Discrete element modeling of porosity distribution in grain bulks

• Term: Two years, beginning in 2016

• Status: Ongoing

• Funding Amount: $59,800

• Lead Researcher(s): Hubert Landry (PAMI)

• Funding Partners: None

Project Description

Preservation of grain quality during storage is critically important to producers as it directly affects their profitability. The economic losses resulting from grain spoilage during storage are difficult to quantify as little reliable data is available. According to the Union of International Associations, it is estimated that $500M USD worth of grain is lost every crop year in the United States, the most significant losses being in storage. Producers losing the content of entire bins because of spoilage highlights that tens of thousands of dollars can be lost at the individual farm level.

Some of the current recommendations for aeration and natural air drying systems for large grain bins are extrapolated from data and information that was developed 20 or 30 years ago, when the size of storage bins was considerably smaller. This may result in improperly sized aeration fans or poorly designed air distribution systems. Improperly sized aeration fans can result in inadequate airflow in the bin. Poorly designed air distribution systems can result in hot-spots or pockets of high moisture or high temperature grain which can put the entire bin at risk of spoiling.

A large portion of the science and best practices is based on the assumption of uniform airflow in the mass of grain. The accuracy of that assumption is questionable and it is being increasingly challenged by the research and practitioners (farmers, agrologists, equipment suppliers) community. Moreover, it is suggested that the porosity distribution inside the mass of grain has a major influence on the airflow distribution (Bartosik and Maier, 2006; Lawrence and Maier, 2011). In turn, the porosity or bulk density distribution is affected by a number of factors such as filling method (Molenda et al., 1993), total volume, type of grain and its moisture content (Thompson et al., 1990), amount of foreign material, bin configuration, and the potential presence of an aeration device. Such aeration devices (e.g., air cube, rocket) have garnered significant interest from producers and it appears that only anecdotal evidence is available to support benefits or performance claims.

There is a need to better understand the porosity distribution inside grain bulks and what factors most influence it. That basic knowledge is a necessary first step to understand airflow distribution inside the mass of grain and support the design and operation of aeration or drying systems. Some key questions that need to be answered include (1) how is the density distribution in grain bins affected by practical parameters such as the bin geometry, grain properties, and filling method, and (2) what impact does the density distribution have on in-bin grain aeration or drying. The proposed research will focus on the first question. The investigator will carry out a literature review and numerical simulations to investigate the density distribution inside grain bins as affected by the physical configuration of the storage system, the filling method, and the grain properties.