Use of ventilation in grain silos to stabilize moisture content of maize during storage

Abstract

Purpose. The purpose of the study was to evaluate the efficiency of different ventilation regimes in silo towers for stabilizing the moisture content of maize grain during storage, as well as to determine the influence of temperature and humidity conditions on changes in physicochemical parameters of the grain during aeration. Methods.The experiments were carried out at an experimental grain storage facility in the Forest-Steppe zone of Ukraine during 2023–2024. The research objects were vertical metal silo towers with capacities of 250 and 400 m³, equipped with active ventilation systems of bottom and combined (bottom–side) types. Microclimate control was provided by a multipoint system of temperature and humidity sensors located at three levels of the grain bulk. Grain moisture and temperature were measured according to ISO 712 and GOST 13586.5-93, with monitoring every 6–12 hours over 60 days. In parallel, energy consumption, dehydration rate, and changes in grain physicochemical characteristics (moisture, test weight, damage, and microflora development) were recorded. Results. The article presents research results on the efficiency of various ventilation schemes in silo towers aimed at stabilizing maize grain moisture and temperature. Over 60 days of storage, moisture and temperature dynamics were studied under three conditions: without ventilation, with basic (bottom) ventilation, and with combined ventilation. In ventilated variants, grain moisture decreased to 15.4–14.8 % by the 10th day, whereas in control samples it remained above 17.5 %. The most effective was the combined scheme: by the 30th day, moisture reached a stable level of 13.8–13.7 %, ensuring safe storage without thermal drying. The temperature gradient of the grain mass under combined ventilation was only 0.4–0.5 °C, while without ventilation it reached 2.5 °C. Test weight in ventilated variants remained at 711–713 g/L, compared to 698 g/L in non-aerated silos. The best results were obtained under a ventilation regime of 5–6 h/day with air velocity of 0.08–0.11 m/s at night, when ambient temperature dropped below 10 °C and relative humidity exceeded 75 %. In the absence of aeration, zones of self-heating were observed in the upper layers, with increased activity of Fusarium fungi and moisture rising to 18 % by the 45th day of storage.Conclusions. It was proven that the efficiency of maize storage in silo towers directly depends on the chosen ventilation strategy. The most rational option was the combined ventilation regime, which provided rapid moisture reduction to a safe level (≤14 %), uniform temperature distribution, and preservation of more than 97 % of the grain mass. The optimal mode was air supply at 0.08–0.11 m/s for 5–6 hours per day, mainly at night. The obtained results confirm the feasibility of integrating combined ventilation systems into production practice as an energy-saving alternative to traditional drying methods, which is particularly relevant for farms with limited energy resources.