Design Of Control System Based On PLC For Energy-saving Fruit And Vegetable Modified Atmosphere Storage

This paper is about a fresh air control system,which is nearly 400 cubic meters,designed with a company in Weifang.In the design,it controles the preservation environment of fruits and vegetables in the closed storage with the implementation of effective measures,to control the parameters of temperature,oxygen concentration,carbon dioxide concentration,ethylene concentration and humidity in the effective range to achieve the purpose of fresh fruits and vegetables.This design incorporates the parameters of self-tuning PID,the programmable control technology,the sensor technology,the frequency conversion technology and the configuration software and has developed good human-computer interaction of energy-saving atmosphere control storage control system,which is based on programmable control technology.The controlled atmosphere fresh storage system consists of temperature and humidity control,air conditioning,wind speed control,library pressure balance and ventilation control system.It established the mathematical model according to the characteristics of a time-variable,misalignment,the lag complex.The temperature and oxygen concentration are controlled by PID technology.The refrigerating machine and nitrogen generator are designed as frequency control.The design is about the selection and configuration of bodies of the hardware such as touch screen,programmable logic controller,temperature,air,humidity,wind speed,pressure and ventilation.Among them,the air-conditioning control is designed for the gas sampling detection,this method laid the foundation for multi-storeroom group control.This design control system hardware parts composed mainly by program,configuration screen and frequency parameters.The program achieves the data acquisition,calculation and output control of the entire system;a good human-computer interaction touch screen completes the permissions security,data display,operation instructions,monitors the entire system and facilitates the operation effectively.The variable frequency energy-saving test of the control system for controlled atmosphere storage exemplifies the advantages of frequency controlling speed: faster cooling,small fluctuations in temperature,a good energy-saving effect.The paper realizes the regulation of the preservation of the environment,to complete the storage of fruits and vegetables.The design system is simple,stable,practical.It meets the current demand for fresh fruits and vegetables and responds the active promotion of the atmosphere of preservation technology.