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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
Original

Abstract

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.

Keywords

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

C

constant

CC

correlation coefficient

c

dimensionless moisture concentration

D

diffusion coefficient (m2h−1)

E

sum of the squared differences

Es

standard deviation

d

constant

f

element of the set base function

J0

0th order Bessel function

L

half-length of a rough rice grain (mm)

m

moisture content with respect to dry basis

mr

moisture ratio

R

radius of a rough rice grain (mm)

r

dimensionless radial coordinate for the grain

S

surface area (mm2)

T

temperature (K)

t

dimensionless time

V

volume (mm3)

z

dimensionless axial coordinate along the grain

Greek symbols

2

laplacien

γn

n-th eigenvalue

αn

roots of zeroth order Bessel function

βn

roots of cosine function

χ2

mean squared deviation

φ

relative humidity

τ

tempering time (h)

dimensionless half-length of rough rice grain

ψn

n-th eigenfunction

Superscript

*

dimensional quantities

Subscripts

e

equilibrium condition

o

initial condition

s

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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