CONVENTIONAL BASIC DESIGN FOR CONVECTION OR CONDUCTION DRYERS

The items to be considered prior to selection of dryers are explained, and a simple method for a rough estimation of dryer sizes was proposed based on data obtained from operating industrial dryers.

The equations of basic design for batch or continuous type dryers were derived. The heat was supplied to materials by convection and/or conduction. The equations were simplified to the case when the falling rate of drying is proportional to the moisture content of materials under the constant drying conditions. The heat transfer coefficient used in the equations can be determined based on the calculations or the data obtained from the experimental or industrial dryers. The equations are useful for estimating the scale-up effect of dryers.     

OPTIMAL DESIGN OF WELL-MLXED FLUIDIZED BED DRYERS

ABSTRACT

In a recent article, Baker described a novel technique for estimating the energy consumption of well-mixed fluidized bed dryers based on the use of experimental drying curves. An integrated approach to performing sizing and energy consumption calculations for such dryers using this technique is described in the present paper. A computer program, which includes not only the dryer simulator but also a heat recovery module and an exhaust air recycle option, is used to evaluate the viability of different energy-conservation strategies. The effects of operating parameters such as bed temperature, solids loading and air velocity on energy consumption and bed area are also explored. The observed drying kinetics are shown to have a major effect on the optimal design and operation of the dryer.     

DEVELOPMENT OF A FUZZY EXPERT SYSTEM FOR THE SELECTION OF BATCH DRYERS FOR FOODSTUFFS

ABSTRACT

The selection of dryers is an art in which knowledge, experience and science all play important roles. Historically, dryer selection has been made by experts on the basis of their extensive knowledge. However, in recent years, computer-based techniques have been developed, which have the potential of at least partially deskilling this process. Of the various possibilities, fuzzy expert systems, in which the selection qualifiers are represented as linguistic rather than numerical variables, are the most promising. This paper describes the development of a fuzzy system for the selection of batch dryers for food products. It featured a novel modular approach in which independent selection goals for dryer type, atmospheric, vacuum or freeze operation, and single or multiple units were adopted. This made the system particularly flexible and amenable to adaptation. The program starts from a ‘ drying process checklist“ in which the principal process variables are specified, and provides a ranked list of feasible alternative dryers. The algorithm was extensively tested and provided quite plausible results. Four representative case studies are presented and discussed.     

DEVELOPMENT OF A FUZZY EXPERT SYSTEM FOR THE SELECTION OF BATCH DRYERS FOR FOODSTUFFS

The selection of dryers is an art in which knowledge, experience and science all play important roles. Historically, dryer selection has been made by experts on the basis of their extensive knowledge. However, in recent years, computer-based techniques have been developed, which have the potential of at least partially deskilling this process. Of the various possibilities, fuzzy expert systems, in which the selection qualifiers are represented as linguistic rather than numerical variables, are the most promising. This paper describes the development of a fuzzy system for the selection of batch dryers for food products. It featured a novel modular approach in which independent selection goals for dryer type, atmospheric, vacuum or freeze operation, and single or multiple units were adopted. This made the system particularly flexible and amenable to adaptation. The program starts from a ' drying process checklist“ in which the principal process variables are specified, and provides a ranked list of feasible alternative dryers. The algorithm was extensively tested and provided quite plausible results. Four representative case studies are presented and discussed.     

THE DESIGN AND PERFORMANCE OF CONTINUOUS WELL-MIXED FLUIDIZED BED DRYERS - AN ANALYTICAL APPROACH

Abstract

In a previous study, a unified approach to the calculation of the size and energy consumption of well-mixed fluidized bed dryers was developed. A computer code was written and a parametric study undertaken to determine the effects of the principal operating variables. The results were shown to depend on the form of the drying kinetics. The present paper describes the formulation of an analytical model of a well-mixed fluidized bed dryer, which applies for materials that exhibit linear falling-rate drying. These materials are typified by small hygroscopic particles, which are frequently dried in such equipment. Equations are presented that enable the drying time, specific energy consumption, heater duty and bed area to be calculated. The predictions of these equations agreed well with previously published experimental findings and with the results of computer simulations for a typical solid (ion exchange resin) exhibiting the required drying characteristics.     

