DISSERTATIONS AND THESES IN DRYING WRITTEN IN CZECHOSLOVAKIA IN THE PERIOD 1975 - 84

Research and development of drying processes and equipmect has a long tradition in Czechoslovakia (1). There are at least 10 top reoearch centers where drying of varicus materials has been studied. Remarkable attention to drying theory and application is also paid at Czechoslovak universities which yields numerous theses dealing with various aspects of the drying process. The total of 52 M.Sc. theses oriented to drying and/or dryers had been published in the last decade. Moreover, 22 Ph.D. theses were carried out in the same period. This represents an important source of theoretical and experimental results. However all theses had been mitten in the Czech or Slovak language, and therefore their wide international application is rather limited. They are summari-zed in the following list.     

DRYING RESEARCH AND DEVELOPMENT IN CZECHOSLOVAKIA

This paper provides general information on drying R 6D activities in Czechoslovakia. This survey report lists the main topics in drying according to individual industrial sectors in which drying plays an important role. Drying R 6D carried out in Czechoslovak Universities is also cited. The paper includes an extensive list of references, mainly proceedings of national drying conferences, symposia, and meetings     

DRYING RESEARCH AND DEVELOPMENT IN CZECHOSLOVAKIA

This paper provides general information on drying R 6D activities in Czechoslovakia. This survey report lists the main topics in drying according to individual industrial sectors in which drying plays an important role. Drying R 6D carried out in Czechoslovak Universities is also cited. The paper includes an extensive list of references, mainly proceedings of national drying conferences, symposia, and meetings     

RATE OF DRYING AND STRESSES IN THE FIRST PERIOD OF DRYING

The paper presents a computer simulated processes and illustrate how the drying induced stresses are influenced by the rate of drying. It is shown that the moisture transport coefficient, and thus the rate of drying, depends on the thermal state of the drying material, defined by the wet-bulb temperature. Through these simulated processes one can observe the evolution of the moisture content and stress distributions during drying at constant, but in each process different, wet-bulb temperatures. A convective drying process of a bar with rectangular cross-section is considered as example, and a two-dimensional initial-boundary value problem is solved numerically with the use of the finite element method. The numerical results are visualised in spatial diagrams.     

THESES/DISSERTATIONS/1963-1983, POLAND

ABSTRACT

A fluidized bed of inert particles lpar;packing)--> can be used advantageously for the drying of paste-like materials of high moisture content. Wet pasty material is fed into a fluidized bed of chemically inert coarse particles. The wet material coats the surface of the inert particles. Drying takes place mainly in the thin layer formed on the surface of particles. After reaching a certain moisture content, the dried material film breaks off the surface of the packing particles, and leave the fluidized bed as a fine powder in the exit gas stream.

Experiments were performed using different organic and inorganic materials e.g. raw materials from human and veterinary     

AN APPROXIMATION METHOD FOR THE DETERMINATION OF THE DISTRIBUTION OF TEMPERATURE AND OF MOISTURE CONTENT IN THE FALLING RATE PERIOD OF DRYING

The present paper deals with the periods of dif- ferent drying mechanism. A calculation method is pre- sented for the temperature distribution of the material during these periods and for distribution of moisture content in the falling rate period. The test material was a 100 x 100 x 30 mm gypsum plate.     

AN APPROXIMATION METHOD FOR THE DETERMINATION OF THE DISTRIBUTION OF TEMPERATURE AND OF MOISTURE CONTENT IN THE FALLING RATE PERIOD OF DRYING

The present paper deals with the periods of dif- ferent drying mechanism. A calculation method is pre- sented for the temperature distribution of the material during these periods and for distribution of moisture content in the falling rate period. The test material was a 100 x 100 x 30 mm gypsum plate.     

塑料的干燥及其设备

介绍塑料干燥的特点，方法和干燥设备的原理，结构及选用。     

DRYING RESEARCH AND DEVELOPMENT IN THE GERMAN DEMOCRATIC REPUBLIC

A summary is given of papers published in the GDR in the field of drying including drying theory, dryer models, sensor development, and analysis of industrial dryers.

Today in the GDR more than 10 000 dryers using 280 000 TJ/a are operated. So drying research and development mainly is driven by practical considerations, but there are pure theoretical approaches to dryer modelling and development of sophisticated drying sensors of general intereet too.     

