The Mechanism of a Temperature Decrement of Porous Materials Immersed in a Fluidized Bed in Drying

Tatemoto, Yuji; Mawatari, Yoshihide; Sugita, Keiichi; Shiota, Yoichi; Noda, Katsuji

doi:10.1252/jcej.37.875

Cited by 18 publications

(5 citation statements)

References 14 publications

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“…Only in the case of glass beads was there a period when the temperature of the sample center decreased with time, which was discussed in our previous paper. [29] In this study, the temperature of the sample center when the temperature was almost constant with time was used as the index of the sample temperature in drying (T c,c ). The value of T c,c in the case of silica gel beads was almost equal to that in the case of glass beads in both pressures in the drying chamber.…”

Section: Methodsmentioning

confidence: 99%

Effect of Fluidizing Particle on Drying Characteristics of Porous Materials in Superheated Steam Fluidized Bed under Reduced Pressure

et al. 2008

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The hygroscopic porous particle was used as the fluidizing particle for the superheated steam fluidized bed drying under reduced pressure. A relatively large material was immersed in the fluidized bed as the drying sample. The drying characteristics of the sample were examined experimentally and the results were compared with those in the case of inert particle fluidized bed.The water transfer from the sample to the fluidizing particle bed in the case of hygroscopic porous particle facilitated the drying regardless of pressure and temperature in the drying chamber. The increment degree of the sample temperature at the earlier period of drying was smaller in the case of hygroscopic porous particle than in the case of inert particle, and the phenomenon was more remarkable in the case of superheated steam than in the case of hot air. INTRODUCTIONThe quality of a dry product is strongly affected by the drying process. During the drying process, heat-sensitive materials such as food and pharmaceuticals must be kept at low temperature. The freeze dryer is used for such materials, but the long drying time and the large amount of energy are necessary for the drying. Therefore, the development of a dryer that has low drying temperature, high drying rate, and high energy efficiency is required for heat-sensitive materials.Under reduced pressure, the material temperature in drying becomes lower. Under extremely low pressure, however, the convective heat transfer rate from the drying gas to the material is low and the drying time becomes much

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Section: Methodsmentioning

confidence: 99%

Effect of Fluidizing Particle on Drying Characteristics of Porous Materials in Superheated Steam Fluidized Bed under Reduced Pressure

et al. 2008

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“…The heat transfer coefficients in the fluidized bed were more than 10 times higher than those in hot air. [15,23] The heat transfer coefficient included the thermal radiation and thermal conduction from the fluidizing particles. The highest drying rate for all cases is found in the case of the fluidized bed of glass beads.…”

Section: Mathematical Modelsmentioning

confidence: 99%

Drying Characteristics of Carrots Immersed in a Fluidized Bed of Fluidizing Particles Under Reduced Pressure

Tatemoto

Michikoshi

2014

Drying Technology

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The drying characteristics and properties (color and shrinkage) of carrots (as a representative agricultural product) were experimentally examined in a fluidized bed under reduced pressure. Dry hot air and superheated steam were used as the drying gases. Rice and carrot powders (0.125-0.355 mm in diameter) were used as the fluidizing particles, in addition to glass beads (0.12 mm in diameter).It was confirmed that the drying rate using a fluidized bed was much higher than without a fluidized bed (hot-air drying), regardless of the type of fluidizing particles used. Under reduced pressure, both with and without a fluidized bed, the drying rate was higher than that at atmospheric pressure using hot air. The drying rate was sufficiently high for fluidized-bed drying with superheated steam, though the drying rate was higher with hot air than with superheated steam. As the drying temperature increased, the volume ratio (befor/after drying) of the sample increased. At high drying temperatures (373 and 423 K in the present study), the color of the sample changed; in other words, a heat-induced change in the properties of the carrot was observed. At a low drying temperature (333 K in the present study), the drying method did not affect the color of the carrot; i.e., the color of the dried material was maintained even in a fluidized bed under reduced pressure when the drying rate was higher. INTRODUCTIONThe drying process affects the quality of a dried product. In particular, heat-sensitive materials such as food, agricultural products, and pharmaceuticals need to be kept at a low temperature while being dried. Vacuum and freeze dryers have been used for the low-temperature drying of such materials. However, these dryers have certain problems; a long drying time and a large amount of energy are required for drying. It is necessary to manufacture a dryer that has a low drying temperature, high drying rate, and high energy efficiency for drying heat-sensitive materials.

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“…The modeling and the advancement of freeze drying of foods are carried out by Sagara. [38,39] Fluidized Bed Drying Several works on fluidized bed drying are faced to not only fundamentals, [40,41] but also development of multi-functional dryers to work simultaneously as mixing, filtration, extraction-filtration, granulation, or crystallization. [42] Vibration fluidized bed dryers are also developed for hard fluid particulates that are classified into the C particles in the Geldert chart, and paid attention as suitable dryers for removing remaining solvents under the guidline of pharmaceutical chemicals regulated in GMP (Good Manufacturing Practice).…”

Section: Freeze Dryingmentioning

confidence: 99%

Recent R&D on Drying Technology in Japan

Itaya

Mori

2006

Drying Technology

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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. INTRODUCTIONDrying is an important technology in several fields and consumes a large amount of energy. In Japan, a number of R&D projects on drying technologies are carried out to improve the energy efficiency as well as to reduce drying time in fields of food, ceramics, powder, pharmacy, film coating, etc., while maintaing their highest quality. Recently, there has been research to add an effective function and to model the drying behavior for optimum design and precise operation or control.The objective of this article is to introduce the R&D on innovative drying technology performed in Japan. The trend of drying technology is concerned with the energy situation in Japan. The outlook of the current energy situation surrounding Japan was briefly surveyed preliminarily. The overview includes fundamentals as well as industrial technology. The brief topics consist of prediction of drying characteristic curves, drying of specific materials like aqueous polymer solution, coated film, agricultural products or wastes, food, ceramics, spray drying, freeze drying, fluidized bed drying, superheated steam drying, and microwave drying. An

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The Mechanism of a Temperature Decrement of Porous Materials Immersed in a Fluidized Bed in Drying

Cited by 18 publications

References 14 publications

Effect of Fluidizing Particle on Drying Characteristics of Porous Materials in Superheated Steam Fluidized Bed under Reduced Pressure

Effect of Fluidizing Particle on Drying Characteristics of Porous Materials in Superheated Steam Fluidized Bed under Reduced Pressure

Drying Characteristics of Carrots Immersed in a Fluidized Bed of Fluidizing Particles Under Reduced Pressure

Recent R&D on Drying Technology in Japan

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