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  • Author: Ryszard Kulig x
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Abstract

This paper presents the results of pea straw compaction efficiency tests. The compliance of the tested material to pressure agglomeration was assessed depending on the compaction pressure used (45-113 MPa). The compaction was carried out using a Zwick testing machine, type Z020/TN2S, and a closed die pressing unit. It was found that, along with the pressure increase, the material density in the chamber increased (from 1.255 to 1.76 g∙cm−3), as well as the agglomerate's density (from 0.739 to 1.05 g∙cm−3) and the product's mechanical resistance (from 0.31 to 0.69 MPa). Increasing the compaction pressure in the analyzed range increased the unit value of compaction work, from 17.16 to 34.27 J·g−1.

Abstract

Wheat kernel is made up of structures of different apparent viscosities with varied ability to withstand stress and dissipate strain energy. Its complex mechanical behaviour determines technological susceptibility and is important for wheat quality assessment. The aim of the study was the examination of the Peleg and Normand model to characterize the overall stress relaxation behaviour of wheat kernel at varying loading conditions. The relaxation experiments were made with a help of a universal machine Zwick Z020 in compression at four distinct initial load levels, i.e., 20, 30, 40, and 50 N. The measurements were made for intact wheat kernels at seven levels of moisture content. Relaxation characteristics were approximated with the help of Peleg and Normand formula. An interactive influence of the load level and moisture on Peleg and Normand constants have been confirmed. The initial loading level had none or only slight effect on the model coefficients (Y(t), k 1 and k 2). The parameters of the Peleg and Normand model decreased with the increase of water content in kernels. For moist kernels, a higher amount of absorbed compression energy was relaxed, since less energy was necessary to keep the deformation at a constant level.

Abstract

The objective of the paper was to determine the impact of moisture and rotational speed of threshers on the process of crushing of lupine seeds. Raw material was led to four levels of moisture from 8 to 14% every 2%. The studies were carried out on the laboratory hammer mill with the use of variable speeds of mill hammers within 5500-7000 rot∙min−1. The studies that were carried out proved significant relations (p<0.05) between the analysed process variables and energy consumption and susceptibility of seeds to crushing. It was stated that along with the increase of the rotational speed, a reduction in the drop of the average dimension of particles of mill takes place. Along with the increase of moisture of lupine from 8 to 14% a unit energy of crushing increases on average by approx. 83%. It was proved that the susceptibility ratio of seeds to crushing increases along with the increase of raw material moisture. Such relations were determined for all investigated rotational speeds of hammers.