为阐明秸秆纤维尺寸对真空脱水成型的育秧基质块干燥及吸水速率的影响,利用粗粉发酵磨浆(A),细粉发酵磨浆(B),细粉发酵(C)3种纤维处理工艺经真空脱水制备水稻育秧基质块,通过基质块中纤维尺寸频率分布、纤维与水分结合能,结合不同基质块孔隙度、干燥和吸水速率变化,拟合出育秧基质块的干燥及吸水模型.结果表明,磨浆和粉碎分别减小纤维直径和长度,基质块A的纤维长宽比最大为19.5,持水孔隙和总孔隙度分别达到85.66%和93.48%,纤维与水分结合能(XA=0.11 kg water/kg DS)显著优于其余纤维处理工艺.干燥动力学Logarithmic模型较优拟合出基质块水分损失速率,纤维长宽比最小的基质块C的水分干燥速率最快为0.29 kg/(kg·h),水分扩散系数最大为1.962×10-5 m2/s,基质块C达到饱和含水率的时间最短为61.5 min,但饱和含水率数值最低为531.06%.综上所述,细分发酵工艺制备的纤维长宽比小的基质块干燥效率和吸水速率最优.
Effect of Straw Fiber Size on Drying and Water Absorption Rate of Straw Rice Seeding Mats
The aim was to illustrate the effect of straw fiber size on drying and water absorption rate of vacuum dehydrated seeding mats.In this paper,rice seedling mats were prepared by vacuum dehydration using three fiber processing techniques including coarse crushing fermentation grinding(A),fine crushing fermentation grinding(B)and fine crushing fermentation(C).According to the fiber size frequency distribution,fiber and water binding energy in the seedling mats,combined with the changes of porosity degree,drying and water absorption rate of different seedling mats,we simulated the drying and moisture absorption model of seedling mats,respectively.The results showed that the fiber diameter and length were reduced by defibrination and grinding respectively.The fiber length-to-width ratio of seedling mat A was up to 19.5,and the water-holding porosity degree and total porosity degree reached 85.66%and 93.48%,respectively.The binding energy of fiber and water(XA=0.11kg water/kg DS)was significantly better than those of other fiber treatments.The Logarithmic model of drying kinetics might fit the water loss rate of seedling mats optimally.The seedling mat C with the smallest fiber length-to-width ratio had the fastest moisture drying rate of 0.29 kg/(kg·h),the highest water diffusion coefficient was 1.962×10-5 m2/s,and the shortest time for matrix seedling mat C to reach the saturated water content was 61.5 min.However,the saturation moisture content was the lowest to 531.06%.In summary,the seedling mat by fine crushing fermentation with smaller fiber aspect ratio has the better drying efficiency and water absorption rate.
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