Monte Carlo simulation of the collective behavior of food particles in pneumatic drying operation

Although most of the time drying operation aims at controlling the mean batch behavior, the quality of the final product is often related to the individual behavior of the supplied materials in a batch. The mean batch models provide limited information for quality evaluation studies. Since the initial physical and thermal properties of rice powder in a batch influence the final condition of product dried with a pneumatic dryer, a Monte Carlo simulation with initial random parameters is useful to investigate the individual behavior of rice particle during pneumatic drying. In this study, we analyzed the influence of initial moisture content and particle diameter of rice powder on the conditions of the final product in pneumatic drying process. Samples of initial moisture content and particle diameter distributions were generated by means of the covariance decomposition algorithm and Monte Carlo simulations with 5000 runs based on momentum, energy and mass balances between drying air and rice particles were performed to obtain the profiles of the response variables, rice powder temperature, moisture content and particle diameter, in a pneumatic dryer. The developed pneumatic conveying drying (PCD) model could describe the complex behavior of rice particles in a batch.     

Hydration of grain kernels and its effect on drying

Different hydration methods have been considered and their effect on the drying characteristics of corn and amaranth grains have been studied at different drying temperatures and the results compared with those for the fresh materials. The effect of hydration on drying was found to depend on the type of grain. In general, for corn hydrated grain particles the moisture content was found to be in a looser condition than it was in the fresh grains, and hence, smaller effective diffusion coefficients where found for the latter. Such differences were found to increase with increasing drying temperature. Also a first-order irreversible kinetic model was applied to the drying data for hydrated and fresh corn and a reduction on the drying activation energy was observed by the humidification process. In contrast, for the relatively small amaranth grains, both hydrated and fresh particles showed similar drying characteristics. The results suggest that drying kinetics and transport properties obtained for rehydrated grains can overestimate drying rates for the corresponding freshly harvested material, especially at relatively high moisture contents and for relatively large grain particles like corn.     

Convective hot air drying of blanched yam slices

In this study, a laboratory convective hot air dryer was used for the thin layer drying of blanched yam slices and experimental moisture ratio was compared with Newton, Logarithmic, Henderson and Pabis, modified Henderson and Pabis, approximation of diffusion, modified page 1, two-term exponential, Verma et al. and Wang and Singh models. Among all the models, the approximation of diffusion model was found to satisfactorily describe the kinetics of air-drying of blanched yam slices. The increase in air temperature significantly reduced the drying time with no constant rate period but drying occurs in falling rate period. The effective diffusivity values varied between 7.62 × 10⁻⁸ to 9.06 × 10⁻⁸ m² s⁻¹ and increased with increase in temperature. An Arrhenius relation with an activation energy value of 8.831 kJ mol⁻¹ showed the effect of temperature on moisture diffusivity.     

分子筛旋转闪蒸干燥系统中密封结构的改进

针对分子筛预干燥系统中搅拌轴密封腔在使用过程中存在的问题,设计了一种气体保护填料密封结构,该密封结构在分子筛生产干燥工艺中应用,运行效果良好。     

Solaris10的设备和设备驱动管理

通过对Solaris基本的驱动规格的研究,介绍了Solaris下的设备驱动器和设备配置,比较了Solaris10和linux2.6环境下设备驱动配置的异同。文章涉及的大部分内容可以在早期的版本中使用。     

对矿业权价值和价款的思考

矿产资源是一种实物性财产,矿产资源所有权是指矿产资源的国家所有权,矿业权是指直接支配国家所有的矿产资源进行开发利用并享受因此所得利益的一种权利。计划经济体制时期实行的是矿产资源无偿使用和矿业权无偿取得制度,市场经济体制要求实行矿产资源有偿使用和矿业权有偿取得制度。矿产资源使用和矿业权取得制度的建设要区分矿产资源利用的三个阶段:勘查(调查)发现、勘查评价和开采阶段。矿业权的价值由矿业权国家所有者收益和矿业权投资者收益两者构成;矿业权投资者收益取决于矿业权价值、不取决于出资额。矿业权价款的内函是矿业权国家所有者收益和矿业权国家投资者收益之和。     

Modeling of a convective-infrared kiwifruit drying process

This paper aims to evaluate the experimental performance of a convective-infrared system with heat recovery (CIRHR) at different drying temperatures (40, 45, 50 and 55 °C) and 0.5 m/s air velocity and also to discuss and predict the performance of system on energy consumption and drying kinetics of sliced kiwifruit using artificial neural networks (ANNs). The energy efficiency values were obtained between 2.85% and 32.17%. The ANN model was used to predict the energy consumption of the system and moisture content of the kiwifruit. The back-propagation learning algorithm with Levenberg–Marquardt (LM) and Fermi transfer function were used in the network. The coefficient of determination (R²), the root means square error (RMSE) and the mean absolute percentage error (MAPE) were calculated as 0.99, 0.001 and 0.34, respectively. It can be concluded that predicted values are in good agreement with experimental results.     

不同干燥方法对花生蛋白功能特性的影响

以花生蛋白为原料,分别采用热风干燥、真空干燥、微波干燥和微波结合真空干燥对花生蛋白进行干燥处理,比较不同的干燥方式对花生蛋白功能特性(吸油性、持水性、乳化性、乳化稳定性、起泡性能和起泡稳定性)的影响。实验表明,微波结合真空干燥的花生蛋白不仅干燥时间短,而且具有较好的功能特性,微波结合真空干燥是一种干燥花生蛋白的适宜方法。     

低场核磁成像技术研究稻谷缓苏的机理

低场核磁共振成像技术研究了缓苏过程中稻谷颗粒内部水分分布情况,缓苏前1~2 h内颗粒内部水分趋于平衡。6种常见的干燥模型对颗粒内部水分扩散过程进行了拟合,得出双指数模型拟合效果最好,说明稻谷的缓苏过程存在两种水分传递过程,颗粒内部的水分扩散及颗粒表面的对流共同作用于颗粒内部水分梯度的消退。