Sizing of pressure aeration systems for stored grain

Abstract

Aeration is widely used to cool grain, preserving the physical conditions of the stored product and appearing as one of the most important practices of the postharvest sector in terms of food security. The proper sizing of the aeration system components is essential for guaranteeing the correct operation and management of this preventive technique. Either pressure or suction airflow could be used in most grain storage structures, with pressure systems being most popular. In this article, procedures required when sizing pressure aeration systems for stored grain are discussed. The main equations and recommendations for selecting the proper fan power and size are presented, aiming at allowing to deliver the adequate aeration airflow rate for grain storage during aeration. Technical information about how to calculate the dimensions of roof vents are also showed, in order to provide natural ventilation inside the storage and avoid under-roof condensation. Additionally, a methodology for calculating the dimensions of the aeration perforated ducts is proposed, aiming at suitable uniformity of airflow in the grain mass during this process. Technical and scientific information described in the literature were integrated with empirical rules and recommendations, resulting in a guideline capable of helping students and engineers that need to size pressure grain aeration systems for flat and cylindrical bins.