Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Exergetic Analysis of a Continuous Bi-Axially Oriented Polypropylene (bopp) Film Unit in a Plastic Processing Plant(Inderscience Enterprises Ltd., 2009) Balta, M. Tolga; Hepbaşlı, Arif; Hancıoğlu, Ebru; Özcanlı, Şevket Cihangir; Yılmazer, Ertan; Yurdakul, İbrahim; Dişbudak, ÖzgürThis paper deals with an exergy analysis of the stretching process of bi-axially oriented polypropylene films using a hot oil coiler along with stretching and crystallising unit. Exergy destructions and efficiencies in each of the system components are calculated, while the exergy loss and flow diagram (the so-called Grassmann diagram) is presented for the transverse direction (TD) unit. The so-called functional (on the product or benefit/fuel basis) and universal (on the output/input basis) exergy efficiency values of the TD unit are calculated to be 26.40% and 28.46% at a recommended exhaust air relative humidity of 0.0098 kg water/kg air, respectively.Article Citation - WoS: 27Citation - Scopus: 28An Exergetic Performance Assessment of Three Different Food Driers(SAGE Publications Inc., 2010) Hepbaşlı, Arif; Erbay, Zafer; Çolak, Neslihan; Hancıoğlu, Ebru; İçier, FilizIn this study, plum slices were dried in three different driers (tray, fluid bed, and heat pump (HP) driers). Drying experiments were carried out at an air temperature range of 45-55 °C with an air velocity of 1.5 m/s. The performance of the driers along with their main components was evaluated and compared by using the exergy analysis method. The most important component for improving the system efficiency was determined to be the fan-heater combination for both the tray and fluid bed driers, and the motor-compressor assembly for the HP drier. The exergy loss and flow diagram (the so-called Grassmann diagram) of the driers was also presented to give quantitative information regarding the proportion of the exergy input dissipated in the various system components. Effects of the drying air temperature on the performance of the drying process were discussed. The highest exergetic efficiency values were obtained to range from 72.72 to 75.66 per cent for the HP drier, followed by the tray and fluid bed driers varying between 37.94 and 39.46 per cent, and between 22.83 and 24.07 per cent, respectively.Article Citation - WoS: 71Citation - Scopus: 77A Comparative Study on Exergetic Performance Assessment for Drying of Broccoli Florets in Three Different Drying Systems(Taylor and Francis Ltd., 2010) İçier, Filiz; Çolak, Neslihan; Erbay, Zafer; Hancıoğlu Kuzgunkaya, Ebru; Hepbaşlı, ArifThis article deals with the exergy analysis and evaluation of broccoli in three different drying systems. The effects of drying air temperature on the exergy destruction, exergy efficiency, and exergetic improvement potential of the drying process were investigated. The exergy destruction rate for the drying chamber increased with the rise in the drying air temperature at 1.5 m/s, both in the tray and the heat pump dryer. The highest exergy efficiency value was obtained as 90.86% in the fluid bed dryer in comparison to the other two drying systems and the improvement potential rate was the highest in the heat pump dryer during drying of broccoli at the drying air temperature of 45°C and the drying air velocity of 1.0 m/s. © 2010 Taylor & Francis Group, LLC.Article Citation - WoS: 3Citation - Scopus: 4Exergy analysis of food drying processes(Springer Verlag, 2010) Çolak, Neslihan; Balta, Mustafa T.; İçier, Filiz; Hancıoğlu, Ebru; Hepbaşlı, Arif; Erbay, ZaferIt is well known that micro-level system parameters may have some great impact on macro-level energy aspects, the environment, and sustainability. Of course, if one wants to approach these thermodynamically, there are two ways: energy analysis through the first law of thermodynamics and exergy analysis through the second law of thermodynamics. Exergy analysis is an essential tool to expose the impacts of a power generating device on exergy-based sustainability; sustainability is necessary to overcome current ecological, economic, and developmental problems (Dincer and Rosen, 2005). In this regard, some new exergy-based sustainability parameters for a PEM fuel cell have been developed and studied parametrically to investigate how they will help measure the level of environmental impact and sustainable development (Midilli and Dincer, 2009). These types of parameters may also be applied to other energy-related systems.Article Citation - WoS: 50Citation - Scopus: 50Exergoeconomic analysis of plum drying in a heat pump conveyor dryer(Taylor and Francis Ltd., 2010) Hepbaşlı, Arif; Çolak, Neslihan; Hancıoğlu, Ebru; İçier, Filiz; Erbay, ZaferIn this study, plum slices were dried in a heat pump dryer designed and constructed in Ege University, Izmir, Turkey. Drying experiments were carried out at an air temperature range of 45-55°C. The performance of the dryer along with its main components were evaluated using an exergy analysis method. Exergy destruction and capital cost rates were used for the exergoeconomic analysis, which is based on the quantities exergy, cost, energy, and mass (EXCEM) method. Exergy destruction rates to capital cost values Rex were obtained to vary between 1.668 and 2.063 W/ USD at different drying air temperatures. Ren values were observed to range from 6.258 to 5.749 W/USD. Ren values decreased as the drying air temperature increased, contrary to Rex values. Ṙex and Ṙen values increased linearly with increasing temperature due to the loss, whereas Ṙen decreased due to the relatively higher energy utilization efficiency of the heat pump. In the compressor, Ṙen and Ṙex values decreased with the increase in the temperature contrary to the other components. Ṙex had the lowest value in the drying duct. However, in the compressor, expansion valve, and heat recovery, Ṙex values were found to be higher and should be improved in these units. © 2010 Taylor & Francis Group, LLC.Article