2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 170 -
TABLE
II
D
ETERMINATION OF EQUILIBRIUM MOISTURE CONTENT
(
EMC
)
FOR UNSMOKE SHEET RUBBER
Model
Arbitraryconstants
R
2
RMSE
A
B
C
D
E
Modified Halsey [5]
0.37689
-33174.9610
107.42137
2.26379
-
0.953
0.00029
Modified Oswin [9]
0.41698
-0.00248
3.68431E-06
0.53727
0.00137
0.949
0.00030
Modified Henderson [9]
27158.897
-308.29795
2.22803
-
-
0.879
0.00046
Modified Smith [10]
0.04435
0.00013
1.59189E-08
-
-
0.835
0.00054
Fig. 4 Illustrates the effect of relative humidity on
EMC value of piece of rubber sheet among air
surrounding temperature of 40°C and relative humidity of
10-90%, it shows that the EMC increased with increasing
of RH at constant temperature, the Modified Halsey
model has good relation to the experimental values.
0.0
0.2
0.4
0.6
0.8
1.0
0
20
40
60
80 100
Equilibrium Moisture Content
(%dry-basis)
Relative Humidity (%)
Experiment 40ºC
Modified Halsey
Modified Oswin
Modified Henderson
Modified Smith
Fig. 4. Comparison equilibrium moisture content between experimental
data and expected data of NR at relative humidity of 10-90% and
temperatures of 40°C.
B. Drying kinetic and mathematics model
Fig. 5, 6, 7 and 8 show the moisture ratio during drying
time at various drying strategies. Fig. 5 showed that the
drying of combined green house 48 hours and
conventional faster period than combined green house 24
hours and conventional drying. Fig. 6 showed that
temperature in the combined open sun and conventional
drying was found that the moisture ratio is similar.
However, the drying time at high temperatures faster than
at low temperatures.
0.0
0.2
0.4
0.6
0.8
1.0
0 50 100 150 200 250 300
Moisture Ratio, MR
Drying time (h)
GH 24hr (31.5ºC, RH= 60%) +
Conventional (28.7ºC, RH= 55%)
GH 48hr (35.0ºC, RH= 67%) +
Conventional (29.3ºC, RH= 51.5%)
Fig. 5. Evolution of the moisture ratio of unsmoked sheet rubber using
combined a green house and conventional drying.
0.0
0.2
0.4
0.6
0.8
1.0
0
100
200
300
400
Moisture Ratio, MR
Drying time (h)
Open sun 12hr (26.8 ºC, RH= 58%)
+ Conventional (28.1ºC, RH= 60%)
Open sun 24hr (27.4ºC, RH= 55%)
+ conventional (28.9ºC, RH= 55%)
Open sun 48hr (27.8ºC, RH= 55%)
+ Conventional (29.5ºC, RH= 53%)
Fig. 6. Evolution of moisture ratio of unsmoked sheet rubber using
combined open sun and conventional drying.
0.0
0.2
0.4
0.6
0.8
1.0
0
100
200
300
Moisture Ratio, MR
Drying Time (h)
IR 4000W (63
°
C)
Hot- air (62.1ºC)
GH (36.1ºC, RH= 65.6%)
Open sun 12hr (26.8 ºC, RH= 58%)
+ Conventional (28.1ºC, RH= 60%)
Fig. 7. Evolution of moisture ratio with drying time of unsmoked rubber
sheet at any drying conditions.
Fig. 7 comparison of moisture ratio between
experimental of unsmoked rubber sheet at any drying
conditions, showed that the effect of energy used in
drying rubber during temperature 26-64ºC was found that
drying with infrared radiation alone can reduce the
moisture content of materials to be faster than other
energy source, that would be caused by radiation heat
thermal infrared radiation can pass into the material than
the heat transfer by convection alone. Comparison of
drying with the drying conditions in both the case of a
drying one step and two steps, all conditions showed that
factors affecting the drying temperature, drying rate and
dried at high temperatures used in drying time is shorter
than the drying temperature range under all sources of
heat.
At the beginning of drying time, moisture ratio of
rubber decreased rapidly because the main part of
moisture content of sample exists around the exterior
surface, thus allowing the easier water removal without
