Static Pressure-Airflow Relationships in Packed Beds of Granular Biological Materials Such as Grain-II

Bakker-Arkema, F. W.; Patterson, Ronald J.; Bickert, W.G.

doi:10.13031/2013.38249

Cited by 21 publications

(18 citation statements)

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“…2 and indicate that the pressure drop decreased with increase in grain moisture content. Other workers have reported similar results (Shedd, 1953; Patterson et al. , 1971; Akritidis & Siatras, 1979; Farmer et al.…”

Section: Resultssupporting

confidence: 69%

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The resistance of packed beds of moth gram (Vigna aconitifolius) to airflow

Nimkar¹,

Khobragade

2006

Int J of Food Sci Tech

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The resistance of packed beds of clean moth gram (Vigna aconitifolius) to airflow was studied at moisture contents varying from 5.64 to 19.42% dry basis (d.b.) and at superficial air velocities ranging between 0.0104 and 0.8321 m s )1 with bed depths of 0.2-0.6 m and bulk densities ranging from 745 to 875 kg m )3 . The airflow resistance of moth gram increased with increase in airflow rate and bulk density and decreased with moisture content. Results indicated that a 13.78% increase in moisture content decreased the pressure drop by 26.58% whereas, a 7.7% increase in bulk density increased the pressure drop by 43%. The modified Shedd's equation and Hukill and Ives equation were evaluated to see if they predicted pressure drop accurately. Airflow resistance was accurately described by the modified Shedd's equation. The statistical model that related airflow rate and bulk density could fit pressure drop data reasonably well. For loose fill beds an increase in grain moisture content increased the minimum fluidization velocity value from 1.1009 to 1.2391 m s )1 whereas, for grain beds with 12.47% moisture content, the increase in bulk density decreased the minimum fluidization velocity value from 1.1152 to 1.0306 m s )1 .

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Section: Resultssupporting

confidence: 69%

“…It has revealed that very few studies on airflow resistance of legumes, viz., soybean (Henderson, 1944; Shedd, 1951), peas (McEwen et al. , 1954; Osborne, 1961), beans (Osborne, 1961; Patterson et al. , 1971; Wilhelm et al.…”

Section: Introductionmentioning

confidence: 99%

The resistance of packed beds of moth gram (Vigna aconitifolius) to airflow

Nimkar¹,

Khobragade

2006

Int J of Food Sci Tech

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“…Madamba et al (1994) reported that the resistance to airflow through garlic slices can be characterized by modified Ergun equation. This equation has been used successfully to describe the airflow resistance through granular materials (Patterson et al, 1971;Bern and Charity, 1975). Airflow resistance data for pistachio nuts were fitted to these three models (Shedd, Hukill and Ives, and Ergun models) using the non-linear regression analysis, PROC NLIN of SAS statistical package (SAS, 2001).…”

Section: Analysis Of Airflow-pressure Drop Datamentioning

confidence: 99%

Resistance of bulk pistachio nuts (Ohadi variety) to airflow

Kashaninejad

Tabil

2009

Journal of Food Engineering

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“…flow b u v h beds of rnm Bakker-Arkema et al (1969) modified Ergun's Eq. 3 to describe pressure drop versus airflow in packed beds of cherry pits.where Kg is a product dependent constantPatterson et al (1971) modified Eq. 7 by rearranging the multiplier of velocity turns into two parameters a and p. The modified equation was given as:…”

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confidence: 99%

Generalized Equation for Airflow Resistance of Bulk Grains With Variable Density, Moisture Content and Fines∗

Sokhansanj

1994

Drying Technology

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The pressure drop versus airflow data for several types of grains were compiled and a grain specific generalized pressure drop versus airflow equation was developed. The equation predicted pressure drop as a function of airflow when porosity, moisture content and fine concentration were specified. The effect of properties of airflow on the resistance of bulk grain to airflow was also considered in the generalized equation. A modified Leva's equation was developed. The similarity between the grain specific equation and the modified Leva's equation led to a method for estimating the shape factor for irregularly shaped particles. LElTRODUCTIONThe ASAE Standard D272.2 (ASAE, 1992) has more than 20 individual curves relating pressure drop to airflow. The main problems with these curves are: (1) their range * Journal Paper No. MS-930806 TN. LI AND SOKHANSANJof applicability is limited; (2) their accuracy is questionable when applied to different varieties of a grain type; and (3) for a new type of grain for which pressure-airflow rate c w e is not available, only a visual interpolation is possibte.Factors that affect the resistance of bulk grains to airflow include air viscosity and density, porosity of the bulk material. orientation of the particles in the buk. size, shape and panicle surface condition. These factors are highly interdependent and thus it is difficult to develop a unique curve or mathematical model to relate pressure drop to air flow as a function of these factors. Equation 1 developed by Shedd (1953), and Eq. 2 developed by Hukill and Ives (1955) are used extensively to relate airflow to pressure drop in agricultural grains. The symbols and units in Eqs. 1 and 2 and in subsequent equations are defined in nomenclature. Equations 1 and 2 are specific to the experimental condition. They do not provide sufficient understanding of the importance of various factors affecting the pressure drop. The objective of this research was: (1) to review literature pertaining to pressure drop in bulk particulate materials; (2) to compiIe pressure drop data over a wide range of grain types (size and shape), densities (fines content), airflow rates; (3) to develop a generalized mathematical model of pressure drop versus airflow for agricultural grains. Generalized flow eauations through oorous media Ergun (1952) studied the pressure drop through fixed bed of granular solid materials. He confirmed the Reynolds theory that the pressure loss can be treated as the sum of the kinetic and viscous energy losses. Based on the work of Kozeny (1927), Carman (1937), and Burke and Plurnrner (1928). Ergun (1952) proposed chat the viscous energy losses in a granular fixed bed are proportional to (~-e )~/ &~ and the kinetic energy losses to (1-&)I€*, and hence suggested the following generalized equation to predict the pressure drop in a packed column: Downloaded by [RMIT University] at 16:18 15 March 2015 AIRFLOW RESISTANCE OF BULK GRAINS where fE is the modified friction coefficient and The particle diameter Dp in Eq. 3 is defined by...

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Static Pressure-Airflow Relationships in Packed Beds of Granular Biological Materials Such as Grain-II

Cited by 21 publications

References 0 publications

The resistance of packed beds of moth gram (Vigna aconitifolius) to airflow

The resistance of packed beds of moth gram (Vigna aconitifolius) to airflow

Resistance of bulk pistachio nuts (Ohadi variety) to airflow

Generalized Equation for Airflow Resistance of Bulk Grains With Variable Density, Moisture Content and Fines∗

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