Physical properties and effective thermal diffusivity of soybean grains as a function of moisture content and broken kernels

作者：Pohndorf Ricardo Scherer^*; da Rocha Jeferson Cunha; Lindemann Igor; Peres Wilner Brod; de Oliveira Mauricio; Elias Moacir Cardoso

来源：Journal of Food Process Engineering, 2018, 41(1): UNSP e12626.

DOI：10.1111/jfpe.12626

The objective of this work was to evaluate the influence of the amount of broken kernels in relation to the whole grains (0, 15, and 30%) and moisture content (5, 10, and 15% wet basis) on some physical properties of soybeans (bulk density, porosity, and angle of repose) using response surface methodology. In addition, the effective thermal diffusivity ((ef)) was determined and empirical models were proposed to improve equipment design and drying and storage operations of soybeans. The results indicated that the moisture content changes and the addition of broken kernels in the whole soybeans caused increases in bulk density (from 6732 to 693 +/- 3kg/m(3)) and angle of repose (from 26.6 +/- 0.3 to 31.2 +/- 0.3 degrees) and decrease in porosity (from 45.1 +/- 0.1 to 41.3 +/- 0.4%). The effective thermal diffusivity values increased with increasing moisture content and the addition of broken kernels, in the range of 5.7x10(-8) to 9.5x10(-8)m(2)/s. The proposed empirical model for determination of effective thermal diffusivity was predictive and significant (p<.05).
Practical applicationsThe presence of split and broken soybeans has been a problem due to the lack of uniformity of stored grain mass, causing significant loss of quality and difficulty in operational handling. In this way, the knowledge of the engineering properties of soybeans is a key factor in determining the design of the drying, storage, aeration, processing, and handling systems. Bulk density is needed for the design of drying and aeration systems. Porosity can affect the rate of heat and mass transfer during aeration and drying operations and the design of hoppers for processing machinery and bulk grain storage requires angle of repose data. In addition, the thermal diffusivity elutes the heating rate of grains stored in steel silos.

• 出版日期2018-2