Pressure difference across an aerated seed bulk for some common duct and store cross-sections

Hunter, A. J.

doi:10.1016/0021-8634(83)90135-x

Cited by 39 publications

(14 citation statements)

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“…Ergun model includes the influence of the void fraction, particle diameter, air density and viscosity. For simplicity of use, factors other than airflow rate can be lumped in two parameters for each agricultural material, so model (3) becomes an Ergun-type equation (Giner and Denisienia, 1996;Hunter, 1983) of the form: Giner and Denisienia, (1996) reported that Ergun-type equation behaved better than Hukill and Ives equation and both presented lower errors than Shedd equation. Madamba et al (1994) reported that the resistance to airflow through garlic slices can be characterized by modified Ergun equation.…”

Section: Analysis Of Airflow-pressure Drop Datamentioning

confidence: 98%

Resistance of bulk pistachio nuts (Ohadi variety) to airflow

Kashaninejad

Tabil

2009

Journal of Food Engineering

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Section: Analysis Of Airflow-pressure Drop Datamentioning

confidence: 98%

Resistance of bulk pistachio nuts (Ohadi variety) to airflow

Kashaninejad

Tabil

2009

Journal of Food Engineering

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“…Nozes com essa umidade podem ser armazenadas em silos aerados por até quatro semanas; para longas estocagens, recomenda-se umidade de 0,015 b.s. MASON (1999) enfatizou que os produtores não devem secar a macadâmia até 0,035 b.s. porque as amêndoas serão danificadas no transporte.…”

Section: Introductionunclassified

Queda de pressão estática por meio de uma coluna de noz macadâmia

2005

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RESUMO:As unidades de beneficiamento de macadâmia adotam silos secadores distintos, para cada etapa de secagem, a fim de garantir a manutenção da qualidade do produto pela redução da umidade a níveis desejáveis. Diante da necessidade de quantificar a resistência apresentada pelas nozes, submetidas a diferentes fluxos de ar durante a secagem, bem como avaliar a possibilidade de utilização de modelos empíricos, que estimem o gradiente de pressão a partir da vazão de ar, conduziram-se vários testes em laboratório para obtenção de dados experimentais e ajuste de modelos. Frutos de macadâmia (M. integrifolia), com umidade de 0,11 b.s., após limpeza e classificação, foram colocados no interior de um protótipo constituído por uma coluna de chapa galvanizada (com tomadas para medição da pressão estática), plenum e ventilador, sendo submetidos a diferentes fluxos de ar. Os testes consistiram de três medidas por profundidade, para cada um dos três lotes de nozes, perfazendo um total de nove medidas de pressão estática por profundidade na coluna. Os resultados obtidos permitiram concluir que os fluxos de ar testados apresentaram efeito significativo sobre a queda de pressão estática na coluna de macadâmia, a qual aumentou linearmente com a profundidade. Os dados experimentais ajustaram-se muito bem aos modelos de Shedd e Hunter, sugerindo sua boa aplicabilidade para a macadâmia. PALAVRAS-CHAVE: gradiente de pressão estática, modelos empíricos, macadâmia. STATIC PRESSURE DROP THROUGH A COLUMN OF MACADAMIA NUTABSTRACT: The macadamia processing units use different drying silos, for each drying stage, in order to reduce nuts-in-shell moisture content. Due to the need to quantify the resistance presented by the nuts submitted to different drying airflows, as well as, to evaluate the use of empiric models that predicted pressure losses from airflow, it was carried out several tests in laboratory to obtain experimental data and adjustment of models. Macadamia nuts (M. integrifolia) with 0.11 b.s. moisture content after cleaning and classification were placed into an apparatus constituted by a column of galvanized sheet (in different positions for measuring the static pressure), plenum and fan, being submitted to different airflows. The tests consisted of three repetitions (measures), with three lots of nuts, bringing up to nine measures of static pressure for each position in the column. The obtained results allowed to conclude that the tested airflows showed significant effect on the static air pressure in the macadamia column, which increased lineally with the depth. The experimental data adjusted very well to the Shedd and Hunter's models, suggesting their good suitability for macadamia.

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“…Boyce and Davis [19] experimentally investigated the pressure drop in grain stores with aeration ducts. Simulation models for the airflow and pressure drop in grain beds were published by Thorpe [20], Smith [21], and Hunter [22]. After many years, the airflow distribution in mixed-flow dryers got into the focus of research and development.…”

Section: Introductionmentioning

confidence: 99%

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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Pressure difference across an aerated seed bulk for some common duct and store cross-sections

Cited by 39 publications

References 8 publications

Resistance of bulk pistachio nuts (Ohadi variety) to airflow

Resistance of bulk pistachio nuts (Ohadi variety) to airflow

Queda de pressão estática por meio de uma coluna de noz macadâmia

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

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