Browsing by Author "Ozgener L."

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    Exergy analysis of industrial pasta drying process
    (2006) Ozgener L.; Ozgener O.
    In this study we present an energy and exergy modelling of industrial final macaroni (pasta) drying process for its system analysis, performance evaluation and optimization. Using actual system data, a performance assessment of the industrial macaroni drying process through energy and exergy efficiencies and system exergy destructions is conducted. The heat losses to the surroundings and exergy destructions in the overall system are quantified and illustrated using energy and exergy flow diagrams. The total energy rate input to system is 316.25 kW. The evaporation rate is 72 kg h-1 (0.02 kg s-1) and energy consumption rate is found as 4.38 kW for 1 kg water evaporation from product. Humidity product rate is 792 kg h-1 (0.22 kg s-1) and energy consumption rate is found about 0.4 kW for 1 kg short cut pasta product. The energy efficiencies of the pasta drying process and the overall system are found to be as 7.55-77.09% and 68.63%. The exergy efficiency of pasta drying process is obtained to be as 72.98-82.15%. For the actual system that is presented the system exergy efficiency vary between 41.90 and 70.94%. Copyright © 2006 John Wiley & Sons, Ltd.
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    Investigation of the energetic and exergetic performance of the Gonen geothermal district heating system
    (2006) Ozgener L.; Hepbasli A.; Dincer I.
    This article describes a performance evaluation of the Gonen geothermal district heating system (GGDHS) in Balikesir, Turkey on the basis of energy and exergy analyses. The case study covers the actual system data taken from the GGDHS in Balikesir, Turkey. General energy and exergy analyses of the geothermal district heating systems are introduced. Then, these analyses applied to the GGDHS using actual thermodynamic data for its performance evaluation in terms of energy and exergy efficiencies are presented. In addition, a parametric study on the effect of varying reference state properties on the energy and exergy efficiencies of the system that has been conducted to find the optimum performance and operating conditions is explained. In this article, the authors undertake a parametric study to investigate how varying reference temperature from 0 °C to 20 °C will affect the energy and exergy efficiencies of the GGDHS and develop two significant correlations (with a correlation coefficient of 0.99), which can be used for predicting the efficiencies. Two parametric expressions for energy and exergy efficiencies were developed as a function of the reference temperature. Both energy and exergy flow diagrams illustrate and compare the results under different conditions. For the actual system that is presented, the system energy and exergy efficiencies vary between 0.41 and 0.60 and 0.60 and 0.70, respectively. © IMechE 2006.
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    Environmental and exergetic aspects of geothermal energy
    (2006) Baba A.; Ozgener L.; Hepbasli A.
    Geothermal energy is already in the form of heat, and from the thermodynamic point of view, work is more useful than heat because not all heat can be converted to work. Therefore, geothermal resources should be classified according to their exergy, which is a measure of their ability to do work. In recent years there has been a remarkable growth of interest in environmental issues - sustainability and improved management of development in harmony with the environment. Environmental impact assessment is one of the most widely used tools in environmental management. In this study, the environmental and exergetic aspects of geothermal energy, namely the rapid impact assessment matrix method, and, specific exergy index, were studied first. They were then applied to the Tuzla geothermal field in Canakkale and Balcova geothermal field in Izmir, Turkey, respectively. Finally, the results obtained are given and discussed.
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    Investigation of exergetic efficiency and thermodynamic parameters of the salihli geothermal district heating system
    (2007) Ozgener L.; Ozgener O.
    This study investigates thermodynamic parameters and exergetic efficiency of the Salihli geothermal district heating system (SGDHS) in Manisa, Turkey for 2005/2006 heating season. The thermodynamic parameters considered are as follows: (i) fuel depletion rate, (ii) relative irreversibility, (iii) productivity lack, and (iv) exergetic factor. These parameters are determined for the system to assess and compare their individual performances. While the highest relative irreversibilities occur in the heat exchangers with the values of 44% for the SGDHS, exergetic efficiency of the system is found to be 60.3%. Copyright © 2007 by ASME.
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    Exergy and reliability analysis of wind turbine systems: A case study
    (2007) Ozgener O.; Ozgener L.
    The present study undertakes an exergy and reliability analysis of wind turbine systems and applies to a local one in Turkey: the exergy performance and reliability of the small wind turbine generator have been evaluated in a demonstration (1.5 kW) in Solar Energy Institute of Ege University (latitude 38.24 N, longitude 27.50 E), Izmir, Turkey. In order to extract the maximum possible power, it is important that the blades of small wind turbines start rotating at the lowest possible wind speed. The starting performance of a three-bladed, 3 m diameter horizontal axis wind turbine was measured in field tests. The average technical availability, real availability, capacity factor and exergy efficiency value have been analyzed from September 2002 to November 2003 and they are found to be 94.20%, 51.67%, 11.58%, and 0-48.72%, respectively. The reliability analysis has also been done for the small wind turbine generator. The failure rate is high to an extent of 2.28×10-4 h-1 and the factor of reliability is found to be 0.37 at 4380 h. If failure rate can be decreased, not only this system but also other wind turbine systems of real availability, capacity factor and exergy efficiency will be improved. © 2006 Elsevier Ltd. All rights reserved.
