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Thin-Layer Models for Intermittent Drying of Rough Rice

¹PhD candidate, Dept. of Agricultural Machinery Engineering, National Taiwan University, 136 Chou-Shan Road, Taipei, Taiwan, Republic of China. ²Corresponding author. E-mail: hjshieh@ms12.hinet.net ³Professor, Dept. of Agricultural Machinery Engineering, National Taiwan University, 136 Chou-Shan Road, Taipei, Taiwan, Republic of China.

Thin-layer drying data was collected for rough rice from 108 treatments. Four thin-layer equations were derived by regression analysis to predict the drying behavior for deep-bed drying of rough rice. The proposed equations consider the effects of drying air temperature, drying air absolute humidity, drying time interval, and tempering time interval. Drying air temperature range was 35–65°C, drying air absolute humidity range was 10–26 g/kg of dry air, drying time interval was 5–15 min, and tempering time interval was 40–120 min. In addition, the variations of moisture content with tempering time intervals and drying time intervals were considered. Within the tempering time interval range of 40–120 min and drying time interval of 5–15 min, a shorter drying time interval and a longer tempering time interval are preferable in a recirculating type rice dryer.