酒糟流态化干燥压降的实验研究

通过酒糟在流化床干燥器上的冷态实验，得出全床压降随气流速度、料层厚度、物料初始湿含量及气体分布板开孔率的变化规律，经整理数据得出相关参数之间的准则关联式。     

PHOTOVOLTAIC DRYER WITH DUAL PACKED BEDS FOR DRYING MEDICAL HERB

Abstract

This work presents design and optimization of a cylindrical photovoltaic dryer with dual packed beds thermal energy storage for drying medical herb. The dryer is provided with electrical heater where the electrical energy is generated by using photovoltaic system. The electrical heater is designed and sized to realize continuouse drying (day and night) to minimize the drying time. Two packed beds are used to fix the drying temperature in dryer during day and night. The main packed bed thermal energy storage is charged during the sun-hours directly, to realize continued drying after sunset. An efficient PV dryer is devised to work under forced air created by air blower and heated by the electrical coils.     

R & D Needs - Drying of Ceramics

ABSTRACT

New research and development needs for the drying of ceramics are prooosed. The researches on the ceramic drying are briefly reviewed and the role of the drying in the ceramic production process iS summarized. The drying must deal with molded materials and the problem is of significant difference from another drying with particulate materials. It means that the drying must be performed with keeping the molded feature and the insufficient completion of drying and the careless operation influence directly on the product quality The importnance of the R & D on the heat and moisture transfer. shrinking mechanism. the deformation behavior and the strain-stress formation in the molded clay issuggested. The subjects are also pointed out for the further improvement of the ceramic drying process and the precise design of molding with high quality.     

Fish oil microencapsulation as influenced by spray dryer operational variables

The effects of spray‐drying air temperature, aspirator rate (drying air mass flow rate), peristaltic pump rate (feed mass flow rate) and spraying air mass flow rate on microencapsulation properties of fish oil including moisture content, particle size, bulk density, encapsulation efficiency and peroxide were investigated. The process was carried out on a mini spray dryer, and skim milk powder was used as the encapsulating wall material. Results indicated that increasing inlet air temperature increased the particle size, encapsulation efficiency and peroxide value but decreased the bulk density and moisture content of product. Increasing aspirator rate resulted in increased particle size and peroxide value but decreased the moisture content and bulk density. Increase in feed mass flow rate increased the moisture content, particle size, bulk density and peroxide value but decreased the encapsulation efficiency of microcapsules. The encapsulation efficiency and bulk density increased with the increasing aspirator rate but moisture content, particle size and peroxide value decreased.     

气垫干燥器内纸幅跑偏的分析及处理

气垫干燥器是利用热能干燥纸幅的设备,用来除去纸张中压榨或其他机械装置不能或很难脱去水份。在传统的纸张和纸板生产工艺中通常使用烘缸组来进一步提高纸张干度,在现今世界上的大中型浆板生产企业则是用气垫干燥器代替烘缸组达到提高浆幅干度的效果。分析纸幅在气垫内的跑偏处理方法。     

Solar drying vs. open sun drying: A framework for financial evaluation

Initiatives towards large-scale dissemination of solar dryers for drying of agri-produce face severe competition from the largely prevalent practice of open sun drying in most of the developing countries. Therefore, solar drying systems must offer exceptionally attractive financial gains to enhance their acceptance among the potential users. A modest attempt to develop a simple framework to facilitate a comparison of the financial feasibility of solar drying as against open sun drying has been made in the present work. Results of some exemplifying calculations are presented and briefly discussed.     

USE OF DYNAMIC MODELLING FOR THE DESIGN OF BATCH-MODE DEHUMIDIFIER DRYERS

The performance of batch-mode dehumidifier dryers undergoes significant changes during the drying process due to the range of temperature and humidity conditions experienced. Consequently steady-state methods are inapplicable for determining the performance of such kilns. In this paper a dynamic dehumidifier kiln model is used to estimate the drying speed, energy use and annual income for a batch-mode dehumidifier kiln. The model has been validated at both the dryer and dehumidifier levels, and the product is Pinus radiata, an easy-to-dry plantation soft-wood. The results show that control limits for the evaporating and condensing temperatures must be well matched to maximise the drying speed in the constant rate period. In the falling rate period, it is important not to place a lower limit the relative humidity unnecessarily. The use of supplementary heat to accelerate the kiln start-up is shown to have only a small influence on the kiln performance.     

关于三种吸附方法的性能比较

分析了三种常用压缩空气吸附干燥器的工作流程，研究探讨影响其技术性能的主要因素。介绍了无热再生与有热再生干燥器再生能耗的工程计算方法。在此基础上对三种干燥器的经济技术性能作了分析比较。     

OPTIMUM OPERATING CONDITIONS IN DRYING FOODSTUFFS WITH SUPERHEATED STEAM

It is inferred from experimental data that in drying foodstuffs with superheated steam, the initial drying rate has a direct effect on the rate at which the overall drying takes place. That is, the faster the initial drying rate, the shorter the overall drying time. This criterion is very convenient because at the beginning, water moistens the sample external surface so evaporation does not depend on internal sample characteristics, but only on external convective heat and mass transfer rates. Mass and energy balance equations are solved and the result converted into a general initial drying rate equation, in which all dryer characteristics are grouped into one dimensionless parameter. The initial drying rate equation is mathematically maximized and the optimum working conditions determined. The result shows that initial drying rate always increase with increases of either the superheated steam temperature or velocity, but once these two variables are fixed, there exists at least one “optimum” pressure at which the initial drying rate is a maximum. Finally, the initial drying rate and optimum condition equations are applied to three model dryers, a dryer for a flat sheet, a fixed bed dryer and a rotary dryer. In each case, numeric values are computed and plotted as drying rate versus pressure curves, in which the optimum drying rate is also included. Also presented is a chart to compare the optimum pressures as functions of temperature and steam velocity for the three dryers.     

Dynamic Analysis of Drying Energy Consumption

A concept of instantaneous drying and energy efficiencies has been applied to analyze energy consumption in a through-circulation conveyor dryer and a batch fluid bed dryer for synthetic rubber. It is shown that the energy performance of the conveyor dryer can be improved by leveling of the moisture content distribution across the material layer by mechanical agitation, and sectioning of the air plenum in order to reduce inlet air temperature in the last two sections of the dryer. It is also shown that drying of a synthetic rubber in the fluid bed dryer is more energy-efficient than in the conveyor dryer, especially in the constant-rate period. Thus, the largest energy savings could be obtained in a two-stage dryer comprised of the plug-flow fluid bed dryer, and the belt conveyor dryer for removal of the bulk and residual water, respectively.