Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7755
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Conference Object Citation - WoS: 14Citation - Scopus: 16Drying of Olive Leaves in a Geothermal Dryer and Determination of Quality Parameters of Dried Product(Elsevier, 2019) Helvacı, Hüseyin Utku; Menon, Abhay; Helvacı, Hüseyin Utku; Korel, Figen; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; Korel, Figen; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03.06. Department of Energy Systems Engineering; 03. Faculty of EngineeringIn this study, a cabinet type geothermal dryer was designed, operated and tested for drying olive leaves with minimum losses of phenolic content and antioxidant capacity by optimization of drying conditions. Two factors; face centered central composite design was applied and response surface methodology was used to optimize the drying conditions of olive leaves. The results indicate that phenolic content stability were mainly affected by air temperature, whereas antioxidant capacity is affected by both air temperature and velocity (p<0.05). The optimal drying conditions were found to be at 50°C of air temperature and 1 m/s of air velocity for the minimum losses of determined quality parameters, where 88.8% of phenolic content and 95.3% of antioxidant capacity were recovered.Book Part Citation - Scopus: 11Thermodynamic Performance Evaluation of a Geothermal Drying System(Springer Verlag, 2014) Helvacı, Hüseyin Utku; Gökçen Akkurt, Gülden; Helvacı, Hüseyin Utku; Gökçen Akkurt, Gülden; 01. Izmir Institute of Technology; 03.06. Department of Energy Systems Engineering; 03. Faculty of EngineeringRenewable energy sources such as geothermal energy can be used in drying processes as a heat source due to the high energy costs of fossil fuels. In this study, geothermal cabinet type dryer was constructed and situated in Balcova-Narlidere Geothermal Field, Turkey where the clean city water of district heating system is used as an energy source for the dryer. The dryer was tested on site for drying of olive leaves and energy and exergy analyses of the drying process conducted under two cases: Case 1. Exhaust air was rejected to the environment. Case 2. A portion of exhaust air was re-circulated. Energy Utilization Ratio (EUR) was determined as 7.96 for Case 1 and 50.36 for Case 2. The highest rate of exergy destruction occurred in the fan, followed by heat exchanger and the dryer, accounting for 0.2913, 0.05663 and 0.0115 kW, respectively. Exergetic efficiency of the drying chamber was calculated as 89.66 %. Re-circulating the exhaust air decreased the exergy value at the outlet of the dryer from 0.1013 to 0.08104 kW, indicating that re-using the air increases the performance of the dyer.Article Citation - WoS: 5Citation - Scopus: 7Hydrogeochemistry and Environmental Properties of Geothermal Fields. Case Study: Balçova, Izmir-Turkey(Taylor and Francis Ltd., 2012) Çakın, Ayça; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; Baba, Alper; Baba, Alper; Eroğlu, Ahmet Emin; 04.01. Department of Chemistry; 03.03. Department of Civil Engineering; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyBalcova Geothermal Field hosts the largest geothermal district heating system of Turkey and a number of shallow groundwater wells that are used for irrigation of the agricultural activities. The present study aims to assess the influence of geothermal fluid on groundwater by determining the hydrogeochemical properties of the water resources. A sampling program was conducted for 10 months and samples were collected from geothermal and groundwater wells including re-injected fluid. Trace and major elements, and the types of waters were determined. The results of groundwater analysis showed that the concentrations of some toxic species, such as arsenic, boron, and fluoride, exceeded the limits of drinking water standards set by TSE, EPA, and WHO.Article Citation - WoS: 22Citation - Scopus: 26Thermodynamic Assessment of Gas Removal Systems for Single-Flash Geothermal Power Plants(Elsevier Ltd., 2009) Yıldırım Özcan, Nurdan; Gökçen Akkurt, Gülden; Yıldırım, Nurdan; Gökçen Akkurt, Gülden; 03.10. Department of Mechanical Engineering; 03.06. Department of Energy Systems Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyGeothermal fluids contain non-condensable gases (NCGs) at various amounts. NCGs flow to a conventional geothermal power plant (GPP) with steam phase and should be withdrawn from the condenser by a gas removal system to prevent increase in condenser pressure and consequently decrease in power generation. Therefore, to remove NCGs from the system is critical especially at high NCG fractions. In this study, the net power output and specific steam consumption of a single-flash GPP is evaluated depending on the separator pressure, NCG fraction and wet bulb temperature of the environment, and three different conventional gas removal options which are two-stage steam jet ejector system, two-stage hybrid system and two-stage compressor system. A simulation code is written in EES to model the plant for each option. The model uses the data of Kizildere Geothermal Power Plant (KGPP) - Turkey, which is a single-flash plant with extremely high NCG fraction, to allow a comparison between the results of the modelling and the operational data of an actual single-flash GPP. Under given conditions, thermodynamic analysis resulted that NCG fraction is the most significant factor on GPP performance and the compressor system is the most efficient and robust option where the influence of the NCG fraction is limited.