道康宁中国网站与公司全球企业网站接轨

道康宁中国公司目前宣布其中国网站已正式迁移至道康宁的全球企业网站，将为中国客户提供一个了解公司和有机硅资讯的国际平台。     

税务系统网站的建设管理

税务系统内部网络及其网站以信息发布速度快、信息量大、页面设计灵活、不受时间和地域限制的特点,在日常工作中发挥着越来越重要的作用。税务网站的建设、维护和管理必须遵循保密、高效、实用的原则,以信息化的发展促进税务系统的整体工作。     

多媒体技术在电子商务网站建设中的应用

目前我国的电子商务网站还存在着很多问题,对电子商务的网站建设规划应尽快实施。总结现今电子商务网站建设与多媒体技术存在的各种问题,总的来说,这些问题出现的原因大致分为这几类,网站基础安全措施差、使用者缺少基本法律常识、缺乏职业素养、没有销售职责规划与处理方案等,为应对这些问题,提出了创建网站基础安全措施、普及使用者相关的法律基础与职业素养等解决方案。     

构建企业网站技术问题的探讨

企业网站是企业进行自我宣传和信息发布的窗口,是实现对外交互、开展业务的平台。本文针对构建企业网站存在的问题,结合本院网站设计中的实际问题,提出了网站设计应遵循的原则,以及一些值得注意的问题。网站做的是否成功,除了要考虑外观设计,内容组织外、网站建设的前期策划和用户调查非常重要。文章从几个方面对于构建网站的特殊性做出了详细的说明。     

浅谈化工材料营销网站建设中存在的问题

针对化工材料营销网站建设理念的形成展开探讨,在此基础上重点分析了开展营销网站建设中所使用的技术以及理念上的问题,并结合化工材料营销网站实例对解决方案进行分析,进一步提升工作计划的完善效果,提升化工材料网站营销的顺利程度,为扩大市场竞争能力打下稳定的基础。     

大化集团网站建设方案

从Internet网络应用的角度出发，结合大化集团网站建设的实际特点，具体分析、介绍了大化网站建设过程中应具备的几大模块功能，对大化集团国际互联网建设过程中存在的问题和解决的方法加以阐述，并将企业网站的推广方式予以介绍。     

氯仿干燥技术探讨

氯仿,即三氯甲烷,是甲烷多氯化物的一种。常温下是一种无色液体,比重1.485,沸点61.2℃。氯仿主要用作有机溶剂,同时也是有机合成的原料,如制作氟里昂(F_21、F_22、F_23)、作制药的中间体。     

氯气干燥工艺探讨

1 概述 氯气干燥是氯碱厂的一个重要工序,它的任务是脱除氯气中的水分,以满足氯产品的生产要求。但是在许多氯碱厂中,氯气干燥效果并不理想,尽管采取某些措施,如购买高质量的浓硫酸和尽可能降低进干燥塔的硫酸温度,但氯气中含水量仍然只能降至500×10~(-6)左右,甚至有些厂的氯气含水高达1000×10~(-6),影响了氯产品的生产。 本文对氯气干燥工艺作进一步的探讨,     

高密度聚乙烯粉末干燥技术探讨

<正> 一、概述 高密度聚乙烯通过不同的成型方法,已广泛用于制造各种用途的中空容器、薄膜、周转箱、钙塑瓦楞箱、管、棒、板和电线、电缆等各种制品。又由于高密度聚乙烯的结晶度高、强度大、伸长率高,可代替工程塑料使用。随着用途的多样化和加工技术的不     

生物制药工艺学精品课程网站设计与建设

生物制药工艺学是制药工程专业的一门主要的专业理论课,我们结合网站的使用构造成精品课程,这将推动教学改革、提高教学效果。文章介绍了精品课程建设的意义,精品课程与网络结合的意义以及网站建设的具体情况等。     

Modeling and Performance Investigation of a Closed-Type Thermoelectric Clothes Dryer

In present work, a closed-type clothes dryer with thermoelectric elements was developed. The looped air circulation was designed to simultaneously recycle waste heat and enhance dryer performance. A mathematical model of heat transfer, based on one-dimensional treatment of thermal and electric power, is conducted. The cooling and heating productions are both correlated in terms of electric resistance, thermal conductivity, and electric current. Experimental investigation on drying of clothes has been attempted, covering the drying air temperature, initial-input electric power, and total weight of wet clothes, with drying rate and specific moisture extraction rate as evaluating indexes. Generally, the drying rate was found to increase first and decrease afterwards as time decayed. Analytical and experimental results demonstrate that optimal performance of the thermoelectric dryer strongly depends on intensities of these operating parameters.     

Drying of Diced Carrot in a Combined Microwave-Fluidized Bed Dryer

Drying of diced carrot (∼90% wet basis) was carried out in a laboratory microwave fluidized-bed dryer (MFB) and in a standard fluidized-bed dryer (FB). It was found that the drying time in the MFB dryer is 2-5 times shorter than in the FB dryer. Drying efficiency (DE) is a function of moisture content, microwave power and temperature of drying agent. Higher values of DE are obtained for MFB dryer. For both drying systems the water removal was proceeding in two-stage falling rate period (except short initial term).     

