Estudo da influência termohigrométrica do ar no tempo de secagem de grãos

Abstract

The Brazilian economy is driven by agricultural production, making the country the largest grain exporter in the world. As a result, the quality requirements of the international market are increasingly present days, fostering technologies in grain production and processing. Thus, there is a need for faster grain drying processes that promote less damage to the product. With these circumstances, the present Final Paper theoretically analyzed the influence of drying air properties on the drying process time of corn, soybean, rice and wheat grains. The calculations were based on Thompson's method for a fixed bed dryer, commonly applied in small and mediumsized rural properties. The results demonstrate that, with the increase of the drying air temperature, there is a reduction in the process time. When analyzing the reduction of relative humidity of the air, the results were more expressive in lower temperatures. Soybean grains, due to their mostly hydrophobic composition, suffer intense dehydration when exposed to drying air with relative humidity equal to or less than 40%, failing to meet commercial quality requirements. The desorption isotherms were constructed for all the studied grains, presenting the expected behavior and validating the calculation methodology. In general, the reduction of relative humidity promotes a reduction in drying time, in addition to providing the possibility of carrying out the process at lower temperatures.