Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Experimental Investigation and Computational Fluid Dynamics (cfd) Analysis of Geothermal Sourced Hot Air Drying(Izmir Institute of Technology, 2022) Helvacı, Hüseyin Utku; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; Helvacı, Hüseyin Utku; 01. Izmir Institute of Technology; 03.06. Department of Energy Systems Engineering; 03. Faculty of EngineeringDrying is one of the oldest methods used to increase the product's shelf life and reduce transportation costs, consisting of heat and mass transfer between the product and the surrounding environment. One of the most common drying methods is hot air drying. The most critical parameters in hot air drying processes are drying air temperature, air velocity and relative humidity. Renewable energy resources can be used as heat/electricity in drying processes. Geothermal energy resources are highly suitable for hot air drying with their temperature compatibility and reliability. The geothermal resources in Turkey have a high potential for hot air drying. This Thesis examines tomato slices' quality parameters at different drying air temperatures and velocities. A cabinet-type geothermal sourced hot air dryer is installed in the Yenikale Heat Center of the Balcova-Narlidere Geothermal District Heating System in Izmir-Turkiye. Drying experiments are carried out at 40-60-80°C air temperatures and 0.5-1.5 m/s air velocities to examine their effects on drying kinetics and quality of dried tomatoes, such as pH, color, and moisture. With the help of the data obtained, drying time, drying rate, moisture rate, and effective diffusion coefficients are determined, and dimensionless moisture rate is modeled using thin layer models. Also, energy and exergy analyses are made for each experiment. Finally, experimental and simulation results are compared by using CFD to perform experimental design. The simulations created by using CFD are obtained in a much shorter time and more accurately since all materials used for the experiment are idealized.Master Thesis Design and Tests of a Geothermal Dryer and Determination of Quality Parameters of Dried Product(Izmir Institute of Technology, 2012) Helvacı, Hüseyin Utku; Helvacı, Hüseyin Utku; Gökçen Akkurt, Gülden; Gökçen Akkurt, Gülden; 01. Izmir Institute of Technology; 03.06. Department of Energy Systems Engineering; 03. Faculty of EngineeringDrying which is a heat and mass transfer process between the product surface and its surrounding medium and within the product is practised to enhance the storage life and reduce transportation costs of products. Olive leaves are the plants which have been used for medicinal purposes are often dried before use. Renewable energy sources such as geothermal energy can be used in drying processes as heat source besides fossil fuels. The temperature and the thermal potential of geothermal resources in Turkey is high enough to be used in drying process. In this thesis, a geothermal cabinet type drier was constructed and placed in Balcova-Narlidere geothermal field. To be able to determine drying parameters (temperature and velocity) and whose effects on drying kinetics of olive leaves and on the quality parameters of dried olive leaves (antioxidant content and phenolic content), drying experiments were carried out at three different air temperatures (40, 50 and 60 °C) and at three air velocities (0.5, 1, 1.5 m/s). During the experiments temperature, relative humidity and velocity of drying air was measured and recorded. Then, using the measured data drying time, drying rate, moisture ratio and effective diffusivity was determined and moisture ratio was modelled using thin-layer models. The quality parameters which are total antioxidant activity and total phenolic content were determined using spectrophotometric techniques. To evaluate the performance of the dryer, energy and exergy analyses were conducted. The drying time was determined as 240 – 555 min. (4 – 10) hour which is quite short comparing with open air sun drying. Optimum drying air temperature and velocity which gives the minimum total phenolic content and antioxidant loss value were determined by response surface methodology as 50 °C and 1 m/s, respectively. The energy utilization was found 0.3316 kW and the energy utilization ratios were found 50.36% and 7.96% for the case at drying air is re-circulated and the case at drying air was no re-circulated, respectively.