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ANALYSIS OF SOME EXERGOECONOMIC PARAMETERS OF A SMALL WIND TURBINE SYSTEM
(Taylor & Francis Inc, 2009) Ozgener, Onder; Ozgener, Leyla; Dincer, Ibrahim
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 (R(en)) changes between 0.007 and 0.813 at different wind speeds, the ratio of exergy loss rate to capital cost (R(ex)) 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.
Determining the optimal design of a closed loop earth to air heat exchanger for greenhouse heating by using exergoeconomics
(Elsevier Science Sa, 2011) Ozgener, Onder; Ozgener, Leyla
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 degrees 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. (C) 2010 Elsevier B.V. All rights reserved.
Effects of meteorological variables on exergetic efficiency of wind turbine power plants
(Pergamon-Elsevier Science Ltd, 2010) Baskut, Omer; Ozgener, Onder; Ozgener, Leyla
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/m(3)). While pressure difference (Delta P) 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 (kg(water)/kg(dry 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. (C) 2010 Elsevier Ltd. All rights reserved.
Energetic performance test of an underground air tunnel system for greenhouse heating
(Pergamon-Elsevier Science Ltd, 2010) Ozgener, Leyla; Ozgener, Onder
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 degrees C, with an average value of 15.5 degrees C. When the system operates, the greenhouse air is at a minimum day temperature of 13.1 degrees 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. (C) 2010 Elsevier Ltd. All rights reserved.
Energy and exergy analysis of electricity generation from natural gas pressure reducing stations
(Pergamon-Elsevier Science Ltd, 2015) Neseli, Mehmet Alparslan; Ozgener, Onder; Ozgener, Leyla
Electricity generation or power recovery through pressure reduction stations (PRS) for general use has not been realized in Izmir. The main objective of the present study was to do a case study for calculating electricity to be recovered in one natural gas pressure reduction stations in Izmir. It is the first forecasting study to obtain energy from natural gas pressure-reducing stations in Izmir. Energy can be obtained from natural gas PRS with turbo-expanders instead of using throttle valves or regulators from the PRS. The exergy performance of PRS with TE is evaluated in this study. Exergetic efficiencies of the system and components are determined to assess their individual performances. Based upon pressure change and volumetric flow rate, it can be obtained by recovering average estimated installed capacity and annual energy 494.24 kW, 4113.03 MW h, respectively. In terms of estimated installed capacity power and annual energy, the highest level is 764.88 kW, approximately 6365.34 MW h, in Aliaga PRS. Also it can be seen that CO2 emission factor average value is 295.45 kg/MW h. (C) 2015 Elsevier Ltd. All rights reserved.
Energy and exergy analysis of electricity generation from natural gas pressure reducing stations
(Pergamon-Elsevier Science Ltd, 2015) Neseli, Mehmet Alparslan; Ozgener, Onder; Ozgener, Leyla
Electricity generation or power recovery through pressure reduction stations (PRS) for general use has not been realized in Izmir. The main objective of the present study was to do a case study for calculating electricity to be recovered in one natural gas pressure reduction stations in Izmir. It is the first forecasting study to obtain energy from natural gas pressure-reducing stations in Izmir. Energy can be obtained from natural gas PRS with turbo-expanders instead of using throttle valves or regulators from the PRS. The exergy performance of PRS with TE is evaluated in this study. Exergetic efficiencies of the system and components are determined to assess their individual performances. Based upon pressure change and volumetric flow rate, it can be obtained by recovering average estimated installed capacity and annual energy 494.24 kW, 4113.03 MW h, respectively. In terms of estimated installed capacity power and annual energy, the highest level is 764.88 kW, approximately 6365.34 MW h, in Aliaga PRS. Also it can be seen that CO2 emission factor average value is 295.45 kg/MW h. (C) 2015 Elsevier Ltd. All rights reserved.
Energy and exergy analysis of electricity generation from natural gas pressure reducing stations
(Pergamon-Elsevier Science Ltd, 2015) Neseli, Mehmet Alparslan; Ozgener, Onder; Ozgener, Leyla
Electricity generation or power recovery through pressure reduction stations (PRS) for general use has not been realized in Izmir. The main objective of the present study was to do a case study for calculating electricity to be recovered in one natural gas pressure reduction stations in Izmir. It is the first forecasting study to obtain energy from natural gas pressure-reducing stations in Izmir. Energy can be obtained from natural gas PRS with turbo-expanders instead of using throttle valves or regulators from the PRS. The exergy performance of PRS with TE is evaluated in this study. Exergetic efficiencies of the system and components are determined to assess their individual performances. Based upon pressure change and volumetric flow rate, it can be obtained by recovering average estimated installed capacity and annual energy 494.24 kW, 4113.03 MW h, respectively. In terms of estimated installed capacity power and annual energy, the highest level is 764.88 kW, approximately 6365.34 MW h, in Aliaga PRS. Also it can be seen that CO2 emission factor average value is 295.45 kg/MW h. (C) 2015 Elsevier Ltd. All rights reserved.
