运用Peleg模型,研究了小米在不同温度和时间浸泡条件下的吸水性质,并对其吸水动力学进行了分析。结果表明,在浸泡的初始阶段小米以很高的速率吸收水分,随后小米含水量的变化逐渐趋于平缓,最后小米含水量达到平衡;Peleg方程对小米在不同...运用Peleg模型,研究了小米在不同温度和时间浸泡条件下的吸水性质,并对其吸水动力学进行了分析。结果表明,在浸泡的初始阶段小米以很高的速率吸收水分,随后小米含水量的变化逐渐趋于平缓,最后小米含水量达到平衡;Peleg方程对小米在不同温度下的吸水过程能够较好地拟合,R2均大于0.99,且相对误差均小于5%,其中,速率常数K1与容量常数K2均随温度的升高而降低;将温度与其对应的速率常数K1进行阿尼乌斯方程拟合,R2为0.97,拟合度较高,并得到小米在浸泡过程中的活化能为11.003 k J/mol。展开更多
Water absorption characteristics of maize (<i>Abotem</i><span>,</span> <i>Abeleehi</i>, and <i>Dorke</i><span> <i>SR)</i></span> hybrids grown in...Water absorption characteristics of maize (<i>Abotem</i><span>,</span> <i>Abeleehi</i>, and <i>Dorke</i><span> <i>SR)</i></span> hybrids grown in Ghana were investigated using models obtained from Fick’s law of diffusion. The maize kernels were soaked in water at four different temperatures of 30<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C, 40<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C, 50<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C and 60<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C to evaluate their water absorption behaviours. The results indicated that temperature and variety were the major factors controlling water absorption patterns. The diffusion coefficients of the hybrids were found to differ in the order of <i>Dorke</i><span> <i>SR</i> </span>> <i>Abeleehi</i><span> </span>><span> <i>Abotem</i></span> and increased as the soaking temperature increased. The calculated water diffusivities varied from (2.54 - 3.49) × 10<sup>-10</sup> m<sup>2</sup>/s for <i>Abotem</i>, (2.64 - 3.59) × 10<sup>-10</sup> m<sup>2</sup>/s for <i>Abeleehi</i><span>, (3.21 <i>-</i> </span>4.20) × 10<sup>-10</sup>/s for <i>Dorke</i><span> <i>SR</i>.</span> The Arrhenius-<span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "="">type equation was able to describe the strong effect of temperature on the diffusion coefficient of the hybrids. The activation energy values obtained were7.50 kJ/mol for <i>Abeleehi</i>, 6.27 kJ/mol<span> </span>for <i>Dorke</i><span> <i>SR</i> </span>and 9.09 kJ/mol for <i>Abotem</i>. Results indicated that temperature and variety were the major factors controlling water absorption patterns.</span></span></span>展开更多
This paper presents the importance and the cycle choice for long-distance transportation of low-grade thermal energy, and the thermodynamic and hydrodynamic feasibility of single-effect ammonia-water absorption system...This paper presents the importance and the cycle choice for long-distance transportation of low-grade thermal energy, and the thermodynamic and hydrodynamic feasibility of single-effect ammonia-water absorption system for heat or cold transportation over long distance are also involved. A model of a long-distance thermal energy transportation system is built and analyzed, which shows satisfactory and attractive results. When a steam heat source at 120℃ is available, the user site can get hot water output at about 55℃ with the thermal COP of about 0.6 and the electric COP of about 100 in winter, and cold water output at about 10℃ with the thermal COP of about 0.5 and the electric COP of 50 in summer. A small-size prototype is built to verify the performance analysis. Basically the experimental data show good accordance with the analysis results. The ammonia-water absorption system is a potential pro-spective solution for the heat or cold transportation over long distance.展开更多
文摘运用Peleg模型,研究了小米在不同温度和时间浸泡条件下的吸水性质,并对其吸水动力学进行了分析。结果表明,在浸泡的初始阶段小米以很高的速率吸收水分,随后小米含水量的变化逐渐趋于平缓,最后小米含水量达到平衡;Peleg方程对小米在不同温度下的吸水过程能够较好地拟合,R2均大于0.99,且相对误差均小于5%,其中,速率常数K1与容量常数K2均随温度的升高而降低;将温度与其对应的速率常数K1进行阿尼乌斯方程拟合,R2为0.97,拟合度较高,并得到小米在浸泡过程中的活化能为11.003 k J/mol。
文摘Water absorption characteristics of maize (<i>Abotem</i><span>,</span> <i>Abeleehi</i>, and <i>Dorke</i><span> <i>SR)</i></span> hybrids grown in Ghana were investigated using models obtained from Fick’s law of diffusion. The maize kernels were soaked in water at four different temperatures of 30<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C, 40<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C, 50<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C and 60<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">º</span>C to evaluate their water absorption behaviours. The results indicated that temperature and variety were the major factors controlling water absorption patterns. The diffusion coefficients of the hybrids were found to differ in the order of <i>Dorke</i><span> <i>SR</i> </span>> <i>Abeleehi</i><span> </span>><span> <i>Abotem</i></span> and increased as the soaking temperature increased. The calculated water diffusivities varied from (2.54 - 3.49) × 10<sup>-10</sup> m<sup>2</sup>/s for <i>Abotem</i>, (2.64 - 3.59) × 10<sup>-10</sup> m<sup>2</sup>/s for <i>Abeleehi</i><span>, (3.21 <i>-</i> </span>4.20) × 10<sup>-10</sup>/s for <i>Dorke</i><span> <i>SR</i>.</span> The Arrhenius-<span><span><span style="font-family:;" "=""> </span></span></span><span><span><span style="font-family:;" "="">type equation was able to describe the strong effect of temperature on the diffusion coefficient of the hybrids. The activation energy values obtained were7.50 kJ/mol for <i>Abeleehi</i>, 6.27 kJ/mol<span> </span>for <i>Dorke</i><span> <i>SR</i> </span>and 9.09 kJ/mol for <i>Abotem</i>. Results indicated that temperature and variety were the major factors controlling water absorption patterns.</span></span></span>
基金Supported by Shanghai Municipal Science and Technology Committee (Grant No.06SR07106) in ChinaShanghai Pujiang Program (Grant No.06PJ14061) in China and Programme Interdisciplinaire Energie du CNRS-"VALOTHERM" in France
文摘This paper presents the importance and the cycle choice for long-distance transportation of low-grade thermal energy, and the thermodynamic and hydrodynamic feasibility of single-effect ammonia-water absorption system for heat or cold transportation over long distance are also involved. A model of a long-distance thermal energy transportation system is built and analyzed, which shows satisfactory and attractive results. When a steam heat source at 120℃ is available, the user site can get hot water output at about 55℃ with the thermal COP of about 0.6 and the electric COP of about 100 in winter, and cold water output at about 10℃ with the thermal COP of about 0.5 and the electric COP of 50 in summer. A small-size prototype is built to verify the performance analysis. Basically the experimental data show good accordance with the analysis results. The ammonia-water absorption system is a potential pro-spective solution for the heat or cold transportation over long distance.
