低温热泵穿流干燥新鲜稻谷实验研究
Study on fresh paddy drying process in a cross-flow heat pump dryer
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摘要: 利用自主研发的搅拌式-热泵穿流干燥仓,研究了新鲜稻谷的脱水过程。考察了热泵干燥条件对稻谷干燥品质和过程性能的影响。结果表明,稻谷热泵干燥一直处于降速干燥阶段;当热泵干燥温度为35℃时,干燥仓可用7.5h将300kg稻谷从25%的初始含水率降至14%,过程单位能耗为2022kJ/kgwater,爆腰增率为1.3%。通过与热风干燥、自然晒干过程比较发现,较之自然晒干,热泵干燥可以大幅度缩短干燥时间,阻止稻谷发霉;较之热风干燥,温和的热泵干燥可以获得较低的爆腰增率,单位能耗低。该结论可以为基于热泵干燥技术的循环式干燥机以及间歇式大型干燥机械的开发提供依据。Abstract: 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.
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