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    Exergoeconomic analysis of small industrial pasta drying systems
    (2007) Ozgener L.
    In the current study, author performs an exergoeconomic analysis of an industrial pasta final drying process. The relations between capital costs and thermodynamic losses for the devices in the system are investigated. Thermodynamic loss rate-to-capital cost ratios are used to show that, for the devices and the overall system, a systematic correlation appears to exist between capital cost and exergy loss (total or internal), but not between capital cost and energy loss or external exergy loss. This correlation may imply that devices in a successful industrial pasta drying system is configured so as to achieve an overall optimal design, by appropriately balancing the thermodynamic (energy- and exergy-based) and economic (cost) characteristics of the overall system. Thermodynamic loss rate to capital cost values Ren and Rex are obtained as 0.016-0.004, while total energy rate input value to system change between 304.85 and 316.25 kW. Energetic and exergetic efficiencies of the system processes are determined in an attempt to assess their individual performances. The energy and exergy efficiencies of the overall system are found to be as 72.1 and 65.4 per cent, respectively. © IMechE 2007.
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    Exergoeconomic analysis of geothermal district heating systems: A case study
    (2007) Ozgener L.; Hepbasli A.; Dincer I.; Rosen M.A.
    An exergoeconomic study of geothermal district heating systems through mass, energy, exergy and cost accounting analyses is reported and a case study is presented for the Salihli geothermal district heating system (SGDHS) in Turkey to illustrate the present method. The relations between capital costs and thermodynamic losses for the system components are also investigated. Thermodynamic loss rate-to-capital cost ratios are used to show that, for the devices and the overall system, a systematic correlation appears to exist between capital cost and exergy loss (total or internal), but not between capital cost and energy loss or external exergy loss. Furthermore, a parametric study is conducted to determine how the ratio of thermodynamic loss rate to capital cost changes with reference temperature and to develop a correlation that can be used for practical analyses. The correlations may imply that devices in successful district heating systems such as the SGDHS are configured so as to achieve an overall optimal design, by appropriately balancing the thermodynamic (exergy-based) and economic (cost) characteristics of the overall systems and their devices. © 2006 Elsevier Ltd. All rights reserved.
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    A key review on performance improvement aspects of geothermal district heating systems and applications
    (2007) Ozgener L.; Hepbasli A.; Dincer I.
    This paper deals with a comprehensive analysis and discussion of geothermal district heating systems and applications. In this regard, case studies are presented to study the thermodynamic aspects in terms of energy and exergy and performance improvement opportunities of three geothermal district heating systems, namely (i) Balcova geothermal district heating system (BGDHS), (ii) Salihli geothermal district heating system (SGDHS), and (iii) Gonen geothermal district heating system (GGDHS) installed in Turkey. Energy and exergy modeling of geothermal district heating systems for system analysis and performance evaluation are given, while their performances are evaluated using energy and exergy analysis method. Energy and exergy specifications are presented in tables. In the analysis, the actual system operational data are utilized. In comparison of the local three district heating systems with each other, it is found that the SGDHS has highest energy efficiency, while the GGDHS has highest exergy efficiency. © 2006 Elsevier Ltd. All rights reserved.
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    Parametric study of the effect of reference state on energy and exergy efficiencies of Geothermal District Heating Systems (GDHSs): An application of the Salihli GDHS in Turkey
    (2007) Ozgener L.; Hepbasli A.; Dincer I.
    A parametric study of the effect of reference state on the energy and exergy efficiencies of geothermal district heating systems is presented. In this regard, the work consists of two parts: a modeling study covering energy and exergy analysis and a case study covering the actual system data taken from the Salihli Geothermal District Heating System (SGDHS) in Manisa, Turkey. General energy and exergy analysis of the geothermal district heating systems is introduced along with some thermodynamic performance evaluation parameters. This analysis is then applied to the SGDHS using actual thermodynamic data for its performance evaluation in terms of energy and exergy efficiencies. In addition, a parametric study on the effect of varying dead state properties on the energy and exergy efficiencies of the system that has been conducted to find optimum performance and operating conditions is explained. Two parametric expressions of energy and exergy efficiencies were developed as a function of the reference temperature. Both energy and exergy flow diagrams illustrate and compare results under different conditions. It has been observed that the exergy destructions in the system particularly take place as the exergy of the fluid lost in the heat exchanger, the natural direct discharge of the system (pipeline losses), and the pumps, which account for 31.17%, 8.98%, and 4.27% of the total exergy input to the SGDHS, respectively. For the actual system that is presented, the system energy and exergy efficiencies vary between 0.53 and 0.73 and 0.58 and 0.59, respectively.