THE DESIGN AND PERFORMANCE OF CONTINUOUS WELL-MIXED FLUIDIZED BED DRYERS - AN ANALYTICAL APPROACH

In a previous study, a unified approach to the calculation of the size and energy consumption of well-mixed fluidized bed dryers was developed. A computer code was written and a parametric study undertaken to determine the effects of the principal operating variables. The results were shown to depend on the form of the drying kinetics. The present paper describes the formulation of an analytical model of a well-mixed fluidized bed dryer, which applies for materials that exhibit linear falling-rate drying. These materials are typified by small hygroscopic particles, which are frequently dried in such equipment. Equations are presented that enable the drying time, specific energy consumption, heater duty and bed area to be calculated. The predictions of these equations agreed well with previously published experimental findings and with the results of computer simulations for a typical solid (ion exchange resin) exhibiting the required drying characteristics.     

横掠螺旋翅片管管束对流换热的试验研究

本文在考虑影响气体横掠螺旋翅片管管束的对流换热的诸因素的基础上,使用两相闭式热虹管为传热元件,根据等雷诺数法的原则,通过试验及数据处理,对传热特性和阻力特性进行了分析和研究,并提出相应的数学准则式,这些公式可为设计提供依据。     

乙炔二聚外循环型和直筒标准型鼓泡式反应器的放大设计

用数学模型法对１万ｔ／ａ氯丁橡胶生产厂乙炔二聚合成乙烯基乙炔的外循环鼓泡式反应器和直筒标准型鼓泡式反应器进行了放大设计。结果表明，当反应器原料进口压力相同时，外循环型鼓泡式反应器的ＭＶＡ选择性为直筒标准Ａ型的１．９２倍，有效反应体积为后者的８６％，气体输送功为后者的７８％。     

陶瓷设计空间拓展的再认识

随着社会的发展，工业革命后出现的大量新型材料如塑料、钢管、纤维等使陶瓷材质在我国日常生活领域的地位受到了残酷冲击，处于萎缩的状态。但陶瓷作为一种健康材质，在现代生活中应当得到重新认识，拓展更广阔的设计空间。从六个方面阐述了陶瓷材质与其设计空间的再认识过程。     

隔热条异型材挤出模具设计

通过对隔热条异型材截面形状及原材料挤出成型性能的分析,设计了异型材挤出口模形状、流线形流道及挤出模具结构。经实践证明,该模具口模形状及尺寸设计正确,流线形流道设计合理,能生产出满足尺寸精度要求的隔热条异型材。     

洗衣机排水阀注塑模设计

通过对洗衣机排水阀塑料件的分析,设计了洗衣机排水阀注塑模。着重介绍该注塑模的顺序脱模机构及工作过程,解决了模具开模时侧向长型芯与小型芯接触面的摩擦问题。该模具设计合理,动作准确可靠,塑料件质量良好,完全能够满足用户的要求。     

稳健性设计在转氨酶发酵优化过程中的应用

转氨酶是酶法生产氨基酸工艺中的重要酶种,高产量的酶必须涉及菌体的生长和酶的合成需要.从酶发酵过程的稳健性出发,应用低灵敏度的稳健性设计手段对转氨酶的发酵产酶过程进行了优化设计.通过实验发现通气量和搅拌速度两个工艺参数对发酵产酶结果影响较大,而培养基成分、发酵初始pH值及发酵温度的影响较小.并得到了结果稳定的最优发酵条件:通气量0.6L·min^-1,搅拌速度500 r·min^-1,温度35℃,pH值6.5,玉米浆2％.经实验验证,发酵结果稳定且符合最优目标值.     

