摘要
为了实现小麦秸秆含水率的便捷、快速和准确测量,设计了一种以AT89S52单片机为控制器,分别利用平行极板式电容传感器,DS18B20温度传感器和FSR402压力传感器测量电容、温度和容积密度,以液晶显示器显示测量结果的小麦秸秆含水率测量仪。通过试验分析了电容、温度和容积密度测量模块的精度;进而以冬小麦秸秆为对象,研究了秸秆的湿基含水率(10.6%～19.6%)、温度(5～35℃)和容积密度(77.2～103.6kg/m3)对输出电容的影响;建立了电容与主要影响因素的关系模型,并对模型的可靠性及含水率预测精度进行了检验。结果表明,所设计测量仪的含水率绝对测量误差是0.9%～2.2%,灵敏度为0.3%,响应时间小于2s。研究为灵敏、快捷的小麦秸秆含水率检测仪的设计提供了参考。
Faced with the worldwide shortage of forest resources, industry is showing increasing interest in using straw. Moisture content is listed as a main criterion in wheat straw consuming market. Not only since the unit price is based on weight, but also because moisture content is an important factor which affect straw products’ quality. Wheat straw is a main kind of straws all over the world. In order to detect moisture content of wheat straw conveniently, rapidly and precisely, a moisture content meter was designed with AT89S52 single-chip microcomputer as controller, parallel plate, DS18B20 and FSR402 as capacitance sensor, digital temperature sensor and pressure sensor to detect capacitance, temperature and bulk density of wheat straw, respectively. Liquid crystal display was adopted to show the obtained data. The meter’s accuracy on measuring capacitance, temperature and bulk density was tested. “Xinong 979”winter wheat straw was used as sample to study the influence of moisture content on output capacitance. The tests were set at five levels （10.6%, 13.6%, 15.6%, 17.3% and 19.6% in wet basis）, temperature range from 5℃ to 35℃ with 5℃ interval, and three bulk density levels （generally from 77.2 kg/m3 to 103.6 kg/m3）. The model describing capacitance and main factors was regressed. Newton iteration method was applied to program for predicting moisture content from obtained data. The model’s feasibility in predicting moisture content from 10%-20% at 5-35℃ was verified. The results indicated that the output voltages of designed circuits for sensing capacitance and pressure had good linear relationship with real capacitance and pressure values, with coefficients of determination higher than 0.996. The absolute temperature error was ±0.2℃. Over the investigated ranges of moisture content, temperature and bulk density, the obtained capacitance value increased with increasing moisture content, temperature and bulk density. The relationship between capacitance and moisture content, temperatu
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2013年第1期33-40,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
公益性行业(农业)科研项目(201003063-07)
关键词
秸秆
含水率
仪器
电容
温度
容积密度
straw, moisture, equipment, capacitance, temperature, bulk density
