甘蓝型油菜籽热风干燥特性及其数学模型

Characteristics and Mathematical Models for Hot-air-dried Rapeseed (Brassica napus)

摘要:

油菜籽的干燥和储存直接影响种用油菜籽的生理特性和作物产量以及加工用油菜籽的加工特性和制油品质，为了给油菜籽热风干燥装置设计、工艺和过程控制优化提供基础依据，本文研究了不同初始含水率、热风温度和风速条件下甘蓝型油菜籽的热风干燥特性，比较了10种数学模型在甘蓝型油菜籽热风干燥中的适用性。结果表明：油菜籽热风干燥过程没有出现明显的恒速干燥阶段，干燥主要发生在降速干燥阶段；Page模型是描述油菜籽干燥特性的最佳数学模型，由模型预测的干燥特性曲线与实验所得的干燥曲线一致性好；热风温度是影响油菜籽热风干燥的主要因素，随着热风温度的升高，油菜籽的有效水分扩散系数增大，当热风温度从45 ℃增加到65 ℃时，其有效水分扩散系数由3.835×10-10 m2/s增加到7.666×10-10 m2/s，油菜籽的干燥活化能为29.26 kJ/mol。

Abstract:

Drying and storage of rapeseed directly affects its physiological characteristics, potential for breeding, as well as processing characteristics and quality of rapeseed oil produced. In order to provide a technical basis for designing equipment and optimization of process control for hot-air drying of rapeseed, the characteristics of hot-air-dried rapeseed (Brassica napus) under different conditions of moisture content, hot air temperature, and air velocities were investigated, and the applicability of 10 mathematical models for the process of hot air-drying rapeseed was compared. The results showed that there was no apparent constant-rate drying period in the hot-air-drying process, and moisture removal mainly occurred in the falling-rate drying period. Of the various models tested, the page model was found to be the best mathematical model for describing the drying characteristics of rapeseed and the predicted drying characteristic curves fitted well with results obtained. Hot air temperature was the main factor that affected the drying process of rapeseed. With the increase of temperature, the effective moisture diffusion coefficient of rapeseed increased. When the hot air temperature increased from 45 ℃ to 65 ℃, the coefficient increased from 3.835 × 10-10 m2/s to 7.666×10-10 m2/s and the activation energy for rapeseed drying was 29.26 kJ/mol.