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; Aydemir, Levent Yurdaer; Korel, Figen; Gökçen Akkurt, GüldenIn 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, GüldenRenewable 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.