摘要:

This study deals with the drying / curing process of a model car painting applied on SMC type support and more precisely with the bubbling phenomenon (craters, chips, bubbles, etc.) which appears during the industrial drying of these materials.

ISSN:0737-3937    

DOI:10.1080/07373930008917700

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This study deals with the bubbling phenomenon which appears in some drying conditions on paint films applied as thin layers on SMC substrates. The bubbles and craters origin can be due either to reactions which may occur at the interface paint / SMC either to inadequate drying conditions which affect the polymerization reaction (gelation, viscosity) and the solvent vaporization.

ISSN:0737-3937    

DOI:10.1080/07373930008917701

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Implicit equations relating the dimensionless drying rate to the reduced moisture content for porous non-hygroscopic slabs have been determined. This study is based on the receding evaporative front model and on the assumption of a parabolic moisture content profile in the diffusional zone of the wet region. The characteristic functions derived depend on the relative position of the receding evaporative front. Two cases were considered : the drying of thick products and the drying of thin products. It has been observed that the relationships corresponding to the C.D.C obtained for thick products depend on the initial. On the other hand, it was observed that experimental CDC. of plaster slabs determined for many thicknesses and various plaster textures depend strongly on these two parameters. Furthermore, the model presented gives good results only for thin products.

ISSN:0737-3937    

DOI:10.1080/07373930008917702

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The conclusions drawn by researchers on the source of changing shrinkage rates are discussed. The objective of this study was to determine the source of changing shrinkage rates early in drying and whether shrinkage would make a useful parameter for an automated kiln control system. In this study, four loads of red oak and one of maple were kiln dried using established schedules Shrinkage of the lumber was continuously recorded, and moisture content and released elastic strain were periodically recorded. The moisture content and strain data showed that the changing shrinkage rates early in drying boards were caused by reduced internal stress levels, not the occurrence of fiber saturation point or temperature as reported by some. Results of this study indicate it may be possible to develop an automated kiln system using shrinkage as the controlling parameter. This would reduce the drying time while avoiding additional drying defects.

ISSN:0737-3937    

DOI:10.1080/07373930008917703

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Volumetric and thickness shrinkage evaluated by direct measurement and n-heptane displacement were determined during convective and freeze drying ofGolden deliciousapples. For convective drying, the influence of blanching and diameter/thickness ratio of the apple disks used were analysed at different levels of moisture content under constant conditions. It was found that shrinkage of dried samples, both by convection and by freeze-drying, is anisotropic to a level which depends on sample geometry (ratio diameter/thickness) used. Blanching did not affect shrinkage results.

ISSN:0737-3937    

DOI:10.1080/07373930008917704

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this paper the shrinkage of Dates (Phoenix dactilyferaL.) during drying was observed. Samples were dried in a convective tray dryer under three different conditions (60°C-11.1%RH, 70°C-7.2%RH and 80°C-4.7%RH) and three different air velocities (0.5m/s, l.0m/s and 1.5m/s). Sample shrinkage was directly (using a caliper) and indirectly measured (snapshot area measured). The indirect manner shows a higher precision. The geometry applied in the shrinkage solution proved that the ellipsoidal geometry of the dates, may be successfully approached to a cylinder. Three mathematical models developed by Suzuki et al. (1976) were applied to correlate the dates surface to its moisture content. The core model presented the best fit to the experimental data.

ISSN:0737-3937    

DOI:10.1080/07373930008917705

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Effects of temperature of oil (160, 170 and 180° C) and duration of pre-drying (0.00, 0.25, 0.50, 0.75 and 1.00 h) on the kinetics of moisture removal and oil uptake, and quality of French fries were studied. Frying times at each combination of temperature and pre-drying duration were standardized on the basis of sensory characteristics of the product in the preliminary trials. Results indicated that the rate of both moisture loss and oil uptake were higher in the beginning followed by a decrease in the later stages of frying. Mathematical models were developed to describe both the moisture removal and oil uptake by French fries. French fries prepared from potato fingers blanched in water for 4 min at 85° C and fried (without pre-drying) at 180° C were judged to be the most acceptable.

ISSN:0737-3937    

DOI:10.1080/07373930008917706

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The disposal of sludge generated by water treatment plants poses major financial and environmental problems. Drying of the sludge is an essential pan of any disposal process which may include incinerating, landfilling or upgrading. In the present study, experiments were carried out to investigate the drying of sludge in a spouted bed and to characterize the hydrodynamics and mass transfer mechanisms. The effect of bed moisture content on the minimum spouting velocity (Ums) was examined for sludge granules. Umswas found to increase with increasing the moisture content of the sludge particles. The gas phase mass transfer coefficient in the dryer was determined using porous calcined alumina particles and the results were compared with predictions by correlations available in the literature. The existing correlations gave poor predictions for the mass transfer coefficient. A new correlation for the mass transfer coefficient in a spouted bed dryer was developed based on the experimental results.

ISSN:0737-3937    

DOI:10.1080/07373930008917707

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In order to increase the movement of the particles in the annular region of a conical spouted bed, a mechanical stirrer was incorporated. This led to a study of the fluid dynamics of the conical spouted bed of inert particles under different operating conditions: mass of inert particles, ratio of inert particles to suspension volumes, type of stirrer (2 designs) and stirrer speed.

ISSN:0737-3937    

DOI:10.1080/07373930008917708

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The effect of process variables and blanching on the rate of dewatering of apple slices through immersion in glucose solutions was analyzed. The adequacy of the Hawkes and Flink's and Peleg's models for fitting the rate data was evaluated as well as the structural changes produced in the tissue subjected to osmotic process. High concentration values (33-42 % (w/w)) of the soaking solution favored significantly water loss (WL) but only slightly affected solid gain (SG). Increasing system temperature over the range 20-50 °C generally provided an increase in WL and in SG. The increase in thickness decreased significantly both mass transfer rates. The use of sucrose instead of glucose lead to a greater SG while blanched samples showed higher rates of WL and SG. Microscopic studies revealed that, when applying short treatments, cells appeared slightly shrinked and cells walls folded. After long treatments, although an extensive

ISSN:0737-3937    

DOI:10.1080/07373930008917709

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor