Study On Measurement And Control Technology Of Environmental Factors Of Carbon Sink Plant Culture System

In recent years,the phenomenon of global warming is becoming more and more serious,which affects the growth of plants and the survival of human beings in varying degrees.The main cause of global warming is CO₂,so it is very important to reduce CO₂ from the atmosphere economically and effectively for alleviating the global warming.The behavior that forest absorbs CO₂ through photosynthesis is called forest carbon sink,it is the main way to reduce CO₂ from atmosphere.In order to give full play to the carbon sink capacity of forest,it is necessary to estimate the amount of forest carbon sink and study the relationship between forest carbon sink ability and environmental factors?temperature,humidity,etc.?.Methods for carbon sink estimation of vegetation?including forests,flowers,etc?include the inventory method,the Eddy covariance method,the box method.The box method is the development direction of carbon sink estimation methods in the future,because it is easy to implement and its measurement error is small.At present,the box type system used for carbon sink measurement generally does not have the ability of environmental control or control limited.In the study,for the problems that the traditional box type system is difficult to measure carbon sink chronically and is difficult to be used to study the relationship between the vegetation carbon sink ability and environmental factors,a carbon sink plant culture system is studied.The carbon sink plant culture system includes work box,incubator and virtual instrument for measuring and controlling,it can control the growth environment of the experimental object,especially for the temperature field control and can be combined with the CO₂ concentration detection system which is another branch of project to form a carbon sink measurement system.The carbon sink plant culture system can not only be used to estimate the carbon sink of vegetation,but also can be used to study the relationship between vegetation carbon sink ability and temperature.In this paper,the basic structure and hardware composition of the carbon sink plant culture system are introduced firstly,the working principle and implementation of the system are illustrated.Then the CFD simulation software Fluent is used to simulate the temperature field inside the incubator,the relationship between the temperature field uniformity in the plant area of incubator and the position,number,air supply velocity of the hot air machine are studied.Finally,the best position and air supply velocity of the hot air machine are found.Based on the simulation analysis of the temperature field in incubator,a control strategy for the temperature field of the incubator is proposed.The variable universe fuzzy PID control method is used to control the average temperature of the incubator,and the threshold control method is used to control the maldistribution of the temperature field in incubator,and finally the temperature field of the incubator is controlled by the two.The contraction-expansion factor of variable universe fuzzy PID controller is improved,and the piecewise function contraction-expansion factor can reduce the computational complexity while ensuring the control precision.The improved variable universe fuzzy PID controller is simulated and analyzed by MATLAB,and its dynamic characteristic is better than that of PID and fuzzy PID controller without variable universe processing.The LabVIEW is used to design the measurement and control virtual instrument to realize the monitoring of the environmental factors and the control strategy of the temperature field in the incubator.Based on the measurement and control virtual instrument,the whole carbon sink plant culture system is debugged,and the internal environment of the incubator is controlled,the control results of temperature field are given.The results show that the steady state error is not more than 0.5?for the control of the average temperature,the maximum temperature difference between the adjacent layer of temperature field is not more than 0.6?,which can meet the requirement of the system and can provide a good foundation for the study of forest carbon sink.