Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/35483
標題: 乾燥條件對稻穀乾燥之影響
Effects of drying condition on rice curing
作者: Huang, I-Lin
黃異麟
關鍵字: Rice curing;稻穀乾燥;Drying condition;乾燥條件
出版社: 農業機械工程學系
摘要: 
本研究旨在探討乾燥條件對稻穀乾燥的影響。以大量稻穀模擬實際稻
穀乾燥作業,乾燥條件包含乾燥熱風溫度、相對濕度與風量。經由穀層厚
度50公分之大量稻穀進行乾燥實驗,分析熱風乾燥穀層現象與稻穀之碾米
率,以尋求最適之乾燥條件。 由加溫間歇式乾燥實
驗(乾燥/均化時間比為15/75分鐘)發現,對於穀層厚度10公分之薄層乾
燥而言,通風溫度與濕度對於乾燥速率有顯著影響,但風量的影響則較不
顯著;在穀層厚度10公分以上之厚層乾燥方面,乾燥條件設定為通風溫
度45℃、相對濕度 2.7%、風量0.23 cmm/kg 時,各穀層之乾燥效果有較
佳之均勻性。由常溫連續式乾燥實驗發現,通風溫度30℃、相對濕度8.7
%、風量 0.23cmm/kg之乾燥條件,其乾燥效果可達到穀層厚度50公分處
,而使各穀層稻穀之乾燥效果均勻性大幅提高,同時能大量縮短實際乾燥
作業時間。
當乾燥深度小於10公分之薄層間歇加熱乾燥,其含水率變化之實驗值,與
牛頓修正模式之預測值高度相關,決定係數 R-square皆達0.99以上;模
式中之A、k值則依據乾燥條件而建立一複直線迴歸方程式,其複相關係
數亦皆高達0.92以上。在常溫連續式乾燥實驗結果中,牛頓修正模式與擴
散模式皆適稱,其決定係數 R-square皆達0.99以上。 當通風溫
度在40℃以下時,溫度對薄層乾燥之稻穀完整米率沒有明顯的影響,其完
整米率皆達71%以上;但通風溫度高於45℃時,溫度提高則完整米率急遽
下降,當溫度為50℃時約下降 2%。對於厚層乾燥而言,完整米率將隨著
穀層厚度的增加而提高。

In this research, the effects of the hot-air conditions on
rice mechanical curing are studied. The investigating parameters
include the hot-air temperature, the relative humidity and the
air flow rate. By using a stationary type drying machine to cure
rice of 50 cm deep layer, the optimum drying conditions are
obtained through the analysis of the drying phenomenon and the
milling yields in different rice layers.
The result of the the intermittent drying test (15 min drying
time / 75 min drying time) indicate that the hot-air temperature
and the relative humidity has significant influence on the
drying rate, yet the effect of the air flow rate is secondary as
the depth of the layer lower than 10 cm. A better drying
condition of the hot-air temperature 45℃, relative humidity
2.7% and air flow rate 0.23 cmm/kg is obtained. This condition
can better cure rice more uniformly up to layer depth of 30 cm.
For the continuous drying test, the best drying condition of air
temperature 30℃, relative humidity 8.7%RH and air-flow rate
0.23cmm/kg is demonstrated. This drying condition can raise the
drying ability dramatically and uniformly cover the drying layer
up to 50cm. The drying time is also reduced as compared to the
former tempering test. When the layer depth
lower than 10 cm, the intermittent and continuous drying tests
are in consistent with the thin layer model. For the
intermittent drying experiment, the modified Newton's model can
precisely predict the moisture content change and all the
coefficients of determination R-square are larger than 0.99.
Using the multiple linear regression principle, the relations of
parameters A(constant coefficient) and k(drying constant) relate
to the hot-air drying conditions are established respectively.
Both equations are highly correlated to the drying conditions
performed, and the multiple correlation coefficients of this two
cases are higher than 92%. During the continuous drying
processes, the moisture content changes can be accurately
predicted from equations respectively derived from the modified
Newton's model and the diffusion model. It is found that the
diffusion equation is more suitable on this case and all the
coefficients of determination arelarger than 99%. The
experimental results also show that the milling property of rice
is not affected by temperature lower than 40℃ and the value of
head yield is up to 71% as the drying layer lower than 10 cm.
When the hot-air temperature increases over 45℃, the head yield
rate rapidly drops and the dropping value is about 2% at
temperature 50℃. In the deep layer drying, the head yield rate
is raised as the depth of drying layer increased.
URI: http://hdl.handle.net/11455/35483
Appears in Collections:生物產業機電工程學系

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