Citation - WoS: 30Citation - Scopus: 32Performance investigation of the drying of parsley in a tray dryer system(Inderscience Enterprises Ltd., 2010) Hancıoğlu, Ebru; Hepbaşlı, Arif; İçier, Filiz; Erbay, Zafer; Çolak, NeslihanThe performance of a tray dryer system for the parsley drying process was assessed using energy and exergy analysis methods in this study. The drying temperature ranged from 40°C to 60°C, while the drying air velocity varied from 0.5 m/s to 1.5 m/s. The higher temperature and lower velocity led to higher exergy and energy efficiencies. The exergy efficiency value for the overall system on a product/fuel basis was found to be 3.62%. The values for Specific Moisture Extraction Rate (SMER) and Specific Moisture Exergetic index (SMExR) were obtained to be 0.08 and 2.47 kg/kWh, respectively. Copyright © 2010 Inderscience Enterprises Ltd.Article Citation - WoS: 30Citation - Scopus: 36Overview of Kizildere Geothermal Power Plant in Turkey(Elsevier Ltd., 2004) Gökçen Akkurt, Gülden; Öztürk, Harun Kemal; Hepbaşlı, ArifAchieving sustainable development is a target that is now widely seen as important in worldwide public opinion. In this context, the utilization of renewable energy resources such as solar, geothermal and wind energy appears to be one of the most efficient and effective ways of achieving this target. Recently, power generation from geothermal energy has become of big importance in Turkey, which is located on the Mediterranean sector of the Alpine-Himalayan Tectonic Belt and is among the first seven countries in abundance of geothermal resources around the world. The main objective in doing the present study is twofold, namely: (a) to investigate Turkey's geothermal energy potential for power generation and (b) to overview the Denizli-Kizildere geothermal power plant (DKGPP) with an installed capacity of 20.4 MWe, which is at present the only operating geothermal power plant of Turkey. Based on the drilling data, which have been gathered to date, Turkey's geothermal energy potential for power generation is determined to be 764.81 MWe. Electricity generation projections of Turkey are also 500 MWe from Germencik, Kizildere, Tuzla and several of the other fields by the year 2010 and 1000 MWe by 2020. The Denizli-Kizildere geothermal field has an estimated capacity of 200 MWe. The DKGPP was put into operation in 1984 and has been operated since then. It produced an electrical energy of 89,597 MWh in 2001, representing an electric power of 10.6 MWe in the same year. Present applications have shown that in Turkey, geothermal energy is a promising alternative and can make a significant contribution towards reducing the emission of greenhouse gases. As the public recognizes the projects, the progress will continue.Article Citation - WoS: 15Citation - Scopus: 16Geothermal Fields Suitable for Power Generation(Taylor and Francis Ltd., 2004) Gökçen Akkurt, Gülden; Öztürk, Harun Kemal; Hepbaşlı, ArifTurkey is located on the Mediterranean sector of Alpine-Himalayan Tectonic Belt with many grabens, acidic volcanism, hydrothermal alteration zones, numerous hot springs and fumaroles. The data gathered since 1962 indicate that Turkey has a high geothermal energy potential. By comparison, it is among the first seven countries in abundance of geothermal resources around the world, while the share of its potential used is only about 2%. This means that considerable studies on geothermal energy could be conducted in order to increase energy supply and to reduce atmospheric pollution in Turkey. The main objective of the present study is threefold, namely: (1) to overview Turkey's geothermal fields suitable for power generation together with their possible utilization opportunities, (2) to present problems encountered and research projects developed in the Denizli-Kizildere geothermal field with an estimated capacity of 200 MWe and (3) to assess the current status of geothermal energy use for electric energy production in Turkey. The Denizli-Kizildere geothermal power plant with an installed capacity of 20.4 MWe which is, at present, the only operating geothermal power plant of Turkey, was put into operation in 1984, while electricity from geothermal energy has been produced commercially since 1913. This plant produced on average an electrical energy of 84,920 MWh in the period between 1998-2001, representing an average electric power of 10.45 MWe in the same period. Parallel to the development of the geothermal energy utilization in the country, it is projected that, by the years 2010 and 2020, the total geothermal power installed capacity will increase to 500 MWe, respectively.Article Citation - WoS: 55Citation - Scopus: 67Evaluating Performance Indices of a Shopping Centre and Implementing Hvac Control Principles To Minimize Energy Usage(Elsevier Ltd., 2004) Canbay, Çağlar Selçuk; Hepbaşlı, Arif; Gökçen Akkurt, GüldenHeating, ventilating and air-conditioning (HVAC) systems in buildings must be integrated with an efficient control scheme to maintain comfort under any load conditions. Efficient HVAC control is often the most cost-effective option to improve the energy efficiency of a building. However, HVAC processes are non-linear, and characteristics change on a seasonal basis so the effect of changing the control strategy is usually difficult to predict. The present study aims to reduce energy consumption by defining new HVAC control strategies and tuning control loops in a shopping centre. First, an energy audit was performed to investigate the potential for energy savings and to redefine the control scenarios, while a methodology for the shopping centre was developed. Performance indices were then calculated and compared with the yardsticks. Next, normalised performance indices were computed to reach out a better understanding of the building's efficiency. Finally, new strategies were implemented with the help of the existing building management system (BMS) and about 22% of energy saving was achieved.