BALKABAĞININ AKIŞKAN YATAKLI KURUTUCUDA KURUTULMASININ DENEYSEL VE TEORİK İNCELENMESİ

Bu çalışmada balkabağının akışkan yataklı kurutucuda kurutma karakteristiği incelenmiştir. Deneyler için balkabağı tarla hasadından sonra küp şeklinde kesilerek, 50, 60 ve 70 °C’deki üç farklı sıcaklıktaki hava ile akışkan yataklı kurutucuda kurutulmuştur. Kurutulan balkabağının başlangıç nemi ıslak bazda %95 (kuru bazda %1930) mertebelerinde olup akışkanlaşma hızı 3,5 m/s seçilmiştir. Deney sonuçlarından, akışkan yataklı kurutucuda oldukça yüksek kuruma hızlarına ulaşıldığı ve böylece kuruma sürelerinin klasik yöntemlere ve sabit yataklı kurutuculara göre çok kısa sürelere indiği görülmüştür. Kurutma deneylerimizde en fazla 120 dakika sonunda %6’dan düşük bal kabağı nemlerine ulaşmak mümkün olmuştur. Bal kabağı kurutmanın matematiksel modellenmesi için literatürde sıkça kullanılan yarı-teorik modellerden Lewis modeli, Henderson ve Pabis modeli, Page modeli ve logaritmik ince tabaka kurutma modelleri seçilmiştir. Bunun yanında Fick’in birinci yasası olan kurutma teorik modeli ile de kurutma karakteristiği incelenmiştir. Bu modelde hesaplanan etkin difüzyon katsayılarının sonuçları, literatürdeki değerleri ile karşılaştırılmıştır. Akışkan yataklı kurutucuda hesaplanan etkin difüzyon katsayıları, sabit yataklı kurutuculara göre %70’lere varan daha yüksek değerlere ulaşmıştır. Bunun yanında etkin difüzyon katsayılarının sıcaklığa bağımlılıkları Arrhenius denklemi ile açıklanmıştır.

Anahtar Kelimeler:

Balkabağı, Kurutma; Akışkan Yataklı Kurutucu; Kurutma Karakteristiği

Experimental and Theoretical Investigation of Pumpkin Drying in Fluidized Bed Dryer

Thin layer drying characteristics of pumpkin cube were experimentally investigated in a fluidized bed dryer. Experiments were performed at three different drying temperatures: 50, 60 and 70 °C. Pumpkin used in the experiments had an initial moisture content of 95% wet basis (1930 % dry basis). The drying air velocities were set to 3.5 m/s to achieve fluidization. Experimental results show that large drying rates are obtained in the fluidized bed dryer, which are much higher than those obtained with conventional methods and convective tray dryer. In just 120 minutes moisture contents lower than 6% wet basis were achieved. Pumkin drying was mathematically modeled using the Lewis, Henderson ve Pabis, Page, and logaritmic models, all of which are semi-emperical models widely applied in the literature. Using Fick’s first law effective diffusivities were calculated and compared with those in the literature. Effective diffusion coefficients obtained in the fluidized bed dryer were up to 70% higher than the diffusion coefficients obtained in convective tray dryers. Temperature dependence of effective diffusion coefficients was described by an Arrhenius-type relationship.

Keywords:

Pumpkin, Drying; Fluidized Bed Dryer; Drying Characteristics,

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