DRYING RESEARCH AND DEVELOPMENT IN THE GERMAN DEMOCRATIC REPUBLIC

A summary is given of papers published in the GDR in the field of drying including drying theory, dryer models, sensor development, and analysis of industrial dryers.

Today in the GDR more than 10 000 dryers using 280 000 TJ/a are operated. So drying research and development mainly is driven by practical considerations, but there are pure theoretical approaches to dryer modelling and development of sophisticated drying sensors of general intereet too.     

DRYING OF STICKY GRANULAR MATERIALS DWING THE CONSTANT RATE PERIOD IN A VIBRATED FLUIDIZED BED

Experimental results on the drying characteristics in a vibrated fluidized bed IVFB) for sticky and agglomerating materials under various conditions of the operating parameters are presented.The dynamics of the 'FB of wetted materials and the effects of parameters, such as vibration amplitude and frequency, initial moisture content, initial bed height, particle size, and air velocity and temperature on the drying rate during the constant rate period were studied experimentally.     

DRYING OF STICKY GRANULAR MATERIALS DWING THE CONSTANT RATE PERIOD IN A VIBRATED FLUIDIZED BED

Experimental results on the drying characteristics in a vibrated fluidized bed IVFB) for sticky and agglomerating materials under various conditions of the operating parameters are presented.The dynamics of the \'FB of wetted materials and the effects of parameters, such as vibration amplitude and frequency, initial moisture content, initial bed height, particle size, and air velocity and temperature on the drying rate during the constant rate period were studied experimentally.     

EFFECT OF VIBRATION ON THE DRYING RATE DURING THE FALLING RATE PERIOD

The results of an experimental study on the drying characteristics in vibrated fluidized beds of corn plumule, silica gel and citric acid are presented. Application of vibration was found to enhance the drying rate during the falling rate period. In the optimum range of vibration parameters, the critical moisture content decreased significantly as compared with that in conventional fluidized beds of the same material.     

EFFECT OF VIBRATION ON THE DRYING RATE DURING THE FALLING RATE PERIOD

The results of an experimental study on the drying characteristics in vibrated fluidized beds of corn plumule, silica gel and citric acid are presented. Application of vibration was found to enhance the drying rate during the falling rate period. In the optimum range of vibration parameters, the critical moisture content decreased significantly as compared with that in conventional fluidized beds of the same material.     

ANALYSIS AND OPTIMIZATION OF THE CONDITIONING PHASE IN TIMBER DRYING

The conditioning phase of the conventional timber drying process has been investigated. Due to wood shrinkage, tensile stress will develop in the surface layer of the board during drying. This stress combined with the change in MC causes mechano-sorptive creep. If the process is abruptly terminated when the target MC is reached, then there will be a considerable internal MC gradient and the creep deformation will cause distortions in subsequent machining. A conditioning phase is often introduced at the end, in order to reduce these problems. The conditioning phase has been analyzed with a wood drying simulation model. It is shown that traditional conditioning cannot completely reverse the deformations, even at very long conditioning times. An optimizing procedure has thus been used to create a new conditioning “schedule” which gives the best possible result within a given time. Features of such optimized schedules are presented. As the surface layer is elongated during drying, there is a risk that considerable stress develops as the moisture profile levels out. In some cases internal checking will be the result. The optimization procedure is thus modified to avoid such situations and the impact on the conditioning schedule is discussed.     

ANALYSIS AND OPTIMIZATION OF THE CONDITIONING PHASE IN TIMBER DRYING

The conditioning phase of the conventional timber drying process has been investigated. Due to wood shrinkage, tensile stress will develop in the surface layer of the board during drying. This stress combined with the change in MC causes mechano-sorptive creep. If the process is abruptly terminated when the target MC is reached, then there will be a considerable internal MC gradient and the creep deformation will cause distortions in subsequent machining. A conditioning phase is often introduced at the end, in order to reduce these problems. The conditioning phase has been analyzed with a wood drying simulation model. It is shown that traditional conditioning cannot completely reverse the deformations, even at very long conditioning times. An optimizing procedure has thus been used to create a new conditioning “schedule” which gives the best possible result within a given time. Features of such optimized schedules are presented. As the surface layer is elongated during drying, there is a risk that considerable stress develops as the moisture profile levels out. In some cases internal checking will be the result. The optimization procedure is thus modified to avoid such situations and the impact on the conditioning schedule is discussed.