pergamon-Elsevier Science Ltd, 2006) Aras, Haydar; Balli, Ozgur; Hepbasli, ArifThe main objective of the present study is to develop new hybrid models to predict the monthly average daily diffuse solar radiation on a horizontal surface over Turkey's Central Anatolia Region (CAR), which covers the 12 provinces (Afyon, Ankara, Cankiri, Corum, Eskisehir, Kayseri, Kirsehir, Konya, Nevsehir, Nigde, Sivas and Yozgat), as an example. The models proposed by many investigators to estimate the diffuse solar radiation were reviewed. Although the global solar radiation and sunshine duration have been measured by the Turkish State Meteorological Service (DMI) over all the country since 1964, the diffuse solar radiation has not been measured. The twelve new hybrid models for estimating the monthly average daily diffuse solar radiation on a horizontal surface in the CAR were validated, and thus, the most accurate model was selected for guiding future projects. (c) 2005 Elsevier Ltd. All rights reserved.Öğe Exergetic and Environmental Analyses of Turbojet Engine(Springer International Publishing Ag, 2020) Yuksel, Burak; Balli, Ozgur; Gunerhan, Huseyin; Hepbasli, Arif; Atalay, HalilThis study deals with exergetic and environmental analyses of turbojet engine used on the military training aircrafts. in the analysis, the engine data measured in the Engine Test Cell at First Air Maintenance and Factory Directorate of Turkish Air Forces in Eskisehir, Turkey are utilized. the exergy balance equations are derived for each component of the engine along with the overall the engine. Several thermodynamic parameters (the fuel exergy depletion ratio, the productivity lack ratio, the relative exergy consumption ratio, exergetic improvement potential, exergetic improvement potential ratio, relative exergetic improvement potential, exergetic fuel-product ratio, and sustainability index) are used to evaluate the performance of the engine and its main components (the air compressor, the combustion chamber, the gas turbine, the exhaust forward duct, the aft exhaust duct, and the mechanical shaft). Exergy losses and destructions are investigated to determine thermodynamic inefficiencies. the exergetic efficiency of the engine is determined to be 18.77%. the highest exergy destruction rate of 2921.01 kW in the engine occurs within the combustion chamber. the mechanical shaft of the engine has the maximum sustainability index of 100.65. An environmental analysis of the engine is also performed.Öğe Exergetic and exergoeconomic analysis of an Aircraft Jet Engine (AJE)(Inderscience Enterprises Ltd, 2008) Balli, Ozgur; Aras, Haydar; Aras, Nil; Hepbasli, ArifThis study deals with energy, exergy and exergoeconomic analysis of an Aircraft Jet Engine (AJE) as named J69-T25A used on T-37B/C model training aircrafts. In the analyses, the engine data measured in the engine test cell at First Air Supply and Maintenance Center of Turkish Air Forces are used. Quantitative exergy and exergoeconomic cost balance equations are derived for each components of the engine and the overall J69-T25A engine. Exergy destructions within the engine components are investigated to determine thermodynamic inefficiencies. Cost balances and auxiliary equations are also applied to each components of the engine for observing cost formation. Additionally, exergy cost rate and unit exergy cost rate of each products of the engine are accounted.Öğe Exergetic performance evaluation of a combined heat and power (CHP) system in Turkey(John Wiley & Sons Ltd, 2007) Balli, Ozgur; Aras, Haydar; Hepbasli, ArifThis study deals with the exergetic performance assessment of a combined heat and power (CHP) system installed in Eskisehir city of Turkey. Quantitative exergy balance for each component and the whole CHP system was considered, while exergy consumptions in the system were determined. The performance characteristics of this CHP system were evaluated using exergy analysis method. The exergetic efficiency of the CHP system was accounted for 38.16% with 49 880 kW as electrical products. The exergy consumption occurred in this system amounted to 80 833.67 kW. The ways of improving the exergy efficiency of this system were also analysed. As a result of these, a simple way of increasing the exergy efficiency of the available CHP system was suggested that the valves-I-III and the MPSC could be replaced by a 3500 kW-intermediate pressure steam turbine (IPST). If the IPST is installed to the CHP system (called the modified CHP (MCHP) system), the exergetic efficiency of the MCHP system is calculated to be 40.75% with 53 269.53 kW as electrical products. The exergy consumption is found to be 77 444.14 kW in the MCHP system. Copyright (C) 2006 John Wiley & Sons, Ltd.