Perspectives on Developments in Drying

In this article, the significance, characteristics, and reasons for growing interest in drying are presented. Some remarks on university–industry interactions and energy aspects are given. The trends in drying research and techniques emerging in connection with future opportunities in the area of chemical and process engineering are discussed.     

Development of Solar Drying

Importance of Solar Drying is increasing worldwide, especially in areas where the use of the abundant, renewable and clean solar energy is essentially advantageous. In the developing countries and in rural areas the traditional open-air drying methods should be substituted by the more effective and more economic solar drying technologies.

R&D needs should be considered in the basic research and experimental fields; in performance measurement; in the modelling-simulation-design and testing. The international co-operation of experts should be improved and more efforts would be needed in the policy and in the public information.     

Recent R&D on Drying Technology in Japan

This article presents the outlook of the energy situation in Japan and reviews the recent R&D on innovative drying technologies performed in Japan. The overview of drying includes fundamentals as well as industrial technologies. The topics considered are drying characteristics of several materials, drying of hard-to-handle powders, drying of coatings, drying-induced strain-stress problems, drying modeling, and drying of agricultural wastes for functional recycling and noble dryers. An appropriate combination of heating methods and dryer type can result in significant enhancement of efficiency, drying rate, and/or material quality. The final goal of this article to contribute to providing an idea for development and evaluation of precise drying systems with a high performance and an effect of energy saving in drying.     

An Overview of Recent Developments and Some R&D Challenges Related to Drying of Foods

Thermal dehydration is the most common and cost-effective technique for preservation of foods and for the production of traditional as well as innovative processed products such as snacks with desired functionalities. The basic intent of this article is to provide a global overview of emerging and innovative thermal drying technologies that are already commercialized or show potential of industrial exploitation upon successful R&D to sort out some limitations. New drying technologies are needed to enhance quality, reduce energy consumption, improve safety, and reduce environmental impact. Mathematical modeling can be used for cost-effective development of untested novel designs to reduce the cost and time required for innovation. As examples of emerging drying technologies we consider selected dehydration techniques with imminent commercialization potential. These include heat pump–assisted drying, microwave-assisted drying, low-pressure superheated steam drying, pulse combustion spray drying, pulsed and ultrasound-assisted osmotic dehydration, as well as novel gas–particle contactors such as impinging streams and pulsed fluidized beds. Multistage drying, intermittent drying, and the use of hybrid drying technologies—which combine advantages of different dryers without some of their limitations—will be outlined. This article also discusses various methods of energy minimization, and the potential for use of renewable energy will also be discussed briefly. Although this overview emphasizes food dehydration, the themes covered are applicable to other materials as well.     

Recent R&D on Drying Technology in Japan

This article presents the outlook of the energy situation in Japan and reviews the recent R&D on innovative drying technologies performed in Japan. The overview of drying includes fundamentals as well as industrial technologies. The topics considered are drying characteristics of several materials, drying of hard-to-handle powders, drying of coatings, drying-induced strain-stress problems, drying modeling, and drying of agricultural wastes for functional recycling and noble dryers. An appropriate combination of heating methods and dryer type can result in significant enhancement of efficiency, drying rate, and/or material quality. The final goal of this article to contribute to providing an idea for development and evaluation of precise drying systems with a high performance and an effect of energy saving in drying.     

近年来喷雾干燥技术研究进展和展望

喷雾干燥是目前市场上常见的一种干燥方式,喷雾干燥过程的复杂性研究已经有很多成果,喷雾干燥的低热效率给设备研究人员和企业界留下了较大的研发空间,需要不断地去完善其流程和工艺,以满足市场和产品本身的需要。从分析喷雾干燥的研究现状入手,介绍喷雾干燥领域新的研究成果及设备与工艺的发展情况,总结并提出了目前较新的研究课题和方向。     

