太阳辐射强度对污泥干燥特性的影响

Effects of solar radiation intensity on sludge drying characteristic

采用敞口型、温室型、温室-集热型3种干燥装置,研究了污泥在不同太阳辐射强度下的含水率变化,结果显示,太阳能干燥污泥的传热机理主要是太阳微波辐射及空气对流换热,干燥过程存在初始、增速、恒速、降速4个区别明显的阶段,并且空气流速对干燥过程的影响权重大于空气温度。当平均太阳辐射强度大于620W/m2时,能在180 min内将污泥的含水率降到38%以下;大于900 W/m2时,含水率能在120 min内降至38%。研究使用Logarithmic模型,建立了仅含太阳辐射强度S、干燥时间τ两种变量的干燥特性方程,简化了污泥干燥一般规律的预测计算。模型计算结果和实验值吻合较好,误差小于3.9%。

The moisture content and drying characteristics of sludge under different solar radia-tion intensity were researched in three drying devices （ exposed, greenhouse, and greenhouse-heattype）. Results showed that the heat transfer mechanism of drying sludge was mainly solar mi-crowave radiation and air heat convection. Sludge drying process consisted of initial, increasingspeed, constant speed, and decreasing speed. Air velocity had a greater influence than air temper-ature. The sludge moisture content was decreased to 38% within 180 min when average solar radia-tion intensity was more than 620 W/m2, while it was also bring the same results within 120 min （av-erage solar radiation intensity 〉900 W/m2）. A simplified drying characteristic equation, which fittedexperimental values well with fractional error of less than 3.9%, was established using Logarithmicmodel, taking into account onty two parameters of solar radiation intensity and drying time.