Drying Characteristics of Carrot and Green Pumpkin Slices in Waste Heat Dryer

  • Lee, Gwi-Hyun (Department of Biosystems Engineering, Kangwon National University)
  • Received : 2012.01.29
  • Accepted : 2012.02.29
  • Published : 2012.02.25


Purpose: Drying characteristics of the sliced carrot and green pumpkin were investigated by using the waste heat dryer. Methods: The effects of drying temperature ($T$) and slice thickness affecting drying time were analyzed. Mathematical models for the drying curves were determined with statistical analysis of drying data. Effective diffusivity was determined for the slices of carrot and green pumpkin under various drying conditions. Results: Drying time was reduced at the drying conditions of thinner slice and higher drying temperature. Moisture ratio ($MR$) according to drying time ($t$) was well presented as an exponential function at all of drying conditions for the slices of carrot and green pumpkin with the determination coefficient ($r^2$) of >0.99. The values of effective diffusivity ($D_{ff}$) of the slices for carrot and green pumpkin were increased with increasing the drying temperature. The relationship between Ln($D_{ff}$) and $1/T$ was linear with the determination coefficient ($r^2$) of >0.97. Conclusions: Drying model was well established as an exponential function at all of drying conditions for drying samples.


Grant : Forest Science & Technology Projects

Supported by : Korea Forest Service


  1. Abe, T. and T. M. Afzal. 1997. Thin-layer infrared radiation drying of rough rice. Journal of Agricultural Engineering Research 67:289-297.
  2. Adu, B. and L. Otten. 1996. Diffusion characteristics of white beans during microwave drying. Journal of Agricultural Engineering Research 64:61-70.
  3. Afzal, T. M. and T. Abe. 2000. Simulation of moisture changes in barley during far infrared radiation drying. Computers and Electronics in Agriculture 26:137-145.
  4. Chinnan, M. S. 1984. Evaluation of selected mathematical models for describing thin-layer drying of in-shell pecans. Transactions of the ASAE 27(2):610-615.
  5. Coumans, W. J. 2000. Models for drying kinetics based on drying curves of slabs. Chemical Engineering and Processing 39:53-68.
  6. Crank, J. 1975. The Mathematics of Diffusion. 2nd ed. Oxford, UK: Clarendon Press.
  7. Doymaz, I. and M. Pala. 2002. Hot-air drying characteristics of red pepper. Journal of Food Engineering 55(4): 331-335.
  8. Duc, L. A., S. J. Hong, J. W. Han and D. H. Keum. 2008. Estimation of effective moisture diffusivity of rapeseed (Brassica napus L.). Journal of Biosystems Engineering 33(5):296-302.
  9. Ekechukwu, O. V. 1999. Review of solar-energy drying system I: an overview of drying principles and theory. Energy Conversion and Management 40:593-613.
  10. Fu, W. and W. Lien. 1998. Optimization of far infrared heat dehydration of shrimp using RSM. Journal of Food Science 63(1):80-83.
  11. Henderson, J. M. and S. M. Henderson. 1968. A computational procedure for deep-bed drying analysis. Journal of Agricultural Engineering Research 13(2):87-95.
  12. Henderson, S. M. and S. Pabis. 1961. Grain drying theory: I. Temperature effects on drying coefficient. Journal of Agricultural Engineering Research 6(3):169-174.
  13. Henderson, S. M. and R. L. Perry. 1976. Agricultural Process Engineering. Westport, CT: AVI Publishing Co.
  14. Kim, H. and J. W. Han. 2009. Low temperature drying simulation of rough rice. Journal of Biosystems Engineering 34(5):351-357 (In Korean, with English abstract).
  15. Lee, G. H, W. S. Kang and F. Hsieh. 2004. Thin-layer drying characteristics of chicory root slices. Transactions of the ASAE 47(5):619-1624.
  16. Lee, G. and F. Hsieh. 2008. Thin-layer drying kinetics of strawberry leather. Transactions of the ASAE 53(5): 1699-1705.
  17. Madamba, P. S., R. H. Driscoll and K. A. Buckle. 1996. The thin-layer drying characteristics of garlic slices. Journal of Food Engineering 29(1):75-97.
  18. Misra, M. K. and D. B. Brooker. 1980. Thin-layer drying and rewetting equations for shelled yellow corn. Transactions of the ASAE 23(5):1254-11260.
  19. Osborn, G. S., G. M. White and L. R. Walton. 1991. Thinlayer moisture adsorption equation for soybeans. Transactions of the ASAE 34(1):201-206.
  20. Pabis, S. and S. M. Henderson. 1961. Grain drying theory: II. Journal of Agricultural Engineering Research (4): 272-277.
  21. Parry, J. L. 1985. Mathematical modeling and computer simulation of heat and mass transfer in agricultural grain drying: A review. Journal of Agricultural Engineering Research 32(1):1-29.
  22. Ramesh, M. N., W. Wolf, D. Tevini and G. Jung. 2001. Influence of processing parameters on the drying of spice paprika. Journal of Food Engineering 49(1): 63-72.
  23. Sarsavadia, P. N., R. L. Sawhney, D. R. Pangavhane and S. P. Singh. 1999. Drying behavior of brined onion slices. Journal of Food Engineering 40(3):219-226.
  24. Simal, S., A. Femenia, P. Llull and C. Rossello. 2000. Dehydration of aloe vera: simulation of drying curves and evaluation of functional properties. Journal of Food Engineering 43(2):109-114.
  25. Tang, J. and S. Sokhansanj. 1993. Moisture diffusivity in laird lentil seed components. Transactions of the ASAE 36(6):1791-1798.
  26. Weres, J. and D. S. Jayas. 1994. Thin-layer drying of corn: Experimental validation of a new numerical structural model. Canadian Agricultural Engineering 36(2): 85-91.
  27. Youcef-Ali, S., H. Messaoudi, J. Y. Desmons, A. Abene and M. L. Ray. 2001. Determination of the average coefficient of internal moisture transfer during the drying of a thin bed of potato slices. Journal of Food Engineering 48(2):95-101.
  28. Young, J. H. and T. B. Whitaker. 1971. Evaluation of the diffusion equation for describing thin-layer drying of peanuts in the hull. Transactions of the ASAE 14(2): 309-312.