【目的】探究不同部位烟叶烘烤过程中的水分变化及干燥数学模型,为准确预测烟叶烘烤过程水分变化及烟草精准烘烤提供理论依据。【方法】以大理州凤仪烟区烤烟品种云烟85不同部位烟叶为试验材料,运用水分干燥理论,选取6种常用的水分干燥...【目的】探究不同部位烟叶烘烤过程中的水分变化及干燥数学模型,为准确预测烟叶烘烤过程水分变化及烟草精准烘烤提供理论依据。【方法】以大理州凤仪烟区烤烟品种云烟85不同部位烟叶为试验材料,运用水分干燥理论,选取6种常用的水分干燥数学模型,基于Matlab 2014a利用高斯—牛顿算法对数学模型进行非线性最小二乘法拟合求解,并根据筛选的模型进行拟合检验。【结果】不同部位烟叶烘烤过程中水分比均呈下降趋势,中、上部叶干基水含率为1.5~0.5 g/g时干燥速率达最大值,平均干燥速率分别为0.0281和0.0262 g/(g?h),下部叶干基水含率为3.0~1.5、1.5~0.5和0.5~0时干燥速率均呈逐渐递减趋势,平均干燥速率分别为0.0337、0.0285和0.0065 g/(g?h)。不同部位烟叶的水分有效扩散系数在干叶期均随干基水含率的减小而增加,在干筋期随干基水含率的减小而减小。Wang and Singh模型可较好地描述和拟合下、中、上部烟叶烘烤过程中水分干燥的变化规律,决定系数(R2)分别为0.9928、0.9733和0.9653,且验证效果好。【结论】Wang and Singh模型可更好地描述和预测不同部位烟叶烘烤过程中烟叶水分干燥的变化规律。展开更多
Kidney bean seed was dried in a laboratory scale fixed bed. The effect of seed coat on drying dynamic characteristics and the changes of seed coat structure were investigated. A mathematical model was established to s...Kidney bean seed was dried in a laboratory scale fixed bed. The effect of seed coat on drying dynamic characteristics and the changes of seed coat structure were investigated. A mathematical model was established to simulate the drying process and determine the moisture diffusivity. Numerical results agree well with the experimental data. The average moisture diffusivity of the seed with separated coat is 1.67 times larger than that of the seed with coat, and the moisture diffusivity of seed cotyledon is 3.2 times larger than that of the seed coat. It is proved that the seed coat is the most main resistance of mass transfer and is also one of the key points of the optimization of heat and mass transfer for seed drying.展开更多
Water relation parameters of bare-root seedlings of Chinese fir (Cunninghamia lanceolata Hook.) and Masson pine (Pinus massoniana Lamb.) were measured and changes of root growth potential as well as field survival rat...Water relation parameters of bare-root seedlings of Chinese fir (Cunninghamia lanceolata Hook.) and Masson pine (Pinus massoniana Lamb.) were measured and changes of root growth potential as well as field survival rate of both species were studied after the bare-root seedlings were exposed in a sunny field condition. The results showed that Masson pine had a lower osmotic potential (-2.07Mpa) at turgor loss point and at full turgor (-1.29Mpa), compared with Chinese fir (-1.80Mpa and -1.08Mpa respectively). The parameter Vp/V0 (63.27%) of Masson pine was higher than that of Chinese fir (58.03%). This means that Masson pine has a stronger ability to tolerate desiccation, compared to Chinese fir according to analysis of above water relation parameters. Root growth potential and field survival rate decreased with prolonging duration of exposure. The field survival rate of both species was reduced to less than 40% after the seedling being exposed only two hours. Water poten-tials of 1.60 Mpa and -1.70 Mpa were suggested to be critical values for Chinese fir and Masson pine respectively in successful reforestation.展开更多
Double-layered pellet （DLP） roasting is a novel pretreatment method for sulfur and arsenic-bearing gold concentrates. In this process, preparation of DLPs is a fundamental step which is required to produce DLPs with...Double-layered pellet （DLP） roasting is a novel pretreatment method for sulfur and arsenic-bearing gold concentrates. In this process, preparation of DLPs is a fundamental step which is required to produce DLPs with favorable mechanical strength and thermal stability. Studies were carried out to investigate the affecting factors and conditions on the preparation and properties of DLPs. The results show that moisture content has significant influence on DLPs preparation. With the increase of moisture content in the range of no more than 9.8%, drop resistance and compressive strength of green DLPs are raised and the pelletizing dynamics is improved accordingly. The optimum conditions are determined as moisture content of 9.8%, coating time of 14-16 min, drying temperature 〈80 ℃and drying gas velocity 〈1.2 m/s. When DLPs prepared under these conditions are roasted at 600 ℃ for 1 h, favorable removal and solidifying rates can be obtained, in which the removal rates of arsenic and sulfur are 94.38% and 82.55%, and the solidifying rates of arsenic and sulfur reach 99.62% and 99.79%, respectively. These results promise industrial application of DLP roasting.展开更多
Thin potato crisps (2mm) were fried at 170℃, 180℃ and 190℃ for varioustimes from 10s to 180s inclusive. It was found that definite oil uptake, moisture loss trends existduring the frying process. No significant dif...Thin potato crisps (2mm) were fried at 170℃, 180℃ and 190℃ for varioustimes from 10s to 180s inclusive. It was found that definite oil uptake, moisture loss trends existduring the frying process. No significant difference in the oil uptake or moisture loss ratesbetween flat-cut and ridge-cut crisps exists. Also found in this study was that an increased oiltemperature promoted higher moisture loss rates. In turn, the higher moisture loss rates contributedto a higher oil uptake rate. It was found, based on the volumetric plots of oil content υs. watercontent, that the oil uptake rate was proportional to the moisture loss rate. As a result, it hasbeen shown that there is a possibility of having a characteristic curve of oil uptake againstmoisture content.展开更多
