New Food Drying Technologies - Use of Ultrasound

2003 ◽  
Vol 9 (3) ◽  
pp. 215-221 ◽  
Author(s):  
A. Mulet ◽  
J. A. Cárcel ◽  
N. Sanjuán ◽  
J. Bon
Keyword(s):  
Mass Transfer ◽  
Water Availability ◽  
Water Transfer ◽  
Threshold Power ◽  
External Resistance ◽  
Solid Foods ◽  
Mechanical Waves ◽  
Liquid Systems ◽  
Salt Brine ◽  
Solid Liquid

Reducing water availability is one way to preserve food. Water in solid foods is transferred to a fluid, either gas or liquid; during this process both internal and external resistance affect water transfer from the food. As a consequence, any means to reduce those resistances constitute an improvement of the process, and ultrasound appears to be a way to reduce those resistances. Ultrasound are mechanical waves that produce different effects when travelling through a medium. Among others, those related to mass transfer include micro-stirring at the interface, the so called “sponge effect” and cavitations. Ultrasound has so far been applied to dehydration in solid-gas systems like onion drying. Nevertheless, the difficulties for the propagation in the air have led to the development of specially adapted transducers that have been applied in the drying of carrots. In solid-liquid systems, ultrasound has been used in the treatment of products immersed in hypertonic solutions, either in sugar solutions for fruits like apples or in salt brine in the case of cheese or meat. An increase in mass transfer is achieved if the threshold power value for the product is attained.

Pressure Drop and Mass Transfer Studies in Liquid Fluidized Beds

2006 ◽  
Author(s):  
Bhagavatula Venkata Ramana Murthy
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Liquid Velocity ◽  
Water System ◽  
Solid Particles ◽  
Sugar Water ◽  
Minimum Fluidization Velocity ◽  
Liquid Systems ◽  
Mass Transfer Studies ◽  
Solid Liquid

Fluidized beds are widely used in industries for mixing solid particles with liquids as the solid is vigorously agitated by the liquid passing through the bed and the mixing of the solid ensures that there are practically no temperature gradients in the bed even with exothermic or endothermic reactions (Mixing and the segregation in a liquid fluidized of particles with different sizes and densities", The Canadian Journal of Chemical Engineering, 1988). The violent motion of the solid particles also gives high heat transfer rates to the wall or to cooling tubes immersed in the bed. Because of the fluidity of the solid particles, it is easy to pass solid from one vessel to another. In the present experimental work, the relative density between solid and liquid phases on pressure drop under fluidized condition has been studied using the solid-liquid systems namely, glass beads-water, glass beads-kerosene, plastic beads-kerosene and diamond sugar-kerosene. Pressure drop - liquid velocity and void fraction - liquid velocity relationships have been found for all the mentioned solid-liquid systems under fluidized condition and results have been noted. The effect of the nature of the fluid on the minimum fluidization velocity and the pressure drop has been studied. In addition to the pressure drop studies, mass transfer studies have also been conducted with diamond sugar-water system with and without fluidization and results have been obtained. In addition to these, comparison of bed voidage, pressure drop and minimum fluidization velocity between denser and lighter liquids have been studied and the results have been obtained. Also, the value of rate of mass transfer with fluidization is compared that without fluidization for diamond sugar-water system and the results have been obtained.

Analysis of Hydrodynamics and Mass Transfer of Gas-Liquid and Liquid-Liquid Taylor Flows in Microchannels

2019 ◽  
pp. 1-49
Author(s):  
Rufat Abiev
Keyword(s):  
Mass Transfer ◽  
Point Of View ◽  
Process Conditions ◽  
Two Phase ◽  
Physical Point ◽  
Micro Channels ◽  
Liquid Systems ◽  
Simplifying Assumptions ◽  
Liquid Flows ◽  
Solid Liquid

Analysis of hydrodynamics and mass transfer Taylor flows in micro channels of both gas-liquid and liquid-liquid systems on the basis of classical theoretical approach with some simplifying assumptions was performed. Results of theoretical analysis for description of hydrodynamic parameters and mass transfer characteristics were confirmed by comparison with the author's own and available in literature experimental data. It was shown that the main parameters of two-phase Taylor flows could be quite precisely described theoretically: mean bubble/droplet velocity, liquid film thickness, real gas holdup (which is always smaller than so-called dynamic holdup), pressure drop. Peculiarities of liquid-liquid flows compared to gas-liquid Taylor flows in capillaries are discussed. Wettability effect on hydrodynamics was examined. Tools of mass transfer intensification of gas-liquid and liquid-liquid Taylor flow in micro channels are analyzed. Three-layer model for heat and mass transfer has been proposed and implemented for the case of solid-liquid mass transfer for gas-liquid Taylor flows; optimal process conditions for this process are found theoretically and discussed from physical point of view.

