Microwave Drying of Porous Materials

Araszkiewicz, M.; Kozioł, Antoni; Oskwarek, A.; Lupinski, Michal

doi:10.1081/drt-200040014

Cited by 39 publications

(21 citation statements)

References 14 publications

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“…Therefore, at the beginning of the process where the moisture content of the sample exceeds 83.5 % wet basis (5.08 kg water/kg dry matter), the sample will absorb more microwave power causing a very high internal heat generation which in turn produces higher diffusion and thus higher drying rate. As drying proceeds, moisture content within the sample decreases and thus decreasing the absorption of microwave power (Araszkiewicz et al 2004;Darvishi et al 2013;Soysal et al 2006). Besides, the energy efficiency is increasing with increasing microwave power and decreasing slice thickness and microwave power is more effective on efficiency (P ≤ 0.05, Table 2).…”

Section: Energy Analysesmentioning

confidence: 94%

Energetic and exergetic performance analysis and modeling of drying kinetics of kiwi slices

2016

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This work focused on the effects of the moisture content, slices thickness and microwave power on aspects of energy and exergy, drying kinetics, moisture diffusivity, activation energy, and modeling of the thin layer drying of kiwi slices. Results showed that energy and exergy efficiency increased with increasing microwave power and decreasing slice thickness while values of energy efficiency (15.15-32.27 %) were higher than exergy efficiency (11.35-24.68 %). Also, these parameters decreased with a decrease in moisture content. Specific energy consumption varied from 7.79 to 10.02, 8.59 to 10.77 and 9.57 to16.20 to MJ/kg water evaporated for 3, 6 and 9 mm, respectively. The values of exergy loss were found to be in the range of 5.90 and 14.39 MJ/kg water and decreased as the microwave power increased and slice thickness decreased. Effective diffusivity increased with decreasing moisture content and increasing microwave power and slice thickness. Average effective moisture diffusivity of kiwi slices changes between 1.47 × 10

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Section: Energy Analysesmentioning

confidence: 94%

Energetic and exergetic performance analysis and modeling of drying kinetics of kiwi slices

2016

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“…Following moisture reduction, the energy absorbed by the product decreased and the reflected power increased (Araszkiewicz et al, 2004;Mousa and Farid, 2002;Soysal et al, 2006). For this reason, it was observed that as the microwave power increased the energy losses increased, in other words, the values of microwave energy efficiency decreased.…”

Section: Model Name Model Referencesmentioning

confidence: 89%

Characteristics of sunflower seed drying and microwave energy consumption

Darvishi¹,

Khoshtaghaza²,

Najafi³

et al. 2013

International Agrophysics

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A b s t r a c t. The effect of the microwave-convective drying technique on the moisture ratio, drying rate, drying time, effective moisture diffusivity, microwave specific energy consumption, and energy efficiency of sunflower seeds were investigated. Drying took place in the falling rate period. Increasing the microwave power caused a significant decrease in the drying time. The drying data were fitted to four thin-layer drying models. The performance of these models was compared using the coefficient of determination, reduced chi-square and root mean square error between the observed and predicted moisture ratios. The results showed that the Page model was found to satisfactorily describe the microwave-convective drying curves of sunflower seeds. The effective moisture diffusivity values were estimated from Fick diffusion model and varied from 1.73 10 -7 to 4.76 10 -7 m 2 s -1 . Increasing the microwave power resulted in a considerable increase in drying efficiency and a significant decrease in microwave specific energy consumption. The highest energy efficiency and the lowest microwave specific energy consumption were obtained at the microwave power of 300 W.K e y w o r d s: drying, modelling, sunflower seed, microwave energy consumption

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“…Datta 1990, Metaxas & Meredith 1983) that describe how the problem of temperature distribution inside the heated material is connected with its shape. The specific case takes place during microwave-assisted drying of a small sphere, which is supposed to act like a lens and focus the electromagnetic waves inside (Schlunder 1993;Araszkiewicz et al 2004;Remmen et al 1996). In this particular case, the temperature maximum appears to be at the geometrical centre of the particle.…”

Section: Volumetric Heatingmentioning

confidence: 98%

Microwave drying of various shape particles suspended in an air stream

et al. 2006

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Fluidization is an efficient way to dry granular materials. Incorporating microwave heating into the fluidization makes the overall drying process shorter, and the quality of the final products can be improved. However, in order to understand the mechanisms of water removal, an exact knowledge of changes inside the dried material is necessary. The temperature and moisture distribution pattern within the heated material should be identified and analyzed. Unfortunately, the microwave environment makes the measurements very difficult. This paper gives new information on the temperature distribution inside small particles of various shapes dried with microwaves. The tests were carried out in a laboratory-scale, fluid-bed dryer equipped with a microwave source. Five different shapes were examined: sphere, cylinder, halfcylinder, rectangular prism, and prism with triangle base. All particles tested were suspended in an air stream and heated with microwaves. The internal temperature distribution has been analyzed in each case. The rate of drying is also presented and discussed for every case tested.

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Microwave Drying of Porous Materials

Cited by 39 publications

References 14 publications

Energetic and exergetic performance analysis and modeling of drying kinetics of kiwi slices

Energetic and exergetic performance analysis and modeling of drying kinetics of kiwi slices

Characteristics of sunflower seed drying and microwave energy consumption

Microwave drying of various shape particles suspended in an air stream

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