内加热式热泵干燥装置的设计

内加热式热泵干燥装置通过导热加热方式提供物料中水分气化所需热能,可获得较高的能源效率和除湿能耗比。在介绍内加热式热泵干燥装置基本结构和工作过程的基础上,给出了其物料衡算、能量衡算和主要部件选型参数的计算公式,为内加热式热泵干燥装置的设计提供了较好的参考。     

Development of Cross-Flow Fluidized Bed Paddy Dryer

ABSTRACT

A cross-flow fluidized bed paddy dryer with a capacily of 200 kgh was designed, fabricated and tested. Experimental results showed that final moisture content of paddy should not be lower than 23 % dry-basis if quality is to be maintained. Drying air temperature was keot constant at 115°C according to the recommendation of previous work. Results obtained from the mathematical model developed in this study indicatedthat optimum operating parameters should be as follows : air speed of 2.3 m/s, bed thickness of 10 cm and fraction of air recycled of 80 %. At this condition, energy consumption was close to the minimum while drying capacity was near the maximum. A prototype fluidized bed dryer with a capacity of 1 t/h was designed, fabricated and installed with the collaboration of a private company. The unit has been used for almost the whole past harvesting season in 1994 at a paddy merchant sile with preference compared to conventional column continuous dryers. More than 300 tons of paddy were dried without any problems.     

An Investigation of Drying Process of Shelled Pistachios in a Newly Designed Fixed Bed Dryer System by Using Artificial Neural Network

In this paper, the drying of Siirt pistachios (SSPs) in a newly designed fixed bed dryer system and the prediction of drying characteristics using artificial neural network (ANN) are presented. Drying characteristics of SSPs with initial moisture content (MC) of 42.3% dry basis (db) were studied at different air temperatures (60, 80, and 100 °C) and air velocities (0.065, 0.1, and 0.13 m/s) in a newly designed fixed bed dryer system. Obtained results of experiments were used for ANN modeling and compared with experimental data. Falling rate period was observed during all the drying experiments; constant rate period was not observed. Furthermore, in the presented study, the application of ANN for predicting the drying time (DT) for a good quality product (output parameter for ANN modeling) was investigated. In order to train the ANN, experimental measurements were used as training data and test data. The back propagation learning algorithm with two different variants, so-called Levenberg–Marguardt (LM) and scaled conjugate gradient (SCG), and tangent sigmoid transfer function were used in the network so that the best approach can be determined. The most suitable algorithm and neuron number in the hidden layer are found out as LM with 15 neurons. For this number level, after the training, it is found that Root-mean squared (RMS) value is 0.3692, and absolute fraction of variance (R²) value is 99.99%. It is concluded that ANNs can be used for prediction of drying SSPs as an accurate method in similar systems.     

Development of Cross-Flow Fluidized Bed Paddy Dryer

A cross-flow fluidized bed paddy dryer with a capacily of 200 kgh was designed, fabricated and tested. Experimental results showed that final moisture content of paddy should not be lower than 23 % dry-basis if quality is to be maintained. Drying air temperature was keot constant at 115°C according to the recommendation of previous work. Results obtained from the mathematical model developed in this study indicatedthat optimum operating parameters should be as follows : air speed of 2.3 m/s, bed thickness of 10 cm and fraction of air recycled of 80 %. At this condition, energy consumption was close to the minimum while drying capacity was near the maximum. A prototype fluidized bed dryer with a capacity of 1 t/h was designed, fabricated and installed with the collaboration of a private company. The unit has been used for almost the whole past harvesting season in 1994 at a paddy merchant sile with preference compared to conventional column continuous dryers. More than 300 tons of paddy were dried without any problems.     

Modeling of Coriander Seeds Drying in an Impingement Dryer

The aim of this work is to develop a mathematical model to estimate the batch drying curve of coriander seeds in an impingement dryer and to study the axial movement of a seed in a transparent prototype impingement dryer. The apparatus is a horizontal acrylic transparent cylinder with a slight slope to induce the axial and rotational movement of particles. Gas enters tangentially downwards through a narrow slot arranged all along the dryer, flows in a counterclockwise circular motion in the chamber—in crossflow with respect to the solids—and is discharged through an upper lengthwise expansion chamber. As a result of gas drag, the particles advance in a rotational-helicoidal motion between feed and discharge.

Velocity and temperature profiles for gas in 2D turbulent flow were simulated using commercial software from Fluent Inc.^[1,^4] Maximum velocities are shown to be located close the walls; most of the gas is recirculated, and the rest is exhausted. It is assumed that particle trajectories also follow a circular motion near the walls, as observed in the transparent reproduction of the dryer operating with ambient air for small batch of solids and/or a single particle. Air velocities along this trajectory are estimated from the simulated flow field. Particle motion, heating, and drying along this path are described by unsteady momentum, heat, and mass balances when subjected to gas drag and gravity forces.