MASS TRANSFER IN SOLID-LIQUID EXTRACTION AT HIGH SOLUTE CONCENTRATIONS

2018 ◽  
Vol 17 (4) ◽  
pp. 827-839
Author(s):  
Eugenia Teodora Iacob Tudose ◽  
Marcela Popa ◽  
Ioan Mamaliga
Keyword(s):  
Mass Transfer ◽  
Liquid Extraction ◽  
Solid Liquid Extraction ◽  
Solid Liquid

The role of (bio)surfactant sorption in promoting the bioavailability of nutrients localized at the solid-water interface

1999 ◽  
Vol 39 (7) ◽  
pp. 91-98 ◽  
Author(s):  
Ryan N. Jordan ◽  
Eric P. Nichols ◽  
Alfred B. Cunningham
Keyword(s):  
Mass Transfer ◽  
Cell Membrane ◽  
Substrate Concentration ◽  
Water Interface ◽  
Industrial Systems ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Surfactant Sorption

Bioavailability is herein defined as the accessibility of a substrate by a microorganism. Further, bioavailability is governed by (1) the substrate concentration that the cell membrane “sees,” (i.e., the “directly bioavailable” pool) as well as (2) the rate of mass transfer from potentially bioavailable (e.g., nonaqueous) phases to the directly bioavailable (e.g., aqueous) phase. Mechanisms by which sorbed (bio)surfactants influence these two processes are discussed. We propose the hypothesis that the sorption of (bio)surfactants at the solid-liquid interface is partially responsible for the increased bioavailability of surface-bound nutrients, and offer this as a basis for suggesting the development of engineered in-situ bioremediation technologies that take advantage of low (bio)surfactant concentrations. In addition, other industrial systems where bioavailability phenomena should be considered are addressed.

Ultrasound Assisted Solid-Liquid Extraction Devices - Harnessing Active Ingredients from Plant materials – Overview and Analysis

2020 ◽  
Vol 13 ◽  
Author(s):  
Venkatasubramanian Sivakumar
Keyword(s):  
Mass Transfer ◽  
Cell Wall ◽  
Plant Cell ◽  
Plant Cell Wall ◽  
Liquid Extraction ◽  
Active Ingredients ◽  
Plant Materials ◽  
Ultrasound Assisted ◽  
Solid Liquid Extraction ◽  
Solid Liquid

Background: In the growing environmental concern use of natural products, efficient processes and devices are necessary. Solid-Liquid extraction of active Ingredients from Plant materials is one of the important unit operations in Chemical Engineering and need to be enhanced. Objectives: Since, these active ingredients are firmly bound to the plant cell wall membrane, which pose mass-transfer resistance and need to get detached through the use of suitable process intensification tools such as ultrasound and suitable devices. Therefore, detailed analysis and review is essential on development made in this area through Publications and Patents. Hence, the present paper illustrates the development of ultrasound assisted device for solid-liquid extraction are presented in this paper. Methods: Advantages such as % Yield, Reduction in extraction time, use of ambient conditions, better process control, avoidance or minimizing multi stage extraction could be achieved due to the use of ultrasound in extraction as compared to conventional processes. Conclusions: Use of ultrasound to provide significant improvements in the extraction of Vegetable tannins, Natural dyes for application in Leather processing has been demonstrated and reported earlier. These enhancement could be possible through various effects of ultrasound such as better flow of solvents through micro-jet formation, mass transfer enhancement due to rupture of plant cell wall membranes through acoustic cavitation, better leaching due to micro-mixing and acoustic streaming effects. This approach would minimize material wastage; thereby, leading to eco-conservation of plant materials, which is very much essential for better environment. Hence, various methods and design for application of ultrasound assisted solid-liquid extractor device are necessary.

Solid-liquid mass transfer in agitated Newtonian and non-Newtonian fluids

1988 ◽  
Vol 27 (7) ◽  
pp. 1246-1259 ◽  
Author(s):  
Pyare Lal ◽  
Satendra Kumar ◽  
Siddh N. Upadhyay ◽  
Yogendra D. Upadhya
Keyword(s):  
Mass Transfer ◽  
Newtonian Fluids ◽  
Liquid Mass ◽  
Liquid Mass Transfer ◽  
Solid Liquid
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