2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 163 -
Finite cylindrical shape:
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eq
2
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in eq
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-
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1 -9π Dt
1
-25π Dt
MR=
=
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+ exp
+ exp
*
M -M
π
L 9
L 25
L
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2 2
1 0
2 0
3 0
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4×
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λ Dt +
exp - λ Dt +
exp - λ Dt
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λ r
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(7)
The effective diffusion coefficient of water can be
correlated with temperature using the Arrhenius equation
[11].
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RT
aE
exp 0D effD
(8)
IV. RESULTS AND DISCUSSION
A. Equilibrium moisture content (EMC)
From the experiment, the EMC value of GABA
Sungyod rice for the temperature ranges of 40 to 60
q
C
and relative humidity from 10 to 90%. When statistical
analyzed in form of conventional mathematics EMC
model by non-linear regression method. The best fitted
coefficients of the EMC equations were simulated and
shown in Table 3. The results showed that the simulated
results using Modified Oswin model was the best fitted to
the experimental results (R
2
=0.9800 and RMSE=0.0611).
Therefore, the Modified Oswin model used to determine
the relationship of temperature, RH and EMC for analysis
of thin layer drying equation and study the drying
kinetics of GABA rice drying.
TABLE III
CONSTANT OF EQUILIBRIUM MOISTURE CONTENT FOR
GABA SUNGYOD RICE IN RANGE
RELATIVE HUMILITY 10-90%
Model
Constants of
model
R
2
RMSE
Oswin
A=0.072
B=0.4217
0.9438
0.1024
Henderson
A=0.1190
B=1.5663
0.9518
0.0948
Halsey
A= 15.2697
B=-1.7937
0.9373
0.1081
Modified
GAB
A= 38.4299
B=0.0345
C=38.5740
0.9404
0.1055
Modified
Oswin
A=0.5452
B=0.0014
C=0.4048
0.9800
0.0611
The simulated results for all EMC models and
experimental results were fitted for GABA Sungyod rice
as shown in Fig. 1.
Fig. 1. Equilibrium moisture content models of GABA Sungyod
rice at relative humidity from 10 to 90% for temperature 60
q
C.
B.
Apparent density (ρ)
The apparent densities of the GABA Sungyod rice
which was determined by Eq. (3). Result from the
determination of apparent density of GABA rice showed
that apparent density linearly related to moisture content
increased from 507.85 to 574.25 kg/m
3
for the Sungyod.
The calculated results and experimental results were
plotted and illustrated in Fig. 2 while relationships of
apparent density with moisture content of the GABA rice
are expressed in Eq. (9).
Fig. 2. Ralation between apparent density and moisture content
for GABA rice at 20-50% dry-basis.
453.649
2.416M
ρ
(9)
with value of R
2
= 0.998 RMSE = 0.975
C.
Void fraction (ε)
The void fractions of the GABA rice which was
determined by Eq. (4). The results showed that the
percentage of void fraction for GABA rice decreased
with increase of moistness content. The percentage of
void fraction was linearly dependent on moisture content
and was expressed by the following Eq. (10) and Fig. 3.
0.0
5.0
10.0
15.0
20.0
0 10 20 30 40 50 60 70 80 90
Equilibrium moisture content
(% dry-basis)
Relative humility (%)
Experimental data
Oswin's model
Henderson's model
Halsey's model
Modified GAB's model
Modified oswin'model
500
520
540
560
580
600
0 10 20 30 40 50 60
Apparent density (kg/m
3
)
Moisture content (%d.b)
Experimentaldata
(Sungyod)
Model(Sungyod)
