农田二氧化碳浓度梯度原位同步测量系统优化设计与试验

摘要

为准确测量农田近地层二氧化碳浓度梯度分布,降低人为测量所产生的干扰误差,设计了一种二氧化碳浓度梯度原位同步测量系统.该系统由机械采集模块和系统控制模块组成,机械采集模块负责采集气体,系统控制模块实现二氧化碳浓度的自动测量,测量系统在农田中自动进行二氧化碳浓度梯度分布的测量,并采用无线传输技术将测量数据发送至服务器.阐述了测量系统的总体结构以及各模块设计方法,运用Fluent软件模拟了二氧化碳测量的抽气过程,分析优化了测量管路间隔与抽气速度、管道直径的关系,并进行了测量系统室内标定和现场二氧化碳浓度测量试验.试验结果表明,该系统能够较好地测量农田二氧化碳浓度梯度的分布,测量误差不大于4.17％,实现了农田信息的自动获取,对二氧化碳碳汇信息计算具有重要意义.%In order to measure the distribution of carbon dioxide (CO2) concentration gradient in farmland accurately,and reduce the interference error caused by manual measurement,a CO2 concentration gradient in-situ synchronous measurement system was designed,which was equipped in farmland to measure CO2 concentration gradient automatically,and the measurement data could be sent to the host computer server via GPRS wireless transmission technology.The system was composed of a mechanical collection module and an electrical control module.The mechanical acquisition module was responsible for the gas collection,and the system control module was used to realize the automatic measurement of CO2 concentration.The overall structure of the measurement system and the design of each module were introduced,and the pumping process of carbon dioxide measurement was simulated by computational fluid dynamics (CFD) software.The relationships between the distance of the measurement pipeline and the pumping speed,as well as the diameter of the pipeline were analyzed to optimize the system design.The indoor system calibration and outdoor field measurement of carbon dioxide concentration were implemented.The experimental results showed that the system could measure the concentration gradient of farmland carbon dioxide,and the measurement error was not more than 4.17％.The system could realize the automatic acquisition of cropland information,which had important significance to the carbon sequestration information calculation.