scholarly journals Convective and Microwave Assisted Drying of Wet Porous Materials with Prolate Spheroidal Shape: A Finite-Volume Approach

Agriculture ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 507
Author(s):  
Edna G. Silva ◽  
Ricardo S. Gomez ◽  
Josivanda P. Gomes ◽  
Rossana M. F. Figueirêdo ◽  
Alexandre J. M. Queiroz ◽  
...  
Keyword(s):  
Porous Materials ◽  
Finite Volume ◽  
Microwave Power ◽  
Energy Demand ◽  
Microwave Drying ◽  
Convective Heating ◽  
Moisture Removal ◽  
Prolate Spheroidal ◽  
Power Intensity ◽  
Spheroidal Shape

Convective heating is a traditional method used for the drying of wet porous materials. Currently, microwave drying has been employed for this purpose, due to its excellent characteristics of uniform moisture removal and heating inside the material, higher drying rate, and low energy demand. This paper focuses on the study of the combined convective and microwave drying of porous solids with prolate spheroidal shape. An advanced mathematical modeling based on the diffusion theory (mass and energy conservation equations) written in prolate spheroidal coordinates was derived and the numerical solution using the finite-volume method is presented. Here, we evaluated the effect of the heat and mass transport coefficients and microwave power intensity on the moisture removal and heating of the solid. Results of the drying and heating kinetics and the moisture and temperature distribution inside the solid are presented and discussed. It was verified that the higher the convective heat and mass transfer coefficients and microwave power intensity, the faster the solid will dry and heat up.

Colour Change Analysis of Fig Fruit during Microwave Drying

2013 ◽  
Vol 9 (1) ◽  
pp. 107-114 ◽  
Author(s):  
Faroogh Sharifian ◽  
Asad Modarres-Motlagh ◽  
Mohammad Hasan Komarizade ◽  
Ali M. Nikbakht
Keyword(s):  
Microwave Power ◽  
Colour Change ◽  
Microwave Drying ◽  
Colour Space ◽  
Change Analysis ◽  
Power Intensity ◽  
Before And After ◽  
Yellow Orange ◽  
Hue Angle ◽  
Orange Colour

AbstractInvestigation of qualitative indices for the pulsed microwave dried figs (Ficus carica L.) is accomplished through image processing techniques. Three hundred colour pictures of fig fruit before and after drying were prepared in RGB colour space. After converting the RGB colour space into Lab units, colour values in Lab units were analysed before and after drying at five levels of microwave power intensity and six pulsing ratio levels. Kinetic parameters for the colour change were determined using the total colour change parameter, chroma, hue angle and browning index. The results showed that the L value decreases with the pulsing ratio and increases with microwave power intensity while a values remains constant with the microwave power intensity. Values of hue angle for dried fig varied between 1.21 and 1.32 radian, i.e. the dried fruits presented an appealing yellow/orange colour. Additionally, increasing microwave power intensity led to higher browning indices. Based on the resulting values, an optimized microwave drying of fig will be achieved serving as a tool for enhanced economical processing of the fruit.

Study of color kinetics of banana (Musa cavendish) under microwave drying by application of image analysis

2020 ◽  
pp. 108201322098133
Author(s):  
Sagar Nagvanshi ◽  
Subbarao Kotra Venkata ◽  
TK Goswami
Keyword(s):  
Microwave Power ◽  
Vision System ◽  
Power Level ◽  
Microwave Drying ◽  
Slice Thickness ◽  
Order Kinetic ◽  
Drying Time ◽  
Volumetric Heating ◽  
Kinetics Of ◽  
Microwave Power Level

Microwave drying works on the volumetric heating concept promoted by electromagnetic radiation at 0.915 or 2.450 GHz. In this study, banana ( Musa Cavendish) was taken as the sample and treated under microwave drying. The effect of two process variables, namely slice thickness (2, 3.5, and 5 mm) and microwave power (180 W, 360 W, and 540 W), were studied on drying kinetics and color kinetics. It was observed that the inverse variation relationship exists between drying time and microwave power level while drying time and slice thickness exhibited a direct variation relationship. A Computer Vision System (CVS) was developed to measure the color values of banana in CIELab space using an algorithm written in MATLAB software. Once the color parameters were obtained, they were fitted in First and Zero-order kinetic models. Both models were found to describe the color values adequately. This study concludes that microwave drying is a promising dehydration technique for banana drying that reduces the significant time of drying. Application of CVS is an excellent approach to measure the surface color of banana.

scholarly journals Comparative Study of Hot Air Drying and Microwave Drying for Dewatered Sludge

2021 ◽  
Author(s):  
Wittawat Wulyapash ◽  
Awassada Phongphiphat ◽  
Sirintornthep Towprayoon
Keyword(s):  
Microwave Power ◽  
Specific Energy Consumption ◽  
Microwave Drying ◽  
Drying Methods ◽  
Drying Time ◽  
Hot Air ◽  
Air Temperatures ◽  
Dewatered Sludge ◽  
Dried Sludge ◽  
Seafood Processing

Abstract Large amounts of sludge are generated from wastewater treatment in seafood processing industries. Most of the dewatered sludge in Thailand is not utilized and disposed by landfilling. The dried sludge utilization as refuse-derived fuel (RDF) is an alternative solution due to the gross calorific value (GCV), which is greater than 21.9 MJ/kg. However, the key obstacle is its high moisture content of 87.4% (wet basis). Therefore, drying methods using hot air and microwave techniques were investigated for preparing dried sludge. The effects of hot air temperatures (100-150 °C) and microwave power levels (100-800 W) were compared on drying kinetics, specific energy consumption (SEC), and characteristics of the dried products. The results showed that drying times were decreased by increasing the hot air temperatures. In the same way, the increase in microwave power levels decreased the drying time. The application of microwaves contributed to reducing the drying time by more than 46% compared to the hot air. The reduction of drying times resulted in the saving SEC. The GCV of the dried sludge decreased with the decrease in the volatile matter (VM) due to the high component of VM as 79.5-80.3% (dry ash-free basis). The sludge dried by the microwaves showed a lower GCV than the hot air products. However, dried sludges still had high GCV (≥ 20.8 MJ/kg). Furthermore, the minimal variation of the product characteristics demonstrated that the microwave technique could be applied as an alternative drying method with a rapid process compared to the conventional hot air technique.

