A new hybrid drying technique by combining microwave and forced convection drying within a rotary drum, i.e., microwave rotary drying, was developed with the purpose to improve the uniformity of microwave drying. In a laboratory microwave rotary dryer, rewetted soybean was utilized as experimental material to study the effects of drum rotating speed, ventilation flow rate, and specific microwave power on the drying kinetics and cracking ratio of soybean. It was found that, with rotation, the cracking ratio can be lowered but without distinct improvement in the drying rate. Increasing ventilation flow rate and specific microwave power can improve the drying rate, but the cracking ratio also increases as a negative result. The cracking ratio lower than 10% can be attained for ventilation flow rate lower than 2.0 m3·h-1 or specific microwave energy lower than 0.4 kW·kg-1 in the present experiments.
Corresponding Author(s):
LI Zhanyong,Email:zyli@tust.edu.cn
引用本文:
. Soybean drying characteristics in microwave rotary dryer with forced convection[J]. Frontiers of Chemical Engineering in China, 2009, 3(3): 289-292.
Ruifang WANG, Zhanyong LI, Yanhua LI, Jingsheng YE. Soybean drying characteristics in microwave rotary dryer with forced convection. Front Chem Eng Chin, 2009, 3(3): 289-292.
Zhang M, Tang J, Mujumdar A S, Wang S. Trends in microwave related drying of fruits and vegetables. Trends Food Sci Tech , 2006, 17: 524-534 doi: 10.1016/j.tifs.2006.04.011
2
Datta Ashim K, Anantheswaran R C. Handbook of Microwave Technology for Food Applications. New York: Marcel Dekker, Inc, 2001
3
Manickavasagan A, Jayas D S, White N D G. Non-uniformity of surface temperatures of grain after microwave treatment in an industrial microwave dryer. Dry Technol , 2006, 24(12): 1559-1567 doi: 10.1080/07373930601030796
4
Dominguez-Tortajada E, Plaza-Gonzalez P, Diaz-Morcillo A, Balbastre J V. Optimisation of electric field uniformity in microwave heating systems by means of multi-feeding and genetic algorithms. Int J Mater Prod Tec , 2007, 29(1-4): 149-162 doi: 10.1504/IJMPT.2007.013134
5
Plaza-Gonzalez P, Monzo-Cabrera J, Catala-Civera J M. New approach for the prediction of the electric field distribution in multimode microwave-heating applicators with mode stirrers. IEEE T Magn , 2004, 40(3): 1672-1678 doi: 10.1109/TMAG.2003.821560
6
Plaza-Gonzalez P,Monzo-Cabrera J, Catala-Civera J M. Effect of mode-stirrer configurations on dielectric heating performance in multimode microwave applicators. IEEE T Microw Theory Tech , 2005, 53 (5): 1699-1706 doi: 10.1109/TMTT.2005.847066
7
George J, Bergman R. Selective Re-Meshing: a new approach to include mode stirring effects in the steady state FDTD simulation of microwave heating cavities. Microw Opt Techn Let , 2006, 48(6): 1179-1182 doi: 10.1002/mop.21572
8
Geedipalli S S R, Rakesh V, Datta A K. Modeling the heating uniformity contributed by a rotating turntable in microwave ovens. J Food Eng , 2007, 82: 359-368 doi: 10.1016/j.jfoodeng.2007.02.050
9
Bows J R. Variable frequency microwave heating of food. J Microwave Power EE , 1999, 34(4): 227-238
10
Yang H W, Gunasekaran S. Comparison of temperature distribution in model food cylinders based on Maxwell's equations and Lambert's law during pulsed microwave heating. J Food Eng , 2004, 64 (4): 445-453 doi: 10.1016/j.jfoodeng.2003.08.016
11
Anfinogentov V I, Garayev T K, Morozov G A. Optimization of dielectric microwave heating by moving radiator. In: Proceedings of the 12th International Conference on Microwave and Telecommunication Technology (IEEE Cat. No. 02EX570) , 2002, 2
12
Kudra T. Dielectric drying of particulate materials in a fluidized state. Dry Technol , 1989, 7 (1): 17-34 doi: 10.1080/07373938908916572
13
Feng H , Tang J. Microwave finish drying of diced apples in a spouted bed. J of Food Sci , 1998, 63 (4): 679-683
14
Reyes A, Campos C, Vega R. Drying of turnip seeds with microwaves in fixed and pulsed fluidized beds. Dry Technol , 2006, 24, 1469-1480 doi: 10.1080/07373930600952818
15
Itaya Y, Uchiyama S, Hatano S, Mori S. Effect of scattering by fluidization of electrically conductive beads on electrical field intensity profile in microwave dryers. Dry Technol , 2005, 23(1-2): 273-287 doi: 10.1081/DRT-200047956
