Comprehensive Analysis of Drying Kinetics, Heat and Mass Transfer, and Thermodynamic Properties in High-Temperature Drying of High-Moisture Corn

Abstract

A shorter growing season, limited fall dry-down period, and risk of early frost in the Northern Plains, US, necessitate the harvest of high-moisture corn. High-temperature drying is essential for preserving grain quality under these conditions. This research systematically characterizes drying behavior, heat and mass transfer, thermodynamic properties, and energy dynamics for high-temperature drying of high-moisture corn. Experimental conditions were drying temperature (65°C–100°C), air velocity (2–3.66 ms⁻¹), initial moisture content (17%–25% wb), ambient temperature (10°C–25°C), and relative humidity (20%–60%). Temperature, air velocity, and initial moisture content significantly influenced drying kinetics, which predominantly occurred in the falling-rate stage and was best described by the Midilli et al. model. The effective moisture diffusivity and convective mass transfer coefficient are significantly impacted by initial moisture content and temperature, leading to a slow-to-moderate drying process. The quadratic relationship between activation energy and air velocity highlights the cooling effect at higher airflow, necessitating greater energy input for moisture diffusion and convection. The thermodynamic analysis defines high-temperature drying of high-moisture corn as both an endothermic and endergonic process, with enthalpy and entropy increasing with moisture content and air velocity. Energy utilization efficiency was found to be strongly influenced by drying temperature–air velocity interaction, with 71.62%–81.82% of energy effectively used for moisture removal. Ambient temperature had a more pronounced impact on energy utilization efficiency than relative humidity. Given these insights, precise control and optimization of drying conditions under specific ambient conditions are essential to enhance energy efficiency and overall drying performance in high-moisture corn drying.