Análise da secagem de Azevém (Lolium multiflorum) em leito fixo com escoamento de ar

Abstract

The livestock is one of the major and traditional economic activities with production rooted in native pasture in Rio Grande do Sul. But in the cold seasons is the need to implement the empty pastures to supply fodder, because the field is composed predominantly of native summer grasses. Ryegrass (Lolium multiflorum) is the most widely used grass in the southern of Brazil, due to the ease and low cost of implementation. However it has problems as forage seed quality regarding low rate of germination and vigor. This is due to present a natural process of threshing, resulting in a harvest of seeds with high moisture content. One way to minimize the problems encountered in the quality of these seeds is the application of appropriate technologies in processing. Among the steps involved in the processing of seed drying process is considered fundamental. It is characterized by heat transfer and mass, allowing the reduction of the water content at appropriate levels, thus enabling the preservation of physiological quality of the product. In this context the work studied the drying conditions of ryegrass in fixed bed dryer with air flowing parallel to obtain better quality seeds. The study was divided in to four stages. The first step was to determine the physical and physiological characteristics of the seed which were obtained the values of true density real and bulk density, average, particle, diameter, sphericity, porosity of the static bad end germination rates. In the second phase of the study aimed at putting rewetting seeds seeds purchased at local markets in damp conditions similar to those found in fresh seeds and clean. The third stage was based on the study of sorption isotherms of seeds reumidificadas for the determination of moisture content. This study was done to a temperature of 40 ° C, using the static method with solutions at various concentrations. Finally, the fourth and final step of the study was conducted reumidificadas seed drying in a fixed bed dryer with air flowing parallel operating at a temperature of 40 ° C and under conditions tray height 0.5, 0.75 and 1.0 cm air speed of 1.0, 1.5 and 2.0 m / s and drying time of 2.0, 2.5 and 3.0 hours. The data obtained were analyzed by drying in an experimental design with 23 duplicate at the midpoint having answers as the final moisture content and germination. We also determined the effective diffusivity values for each studied drying process. The results showed that the drying conditions applied in the seed can significantly influence their final moisture, physiological quality and effective diffusivity values of the process.