2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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110°C and the air flow was passed through the
crumb rubber from the top to the bottom (one
direction).
x
Strategy III, the drying was carried out over 2 stages;
stage 1 the rubber was dried at 130°C with 40 min
drying time and the air flow was passed through the
skim rubber from the top to the bottom and followed
by stage 2 dried at 110°C and the air flow was passed
through the skim rubber from the bottom to the top
(two direction).
Fig.5. Comparisons simulated with experimental average moisture ratio of skim rubber drying ;initial moisture content of 47.5-50.6% dry-basis, final
moisture content of 0.5% dry-basis, drying temperature of 120 to 140
q
C and bed depth of 0.30 m and fraction of recycle of 90%.
Effect of Specific Air Flow Rate
Fig. 6 shows the effect of specific mass flow rate on
specific energy consumption and drying time at drying air
temperature 100-130
q
C. The simulated drying conditions
are specific mass flow rate varying from 0.03 to 0.13 kg
of dry air/s-kg of dry rubber, fraction of air recycled (RC)
of 95 %, initial skim rubber weight of 16.74 kg, ambient
temperature of 30
q
C, and initial moisture content and
final moisture content of 48% and 0.5% dry-basis,
respectively. It is found that SEC depends upon the
specific mass flow rate, namely, the SEC decreases with
increasing specific mass flow rate to a minimum point,
and the SEC increases due to an expressively specific
mass flow rate. It is also found that drying time depends
upon the specific mass flow rate, namely, the drying time
decreases rapidly with increasing specific mass flow rate
when
specific mass flow rate is small; afterwards, the
drying time is nearly constant
.
This is because the higher air flow rates are used a
short drying time and the higher temperature gradient at
the solid surface and though the block rubber resulted in a
higher heat flux. Since the heat flow was faster when air
flow rates were higher, the duration of the vaporization
heating phase was shorter. However, drying with low air
flow rates may reduce specific energy consumption due
to low cost of heat but a long drying time due to higher
cost of operation.
Effect of Drying Air Temperature
The effects of drying air temperature on SEC are also
study. Fig. 6 shows SEC and drying time versus drying
temperature. The simulated drying conditions are drying
air temperature varying from 100 to 130
q
C, fraction of air
recycled (RC) of 95%, specific mass flow rate of 0.03 to
0.13 kg of dry air/s-kg of dry rubber, initial skim rubber
weight of 16.74 kg, ambient temperature of 30
q
C, and
initial moisture content and final moisture content of 48%
and 0.5% dry-basis, respectively. It
is found that the
drying air temperature affect on SEC and drying time,
namely, the SEC decreases a little bit with increasing
drying air temperature. The drying time decreases
markedly with increasing drying air temperature.
However, the drying air temperature should not
exceed 130
q
C due to the limitation of product quality.
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Average moisture ratio
Drying time (min)
Experiment No.1
Simulation
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Drying time (min)
Experiment No.2
Simulated
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Average moisture ratio
Drying time (min)
Experiment No.4
Simulation
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Average moisture ratio
Drying time (min)
Experiment No.5
Simulation
