Effect of swing temperature and alternating airflow on drying uniformity in deep-bed wheat drying

摘要

Lack of timely drying after harvesting resulted in grain losses of approximately 30 million tons in China. Considering the small-scale production mode in rural China, we investigate a new fixed bed drying method that features swing temperature and alternating airflow. Heating and tempering processes are linked and combined in both time and space. The ratio range of the normal flow heating time to the reverse flow heating time with the best wheat drying uniformity under the conditions of the total heating time 78 min is from 0.733 to 0.902. The wheat drying uniformity with tempering is higher by 2.55%, with an improvement rate of 58.7%, compared with that without tempering. With the same heat supply, extending the time and changing the air velocity at the tempering stage exert minimal influence on wheat drying uniformity. Increasing the temperature at the tempering stage effectively improves the wheat drying uniformity with deep-bed and the blower power consumption reduces, but the heat efficiency decreases. Moreover, the wheat drying uniformity improves with increasing air velocity in both drying and tempering processes. According to the drying capacity and economic analysis, the STAA is better than fluidized bed. (C) 2016 Elsevier Ltd. All rights reserved.