息半夏干燥热力学模型建立及影响因素分析

Establishment of Drying Thermodynamics Model and Influencing Factors Analysis of Xi Pinellia ternata

目的:明确影响息半夏干燥过程的各种因素。方法:将新采挖的息半夏大小分档,去皮,分别于75℃、55℃、35℃、55℃热风条件下干燥,定时称重,并测定最终含水量,得出各时段的干基含水量,绘制干燥曲线和速率曲线,并对干燥曲线进行经典干燥模型拟合,对速率曲线进行分析,对产品外观色泽进行统计。结果:息半夏薄层干燥符合Logarithmic模型和Midilli模型,有效水分扩散系数Deff在11.66×10^-10~90.6×10^-10 m^2/s之间,活化能Ea为32.88 KJ/moL;75℃干燥速率最快,但导致息半夏变色,35℃干燥速率过低,导致干燥时间过长;55℃热风干燥产品皱缩,角质化;35℃和55℃干燥产品外观较好。结论:息半夏干燥符合一级动力学方程,应按照Logarithmic模型或Midilli模型设计干燥参数;干燥条件以中温、无风条件为宜。

Objectives:In order to clarify the factors affecting the drying process of Xi Pinellia ternata Thunb.Breit..Thin-layer drying of P.ternata conforms to Logarithmic model and midilli model.Methods:The newly excavated Xi P.ternata was divided into different sizes and peeled,and dried under conditions of 75℃,55℃,35℃and 55℃hot air,respectively.At the same time,the final water content was determined and the dry basis water content of each period was obtained.The drying curve and rate curve were made,and the drying curve was fitted by classical drying model,and the rate curve was analyzed.The appearance and color of the products were statistically analyzed.Results:Thin-layer drying of Xi P.ternata conforms to Logarithmic model and Midilli model.The effective water diffusivity Deff ranges from 11.66×10^-10-90.6×10^-10 m^2/s,and the activation energy Ea is 32.88 KJ/mol.The drying rate at 75℃is the fastest,but it causes the discoloration of Xi P.ternata.The drying rate is too low at 35℃,resulting in too long drying time.55℃hot air drying causes wrinkle and keratinization.The appearance of dried products at 35℃and 55℃is better.Conclusions:The drying process of Xi P.ternata meets the first order kinetic equation.Drying parameters should be designed according to Logarithmic model or Midilli model.Dry conditions are suitable for medium temperature and no wind conditions.