Abstract
This paper presents an experimental and theoretical investigation of drying of moist slab, cylinder and spherical products to study dimensionless moisture content distributions and their comparisons. Experimental study includes the measurement of the moisture content distributions of slab and cylindrical carrot, slab and cylindrical pumpkin and spherical blueberry during drying at various temperatures (e.g., 30, 40, 50 and 60°C) at specific constant velocity (U = 1 m/s) and the relative humidity φ = 30%. In theoretical analysis, two moisture transfer models are used to determine drying process parameters (e.g., drying coefficient and lag factor) and moisture transfer parameters (e.g., moisture diffusivity and moisture transfer coefficient), and to calculate the dimensionless moisture content distributions. The calculated results are then compared with the experimental moisture data. A considerably high agreement is obtained between the calculations and experimental measurements for the cases considered. The effective diffusivity values were evaluated between 0.741 × 10−5 and 5.981 × 10−5 m2/h for slab products, 0.818 × 10−5 and 6.287 × 10−5 m2/h for cylindrical products and 1.213 × 10−7 and 7.589 × 10−7 m2/h spherical products using the Model-I and 0.316 × 10−5–5.072 × 10−5 m2/h for slab products, 0.580 × 10−5–9.587 × 10−5 m2/h for cylindrical products and 1.408 × 10−7–13.913 × 10−7 m2/h spherical products using the Model-II.
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Abbreviations
- A 1 :
-
Constant
- B 1 :
-
Constant
- Bi :
-
Biot number (dimensionless)
- D :
-
Moisture diffusivity (m2/h)
- Fo :
-
Fourier number (dimensionless)
- G :
-
Lag factor (dimensionless)
- k :
-
Moisture transfer coefficient (m/h)
- M :
-
Moisture content (kg H2O/kg d.m.)
- M e :
-
Equilibrium moisture content (kg H2O/kg d.m.)
- M i :
-
Initial moisture content (kg H2O/kg d.m.)
- μ 1 :
-
Root of the transcendental characteristic equation
- R 2 :
-
Correlation coefficient
- S :
-
Drying coefficient (1/h)
- t :
-
Drying time (h)
- T :
-
Air temperature (°C)
- U :
-
Air velocity (m/s)
- Y :
-
Characteristic dimension (m) (half thickness for slab, radius for sphere and cylinder)
- ϕ :
-
Dimensionless moisture content
- φ :
-
Relative humidity
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Acknowledgments
The authors acknowledge the financial support provided by Karadeniz Technical University Research Fund under Grant No 2004.112.003.01 and the Turkish Republic Prime Ministry State Planning Organization (DPT) under grant no 2003K120750. The second author of this article is also indebted to the Turkish Academy of Sciences (TUBA) for the financial support provided under the Programme to Reward Success Young Scientists (TUBA-GEBIT).
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Kaya, A., Aydın, O. & Dincer, I. Comparison of experimental data with results of some drying models for regularly shaped products. Heat Mass Transfer 46, 555–562 (2010). https://doi.org/10.1007/s00231-010-0600-z
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DOI: https://doi.org/10.1007/s00231-010-0600-z