Packing Factors of Whole Grains in Storage Structures

Thompson, Shelby; McNeill, Samuel G.; Ross, I. J.; Bridges, T. C.

doi:10.13031/2013.26677

Cited by 22 publications

(68 citation statements)

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“…A science-based model (based on grain pressure distribution from eq. 1) to predict pack factor was provided by Thompson et al (1987). To date, there has been limited field validation of the WPACKING model.…”

Section: Abstract Shelled Yellow Corn Is Commonly Stored In Concrete Ormentioning

confidence: 99%

“…While Janssen's solution had a major drawback, i.e., the bulk density was assumed constant throughout the grain column, WPACKING solves the differential equation without invoking this simplifying assumption, which allows the varying bulk density to be calculated based on the predicted pressure and laboratory measurements of compressibility. Thompson et al (1987) measured bulk density as a function of pressure and moisture content for several crops (soft red winter wheat, sorghum, corn, soybeans, rice, and hard red winter wheat), including several varieties for each crop. They combined nonlinear models for bulk density of these crops within WPACKING to predict pack factors and estimate standard bushels in a bin based on user inputs for grain as well as bin dimensions and properties.…”

Section: Development Of Wpackingmentioning

confidence: 99%

Section: Development Of Wpackingmentioning

confidence: 99%

“…when stored in bins. While the geometry of a bin can be measured accurately, measuring the variation in bulk material properties of the grain inside the bin can be challenging (Thompson et al, 1987). Bates (1925) was first to research packing of granular materials in storage silos containing wheat, and he proposed that the average packing of wheat was 4.85%.…”

mentioning

confidence: 99%

“…They combined nonlinear models for bulk density of these crops within WPACKING to predict pack factors and estimate standard bushels in a bin based on user inputs for grain as well as bin dimensions and properties. Eventually, the work of Thompson et al (1987Thompson et al ( , 1990 led to the development of ASABE Standard EP413.2 (ASABE, 2010).The objective of this study was to determine the pack factor of corn in on-farm and commercial storage bins with varying bin shape and size and with a typical range of moisture content and initial test weight. A wide range of geographic locations was included to increase the robustness of the dataset.…”

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confidence: 99%

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Pack Factor Measurements for Corn in Grain Storage Bins

Bhadra

Turner

Casada³

et al. 2015

Trans. ASABE

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ABSTRACT. Shelled yellow corn is commonly stored in concrete orrain stored in bins is subjected to packing from pressure caused by the overlying grain mass. Grain packing in bins is defined as the increase in grain bulk density caused by compression from the cumulative weight of the overlying grain material. Because this compression causes relatively large increases in bulk density, accurate pack factors that account for the increase are required for determining the exact amount of grain in a bin. While grain is traded on a mass basis, the vast majority of grain inventory and auditing assessments are based on volume measurements. Accurate pack factors are needed by grain elevator managers and farmers for proper inventory control, and by government agencies for auditing. Because of persistent questions about the accuracy of pack factors currently in use, the USDA Risk Management Agency (RMA) requested work to develop new, more accurate pack factors, which led to the study reported here.It is often difficult to predict how grain will compact because bulk grain consists of a complex matrix of irregularly shaped particles, each with its own characteristics. Thus, most bulk grain packing prediction models have been done empirically (Thompson et al., 1991). In powder technology, there is extensive literature on particle packing (Smalley, 1970). Although Smalley (1970) Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. The USDA is an equal opportunity provider and employer.The commonly used to describe the packing of fine powders with very regular shape and size geometry, it failed to address the situation with whole grains, where the particles are of random shape and size and are compressible.Particle packing in whole grains is believed to vary as a function of the stress variation that exists within a given material type, moisture content, and uncompressed bulk density of the material. To understand the phenomenon of grain packing, it is essential to consider the variation in bulk particle properties (such as density changes, moisture changes, compressibility, flow rate, etc.) when stored in bins. While the geometry of a bin can be measured accurately, measuring the variation in bulk material properties of the grain inside the bin can be challenging (Thompson et al., 1987). Bates (1925) was first to research packing of granular materials in storage silos containing wheat, and he proposed that the average packing of wheat was 4.85%. Bates (1925) included dimension of the bin, shape, test weight, and depth of grain in the packing of wheat calculation.The classic theory provided by Janssen (1895) for predicting pressure in grain bins given in differential form is:This equation was solved by Janssen after simplifying assumptions of constant bulk density (D), lateral to vertical pressure ratio (k), and coefficient of friction (μ), giving:where P j is the unit vertical pressure at depth ...

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Section: Abstract Shelled Yellow Corn Is Commonly Stored In Concrete Ormentioning

confidence: 99%

Section: Development Of Wpackingmentioning

confidence: 99%

Section: Development Of Wpackingmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Pack Factor Measurements for Corn in Grain Storage Bins

Bhadra

Turner

Casada³

et al. 2015

Trans. ASABE

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Estimating bulk density of compacted grains in storage bins and modifications of Janssen's load equations as affected by bulk density

Haque

2013

Food Science & Nutrition

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Janssen created a classical theory based on calculus to estimate static vertical and horizontal pressures within beds of bulk corn. Even today, his equations are widely used to calculate static loadings imposed by granular materials stored in bins. Many standards such as American Concrete Institute (ACI) 313, American Society of Agricultural and Biological Engineers EP 433, German DIN 1055, Canadian Farm Building Code (CFBC), European Code (ENV 1991-4), and Australian Code AS 3774 incorporated Janssen's equations as the standards for static load calculations on bins. One of the main drawbacks of Janssen's equations is the assumption that the bulk density of the stored product remains constant throughout the entire bin. While for all practical purposes, this is true for small bins; in modern commercial-size bins, bulk density of grains substantially increases due to compressive and hoop stresses. Over pressure factors are applied to Janssen loadings to satisfy practical situations such as dynamic loads due to bin filling and emptying, but there are limited theoretical methods available that include the effects of increased bulk density on the loadings of grain transmitted to the storage structures. This article develops a mathematical equation relating the specific weight as a function of location and other variables of materials and storage. It was found that the bulk density of stored granular materials increased with the depth according to a mathematical equation relating the two variables, and applying this bulk-density function, Janssen's equations for vertical and horizontal pressures were modified as presented in this article. The validity of this specific weight function was tested by using the principles of mathematics. As expected, calculations of loads based on the modified equations were consistently higher than the Janssen loadings based on noncompacted bulk densities for all grain depths and types accounting for the effects of increased bulk densities with the bed heights.

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