With respect to the axial trajectory of a coriander seed, for an inlet air velocity of 20 m/s at the slot the average experimental time for a complete circular cycle is 0.18 s and the simulated time is 0.21 s, whereas average experimental residence time is 1.53 s and the simulated time is 0.94 s. Differences between experimental results and simulations are due to air instability, leading to nonhomogeneous air velocity profiles along the equipment. The mathematical model is based on the assumption that air velocity profiles are homogeneous. Experimental observations indicate that the particle does not move along the equipment but sometimes moves backward (or erratically) or spins out advancing, due to an uneven air speed profile, and impacts against the wall. Finally, the drying model gives results that adjust to the batch experimental data, taking into account the deviations found with respect to the axial trajectory from a seed. This is because the model was devised exactly to predict the conduct of the system in batch operation for a particle bed, obtaining results that show the macrocospic response of the equipment (velocity and average temperature of the air). As it happens in this type of phenomenon, the drying rate in the constant period is a function of the adimensional Reynolds number.     

Modeling of Coriander Seeds Drying in an Impingement Dryer

The aim of this work is to develop a mathematical model to estimate the batch drying curve of coriander seeds in an impingement dryer and to study the axial movement of a seed in a transparent prototype impingement dryer. The apparatus is a horizontal acrylic transparent cylinder with a slight slope to induce the axial and rotational movement of particles. Gas enters tangentially downwards through a narrow slot arranged all along the dryer, flows in a counterclockwise circular motion in the chamber—in crossflow with respect to the solids—and is discharged through an upper lengthwise expansion chamber. As a result of gas drag, the particles advance in a rotational-helicoidal motion between feed and discharge.

Velocity and temperature profiles for gas in 2D turbulent flow were simulated using commercial software from Fluent Inc.^{[ 1} Quispe , J.F. ; Canales , E.R. ; Bórquez , R.M. Simulation of turbulent flows in an impingement dryer by an extended κ-ε model . Computer Methods in Applied Mechanics and Engineering 2000 , 190 , 625 – 637 .[Crossref] , [Google Scholar], ⁴ Soto , V. ; Bórquez , R.M. Simulation of superheated steam turbulence flows and heat transfer in an impingement dryer . Drying Technology 2003 , 21 ( 2 ), 311 – 328 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar] ^] Maximum velocities are shown to be located close the walls; most of the gas is recirculated, and the rest is exhausted. It is assumed that particle trajectories also follow a circular motion near the walls, as observed in the transparent reproduction of the dryer operating with ambient air for small batch of solids and/or a single particle. Air velocities along this trajectory are estimated from the simulated flow field. Particle motion, heating, and drying along this path are described by unsteady momentum, heat, and mass balances when subjected to gas drag and gravity forces.

With respect to the axial trajectory of a coriander seed, for an inlet air velocity of 20 m/s at the slot the average experimental time for a complete circular cycle is 0.18 s and the simulated time is 0.21 s, whereas average experimental residence time is 1.53 s and the simulated time is 0.94 s. Differences between experimental results and simulations are due to air instability, leading to nonhomogeneous air velocity profiles along the equipment. The mathematical model is based on the assumption that air velocity profiles are homogeneous. Experimental observations indicate that the particle does not move along the equipment but sometimes moves backward (or erratically) or spins out advancing, due to an uneven air speed profile, and impacts against the wall. Finally, the drying model gives results that adjust to the batch experimental data, taking into account the deviations found with respect to the axial trajectory from a seed. This is because the model was devised exactly to predict the conduct of the system in batch operation for a particle bed, obtaining results that show the macrocospic response of the equipment (velocity and average temperature of the air). As it happens in this type of phenomenon, the drying rate in the constant period is a function of the adimensional Reynolds number.     

A Small-Scale Pneumatic Conveying Dryer of Rough Rice

This article studies the possibility of reducing the high initial moisture content of wet rough rice using a small-scale low-cost pneumatic conveying dryer as a first stage dryer. The parameters investigated are final moisture content, surface temperature of rough rice, head rice yield, drying rate, power consumption per unit mass of evaporated water, and physical characteristics of rice. Parametric effects of the following variables are examined: velocity of drying air from 20 to 30 m/s, feed rate of rough rice from 150 to 350 kg/h, initial moisture content from 22 to 26% (wet basis), and drying air temperature from 35 to 70°C. From the experimental results, it is found that this drying method can be used for fresh rough rice with an initial moisture content of over 24% (wet basis). The drying process is able to lead to very rapid drying without any grain quality problems such as cracks in the rice kernel. The moisture content can be reduced to approximately 18% (wet basis) or about 5-6% of the initial moisture content within 3-4 s. The optimal drying air temperature is in the range of 50 to 60°C. A comparison of pneumatic conveying drying data obtained from the present study with fluidized bed drying data reported in the open literature is also discussed.