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    A parametric study on the exergoeconomic assessment of a vertical ground-coupled (geothermal) heat pump system
    (2007) Ozgener O.; Hepbasli A.; Ozgener L.
    An exergoeconomic model of a vertical ground-source heat pump residential heating system presented in this study uses exergy and cost energy mass (EXCEM) methods. The data obtained from a ground-source heat pump (GSHP) residential heating system installed at the Solar Energy Institute, Ege University, Turkey, are utilized for calculations at different reference temperature values in the range 0-25 °C. The performance of the geothermal heat pump residential heating system is evaluated to indicate how exergoecomic parameter values change with system. We also undertake a parametric study to investigate how varying reference temperatures will affect the exergoeconomic analysis of the GSHP system. A correlation between the ratio of thermodynamic loss rate to capital cost and reference state temperature is developed. © 2006 Elsevier Ltd. All rights reserved.
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    Exergy analysis of two geothermal district heating systems for building applications
    (2007) Ozgener L.; Hepbasli A.; Dincer I.
    This study evaluates the exergetic performance of two local Turkish geothermal district heating systems through exergy analysis. The exergy destructions in these geothermal district heating systems are quantified and illustrated using exergy flow diagrams for a reference temperature of 1 °C using the 2003 and 2004 actual seasonal heating data. The results indicate that the exergy destructions in these systems particularly occur due to losses in pump, heat exchangers, pipelines, and the reinjection of thermal water. Exergy efficiencies of the two systems are investigated for the system performance analysis and improvement and are determined to be 42.89% and 59.58%, respectively. © 2006 Elsevier Ltd. All rights reserved.
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    Monitoring of energetic and exergetic performance analysis of salihli geothermal district heating system
    (2008) Ozgener L.; Ozgener O.
    This study deals with a monitoring and assessment of energetic and exergetic analysis of Salihli Geothermal District Heating System (SGDHS) in Manisa, Turkey. In the analysis, actual system yearly average data of latest heating season are used to assess the district heating system exergetic performance. New exergetic model is improved and compared with old exergetic model results throughout the SGDHS. The new exergy losses occur particularly due to the fluid flow, taking place in the reinjection of thermal water (e.g., geothermal fluid), pumps, and the heat exchanger, as well as the natural direct discharge of the system., Copyright © 2008 by ASME.
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    Thermomechanical exergy and thermoeconomic analysis of geothermal district heating systems
    (2008) Ozgener L.; Ozgener O.
    The current paper presents the thermomechanical exergy and thermoeconomic analysis of geothermal district heating systems (GDHSs) in Turkey. The case studies cover the actual system data taken from the systems in Afyon, Gonen, and Salihli GDHSs, Turkey. General energy and exergy analysis of the GDHSs are introduced. Then the analysis applied to these GDHSs using actual thermodynamic data for their performance evaluations in terms of energy and exergy efficiencies are presented. Besides, thermoeconomic evaluations of GDHSs are given in tables. © IMechE 2008.
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    Analysis of some exergoeconomic parameters of a small wind turbine system
    (2009) Ozgener O.; Ozgener L.; Dincer I.
    This paper investigates some exergoeconomic parameters (energy and exergy loss ratios) for a 1.5 kW wind turbine system, linking capital costs and thermodynamic losses, based on some operating conditions. The results show that while the ratio of energy loss rate to capital cost (Ren) changes between 0.007 and 0.813 at different wind speeds, the ratio of exergy loss rate to capital cost (Rex) changes between 0.006 and 0.411. In addition, the maximum Ren and Rex values are obtained at a wind speed of 12 m/s. Furthermore, a parametric study is undertaken to investigate how varying wind speed will affect the exergoeconomic parameters of the wind turbine system and to develop a correlation between the ratio of thermodynamic loss rate to capital cost and wind speed for practical applications of wind energy systems.
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    Parametric study of the effect of reference state on energy and exergy efficiencies of a small industrial pasta drying process
    (Inderscience Publishers, 2009) Ozgener L.; Ozgener O.
    The paper describes a performance evaluation of the industrial pasta process system in Gaziantep, based in Turkey, on energy and exergy analyses. The case study covers the actual system data taken from the system. General energy and exergy analysis of the system are introduced. This analysis, applied to the system using actual thermodynamic data for its performance evaluation in terms of energy and exergy efficiencies, is presented. In addition a parametric study of the effect of varying reference state properties on the energy and exergy efficiencies of the system has been conducted to find optimum performance and operating conditions, and is explained. Copyright © 2009, Inderscience Publishers.
