Performance of Single and Multi-stage Spouted Bed Drying Systems

ABSTRACT

A mathematical model is developed to predict the performance of single-stage and multi-stage drying systems using spouted beds. The model uses unsteady state analysis for batch operation to simulate the steady state operation of a continuously fed spouted bed. A parametric study is carried out to study the effect of the following parameters on the performance of a single-stage grain drying system: air flow rate per unit mass of the grain in the bed, ambient air temperature and humidity, initial and target moisture contents, the residence time in the bed, and the effectiveness of the heat exchanger to recover the thermal energy in the exhaust air. The parametric study is also extended to investigate the effect of these parameters (except ambient air temperature and humidity) on the performance of the multi-stage system. In addition, the number of stages is also included in the latter study. The results are presented in terms of charts which may be adopted for the design of such systems.     

KINETICS AND MECHANISM OF ISOTOPIC EXCHANGE FOR Co2+/Co Co2+ IN TIN(IV) ANTIMONATE

ABSTRACT

The rate of the isotopic exchange of cobalt ion between tin(IV) antimonate ion exchanger in the Co Co²⁺ form and aqueous solutions vas determined radiometrically. Self-diffusion coefficients for cobalt ion were measured as a function of the variable capacity for that ion in solutions of varying acidity. The effect of a heat treatment on the rate of the isotopic exchange reaction in tin(IV) antimonate vas also studied. The rate vas controlled by the particle diffusion of cobalt ion and increased by heating temperature and decreased with increase of ion exchange capacity. Values for the diffusion coefficentst activation energy and entropy of activation have been evaluated which give some information regarding the mechanism of ion exchange on the surface of inorganic materials.     

Characterization of dynamic system nonlinearities via probabilistic approach

The problem of nonlinearity detection in system identification is treated. A probabilistic approach is taken which facilitates the analysis and enables the treatment of both strong and weak nonlinearities. The analysis shows that third- and fourth-order cumulants of the system output can be used to detect the existence of system nonlinearities, and to characterize their type     

噬菌体在食品安全控制中的研究进展

近年来,噬菌体在食品科学领域中的应用受到国内外研究学者的广泛关注。噬菌体的自身特性表明,其可 作为一种杀菌/抑菌的生物制剂来控制食源性病原菌对食品的污染,是保障食品安全的理想工具。此外,基因工程 技术的发展进一步促进了噬菌体及其产物的安全、高效使用及噬菌体产品的出现。本文就噬菌体在食品安全控制中 的研究进展以及应用前景等方面进行综述。     

复合铸造制备稻壳灰增强AA6061铝合金及表征（英文）

稻壳灰(RHA)是一种有潜力的廉价铝基复合材料的增强颗粒。采用复合铸造方法制备不同稻壳灰含量(0,2%,4%,8%,质量分数)增强的AA6061铝合金复合材料。采用X射线衍射和扫描电镜对所制备复合材料进行表征。X射线衍射谱表明AA6061/RHA铝基复合材料中除RHA颗粒外未形成其他金属间化合物。扫描电镜图片表明RHA颗粒均匀分布在铝基体中。RHA基本分布在晶粒内部。此外,RHA颗粒与铝基体结合良好并形成清晰的界面。RHA颗粒的添加能提高铝基复合材料的显微硬度和抗拉强度。铝基复合材料的拉伸行为与其微观组织密切相关。     

Creep and Densification During Sintering of Glass Powder Compacts

The simultaneous creep and densification of glass powder compacts was studied as a function of low applied uniaxial stress, temperature, and particle size. The creep rate can be expressed as the sum of the contribution from the applied stress that varies linearly with stress, and a contribution due to anisotropic densification that varies linearly with the densification rate. For a constant applied stress, the ratio of the creep rate to the densification rate is almost independent of both termperature and density. While these observations are consistent with the model of Scherer for the viscous sintering of glass, other observations show significant deviations from the model. Both the densification rate and the creep viscosity, which has an exponential dependence on porosity, show much stronger dependence on density compared with theoretical predictions.