Abstract
Fluidization is an efficient way to dry granular materials. Incorporating microwave heating into the fluidization makes the overall drying process shorter, and the quality of the final products can be improved. However, in order to understand the mechanisms of water removal, an exact knowledge of changes inside the dried material is necessary. The temperature and moisture distribution pattern within the heated material should be identified and analyzed. Unfortunately, the microwave environment makes the measurements very difficult. This paper gives new information on the temperature distribution inside small particles of various shapes dried with microwaves. The tests were carried out in a laboratory-scale, fluid-bed dryer equipped with a microwave source. Five different shapes were examined: sphere, cylinder, half-cylinder, rectangular prism, and prism with triangle base. All particles tested were suspended in an air stream and heated with microwaves. The internal temperature distribution has been analyzed in each case. The rate of drying is also presented and discussed for every case tested.
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Abbreviations
- E:
-
Electric field strength, V/m
- f:
-
Frequency, Hz
- P:
-
Power, W
- X:
-
Moisture fracture
- Greek :
-
- \(\varepsilon\) :
-
Porosity
- \({\varepsilon}''\) :
-
Microwave energy dissipation coefficient, F/m
- \(\varepsilon_0\) :
-
Dielectric constant in vacuum, 8,85· 10−12 F/m
- π:
-
Pi number
- Subscripts :
-
- l:
-
Liquid
- s:
-
Solid
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Araszkiewicz, M., Koziol, A., Lupinska, A. et al. Microwave drying of various shape particles suspended in an air stream. Transp Porous Med 66, 173–186 (2007). https://doi.org/10.1007/s11242-006-9013-3
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DOI: https://doi.org/10.1007/s11242-006-9013-3