喷雾干燥在生物质资源加工利用中的研究进展

喷雾干燥技术被广泛应用在许多工业生产领域中,本文从工艺、机理、产品的质量和节能等几个方面对喷雾干燥在生物质资源加工利用中的发展状况进行了概述,发现研究过程中尚存在着一些问题,如由于高进气温度使产品质量下降;在干燥室或工艺管中发生产品粘壁;系统能效低及生物制品中活性物质被破坏等,亟需在工艺及设备等方面改进和提高,因此很有必要对喷雾干燥技术进行更深入的研究。     

Research and Development in Drying: Recent Trends and Future Prospects

Drying R&D has seen nearly exponential growth over the past three decades. Initially driven by the need to conserve energy in this highly energy-intensive operation found in almost all industrial sectors, now the focus is on product quality, environmental impact, safety issues, new products, and processes etc. Drying provides challenging areas for multi- and cross-disciplinary research of fundamental as well as applied nature coupling transport phenomena with material science. An attempt will be made to summarize the new developments in drying technologies, identify recent trends and make predictions about the future trends that may be expected. Also, personal perspectives on models of research appropriate for drying technology will be presented. The need for industry-academia interaction and for a stake of industry in academic research is noted as a key step towards successful transfer of innovative drying technologies to industry. Finally, the weaknesses of the currently popular “closed loop” approach of research in academia, by academia and for academia, resulting on over-emphasis on “high impact-factor” rather than “high impact research” will be discussed. It is hoped that future IDS meetings will increase industry participation by enhancing their impact on industrial adoption of newer more efficient drying technologies. It is essential to make it a worthwhile—even essential—exercise for industry to participate in these meetings.     

Research and Development Needs and Opportunities in Freeze Drying

Experimental and theoretical research and development studies are preposed and presented in important areas of the freeze drying process. The practical importance of the synergistic integration of advanced theoretical models and experiments is indicated, and the potential contributions of the proposed     

Research and Development Needs and Opportunities in Freeze Drying

ABSTRACT

Experimental and theoretical research and development studies are preposed and presented in important areas of the freeze drying process. The practical importance of the synergistic integration of advanced theoretical models and experiments is indicated, and the potential contributions of the proposed     

Status and Developments of Drying Low Rank Coal with Superheated Steam in China

Superheated steam drying (SSD) of low rank coal (LRC) is applied to improve the heating value and thermal efficiency and to reduce greenhouse gas emissions and the danger of spontaneous combustion. It is essential to understand the fundamental aspects of drying LRC with superheated steam supported by funds in China and the development of clean coal technology. It is also important to promote the level of scientific technology relevant to safe energy strategies. The background of SSD based on China's unique energy structure and coal production situation are presented in this article. A comprehensive overview on progress and mechanisms of SSD is provided, including the status of drying technology supported by funds in China, distribution of project field and important research institutions, physical and chemical structure of water in coal, heat and mass transfer processes, mathematical models, and some results for wood, food, hot gas, etc., with particular reference to SSD in drying of LRC in China. There are still many challenges in the application of SSD of LRC in very large-scale power plants, drying equipment, and control technology. Advanced SSD sponsored by the fund project in China shows important significance to energy savings and reducing greenhouse gas emissions.     

污泥热泵干燥速率及能耗的实验研究

利用小型热泵干燥试验台，对污泥干燥过程含水率、空气参数（温度、相对湿度）及热泵参数（制冷工质参数、排水量、能耗等）的变化进行了试验测试，并着重对干燥速率、能量回收率及影响因素进行了分析。试验显示，依靠外热源预热后，污泥干燥过程仅依靠热泵回收的排气余热供热，干燥箱内平均温度可达63℃，最高迭71℃。干燥箱内温度的高低取决于受制冷工况影响的热泵供风温度。污泥干燥速率随空气温度升高和相对湿度的降低而增大，湿基含水率从42．6％到18．74％的平均干燥速率为0．123％／（m·min）。热泵干燥回收排气余热的节能效果显著，并随热泵排水量的增加而增大。平均能量回收率为39．1％，最大值为48．9％和最小值为23．6％，分别发生在热泵排水量最大和最小的阶段。     

