Design Of Pipeline Sampling Water Quality Monitoring System For Pond Juanyang System

In the pond Juanyang system,sensors are usually put into the aquaculture water for m easurement in the process of monitoring the water quality of multiple captive tanks.Howe ver,the above monitoring method has high cost and difficulties in cleaning and maintenan ce.In order to solve this problem,a pipeline sampling water quality monitoring system wa s proposed,which could monitor the water quality of multiple points with only one set of sensors.The main research contents are as follows:(1)Functional requirements analysis and scheme design of the system.Combined wit h the characteristics of multiple monitoring points and high requirements for cost control i n the pond Juanyang system,the functional requirements of water quality monitoring syst em were analyzed,and the scheme of pipeline sampling and monitoring was determined.Moreover,the overall system structure was designed.(2)Design of waterway system.According to the functional requirements of multi-po int water sample collection and self-cleaning of sensors,the structure of the detection mod ule was designed by using Solid Works software,and the waterway of the sampling modul e,cleaning module,overflow and drainage module was designed.Additionally,according to the sampling amount,sampling time and pressure value of sensors,the head and flow o f the pump,the outlet diameter of the nozzle and the working pressure of other component s in the pipeline were calculated.On this foundation,the selection scheme of pump,pipe,valve and nozzle in waterway system was determined.(3)Design of control system.Firstly,the hardware modules were integrated.Selectin g STM32 single-chip microcomputer as the master controller,sensor module,display mod ule,YK-08 eight way relay module,U disk storage module and CC2530 wireless transmit ting and receiving module was connected with STM32 through peripheral circuit to realiz e the monitoring of p H,dissolved oxygen,water temperature and other parameters.Secon dly,the control sequence of next-bit machine was designed.The control of the waterway s ystem and the collection,processing,display,storage and wireless transmission of water q uality data were completed by programming based on keil software and C language.Final ly,the upper computer software was developed by using Lab VIEW to realize the function s of real-time display,storage and abnormal value alarm of water quality data.(4)System operation test.Firstly,the functional modules of the system were tested.S econdly,through the error characteristic experiment,the error between pipeline sampling monitoring and in-situ monitoring was explored,and additionally the main causes of the e rror and the variation law of the error with the length of the pipeline were analyzed.The re sults showed that when the pipeline was arranged in the atmosphere,the error of each wat er quality parameter fluctuated greatly,and the fluctuation degree of the error raised with t he increase of the pipeline length.Furthermore,affected by solar radiation intensity,the va riance of p H error and dissolved oxygen error could reach 0.094 and 0.446(mg/L)~2.Affect ed by air temperature,the variance of water temperature error could reach 4.895(℃)~2.(5)System optimization.According to the results of error characteristic test,the layo ut of pipeline was optimized.Through experiments,the error fluctuation of each water qua lity parameter was found to be small when the pipeline was arranged in the aquaculture w ater.And similarly,the maximum variances of p H error,dissolved oxygen error and water temperature error were 0.029,0.075(mg/L)~2 and 0.346(℃)~2,which were also far less than that when the pipeline was arranged in the atmosphere.When the pipeline length was 10m and 20m,the maximum relative errors of p H,dissolved oxygen and water temperature were-0.61%,0.86%and 0.73%respectively,which were all within the measurement erro r range of their respective sensors and had strong reliability of the system water quality m onitoring.When the pipe length was 30m and 40m,the maximum relative errors of p H,di ssolved oxygen and water temperature were-2.1%,-2.24%and-5.04%respectively.Ex cept for dissolved oxygen,the monitoring errors of p H and water temperature were both b eyond the measurement error range of their respective sensors.Therefore,to solve the pro blem,an error correction model by curve fitting the relative errors of p H and water temper ature was established.The results showed that the relative error and error variance were b oth reduced after correcting.When the pipe length was 30m,the relative error of p H had r educed from-1.21%to 0.02%,and the variance had reduced by 0.001;The relative error of water temperature had decreased from-3.16%to-0.22%,and the variance had decreas ed by 0.018(℃)~2.Besides,When the pipe length was 40m,the relative error of p H had red uced from-2.1%to-0.05%,and the variance had reduced by 0.01;The relative error of water temperature had decreased from-5.04%to-0.20%,and the variance had decreased by 0.036(℃)~2.