Numerical Simulation of Airflow Distribution in Mixed Flow Dryer

Scaar, Holger; Weigler, Fabian; Mellmann, Jochen

doi:10.17660/actahortic.2013.1008.14

Cited by 3 publications

(7 citation statements)

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“…Expectedly, the air flux to the two nearest air ducts 10 and 13 was significantly faster than to the air ducts 11 and 12. This endorses the inhomogeneous air flow pattern of the diagonal arrangement as was already shown by Scaar et al [28]. …”

Section: Air Velocity In the Grain Bulksupporting

confidence: 88%

“…To investigate the airflow distribution in mixed-flow dryers, a mathematical model has been developed by using the Computational Fluid Dynamics [28,37]. For this purpose, the commercial software ANSYS CFX ® was applied.…”

Section: Modelling and Simulationmentioning

confidence: 99%

“…In addition, tracer gas measurements were performed at the next distant outlet air ducts in order to prove the simulated bi-sectioning [28] of the inlet air. No tracer gas could be detected at these remote outlet air ducts.…”

Section: Residence Time Distribution (Rtd)mentioning

confidence: 99%

“…The highest air velocities were observed near the bottom edges of the air ducts, the lowest velocities in the top section of the air ducts. Due to recent advancements in computer hardware and mathematical techniques, the CFD has increasingly been used to simulate airflow patterns in grain bulks [26] and fixed bed dryers [27,28]. A comprehensive review on CFD application in simulating and designing drying processes was given by Jamaleddine and Ray [29].…”

Section: Introductionmentioning

confidence: 99%

“…For this purpose, two methods were selected -the measurement of the isobar distribution within the grain bed and the residence time analysis using the tracer gas pulse method. A numerical model for the airflow through the grain bed of a mixed-flow dryer has been developed in a previous work based on CFD [28]. The measurements were used for model validation and to study the influence of different air duct arrangements and bed materials.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical study of the airflow distribution in mixed-flow grain dryers

et al. 2015

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The aim of this study was to investigate the airflow distribution in the mixed-flow dryer (MFD) and to study the effect of different bed materials and air duct arrangements. The results were used to validate the numerical model developed in a previous work based on the Computational Fluid Dynamics (CFD). A series of experiments have been conducted at a semi-technical MFD test dryer with horizontal and diagonal air duct arrangement.Wheat and rapeseed were used as bed materials. The experiments were performed under isothermal conditions. Two experimental methods were selected and adapted to the measuring problem -the measurement of the isobar distribution within the grain bed and the residence time analysis using the tracer gas pulse method.As could be shown, the isobar distributions measured for wheat and rapeseed agreed well with the model predictions. The numerical model could well calculate the influence of the bed material with its different particle characteristics (e.g. particle shape, particle size, bed porosity). The results obtained from the residence time analysis confirmed the known quartering of the air stream flowing from one inlet air duct to the four surrounding outlet Downloaded by [New York University] at 20:13 22 July 20152 air ducts for the horizontal air duct arrangement. Whereas, in the diagonal air duct arrangement, the air steam from one inlet air duct was nearly halved flowing to the two adjacent diagonal outlet air ducts. These results were confirmed by investigations of the air velocity distribution within the grain bulk. Further experiments are necessary to refine the model. For it, the residence time and isobar measurements will be extended to study the influence of different air properties under real drying conditions, the effect of structural elements and dryer designs.

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Section: Air Velocity In the Grain Bulksupporting

confidence: 88%

Section: Modelling and Simulationmentioning

confidence: 99%

Section: Residence Time Distribution (Rtd)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical study of the airflow distribution in mixed-flow grain dryers

et al. 2015

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Numerical simulation of rice drying process in a deep bed under an angular air duct

Li,

Feng,

et al. 2023

J Food Process Engineering

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The deep‐bed drying process of rice grains was investigated through numerical simulation, employing the porous medium flow field theory and the local thermal nonequilibrium method. Moisture field of rice grains described using thin‐layer equations. On this basis, the deep‐bed drying of rice grains modeled with COMSOL, and verified its plausibility. The results showed that the drying rate of rice grains was significantly accelerated when the hot air temperature was increased from 40°C to 70°C, but the inhomogeneity of rice grains temperature increased by 29.79%, 22.31%, and 17.41% for every 10°C increase. Drying grains faster with vertically arranged an angular air duct, with a 4.88% increase in drying speed in 300 min. The temperature difference between the top and the bottom of an angular air duct with a small width is smaller, about 11°C, and the heating efficiency is better at the top, by 31.28%.Practical ApplicationsGrain dryers are often used in high‐volume grain drying operations and it has been a great challenge to save the energy consumption of the drying process. It is necessary to use numerical simulation to design a reasonable structure of the heating section to improve the energy utilization efficiency of the heating section of the grain dryer. The numerical model proposed in this article can effectively simulate the spatial distribution of moisture content of rice under different structures of grain drying units, which can be used not only for the prediction of drying time but also for analyzing the optimal heating structure from it. A technical basis is provided for the design of grain dryers.

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Fluid flow simulation of industrial fixed bed mixed-flow grain dryer using k-ω SST turbulence model

Visconcini

Andrade

Costa

2021

International Journal of Agricultural and Biological Engineering

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The fluid dynamics analysis on industrial, mixed-flow grain dryers with fixed bed using computational techniques is necessary to assist the design of such equipment contributing to cost reduction in the dryer projects and agricultural drying operations that involve the production of grains in the world. This study presents a Computational Fluid Dynamic (CFD) solution for air flow analysis in an industrial dryer. The air flow at the inlet and outlet of the dryer was investigated using the k-ω SST turbulence model. The dryer region with soybean was considered as a laminar porous medium flow in the permanent and isothermal regime, having for the model a simplified geometry with the tower considered as a porous medium and the air inlet and outlet as a turbulent fluid domain. The flow was treated with a permanent and isothermal regime. Dryer flow and pressures were used according to design parameters. To validate the k-ω SST turbulence model, the velocity profile at the dryer inlet was obtained experimentally, which presented results with good agreement between the numerical and the experimental model. The model obtained satisfactory results of the computational validation of the air flow in the dryer with good convergence requiring a minimum of computational effort, being suitable for the simulation of industrial-scale dryers, as to its air flow through a tower, operating with fixed bed soybean in the steady and isothermal regime.

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Numerical Simulation of Airflow Distribution in Mixed Flow Dryer

Cited by 3 publications

References 0 publications

Experimental and numerical study of the airflow distribution in mixed-flow grain dryers

Experimental and numerical study of the airflow distribution in mixed-flow grain dryers

Numerical simulation of rice drying process in a deep bed under an angular air duct

Fluid flow simulation of industrial fixed bed mixed-flow grain dryer using k-ω SST turbulence model

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