摘要
QPQ氮化盐分析仪基于分光光度技术,检测QPQ氮化盐中氰酸根含量,恒温控制对分析仪检测的精确度有十分重要影响。针对分析仪的三样品检测室设计了一个空气浴恒温控制系统,检测室采用全铜材质,加热方式采用电热丝+TEC(珀尔贴)相结合的温度控制模式,其中电热丝的PID控制参数为P=24,I=128,D=68,可快速加热;TEC采用ADN8830控制芯片,PWM信号驱动MOS管可精确稳定控制样品温度。搭建实验装置,从实验数据可知:电热丝+TEC温控模式,到目标温度63℃时间为300 s,速度快;恒温控制温度为(63.7±0.7)℃,精度高;加热功率低,为5.3 W;检测室比色皿内蒸馏水与铜质外壳温度滞后约为1℃左右,在360 s时温度达到同步,温度同步性好;铜质材料的检测室温度分布方差RSD为0.1,温度分布十分均匀;满足分光光度计温度恒定控制要求。另外,采用ANSYS有限元分析分别模拟铜质和铝质材料检测室的加热过程和温度分布情况,分析所得结论与实验数据相吻合,铜质材料比铝质材料热导性能更优异,十分适合空气浴恒温控制方案。
Based on spectrophotometric technology,QPQ nitrification analyzer is used to detect the content of cyanate.The thermostatic control has a very important influence on the accuracy of the analyzer.In this paper,an air bath thermostatic control system was designed for the three sample testing rooms of the analyzer.The testing room was made of all copper material.The heating mode combined with electric heating wire and TEC,PID control parameter was P=24,I=128,D=68.TEC adopted ADN8830 control chip,and PWM signal driver MOS tube can precisely stabilize the sample temperature.The experimental device was set up.It was known from the experimental data that with the mode heating wire and TEC,the control speed was fast and the heating time was 300 s to reach the target temperature 63 ℃.The constant temperature was at 63.7±0.7 ℃ with high accuracy.Heating power was 5.3 W which was low.The temperature lag between the distilled water and the copper shell in the test chamber was about 1 ℃,and the temperature reached synchronization at 360 s with good temperature synchronization.The temperature distribution variance RSD of the test chamber of copper material was 0.1,and the temperature distribution was very uniform.It met the requirement of constant temperature control of spectrophotometer.In addition,the paper used ANSYS finite element analysis to simulate the heating process and temperature distribution of copper and aluminum material testing rooms respectively.The analysis results were consistent with the experimental data.The thermal conductivity of copper material was better than that of aluminum material,which was very suitable for the air bath temperature control scheme.
作者
武新
李光林
廖金权
WU Xin;LI Guang-lin;LIAO Jin-quan(College of Engineering and Technology,Southwest University,Chongqing 400715,China;Chongqing College of Electronic Engineering,Chongqing 401331,China)
出处
《仪表技术与传感器》
CSCD
北大核心
2019年第10期25-29,共5页
Instrument Technique and Sensor
基金
国家自然科学基金项目(61327002)
重庆市教委科研项目(KJ1729406)