Evaluation of the efficiency of the dryers in thermoplastic vulcanisate extrusion production lines with the energy and exergy analysis method
(Inderscience Enterprises Ltd, 2021) Dogru, Aziz Kagan; Ozgener, Onder; Ozgener, Leyla
In this study, energy and exergy analysis of the drying process in producing a sealing profile with extrusion in Manisa, using real operational data was conducted. The drying system was analysed in regards to changes in ambient temperature (0-30 degrees C) and drying air temperature (75-105 degrees C). The energy efficiency of the system was in the range of 80.79%-88.24% and the exergy efficiency was in the range of 15.88%-41.94%. As a result of the analysis, it can be concluded that the drying conditions with the highest efficiency values were at 0 degrees C outdoor temperature and 75 degrees C drying air.
Exergetic assessment of EAHEs for building heating in Turkey: A greenhouse case study
(Elsevier Sci Ltd, 2010) Ozgener, Onder; Ozgener, Leyla
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. (C) 2010 Elsevier Ltd. All rights reserved.
Exergetic performance assessment of solar photovoltaic cell (PV) assisted earth to air heat exchanger (EAHE) system for solar greenhouse cooling
(Elsevier Science Sa, 2011) Yildiz, Ahmet; Ozgener, Onder; Ozgener, Leyla
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 degrees 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. (C) 2011 Elsevier B.V. All rights reserved.
Exergoeconomic analysis of an underground air tunnel system for greenhouse cooling system
(Elsevier Sci Ltd, 2010) Ozgener, Onder; Ozgener, Leyla
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 (R(ex)) 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%. (C) 2010 Elsevier Ltd and IIR. All rights reserved.
Exergoeconomic analysis of geothermal district heating systems: A case study
(Pergamon-Elsevier Science Ltd, 2007) Ozgener, Leyla; Hepbasli, Arif; Dincer, Ibrahim; Rosen, Marc 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. (c) 2006 Elsevier Ltd. All rights reserved.
Exergy Analysis of Drying Process: An Experimental Study in Solar Greenhouse
(Taylor & Francis Inc, 2009) Ozgener, Leyla; Ozgener, Onder
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.
Exergy analysis of industrial pasta drying process
(John Wiley & Sons Ltd, 2006) Ozgener, Leyla; Ozgener, Onder
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 (c) 2006 John Wiley & Sons, Ltd.
Exergy analysis of two geothermal district heating systems for building applications
(Pergamon-Elsevier Science Ltd, 2007) Ozgener, Leyla; Hepbasli, Arif; Dincer, Ibrahim
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 degrees 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. (c) 2006 Elsevier Ltd. All rights reserved.
Experimental prediction of total thermal resistance of a closed loop EAHE for greenhouse cooling system
(Pergamon-Elsevier Science Ltd, 2011) Ozgener, Onder; Ozgener, Leyla; Goswami, D. Yogi
The design of an earth to air heat exchanger (EAHE) requires knowledge of its total thermal resistance (R(Tot)) for heating and cooling applications. In this research, a 47 m long horizontal, 56 cm 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 0.021 K-m/W as a constant value under steady state condition. (C) 2011 Elsevier Ltd. All rights reserved.
An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling
(Pergamon-Elsevier Science Ltd, 2010) Ozgener, Leyla; Ozgener, Onder
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%. (C) 2010 Elsevier Ltd. All rights reserved.
A key review on performance improvement aspects of geothermal district heating systems and applications
(Pergamon-Elsevier Science Ltd, 2007) Ozgener, Leyla; Hepbasli, Arif; Dincer, Ibrahim
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. (c) 2006 Elsevier Ltd. All rights reserved.
Modeling of driveway as a solar collector for improving efficiency of solar assisted geothermal heat pump system: a case study
(Pergamon-Elsevier Science Ltd, 2015) Ozgener, Onder; Ozgener, Leyla
It is well known that rooftop solar thermal panels increase both power rates of circulation pumps and initial investment cost of solar assisted ground source (geothermal) systems. To avoid both of them it means that the unnecessary energy consumption rates of circulation pump(s) and their initial capital cost, rather than installing rooftop solar thermal panels, driveways can be used as solar collectors for improving efficiency of geothermal heat pump systems (GSHP) and declining initial capital cost of SAGSHPs. Mainly this idea was first put in the middle by Jefferson W. Tester. In this paper, we will examine modeling of driveway as solar thermal panel to enhance efficiency of solar assisted geothermal heat pump system (SAGSHP) depends on its different operating types; yet we will give only a case that is investigated theoretically for solar assisted geothermal heat pump systems. (C) 2015 Elsevier Ltd. All rights reserved.
Modeling of driveway as a solar collector for improving efficiency of solar assisted geothermal heat pump system: a case study
(Pergamon-Elsevier Science Ltd, 2015) Ozgener, Onder; Ozgener, Leyla
It is well known that rooftop solar thermal panels increase both power rates of circulation pumps and initial investment cost of solar assisted ground source (geothermal) systems. To avoid both of them it means that the unnecessary energy consumption rates of circulation pump(s) and their initial capital cost, rather than installing rooftop solar thermal panels, driveways can be used as solar collectors for improving efficiency of geothermal heat pump systems (GSHP) and declining initial capital cost of SAGSHPs. Mainly this idea was first put in the middle by Jefferson W. Tester. In this paper, we will examine modeling of driveway as solar thermal panel to enhance efficiency of solar assisted geothermal heat pump system (SAGSHP) depends on its different operating types; yet we will give only a case that is investigated theoretically for solar assisted geothermal heat pump systems. (C) 2015 Elsevier Ltd. All rights reserved.

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