SONER ÇELEN, Ayşen HAKSEVER, AYTAÇ MORALAR

The Effects of Microwave Energy to the Drying of Apple (Gala) Slices

In this work, the drying behaviors of apple slices with 2, 4, and 6mm thickness were investigated in a microwave conveyor dryer. The effects of different microwave power levels (1050 W, 1500 W and 2100 W) and conveyor speeds (0.175, 0.210 ve 0.245 m/ min) on drying time, color changing and energy consumption have been investigated. The results show that drying time and energy consumption decreases considerably with increasing microwave power and with decreasing conveyor speed. Then, the mathematical models were fitted to the experimental data. According to the results, the Page Model was found to best explain thin layer drying behavior of the apple slices as compared to the other models. Fick’s diffusion model was applied to calculate the effective diffusivities. The effective diffusivity values were found between 1.1916×10−8 m2 /s and 2.7540×10−7 m2 /s. The activation energies were calculated as 156.65, 40.18 and 17.90 W/g for samples thickness of 2, 4 and 6 mm, respectively. At the end of the drying process, minimum energy consumption for 2mm at 0.175 m/min conveyor speed and 2100 W power is calculated as 1.34 kWh. From the results of colour quality, the colour criteria nearest the those of apple slices occurred at 1050 W and 0.210 m/min.

Elma (Gala) Dilimlerinin Kurutulmasına Mikrodalga Enerjisinin Etkileri

Bu çalışmada 2, 4 ve 6mm olarak dilimlenmiş elmanın mikrodalga kurutucuda kuruma davranışı araştırılmıştır. Mikrodalga gücünün (1050 W, 1500 W ve 2100 W) ve konveyör bant hızının (0.175, 0.210 ve 0.245 m/dk) kuruma zamanına, renk değişimine ve enerji tüketimine etkisi araştırılmıştır. Elde edilen sonuçlara göre kuruma zamanı ve enerji tüketiminin mikrodalga gücü ve konveyör bant hızının artmasıyla azaldığı görülmüştür. Daha sonra deneysel sonuçlar matematiksel modellere uygulanmıştır. Sonuçlara göre Page model diğer modeller ile karşılaştırıldığında en uygun model olarak tespit edilmiştir. Fick difüzyon modeli de difüzyon katsayısının tespitinde kullanılarak 1.1916×10−8 m2 /s ve 2.7540×10−7 m2 /s aralığında difüzyon katsayılarının değiştiği belirlenmiştir. Aktivasyon enerjisi de 2, 4 ve 6 mm dilimler için sırasıyla 156.65, 40.18 ve 17.90 W/g olarak hesaplanmıştır. Kurutma prosesinin sonucunda 2mm dilim kalınlığındaki elma için 0.175 m/dk konveyör hızında ve 2100 W gücünde minimum enerji tüketimi 1.34 kWh olarak hesaplanmıştır. Renk kalitesine bakıldığında da taze elmaya en yakın değer 1050 W ve 0.210 m/dk değerlerinde görülmüştür.

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