Convective and Microwave Drying of Prolate Spheroidal Solids: Modeling and Simulation

2019 ◽  
Vol 391 ◽  
pp. 233-238
Author(s):  
E. Gomes da Silva ◽  
E. Santana de Lima ◽  
W.M. Paiva Barbosa de Lima ◽  
A.G. Barbosa de Lima ◽  
J.J. Silva Nascimento ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Heat Balance ◽  
Diffusion Theory ◽  
Microwave Drying ◽  
Drying Process ◽  
Balance Equations ◽  
Prolate Spheroidal ◽  
Moisture Migration ◽  
Prolate Spheroidal Coordinates ◽  
Spheroidal Coordinates

This paper focuses some fundamental aspects of combined convective and microwave drying of prolate spheroidal solids. A transient mathematical modeling based on the diffusion theory (mass and heat balance equations) written in prolate spheroidal coordinates was derived and the importance of this procedure on the analysis of the drying process of wet porous solid, is also presented. Results pointed to the behavior of the moisture migration and heating of the solid with different aspect ratio. Solids with higher area/volume relationships dry and heat faster.

Microwave Drying of Porous Materials

2004 ◽  
Vol 22 (10) ◽  
pp. 2331-2341 ◽  
Author(s):  
M. Araszkiewicz ◽  
A. Koziol ◽  
A. Oskwarek ◽  
M. Lupinski
Keyword(s):  
Porous Materials ◽  
Microwave Drying

Effects of vacuum level and microwave power on rosemary volatile composition during vacuum–microwave drying

2011 ◽  
Vol 103 (2) ◽  
pp. 219-227 ◽  
Author(s):  
Ángel Calín-Sánchez ◽  
Antoni Szumny ◽  
Adam Figiel ◽  
Klaudiusz Jałoszyński ◽  
Maciej Adamski ◽  
...  
Keyword(s):  
Microwave Power ◽  
Microwave Drying ◽  
Volatile Composition ◽  
Vacuum Level ◽  
Vacuum Microwave

Drying Properties and Parameters of Blue Honeysuckles Pulp under Foam Assisted Microwave Drying Conditions

2012 ◽  
Vol 8 (2) ◽  
Author(s):  
Yu Sun ◽  
Xianzhe Zheng ◽  
Xiangwen Xu ◽  
Chenghai Liu ◽  
Qiang Li ◽  
...  
Keyword(s):  
Vitamin C ◽  
Microwave Power ◽  
Influencing Factor ◽  
Continuous Production ◽  
Microwave Drying ◽  
Slow Decline ◽  
Power Loading ◽  
Three Stages ◽  
Drying Properties ◽  
Drying Conditions

The drying properties and optimal parameters of foamed blue honeysuckles pulp under microwave drying conditions were studied. The microwave power, loading mass and thickness were selected as the influencing factors, and objective factors were content of anthocyanin, vitamin C, moisture and values of color of the final blue honeysuckles powder. The drying process may be divided into three stages: acceleration stage, slow decline stage and quick decay stage. The initial drying phase lasted until the moisture content was less than 4 kg/kg. The constant drying phase was long when the influencing factor was loading mass. The deceleration drying phase is short in all conditions. This study achieve the continuous production of blue honeysuckles powder and the optimum experiment parameters were obtained as follows, the content of anthocyanin in honeysuckle powder is 64.58 mg/g, the content of vitamin C is 14.604 mg/g, moisture ratio is 9.88 % and the color value is 9.78 with the microwave power at 8.86 kW, loading mass at100 g and the thickness at 4mm.

scholarly journals DRYING OF ZUCCHINI AND CARROT SLICES: INFLUENCE OF TISSUE STRUCTURE ON MASS TRANSFER PARAMETERS

2022 ◽  
Vol 52 (1) ◽  
pp. 49-54
Author(s):  
Farhad Khoshnam
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Microwave Power ◽  
Moisture Diffusivity ◽  
Tissue Structure ◽  
Moisture Removal ◽  
Average Activation Energy ◽  
Rate Period ◽  
Transfer Parameters

The present work aimed mainly at investigating the influence of tissue structure on dehydration characteristics of zucchini and carrot. Microwave power levels of 100, 350, 550 and 750 W used to dehydrate the samples with thicknesses of 3, 5, 7 and 9 mm. The results showed that moisture removal from the slices occurred in a short accelerating period at the process beginning followed by a falling rate period. The moisture diffusivity increased with both increasing microwave power and the samples thickness where the average values for zucchini and carrot slices changed from 1.17×10-8 to 9.42×10-8 and from 0.73×10-8 to 5.51×10-8 m2 s-1, respectively. The average activation energy for zucchini and carrot slices varied in the range of 1.22–1.68 and 1.57–1.84 W g-1, respectively and decreased with increasing samples thickness.

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