污泥干燥速度曲线的分形维数分析

污泥的干燥速度变化是干燥过程中水分运动的宏观表现，对内部微观的传热传质动力学机制有重要揭示。利用功率谱分析对实验所得间接式加热的污泥干燥速度变化进行分形和混沌特性的判别，并提出Hausdorff维数和整体盒维数的计算方法，以分析其分形规律。通过判断得知，污泥的干燥速度变化具有分形特性。速度变化的Hausdofff维数随参数N值的增大而增大，但波动范围变小，且随着干燥过程进行，其值逐渐减小．另一种反映整体变化的维数——盒维数可以采用变换法计算得出，可用于判别干燥过程的整体分形特性。2种方法所得维数显示，污泥种类和干燥温度等对干燥速度变化的分形均有较大影响。

Fractal Dimensions of Sludge Drying Speed Curves

The change of drying speed is the macroscopical expression of matter transfer during sludge drying process, which can reflect microcosmis kinetics of heat and matter transfer. Indirect sludge drying speed was collected in experiments for its fractal and chaotic characteristics by analyzing power spectrum. Results show that the drying speed of sludge is fractal. Hausdorff dimension and box dimension were employed to analyze the speed fractal. Hausdorff dimension of speed change increases with parameter N, but the fluctuant range decreases. Along with the sludge drying, Hausdorff dimension is gradually reduced. Box dimension, which can be estimated with the variation, is used to analyze the holistic fractal characteristic of drying process. Hausdorff and box dimensions show that the sludge variety and heat temperature have great effect on fractal of drying speed change.