Study and Analysis of Window Characteristics During Continuous Grain Drying

Grain drying is a pivotal post-harvest process that safeguards the storage safety and quality of grain. Conventional drying control strategies, however, predominantly rely on empirical operations and single-parameter monitoring. Although the concept of accumulated temperature has been applied in grain drying, few studies have systematically investigated the dynamic characteristics of drying accumulated temperature windows, resulting in a lack of quantitative and stable control criteria for the drying process. This study first defines the drying accumulated temperature window and further classifies it into three types: the equivalent window, actual window, and good window. On this basis, the window characteristics during continuous grain drying are systematically analyzed, accurate calculation methods for equivalent and actual accumulated temperature are established, and a feasible judgment criterion for the good window is proposed. A MATLAB 2022-based simulation model for continuous corn drying is constructed to verify the proposed methods. Experimental results show that three types of windows exhibit distinct dynamic response characteristics: the equivalent accumulated temperature responds instantaneously to changes in drying conditions, while the actual accumulated temperature has a time lag of one complete drying cycle. After the drying process stabilizes, the absolute difference between equivalent and actual accumulated temperature is controlled within 1500 °C·min. A drying process is identified to enter the good window state when the outlet moisture content stably maintains at 14.5 ± 0.5% for more than 3 h. The established simulation model demonstrates high prediction accuracy, with the mean relative errors of key indicators maintained at approximately 5%. This study clarifies the dynamic mechanism of accumulated temperature windows in continuous grain drying and provides a practical quantitative basis for the intelligent control and efficiency improvement of the grain-drying process.