陶瓷自动配料柔性开发系统硬件的模块化设计

实现陶瓷自动配料是现代陶瓷墙地砖生产的必然发展方向,研制其柔性开发系统有利于实现自动配料系统的柔性开发,并且可大幅节约开发成本。介绍了陶瓷自动配料柔性开发系统硬件包括机械系统和电器系统研制过程中的模块化设计思想和技术。电器控制系统各模块之间采用标准接插件连接,便于设计、维修、移动和扩充,体现了模块化设计方法的优势。     

电风扇灯罩注塑模具设计

通过对电风扇灯罩注塑模具的设计探讨,解决了一模一腔注塑模设计中常遇到的锁模力与胀模力偏心问题,并对外观质量要求高的透明注塑件的注塑模具设计中浇注系统的结构设计、尺寸计算．推出机构的结构设计和模具总体结构设计进行了探讨,找到了解决问题的方法。     

转轮连续进给式蜂窝陶瓷自动切割机的设计

分析了蜂窝陶瓷切割特点和目前蜂窝陶瓷切割机存在的问题,并对解决这些问题而设计的转轮连续进给式蜂窝陶瓷自动切割机的主要技术参数、结构特点和工作原理进行了详细介绍。     

A STUDY OF EXPERIMENTAL DESIGN OPTIMALITY FOR WIENER SYSTEMS

A weakly nonlinear theory of wave propagation in two superposed dielectric fluids streaming through porous media in the presence of vertical electric field and in the absence of surface charges at their interface is investigated in three dimensions. The method of multiple scales is used to obtain a dispersion relation for the linear problem and a Ginzburg-Landau equation with complex coefficients for the nonlinear problem, describing the behavior of the system. The stability of the system is discussed both analytically and numerically in both cases, and the corresponding stability conditions are obtained. It is found, in the linear case, that the stability criterion is independent of the medium permeability and that the medium porosity, surface tension, and dimension all have stabilizing effects the fluid viscosities, velocities, and depths have destabilizing effects, and the electric field has a dual role in the stability of the system. In the nonlinear analysis, it is found that the electric field has a stabilizing effect in two-dimensional disturbances and destabilizing effect in three-dimensional disturbances cases. The surface tension, fluid depths, and medium porosity have stabilizing effects in both two- and three-dimensional disturbance cases and the fluid viscosities, velocities, and medium permeability have destabilizing effects in both cases, and this stability or instability occurs faster for three-dimensional disturbance cases. It is found also that the system is unstable in the absence of fluid velocities or for nonporous media. Finally, the dimension was found to have a dual role (stabilizing as well as destabilizing) in the considered system, while it has a destabilizing effect in the case of nonporous media.     

A STUDY OF EXPERIMENTAL DESIGN OPTIMALITY FOR WIENER SYSTEMS

In the context of nonlinear dynamic system identification for Hammerstein systems, Rollins et al. (2003a) studied the information efficiency of the following two competing experimental design approaches: statistical design of experiments (SDOE) and pseudo-random sequences design (PRSD). The focus of this study is the Wiener system and evaluates SDOE against PRS under D-optimal efficiency. Three cases are evaluated and the results strongly support SDOE as the better approach.     

冰箱内胆真空成型模具设计方法

针对冰箱内胆体积大、壁薄、形状复杂的特点，根据塑料模具设计程序，围绕冰箱内胆真空成型工艺特点，介绍冰箱内胆真空成型模具设计所涉及的内容及设计方法，包括制品结构分析、设计资料的准备、成型体设计、抽芯机构设计、抽气孔设计、加热和冷却系统设计、密封结构设计和切边装置设计等。     

化工设计管道材料表的计算机管理系统

用ＦＯＸＢＡＳＥ建立了化工设计管道材料表的计算机管理系统。只需设计人员将图纸上一些原始数据，诸如管子、阀门、法兰、垫片、管件等的名称及规格提供给计算机，即能自动生成管道材料表。系统大大节约了设计工时，提高了工作效率，保证了设计质量。对于涉外项目，系统能自动生成中英文对照的管道材料表，满足工程设计规范。     

柴油机GFRPA66起动拉盘的注塑模具设计

根据柴油机起动拉盘的使用性能和采用玻璃纤维增强尼龙66（GFRPA66）制作起动拉盘的注射成型工艺要求,提出了带有嵌件、加强筋及侧凹的注塑模的结构设计方案,并对型腔和侧向抽芯机构进行了设计计算。经生产实践验证,该模具结构设计合理,操作方便,能满足使用要求。