文摘【目的】探究不同部位烟叶烘烤过程中的水分变化及干燥数学模型,为准确预测烟叶烘烤过程水分变化及烟草精准烘烤提供理论依据。【方法】以大理州凤仪烟区烤烟品种云烟85不同部位烟叶为试验材料,运用水分干燥理论,选取6种常用的水分干燥数学模型,基于Matlab 2014a利用高斯—牛顿算法对数学模型进行非线性最小二乘法拟合求解,并根据筛选的模型进行拟合检验。【结果】不同部位烟叶烘烤过程中水分比均呈下降趋势,中、上部叶干基水含率为1.5~0.5 g/g时干燥速率达最大值,平均干燥速率分别为0.0281和0.0262 g/(g?h),下部叶干基水含率为3.0~1.5、1.5~0.5和0.5~0时干燥速率均呈逐渐递减趋势,平均干燥速率分别为0.0337、0.0285和0.0065 g/(g?h)。不同部位烟叶的水分有效扩散系数在干叶期均随干基水含率的减小而增加,在干筋期随干基水含率的减小而减小。Wang and Singh模型可较好地描述和拟合下、中、上部烟叶烘烤过程中水分干燥的变化规律,决定系数(R2)分别为0.9928、0.9733和0.9653,且验证效果好。【结论】Wang and Singh模型可更好地描述和预测不同部位烟叶烘烤过程中烟叶水分干燥的变化规律。
文摘Kidney bean seed was dried in a laboratory scale fixed bed. The effect of seed coat on drying dynamic characteristics and the changes of seed coat structure were investigated. A mathematical model was established to simulate the drying process and determine the moisture diffusivity. Numerical results agree well with the experimental data. The average moisture diffusivity of the seed with separated coat is 1.67 times larger than that of the seed with coat, and the moisture diffusivity of seed cotyledon is 3.2 times larger than that of the seed coat. It is proved that the seed coat is the most main resistance of mass transfer and is also one of the key points of the optimization of heat and mass transfer for seed drying.
基金This research was supported by the Sciences Research Foundation of Nanjing Forestry University.
文摘Water relation parameters of bare-root seedlings of Chinese fir (Cunninghamia lanceolata Hook.) and Masson pine (Pinus massoniana Lamb.) were measured and changes of root growth potential as well as field survival rate of both species were studied after the bare-root seedlings were exposed in a sunny field condition. The results showed that Masson pine had a lower osmotic potential (-2.07Mpa) at turgor loss point and at full turgor (-1.29Mpa), compared with Chinese fir (-1.80Mpa and -1.08Mpa respectively). The parameter Vp/V0 (63.27%) of Masson pine was higher than that of Chinese fir (58.03%). This means that Masson pine has a stronger ability to tolerate desiccation, compared to Chinese fir according to analysis of above water relation parameters. Root growth potential and field survival rate decreased with prolonging duration of exposure. The field survival rate of both species was reduced to less than 40% after the seedling being exposed only two hours. Water poten-tials of 1.60 Mpa and -1.70 Mpa were suggested to be critical values for Chinese fir and Masson pine respectively in successful reforestation.
基金Project(51074182)supported by the National Natural Science Foundation of ChinaProject(201012200032)supported by the Fundamental Research Funds for the Central Universities,China
文摘Double-layered pellet （DLP） roasting is a novel pretreatment method for sulfur and arsenic-bearing gold concentrates. In this process, preparation of DLPs is a fundamental step which is required to produce DLPs with favorable mechanical strength and thermal stability. Studies were carried out to investigate the affecting factors and conditions on the preparation and properties of DLPs. The results show that moisture content has significant influence on DLPs preparation. With the increase of moisture content in the range of no more than 9.8%, drop resistance and compressive strength of green DLPs are raised and the pelletizing dynamics is improved accordingly. The optimum conditions are determined as moisture content of 9.8%, coating time of 14-16 min, drying temperature 〈80 ℃and drying gas velocity 〈1.2 m/s. When DLPs prepared under these conditions are roasted at 600 ℃ for 1 h, favorable removal and solidifying rates can be obtained, in which the removal rates of arsenic and sulfur are 94.38% and 82.55%, and the solidifying rates of arsenic and sulfur reach 99.62% and 99.79%, respectively. These results promise industrial application of DLP roasting.
文摘Thin potato crisps (2mm) were fried at 170℃, 180℃ and 190℃ for varioustimes from 10s to 180s inclusive. It was found that definite oil uptake, moisture loss trends existduring the frying process. No significant difference in the oil uptake or moisture loss ratesbetween flat-cut and ridge-cut crisps exists. Also found in this study was that an increased oiltemperature promoted higher moisture loss rates. In turn, the higher moisture loss rates contributedto a higher oil uptake rate. It was found, based on the volumetric plots of oil content υs. watercontent, that the oil uptake rate was proportional to the moisture loss rate. As a result, it hasbeen shown that there is a possibility of having a characteristic curve of oil uptake againstmoisture content.
