基于潜热效应的活立木冻融检测传感器设计与实验

Design of Freeze-thaw Detection Sensor for Standing Forest Stock Based on Latent Heat

针对植物冻融过程中植物水分生理信息(植物水冰含量)难以实时、在线、连续监测及冻融难以准确判断的问题,设计了一种基于潜热效应的活立木冻融检测传感器。通过检测植物冻融过程中潜热释放引起的温度变化对茎干是否冻融进行有效判断,在准确检测冻融点的基础上,根据茎干体积含水率变化计算冻融过程中的茎干体积含冰量及径向冻融深度,同时设计环式弹片探头消除固定式探头对茎干压迫形成的凹槽。标定结果表明,传感器测量结果与真值拟合决定系数超过0.99。静动态特性分析表明,传感器体积含水率和温度测量范围分别为0~68.67%、-30~80℃,动态响应时间小于2 s。室内冻融模拟实验及室外长期冻融监测表明,传感器能够有效检测植物冻融过程中茎干水分生理参数的变化,可以作为植物冻融的有效监测手段。

Aiming to solve the problem that plant water physiological information(plant water and ice content)during freeze-thaw process is difficult to be monitored on-line and continuously in real time and judged accurately by freeze-thaw process.A monitoring sensor for freeze-thaw of living standing trees was designed based on latent heat effect,which detected the temperature caused by latent heat release during plant freeze-thaw process.Based on the accurate detection of freeze-thaw point,the ice content and radial freeze-thaw depth of stem volume during freeze-thaw process were calculated according to the change of moisture content of stem volume.At the same time,a circular projectile probe was designed to eliminate the pressure of fixed probe on stem to form a groove.Calibration results showed that the determination coefficient of fitting between the measured results and the true values of the sensor was more than 0.99.Static and dynamic characteristics showed that the measurement range of moisture and temperature of the sensor was from 0 to 68.67%and-30℃to 80℃,respectively,and the dynamic response time was less than 2 s.The results of indoor freeze-thaw simulation experiment and outdoor long-term freeze-thaw monitoring showed that the sensor can effectively detect the changes of water physiological information during plant freeze-thaw process.It provided a device with independent intellectual property rights,real-time continuous monitoring,low cost and easy installation for agricultural and forestry production and plant freeze-thaw assessment.