Study on fresh paddy drying process in a cross-flow heat pump dryer

The drying process of paddy in a cross-flow heat pump dryer with a stirring device to mix paddy was studied.The influence of temperature and drying rate on quality and the specific energy consumption was investigated.A falling drying rate period was visible during heat pump drying.The result showed that it took about 7.5h to dehydrate 300kg of fresh paddy from moisture content of 25% w.b.to 14% w.b.Meanwhile, the specific energy consumption during the drying process was 2022kJ/kg water, and the crack additional percentage was 1.3%.Compared with solar drying, the heat pump dryer could reduce the drying time and save paddy from moldy.And the heat pump drying could decrease the specific energy consumption and reduce the crack additional percentage compared with hot air drying.These results might be capable of research on recirculating type paddy dryer and batch type paddy dryer based on the heat pump drying.