Browsing by Author "Ozgener O."
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Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item 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.Item Exergetic assessment of EAHEs for building heating in Turkey: A greenhouse case study(Elsevier Ltd, 2010) Ozgener O.; Ozgener L.The present study undertakes an exergy analysis of earth to air heat exchanger (EAHE) and applies to a local one in Turkey. Namely, the exergy performance of an EAHE has been evaluated in a demonstration in Solar Energy Institute of Ege University, Izmir, Turkey. Exergetic efficiencies of the system components are determined as an attempt to assess their individual performances. The daily maximum heating coefficient of performance (COP) value for the system is obtained to be 6.18. The total average COP in the experimental period is found to be 4.74. © 2010 Elsevier Ltd.Item Exergoeconomic analysis of an underground air tunnel system for greenhouse cooling system(2010) Ozgener O.; Ozgener L.This paper investigates some exergoeconomic parameters for an underground air tunnel system based upon some operating conditions. The ratio of exergy loss rate to capital cost (Rex) changes between 0.052 and 0.552. The total exergy losses values are obtained to be from 0.26 kW to 2.50 kW for the system. The daily average maximum cooling coefficient of performances (COP) values for the system are also obtained to be 11.96 for experimental period, while the total average COP is found to be 5.89. The overall exergy efficiency value for the system on a product/fuel basis is found to be 56.9%. © 2010 Elsevier Ltd and IIR. All rights reserved.Item An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling(2010) Ozgener L.; Ozgener O.The present study highlights the exergetic performance characteristics of an underground air tunnel for greenhouse cooling with a 47. m horizontal, 56. cm nominal diameter U-bend buried galvanized ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Underground air tunnel systems, also known as earth-to-air heat exchangers, are recognized to be outstanding heating, cooling and air heating systems. On the other hand, they have not been used yet in the Turkish market. Greenhouses also have important economical potential in Turkey's agricultural sector. Greenhouses should be cooled during the summer or hot days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of underground air tunnels with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future. The exergy transports between the components and the destructions in each of the components of the system are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The daily maximum cooling coefficient of performances (COP) values for the system are also obtained to be 15.8. The total average COP in the experimental period is found to be 10.09. The system COP was calculated based on the amount of cooling produced by the air tunnel and the amount of power required to move the air through the tunnel, while the exergetic efficiency of the air tunnel is found to be in a range among 57.8-63.2%. The overall exergy efficiency value for the system on a product/fuel basis is found to be 60.7%. © 2010 Elsevier Ltd.Item Performance analysis of geothermal district heating and geothermal heat pump applications in buildings(Nova Science Publishers, Inc., 2011) Ozgener L.; Ozgener O.This study describes Geothermal District Heating Systems (GDHSs) and Geothermal Heat Pumps (GHPs) and their energetic and exergetic performance analysis. The case studies cover the actual system data taken from the systems, Turkey. General energy and exergy efficiencies of the GDHSs and GHP are introduced. Then this analysis applied to selected GDHS and GHP system using actual thermodynamic data for theirs recent performance evaluations in terms of energy and exergy efficiencies. © 2011 by Nova Science Publishers, Inc. All rights reserved.Item Exergetic performance assessment of solar photovoltaic cell (PV) assisted earth to air heat exchanger (EAHE) system for solar greenhouse cooling(2011) Yildiz A.; Ozgener O.; Ozgener L.An experimental system was developed and tested in order to investigate the exergetic performance of a solar photovoltaic system (PV) assisted earth-to-air heat exchanger (under ground air tunnel) that is used for greenhouse cooling at the Solar Energy Institute, Ege University, Izmir, Turkey. This system was under operational conditions successfully during the 2010 summer cooling season. This paper provides the experimental results obtained between 18th of August and 26th of August of in 2010. Exergy destruction in the system was calculated and presented in this paper using a reference temperature of 15 °C. Results are discussed and interpreted in the paper for various performance metrics, such as the effect of climatic conditions and operating conditions on the system performance. Results show that the system may be satisfactorily used for greenhouse cooling in the Mediterranean and Aegean regions of Turkey. © 2011 Elsevier B.V. All rights reserved.Item Experimental prediction of total thermal resistance of a closed loop EAHE for greenhouse cooling system(2011) Ozgener O.; Ozgener L.; Goswami D.Y.The design of an earth to air heat exchanger (EAHE) requires knowledge of its total thermal resistance (RTot) for heating and cooling applications. In this research, a 47m long horizontal, 56cm nominal diameter U-bend buried galvanized was studied experimental EAHE used for the determination and evaluation of thermal properties of heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Based on the experimental results, generalized relationships were developed for predicting of thermal resistance of the heat exchanger. Average total heat exchanger thermal resistance was estimated to be 0.021K-m/W as a constant value under steady state condition. © 2011 Elsevier Ltd.Item Determining the optimal design of a closed loop earth to air heat exchanger for greenhouse heating by using exergoeconomics(2011) Ozgener O.; Ozgener L.This investigation deals with an exergoeconomic evaluation of the earth to air heat exchanger (EAHE) application for determining the optimal design greenhouse heating in Izmir, Turkey. The exergy destructions in the system are quantified and illustrated using tables for a reference temperature of 6 °C. The results indicate that the exergy destructions in the system occur primarily as a result of blower losses and heat exchanger losses. These average losses account for 85% and 4.5%, respectively. Both COP and exergy efficiency of the overall system was investigated to analyze and improve the systems performance. The average COP and exergetic efficiency were determined to be 10.51 and 89.25%, respectively. The results may provide useful insights into the relations between thermodynamics and economics for the EAHE heating systems. © 2010 Elsevier B.V. All rights reserved.Item Second law analysis of wind turbine power plants: Cesme, Izmir example(Elsevier Ltd, 2011) Baskut O.; Ozgener O.; Ozgener L.In this study, the energy and exergy efficiency results of the Wind Turbine Power Plants (WTPPs) are presented. Exergy, energy and technical availability analysis are performed. The case study includes the actual system data taken from the system in Cesme, Izmir WTPP. General energy, exergy and other performance parameters are also presented. Investigated WTPP is Turkey's first installed (1998) wind plant (1.50. MW) located in Izmir. Exergy efficiency of the power plant found to be between 0% and 68.20%. The monthly average technical availabilities are 96.11%, 98.71%, 98.52% for turbine 1, turbine 2, and turbine 3, respectively. Furthermore, authors developed some correlations, which are capable of predicting the values of exergy efficiencies of the WTPP for different power factor value. © 2011 Elsevier Ltd.