白菜种子热泵变温最佳干燥过程

为了研究白菜种子热泵变温干燥过程的传热传质机理，利用非稳态干燥动力学方程分析了变温干燥方式在提高干燥速率方面的优势．提出了几种合理可行的热泵变温干燥方式，引入间歇干燥比例系数概念通过对各种变温干燥方式下的水分扩散过程模拟，权衡各种干燥方式在能耗、水分扩散均匀性以及种子生命活力等方面的性能，认为间歇干燥比恒温干燥和变温干燥中的三角形变换、正弦变换的循环干燥方式对种子酶活性和生命力损害小．综合性能较好的最佳变温干燥过程的间歇干燥比例系数为1／3．

Temperature-Variable Optimal Drying Process of Heat Pump for Cabbage Seeds

The principle of heat and mass transfer in temperature-variable drying process of the heat pump for cabbage seeds was studied. On the basis of unsteady drying dynamics equation, the advantages in the rate of moisture diffusion during the temperature-variable drying process were analyzed. Intermittent ratio was introduced, and through the simulation of the moisture diffusion process under temperature-variable drying methods, the energy consumption, uniformity of moisture diffusion and seed vitality were discussed. It was considered that intermittent drying method was better than continuous constant-temperature drying, and triangular and sinusoidal change of cyclic drying method of temperature-variable drying, because intermittent drying method of temperature-variable drying did less damage to enzyme activity and seed vitality. Opti- mal intermittent ratio for over-all properties was 1/3 in the temperature-variable drying process.