Exergetic performance assessment of plug flow fluidised bed drying process of rough rice

Khanali, Majid; Aghbashlo, Mortaza; Rafiee, Shahin; Jafari, Ali

doi:10.1504/ijex.2013.057357

Cited by 71 publications

(35 citation statements)

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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.…”

Section: Resultssupporting

confidence: 74%

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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: 74%

“…Aghbashlo et al (2008) obtained values close to 87% and the values obtained for Khanali et al , 2013 varied between 65% and 74%, approximately. For a drying temperature equal to 343K, the exergy efficiency was about 73%, and these researchers found values about 67%.…”

Section: Resultsmentioning

confidence: 64%

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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“…The rehydration ratio of dried apple slices was computed using the following equation [33]: (27) Toluene displacement method was employed to measure the volume of samples before and after drying. The following equation was applied to calculate the shrinkage of dried samples at the end of drying process [34]: (28) As well, the apparent density was determined by measuring the mass of the samples used for shrinkage measurement before and after drying.…”

Section: Qualitative Measurementsmentioning

confidence: 99%

Improving exergetic performance parameters of a rotating-tray air dryer via a simple heat exchanger

Ghasemkhani

Keyhani

Aghbashlo

et al. 2016

Applied Thermal Engineering

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Highlights: Exergy analysis of a rotating-tray air dryer fitted with a simple air-to-air heat exchanger  Effect of drying air temperature and velocity on exergetic efficiency of the dryer  Promising improvement of exergetic performance parameters of the dryer using the heat exchanger  Potential application of the proposed strategy for recovering waste energy in drying technology AbstractIn this study, exergy analysis was applied for a rotating-tray dryer equipped with a cross-flow plate heat exchanger during drying of apple slices. Three drying air temperatures and tray rotation speeds in the range of 50-80 °C and 0-12 rpm, respectively, were employed. Two drying air velocities in the range of 1-2 m/s were adjusted for each drying temperature and rotation speed with and without application of the heat exchanger. The experiments were conducted to assess the effects of the experimental variables on the exergetic performance parameters of the dryer. Also, the effect of drying conditions on the quality of dried apple slices was assessed by determining rehydration ratio, apparent density, shrinkage, and surface color. In general, the exergetic performance parameters of the dryer depended profoundly on the drying air temperature and velocity. Interestingly, the exergetic efficiency of drying process was significantly improved from a minimum value of 23.0% to a maximum value of 96.1% by using the heat exchanger. Furthermore, the incorporation of heat exchanger did not negatively affect the quality of dried product. Therefore, the strategy presented herein could be a promising approach for waste energy recovery in drying without any unfavorable change in the quality of dried product.

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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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Exergetic performance assessment of plug flow fluidised bed drying process of rough rice

Cited by 71 publications

References 50 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

Improving exergetic performance parameters of a rotating-tray air dryer via a simple heat exchanger

Exergetic simulation of a combined infrared-convective drying process

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