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谷倉低溫通風降溫效果之研究
Effect of Chilled Aeration on Cooling Rate of Stored Paddy
摘要
降溫是人們延長農產品保存期限的重要方法之一。本文主要在探討低溫通風時，稻穀溫度與進氣溫度之差異程度、進氣溼度和穀層高度等因素影響稻穀降溫速率的趨勢以及含水率變動之情形。 低溫通風試驗設定的條件為通風量0.92CMM/t，通風溫度介於20.1℃~21.2℃，溼度介於34.6%~56.2%，貯穀含水率介於13.6%~14.3%(w.b.)，穀溫與進氣溫差11℃~20℃。貯存稻穀之圓筒高度3.5公尺，直徑0.35公尺。當穀溫與進氣溫差愈大時，貯穀降溫速率愈快，所以低溫通風方式能有效地降低穀溫。降溫速率隨著穀層高度之增加而遞減，因此在低溫通風作業必須等待上層穀溫經歷降溫的主要時期以後，才可停止通風，以使通風降溫的效果完全發揮。迴歸分析結果為：降溫速率(℃/h)=(0.2)×（穀溫與進氣溫差，℃）-(0.015)×（穀層高度，m）+2.2。 通風24小時後穀物含水率下降約0.6%~1.1%(w.b.)，通風前後稻穀含水率具有顯著差異。
並列摘要
Reducing temperature is one of the important methods for extending the expiration date of agricultural product. The objective of this study was to study the effects of chilled aeration on cooling rate, adsorption and desorption of stored paddy. The chilled aeration treatments were airflow at 0.92 CMM/t, chilled air temperature between 20.1℃ and 21.2℃,relative humidity between 34.6% and56.2%,and paddy temperature between 31℃ and 41℃.The experimental silo measures 3.50 m in height and 0.35 m in diameter. A step-by-step regression equation was developed as in the following: cooling rate(℃/h)=(0.2)×(temperature difference between paddy and chilled air,℃)-(0.015)×(paddy layer height, m)+2.2 The greater the temperature difference between paddy and chilled air is, the faster the cooling rate. The application of low-temperature air can effectively reduce the temperature of the paddy. The cooling rate is reduced proportionally to the increase of the depth of paddy layer. Aeration process can be stopped only when cooling zone has passed through the upper layer paddy. After 24 hours of chilled aeration, the decrease of paddy moisture content was found between 0.6% and 1.1% w.b. with statistical significance.