摘要
讨论了以由谷物含水量 (介质介电常数 ε)变化引起电容式传感器振荡频率的变化来测量谷物水分的方法。采用同心圆式电容传感器对谷物干燥设备进行在线水分测量及控制 ,建立了定流量条件下谷物水分同电容传感器振荡频率。
The objective of this study is to develop an on line measurement and monitoring system of grain moisture used in drying process of continuous type of dryer. Grain moisture content can be indirectly measured by sensing the dielectric constant of grain. The dielectric constant of grain is mainly affected by the moisture content, as well as other factors such as: temperature, density and variety of grain. A concentric cylinder type of capacitance sensor is designed, fabricated and tested for measuring grain moisture content under various conditions. In the measuring circuitry, the changes of moisture content is firstly converted into changes of dielectric constant and finally converted into changes of oscillation frequency. The relationship between grain moisture content and the sensor oscillation frequency as well as grain temperature under uniform grain flowrate was determined and a mathematical model was then developed. In order to obtain the required grain moisture content, the PI control algorithm is used to control the unloading augur speed. The experimental result shows that the control accuracy of moisture content at the outlet is not more than 0 5%.
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2000年第2期53-55,共3页
Transactions of the Chinese Society for Agricultural Machinery
基金
农业部重点科研项目! (项目编号 :97农机 0 2 0 3 )
