| Summary: | 碩士 === 國立中興大學 === 農業機械工程學系 === 84 === The manner of recirculating rice dryers which is extensively
used in Taiwanis intermittent drying. Intermittent drying is
composed of heating and tampering. A drying cycle includes
heating time and tempering time. In a drying cycle, the drying
time is used to be fixed and the tempering time changes and
signifcantly affects the drying rate and milling quality of
rice.this study focus on the effectof tempering time on drying
rate and milling quality of rice for recirculating drying. the
testing items of quality includethe percentage of brown rice,
polished rice, head yield and germination rate. According to
the experimental results, the following conclusions are drawnas
below:<1> If the tempering time is not included, the heating
time is fixed and the tempering time in a cycle increase,
the total heating time become longer. It points out extending
the tempering time for drying cycle can increase the average
drying rate for only the heating period. On the contrary, if
the tempering time is counted, the drying rate will decrease
with the increase of the tempering time.<2> When the drying
air temperature is above 50℃,the percentage of polished rice
for intermittent drying is higher than continuous drying.
Tempering process benefits the production of polish rice.<3>
The drying air temperture influences more on the head yield than
the time ratio of heating and tempering. When the drying air
temperature is over 50℃, head yield drops obviously for both
intermittent drying and continuous drying.<4> The percentage
of head yield of intermittent drying is always higher than
continuous drying. the percentage of head yield decrease with
the decrease of the tempering time. When tempering time is
less then 70 minites, the percentage of head yield declines
significantly. Therefore, in order to prevent the loss of
the percentage of head yield, the tempering time in a drying
cycle should not be less then 1/7.<5> Drying air temperature
influence the percentage of germination more then tempering.
When the drying air temperature is above 60℃, the percentage
of germination drops apparently. The percentage of germination
for intermittent drying is higher than continuous drying.
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