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    Exergy analysis of drying process: An experimental study in solar greenhouse
    (2009) Ozgener L.; Ozgener O.
    This article examines the exergy variation during drying in solar greenhouses. Exergy efficiencies were derived as functions of drying time and temperature of the drying air. An illustrative example is considered to verify Dincer and Sahin's model and to show the applicability of the model to actual drying processes at different drying air temperatures. This work is intended not only to demonstrate the usefulness of exergy analysis in thermodynamic assessments of drying processes but to provide insights into their performances and efficiencies. In this study, the drying performance of the passively heated solar greenhouse has been investigated. Experimental results under the meteorological conditions of Izmir, Turkey (latitude 38.24 N, longitude 27.50 E), are presented.
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    Monitoring of energy exergy efficiencies and exergoeconomic parameters of geothermal district heating systems (GDHSs)
    (Elsevier Ltd, 2009) Ozgener L.; Ozgener O.
    In this work, the monitoring energy and exergy efficiency results of the last heating seasons of operation of the geothermal district heating systems (GDHSs) and their technical availability analysis and monitoring exergoeconomic parameters are presented. The case studies cover the actual system data taken from the systems in Afyon and Salihli GDHSs, Turkey. General energy, exergy, technical availability, and exergoeconomic analysis of the GDHSs are introduced. Furthermore, the average technical availability, real availability, capacity factor and energy and exergy efficiencies value of GDHSs have been analyzed. © 2008 Elsevier Ltd. All rights reserved.
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    Energetic performance test of an underground air tunnel system for greenhouse heating
    (Elsevier Ltd, 2010) Ozgener L.; Ozgener O.
    The main objective of the present study is to investigate the performance characteristics of an underground air tunnel (UAT) for greenhouse heating with a 47. m horizontal, 56. cm nominal diameter U-bend buried galvanized ground heat exchanger. This system was installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Based upon the measurements made in the heating mode, the average heat extraction rate to the soil is found to be 3.77 kW, or 80.21. W/m of tunnel length, while the required tunnel length in meters per kW of heating capacity is obtained as 12.46. The entering air temperature to the tunnel ranges from 14.3 to 21.5°C, with an average value of 15.5°C. When the system operates, the greenhouse air is at a minimum day temperature of 13.1°C with a relative humidity of 32%. The maximum heating coefficient of performance of the UAT system is about 6.42, while its minimum value is about 0.98 at the end of a cloudy and cold day and fluctuates between these values at other times. The daily average maximum COP values for the system are also obtained to be 6.42. The total average COP in the heating season is found to be 5.16. © 2010 Elsevier Ltd.
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    Investigation of wind energy potential of Muradiye in Manisa, Turkey
    (Elsevier Ltd, 2010) Ozgener L.
    The purpose of this survey is about to investigate wind energy potential of Celal Bayar University Muradiye Campus. The experimental system was commissioned in November 2006 and performance monitoring tests have been conducted since then. Author also undertake a case study to investigate how varying wind speeds considered affect the electricity production of the wind turbine system and to estimate a capacity factor which is defined as the ratio of the average power output to the rated output power of the generator. The collected data are quantified and illustrated in the tables, 07th of November 2006 till 09st of December 2007 for comparison purposes. According to experimental studies between 2006 and 2007 years, yearly average wind velocity is found to be 3.21 m/s at 30 m height and capacity factor is estimated to be 14.1% for Enercon E48 (800 kW) wind turbine. According to these results, the mean wind speed does not provide economical electricity production from the wind energy. © 2010 Elsevier Ltd. All rights reserved.
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    Effects of meteorological variables on exergetic efficiency of wind turbine power plants
    (Elsevier Ltd, 2010) Baskut O.; Ozgener O.; Ozgener L.
    This present paper deals with exergy efficiency results of the Wind Turbine Power Plants (WTPPs). Effects of meteorological variables such as air density, pressure difference between state points, humidity, and ambient temperature on exergy efficiency are discussed in a satisfactory way. Some key parameters are given monthly for the three turbines. Exergy efficiency differs from 0.23 to 0.27 while temperature is changing from 268.15 K to 308.15 K with air density 1.368-1.146 (kg/m3). While pressure difference (ΔP) between inlet and outlet of the turbine differs from 100 to 1100 (Pa), exergy efficiency decreases fairly for different wind speeds. While specific humidity is changing from 0.001 to 0.015 (kgwater/kgdry air), exergy efficiency decreases gently. Generally these meteorological variables are neglected while planning WTPPs, but this neglect can cause important errors in calculations and energy plans. Obtained results indicate that while planning WTPPs meteorological variables must be taken into account. © 2010 Elsevier Ltd. All rights reserved.