Simulation of energetic- and exergetic performance of microwave-assisted fluidized bed drying of soybeans

Ranjbaran, Mohsen; Zare, Dariush

doi:10.1016/j.energy.2013.06.057

Cited by 93 publications

(29 citation statements)

References 32 publications

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“…Similar results were obtained by Rabha et al (2017), Ozgener and Ozgener (2009), Khanali et al (2013) and Aghbashlo et al (2012). However, other authors (Ranjbaran andZare, 2013, Aghbashlo et al 2008a) observed that the exergy efficiency increases with the temperature augmentation; this can be due to moisture saturated surface for which more heat is utilized to evaporate the free moisture. However, when this moisture is less, the moisture begins diffusing from the internal structure to the surface (Rabha et al, 2017)[x].…”

Section: Resultssupporting

confidence: 73%

Exergy Analyses of Onion Drying by Convection: Influence of Dryer Parameters on Its Performance

Castro¹,

Román²,

Echegaray³

et al. 2018

Preprint

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This research work is concerned in the exergy analysis of the continuous-convection drying of onion. The influence of temperature and air flow rate was studied in terms of exergy parameters. The energy and exergy balances were carried out taking into account the onion drying chamber. Its behaviour was analysed based on exergy efficiency, exergy loss rate, exergetic improvement potential rate and sustainability index.The exergy loss rates increase with the temperature and air flow rate augmentation.Exergy loss rate is augmented at higher drying air temperatures and flow rates because the overall heat transfer coefficient increase. On the other hand, the exergy efficiency increases with the air flow rate augmentation. This behavior is due to the energy utilization was improved because the most amount of supplied energy was utilized for the moisture evaporation. However, the exergy efficiency decreases with the temperature augmentation due to the free moisture is less, then, the moisture begins diffusing from the internal structure to the surface. The exergetic improvement potential rate values show that the onion drying process presents a high potential to improve the exergy efficiency. The sustainability index of the drying chamber varied from 1.9 to 5.1. To reduce the environmental impact of the process, the parameters must be modified in order to ameliorate the exergy efficiency of the process.

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Section: Resultssupporting

confidence: 73%

Exergy Analyses of Onion Drying by Convection: Influence of Dryer Parameters on Its Performance

Castro¹,

Román²,

Echegaray³

et al. 2018

Preprint

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“…These unique advantages endow the exergy analysis with great potential application to analyze the energyintensive thermal operations, which are expected to lead to the misleading conclusions by using the conventional energy analysis. Literature survey showed that a remarkable amount of research works have been published regarding the exergy analysis as well as exergoeconomic analysis of drying processes and systems through the experimental and theoretical studies such as hot air drying [5][6][7][8][9][10], fluidised bed drying [11][12][13][14][15][16][17], spray drying [18][19][20][21][22][23][24], heat pump drying with various heating sources [25][26][27], solar drying and greenhouse drying [28][29][30][31][32], freeze drying [33,34], and vacuum drying [35]. The readers are referred to the review paper compiled by Aghbahslo et al [3] in which the application of exergy analysis for drying systems and processes was comprehensively discussed.…”

Section: Introductionmentioning

confidence: 99%

Exergetic simulation of a combined infrared-convective drying process

Aghbashlo

2015

Heat Mass Transfer

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Mass flow rate (kg/s) P Air pressure (kPa) Q Heat transfer rate (kJ/s) R Constant (kJ/kg K) t Drying time (s) T Temperature (K or °C) U Overall heat transfer coefficient (kW/m 2 K) v Air velocity (m/s) V Volume (m 3 ) X Mass fraction (-) Dimensionless numbers Le Lewis number Nu Nusselt number Pr Prandtl number Re Reynolds number Greeks ∆t Simulation time step (s) α Thermal diffusivity (m 2 /s) β Energy quality factor (-) ε Emissivity factor (-) λ Latent heat of water vaporization (kJ/kg) μ Dynamic viscosity of air (Pa s) ρ Density (kg/m 3 ) σ Stephan-Boltzman constant (W/m 2 K 4 ) υ Kinematic viscosity (m 2 /s) φ Hydraulic diameter (m) ψ Exergy efficiency (-) ω Humidity ratio of air (kg water/kg dry air) Subscripts 0 Dead state 1 Wet product 2 Inlet airAbstract Optimal design and performance of a combined infrared-convective drying system with respect to the energy issue is extremely put through the application of advanced engineering analyses. This article proposes a theoretical approach for exergy analysis of the combined infrared-convective drying process using a simple heat and mass transfer model. The applicability of the developed model to actual drying processes was proved using an illustrative example for a typical food. List of symbolsA Surface area (m 2 ) C Specific heat of product (kJ/kg K) D eff Effective moisture diffusivity of water (m 2 /s) E Energy rate (kJ/s) ex Specific exergy (kJ/kg) Ex Exergy rate (kJ/s) F Shape factor (-) h m Mass transfer coefficient (m/s) h T Heat transfer coefficient (W/m 2 K) IR Infrared radiation energy (kJ/s) J Junction k Thermal conductivity of air (kW/m K) D Diameter (m) m Mass (kg) M Moisture concentration (kg water/m 3 ) MC Moisture content (kg water/kg dry matter) * Mortaza Aghbashlo

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“…A posterior research [11], examined the drying of corn grains in a fluidized bed assisted by microwaves, with an initial moisture content of 26% (dry-basis, db), for temperatures between 30 o C and 60 o C and powers between 180 and 900 W. With the experiments thus obtained, an artificial neural network was trained to predict the drying time, achieving a prediction efficiency of 99%. In a parallel area [12], a work developed a simulation for the analyses of the energy and exergy performance of a fluidized bed assisted by microwaves, for the drying of soybeans. The effects of the temperature of the air entering the system, the air speed, the power of the microwave and the thickness of the drying layer were simulated, achieving an 86% similarity with respect to the experimental data.…”

Section: Introductionmentioning

confidence: 99%

Comparative analysis of drying coffee beans using microwave and conventional oven

Muñoz-Neira

Roa-Ardila

Correa-Celi

2019

redin

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This article reports a comparative study of experimental results obtained during the drying of Castilla-variety coffee beans from Santander, Colombia. They were performed by two means: thermal and electromagnetic radiation. Twenty experiments were carried out, ten tests in a microwave cavity at 2,450 MHz-1,080W, and ten tests using a conventional electric oven with temperature controlled at 50±2oC. Experiments were made using samples of coffee beans with parchment, without parchment, and of the only-parchment. For each sample, dimensionless moisture ratio and diffusion coefficients were determined, according to the second law of Fick. We found that the diffusion coefficient of the samples dried in a microwave cavity was twenty-two times higher than the diffusion coefficient of samples dried with thermal radiation. Likewise, it was observed that samples in conventional oven showed a uniform temperature, in contrast with those heated by microwave radiation. Such results are useful for designing hybrid systems for drying coffee beans.

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Simulation of energetic- and exergetic performance of microwave-assisted fluidized bed drying of soybeans

Cited by 93 publications

References 32 publications

Exergy Analyses of Onion Drying by Convection: Influence of Dryer Parameters on Its Performance

Exergy Analyses of Onion Drying by Convection: Influence of Dryer Parameters on Its Performance

Exergetic simulation of a combined infrared-convective drying process

Comparative analysis of drying coffee beans using microwave and conventional oven

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