Öğe Exergoeconomic analysis of a combined heat and power (CHP) system(John Wiley & Sons Ltd, 2008) Balli, Ozgur; Aras, Haydar; Hepbasli, ArifThis study deals with exergoeconomic analysis of a combined heat and power (CHP) system along its main components installed in Eskisehir City of Turkey. Quantitative exergy cost balance for each component and the whole CHP system is considered, while exergy cost generation within the system is determined. The exergetic efficiency of the CHP system is obtained to be 38.33% with 51 475.90 kW electrical power and the maximum exergy consumption between the components of the CHP system is found to be 51 878.82 kW in the combustion chamber. On the other hand, the exergoeconomic analysis results indicate that the unit exergy cost of electrical power produced by the CHP system accounts for 18.51 US$ GW(-1). This study demonstrates that exergoeconomic analysis can provide extra information than exergy analysis, and the results from exergoeconomic analysis provide cost-based information, suggesting potential locations for the CHP system improvement. Copyright (c) 2007 John Wiley & Sons, Ltd.Öğe Global solar radiation potential, part 1: Model development(Taylor & Francis Inc, 2006) Aras, Haydar; Balli, Ozgur; Hepbasli, ArifSolar engineers, architects, agriculturists, and hydrologists dealing with many applications of solar energy require a reasonably accurate knowledge about the availability of solar resources at any place. For this purpose, in the past, several empirical correlations have been developed in order to predict the solar radiation around the world. The present study, consisting of two parts, analyzes global solar radiation over the Central Anatolia Region ( CAR) of Turkey along with its twelve provinces. Part 1 of this study includes the solar radiation models developed, while their statistical analysis is presented in Part 2. In the analysis, the data of the monthly average daily global solar radiation and sunshine duration measured by the Turkish State Meteorological Service in the period from January 1990 to December 1996 are used. Empirical models to estimate the monthly global solar radiation on a horizontal surface for each province are developed. The results obtained have indicated that the models developed here predict solar radiation reasonably well for future projections.Öğe Global solar radiation potential, part 2: Statistical analysis(Taylor & Francis Inc, 2006) Aras, Haydar; Balli, Ozgur; Hepbasli, ArifSolar radiation is the most important parameter in the design and study of solar energy conversion devices. In this regard, many investigators have developed various empirical correlations for the estimation of the solar radiation around the world. The main objective of the present study is to analyze statictically the solar radition models developed in Part 1. In the analysis, the mean percentage error, the mean absolute percentage error, the sum of the squares of relative errors, the relative standard error, the mean bias error, the root square error, and correlation coefficient (R-2) are used used for evaluating the performance of the models studied. It may be concluded that the agreement between measured and estimated values of monthly average daily global solar radiation for the Central Anatolia Region of Turkey along with its twelve provinces is reasonably well.Öğe Thermodynamic and thermoeconomic analyses of a trigeneration (TRIGEN) system with a gas-diesel engine: Part I - Methodology(Pergamon-Elsevier Science Ltd, 2010) Balli, Ozgur; Aras, Haydar; Hepbasli, ArifThis paper consists of two parts. Part 1 deals with the thermodynamic and thermoeconomic methodology of a trigeneration (TRIGEN) system with a rated output of 6.5 MW gas-diesel engine while the application of the methodology is presented in Part 2. The system has been installed in the Eskisehir Industry Estate Zone in Turkey. Thermodynamic methodology includes the relations and performance parameters for energy and exergy analysis, while thermoeconomic methodology covers the cost balance relations, cost of products and thermodynamic inefficiencies, relative cost difference and exergoeconomic factor. (C) 2010 Elsevier Ltd. All rights reserved.Öğe Thermodynamic and thermoeconomic analyses of a trigeneration (TRIGEN) system with a gas-diesel engine: Part II - An application(Pergamon-Elsevier Science Ltd, 2010) Balli, Ozgur; Aras, Haydar; Hepbasli, ArifThe paper is Part 2 of the study on the thermodynamic and thermoeconomic analyses of trigeneration system with a gas-diesel engine. In Part 1, thermodynamic and thermoeconomic methodologies for such a comprehensive analysis were provided, while this paper applies the developed methodology to an actual TRIGEN system with a rated output of 6.5 MW gas-diesel engine installed in the Eskisehir Industry Estate Zone, Turkey. Energy and exergy efficiencies, equivalent electrical efficiency, the Public Utility Regulatory Policies Act (PURPA) efficiency, fuel energy saving ratio, fuel exergy saving ratio and other thermodynamic performance parameters are determined for the TRIGEN system. The efficiencies of energy, exergy, PURPA and equivalent electrical efficiency of the entire system are found to be 58.97%, 36.13%, 45.7% and 48.53%, respectively. For the whole system and its components, exergetic cost allocations and various exergoeconomic performance parameters are calculated using the exergoeconomic analysis based on specific exergy costing method (SPECO). The specific unit exergetic cost of the net electrical power, heat energy in the Factory Heating Center (FHC) heating, heat energy in the Painting Factory Heating (PFH) and chilled water in the absorption chiller (ACh) produced by the TRIGEN system are obtained to be 45.94 USS/GJ, 29.98 US$/GJ 42.42 USS/GJ and 167.52 US$/GJ respectively. (C) 2010 Elsevier Ltd. All rights reserved.
