基于DSC的小麦秸秆比热容分析与曲线拟合

Analyses of the Specific Heat Capacity and Curve Fitting of Biomass Wheat based on the DSC

为了研究和探讨小麦秸秆的比热容特性并建立比热容预测模型,采集44个小麦秸秆样本,使用DSC200F3型差式量热扫描仪,采用参比法测定了样本不同温度的比热容,对测定结果和DSC曲线进行了统计分析,使用MATLAB工具箱中高斯函数（Gaussian）、多项式函数（Polynomial）和有理数函数（Ra-tiond）对样本的DSC曲线进行拟合,建立了小麦秸秆比热容拟合模型,并对模型进行了外部验证.结果表明,在30～200℃温度范围内,小麦秸秆比热容介于0.5831～6.483 5 J/（mg·K）之间,温度对比热容有很大影响,同时受地域、品种和生长环境的影响也较大;小麦秸秆DSC曲线的变化规律及形状基本一致,DSC曲线是近似于正态分布曲线,并有明显的“拖尾”现象;小麦秸秆比热容曲线可以采用高斯函数进行描述,其比热容测试均值与拟合模型预测值之间的相关系数R2为0.9988;和方差SSE以及均方根误差RMSE分别为0.8312和0.0514,有较高的预测精度.

In order to investigate the specific heat capacity of wheat straw and establish a model for predicting specific heat capacity,44 samples of wheat straw were collected.Specific heat ratio of 44 samples in different temperature was measured using differential calorimeter scanner of the type DSC200F3 and reference method.Statistics and analysis made on the heat capacity and DSC curve of 44 kinds of wheat straws.The DSC curve of samples were fitted by the Gauss function,Polynomial function and Rational function in MATLAB.Fitting model of the heat capacity of wheat straw was established and external authentication for the model was made.Results showed that specific heat capacity of wheat straw was between 0.5831 J/（mg·K） and 6.4835 J/（mg·K） durning the temperature 30～200 ℃.The temperature,the geographical,variety and growing environment had a significant influence on specific heat capacity.The variation of wheat straw DSC curve was basically the same with the curve shape similar to the normal distribution curve with apparent ＂tail＂ phenomenon.The heat capacity curve of wheat straw was described using a Gaussian function with high prediction accuracy.The correlation coefficient between the measured mean value and model predictive value of the specific heat capacity was 0.9988.The SSE and RMSE were 0.8312 and 0.051 4,respectively.