种用油菜籽真空干燥动力学特性及对Weibull模型的解析

Analysis of vacuum drying kinetics of rapeseed and analysis of Weibull model

为了获得发芽力较好的种用油菜籽,以及提高其真空干燥效率,将Weibull分布函数应用于油菜籽真空干燥动力学特性的研究。在装载量(50±0.5) g条件下,将初始含水率(M)为16.12%、18.19%、20.26%的油菜籽样品分别置于不同温度(T)(40、50、60、70、80℃)以及不同真空度(V)(0.03、0.04、0.05、0.06、0.07 MPa)进行实验。考察初始含水率(M)、温度(T)及真空度(V)对油菜籽干燥特性的影响。利用决定系数(R^2)、均方根误差(RMSE)、卡方(χ)~23个指标对拟合结果进行评价。对尺度参数(α)、形状参数(β)、水分扩散系数(D^(eff))、有效扩散系数估算值(D_(cal))和几何参数(R_g)进行解析。结果表明,尺度参数(α)与温度(T)和真空度(V)呈负相关,与初始含水率(M)呈正相关;形状参数(β)值均低于1,水分扩散系数(D_(eff))值为6.051×10^(-9)～2.908×10^(-8)m^2/s,几何参数(R_g)值均低于1,油菜籽真空干燥活化能(E_a)为22.369 k J/mol;温度(T)与平均干燥速率(r)呈正相关,与发芽率(g)和芽长(l)呈负相关;真空度(V)仅与平均干燥速率(r)呈正相关;初始含水率(M)与单位能耗(e)呈正相关,与发芽率(g)、芽长(l)以及平均干燥速率(r)均呈负相关。

Weibull distribution function was applied to study the dynamic characteristics of vacuum drying of rapeseed to obtain rapeseed with good germination power and improve their vacuum drying efficiency. The effects of initial moisture content (M),temperature (T),and vacuum degree (V) on the drying characteristics of rapeseed were investigated under the following conditions:(50±0.5) g loading capacity, M : 16.12%,18.19%,20.26%,at 40,50,60,70,and 80 ℃ under different vacuum degree (V)(0.03,0.04,0.05,0.06,0.07 MPa). The fitting results were evaluated by using coefficient of determination ( R^2 ),root mean squared error (RMSE),and reduced chi-square (χ^2 ). The scale parameters (α),shape parameters (β),moisture effective diffusion coefficients ( D eff ),calculated diffusion coefficient (D cal ),and geometric factor (Rg) were analyzed. The results showed that α was negatively correlated with T and V . It was positively correlated with M .β values were below 1,the values of D eff were in a range of 6.051×10^-9 -2.908×10^-8 m^2 /s,and R g was less than 1. The vacuum drying activation energy (Ea) of rapeseed was 22.369 kJ/mol. T was positively correlated with the average drying rate ( r ),and it was negatively correlated with the germination rate (g) and the shoot length (l). V was only positively correlated with r . M was positively correlated with the unit energy consumption (e),and negatively correlated with g , l and r .