MODELLING A MICROWAVE/CONVECTION DRYER FOR DRYING OF POTATO SLICES | ||||
| Misr Journal of Agricultural Engineering | ||||
| Article 8, Volume 29, Issue 4, October 2012, Page 1377-1398 PDF (627.73 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/mjae.2012.101193 | ||||
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| Authors | ||||
| Samir Tayel1; T. H. Ghanem1; A. A. El-Messery1; M.M. Badr2 | ||||
| 1Prof. of Ag. Eng., Fac. of Ag., Al-Azhar Univ., Cairo, Egypt. | ||||
| 2Assist. Lecturer of Ag. Eng., Fac. of Ag., Al-Azhar Univ., Cairo, Egypt. | ||||
| Abstract | ||||
| The aim of the present study is modeling a developed microwave/convection dryer using similitude analysis for drying a thin layer of potato slices (Solanum Tuberosum), which can be helpful in design and operation criterion of this developed thin layer dryer type for drying other agricultural products. Drying time as affected by microwave power and drying air temperature, effective diffusivity "Deff", compatibility of experimental data to Lewis Newton's thin layer drying model and rehydration and color as quality indicators were also studied. Four different levels of microwave power, namely: 85, 175, 250 and 320W, three different drying air temperatures of drying air are 40, 50 and 60oC with air velocity of 1.5 m/s were studied. The results show that the drying time was decreased by increasing microwave power and air temperature. The effective moisture diffusivity "Deff" increased with decreasing moisture content, maximum values of "Deff" were recorded at highest microwave power of 320 W. Lewis Newton's thin layer drying model was highly compatible to experimental data with R2 ranging between 0.754 to 1.00. The rehydration ratios ranged between 2.19 to 3.41 under various drying conditions. There is no significant change in color of the dried potato compared to fresh potato slices | ||||
| References | ||||
|
Crank, J., (1975). The mathematics of diffusion, 2nd ed., Oxford U. Press , Oxford.
Ghanem, T.H., (1998). Solar energy utilization, specifically on drying or sterilization of animal manure under Egyptian conditions for use as protein supplement in animal feed, Ph. D. Th., Ag. Eng. Dept., Fac., of Ag. Al-Azhar Univ.
Ghanem, T.H., (2010). Modeling of refractance window film dryer for liquids. Misr J. Eng., 27 (2): 676 – 687.
Gowen, A. A.; N. Abu- Gannam; J. Frias and J. Oliveira, (2008).Modeling dehydration and rehydration of cooked soybeans subjected to combined microwave- hot air drying. Innovative Food Sc. and Emerging Tec., 9: 129 – 137.
Khraisheh, M. A. M.; T. J. R. Cooper and T. R. A. Magee, (1997).Microwave and air drying. Fundamental considerations and assumptions for the simplified thermal calculations of volumetric power absorption. J. Food Eng., 33: 207 – 219.
Langhaar, Henry L., (1951). Dimensional analysis and theory of models, John Wiley and Sons, INC.
Metaxas, A. C. and R. J. Meredith, (1983). Industrial microwave heating. Peter Pereginus, London, UK.
Reddy, L., (2006). Drying characteristics of Saskatoon berries under microwave and combined microwave-convection heating. M. Sc. Th., Dep. Ag. and Bioresours Eng., U. Saskatchewan, Saskatoon, Canda.
Sanga, E.; A. S. Mujumdar and G. S. Raghavan, (2000). Drying technology in agriculture and food sciences (Principle and applications of microwave drying). Sc. Pub., Lnc. Plymouth, UK: 253 – 289.
Sarsavadia, P. N.; R. L. Sawhney; D. R. Pangavhane and S. P. Singh, (1999). Drying behavior of brined onion slices. Journal of Food Eng., 40: 219- 226.
Sharma, G. P. and S. Prasad, (2001).Drying of garlic (Allium sativum) cloves by microwave- hot air combination. J. Food Eng., 50: 99 – 105.
Shivhare, U. S.; G.S. Raghavan and R. Bosisio, (1991). Drying of corn using Variable microwave power with a surface wave applicator. J. Microwave Power and Electromagnetic Energy, 26 (1): 38 – 44.
Toledo, R. T., (1991). Fundamentals of food process engineering. An AVI book Pub. By Van Nostrand Reinhold. N. Y.: 133- 136.
Torringa, E.; E. Esveld; I. Scheewe; R. B. Vanden and P. Bartels, (2001). Osmotic dehydration as a pre-treatment before combined microwave-hot air drying of mushrooms. J. Food Eng., 49 (2): 185 – 191.
Tulasidas, T. N.; G. S. Raghavan and E. R. Norris, (1993). Microwave and convective drying of grapes. Trans. ASAE, 36: 1861 – 1865.
Yongsawatdigul, J. and S. Gunasekaran, (1996). Microwave vacuum drying of cranberries. Part I: Energy use efficiency. Part II: Quality evolution. J. Food Proc. and Preservation, 20: 121 – 143.
Zhou, L.; V. M. Puri and R. C. Anantheswaran, (1994). Effect of temperature gradient on moisture migration during microwave heating. Drying Tec., 12 (4): 777 – 798. | ||||
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