Heat and Mass Transfer

, Volume 44, Issue 8, pp 905–911 | Cite as

A diffusion based model for intermittent drying of rough rice

  • Ahmet Cihan
  • Kamil Kahveci
  • Oktay HacıhafızoğluEmail author
  • Antonio G. B. de Lima


In this study, intermittent drying behavior of single layer rough rice with a moisture content of between 22 and 24% on the dry basis was simulated by means of a liquid diffusion model based on a prolate spheroid geometry. For this purpose, solution of the liquid diffusion equation was fitted to the experimental data for the drying air temperature 40°C, drying velocity 1.5 ms−1 and tempering periods ranging from 0 to 1 h. In order to make a comparison, solution of the liquid diffusion equation for a finite cylindrical geometry was also fitted to the experimental data. The results show that the liquid diffusion model based on a prolate spheroid geometry explains the drying behavior of rough rice more accurately. The results also show that greater variations occur in diffusion coefficient with increasing tempering time for prolate spheroid geometry which is more realistic geometry for a rough rice grain.


Diffusion Coefficient Prolate Equilibrium Moisture Content Power Supply System Prolate Spheroid 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

List of symbols




correlation coefficient


dimensionless moisture concentration


diffusion coefficient (m2h−1)


sum of the squared differences


standard deviation




element of the set base function


0th order Bessel function


half-length of a rough rice grain (mm)


moisture content with respect to dry basis


moisture ratio


radius of a rough rice grain (mm)


dimensionless radial coordinate for the grain


surface area (mm2)


temperature (K)


dimensionless time


volume (mm3)


dimensionless axial coordinate along the grain

Greek symbols




n-th eigenvalue


roots of zeroth order Bessel function


roots of cosine function


mean squared deviation


relative humidity


tempering time (h)

dimensionless half-length of rough rice grain


n-th eigenfunction



dimensional quantities



equilibrium condition


initial condition


surface condition


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Ahmet Cihan
    • 1
  • Kamil Kahveci
    • 1
  • Oktay Hacıhafızoğlu
    • 1
    Email author
  • Antonio G. B. de Lima
    • 2
  1. 1.Mechanical Engineering DepartmentTrakya UniversityEdirneTurkey
  2. 2.Mechanical Engineering DepartmentFederal University of Campina GrandeCampina GrandeBrazil

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