Optimal Control of the Primary Drying Stage of Freeze Drying of Solutions in Vials Using Variational Calculus

Abstract

The problem of operating freeze drying of pharmaceutical products in vials placed in trays of a freeze dryer to remove free water (in frozen state) at a minimum time was formulated as an optimal control problem. Two different types of freeze dryer designs were considered. In type I freeze dryer design, upper and lower plate temperatures were controlled together, while in type II freeze dryer design, upper and lower plate temperatures were controlled independently. The heat input to the material being dried and the drying chamber pressure were considered as control variables. Constraints were placed on the system state variables by the melting and scorch temperatures during primary drying stage. Necessary conditions of optimality for the primary drying stage of freeze drying process in vials are derived and presented. Furthermore, an approach for constructing the optimal control policies that would minimize the drying time for the primary drying stage was given. In order to analyze optimal control policy for the primary drying stage of the freeze-drying process in vials, a rigorous multi-dimensional unsteady state mathematical model was used. The theoretical approach presented in this work was applied in the freeze drying of skim milk. Significant reductions in the drying times of primary drying stage of freeze drying process in vials were obtained, as compared to the drying times obtained from conventional operational policies.     

Optimal Control of the Primary Drying Stage of Freeze Drying of Solutions in Vials Using Variational Calculus

The problem of operating freeze drying of pharmaceutical products in vials placed in trays of a freeze dryer to remove free water (in frozen state) at a minimum time was formulated as an optimal control problem. Two different types of freeze dryer designs were considered. In type I freeze dryer design, upper and lower plate temperatures were controlled together, while in type II freeze dryer design, upper and lower plate temperatures were controlled independently. The heat input to the material being dried and the drying chamber pressure were considered as control variables. Constraints were placed on the system state variables by the melting and scorch temperatures during primary drying stage. Necessary conditions of optimality for the primary drying stage of freeze drying process in vials are derived and presented. Furthermore, an approach for constructing the optimal control policies that would minimize the drying time for the primary drying stage was given. In order to analyze optimal control policy for the primary drying stage of the freeze-drying process in vials, a rigorous multi-dimensional unsteady state mathematical model was used. The theoretical approach presented in this work was applied in the freeze drying of skim milk. Significant reductions in the drying times of primary drying stage of freeze drying process in vials were obtained, as compared to the drying times obtained from conventional operational policies.     

欧洲陶瓷复合材料开发近况

欧洲在长纤维增强复合材料的制造和应用特别是军事和航天中的应用方面拥有一定的经验,但总的技术水平不及日本和美国,其所用陶瓷增强纤维需从日本和美国进口。为保持欧洲在２１世纪陶瓷复合材料市场中的竞争地位和开发先进陶瓷复合材料在民用工业中的大规模广泛应用,欧洲联盟委员会要求欧洲国家加强合作共同研究开发连续纤维增强陶瓷复合材料。     

浅谈21世纪的化学工程

在参考我国化工界已有战略研究的基础上,进一步分析了当前我国社会经济发展需求和世界科技发展的趋势,指出我国化学工程科学正面临难得的发展机遇,同时也面临多方位的挑战。化学工程作为一个共性的工程学科,既要适应其应用领域的扩展,更要充分利用科学技术发展带来的机遇,扩展深化自身的知识基础,为各种物质转化相关领域提供共性的理论、方法和技术。复杂系统理论的发展、计算技术的进步以及测试技术的提升,为化学工程科学的发展提供了新的动力;经济社会的进步,能源、资源与环境问题的突显以及高技术的发展,大大扩展了化学工程服务的领域。我们应当抓住这一机遇,适应这一变化,为解决能源、资源和环境等领域的瓶颈问题,推动高技术的发展做出贡献,开创化学工程新的发展阶段。