The Temperature And Humidity Control System Of Precision Laboratory

With the development of industry and the progress of science and technology,the research laboratory and equipment room have more and more high precision instruments,and their use and maintenance are increasingly demanding to the surrounding environment.Chinese Spallation Neutron Source(CSNS)is a national key construction during the period of "11th five-year plan",the interior is equipped with different technology areas,and it has a high demand for temperature and humidity.The temperature should be 25 degrees Celsius plus or minus 2 degrees Celsius and the humidity should be less than or equal to 60%.However,Guangdong province belongs to the tropical and subtropical monsoon climate,as a country with more rainfall,humid climate,hot summer and warm winter.In order to ensure the normal operation of the CSNS precision electrical equipment in the laboratory,reduce the waste of human resources on duty at the same time,the requirement to establish a set of perfect air-conditioning temperature and humidity automatic control system.And the system will be automatically controlled for 24 hours throughout the year.This design is precision laboratory air-conditioning temperature and humidity control system,three sets of air conditioning unit is used to analyse the precision laboratory air supply.Based on the analysis of the environmental characteristics of hot summer and warm winter in Guangdong province,two control strategies for heating and cooling are established.Through the determination of temperature and humidity of the monitoring point,through the analysis and calculation,this system use the PID adjustment of water valve opening and the number of start-up segments of the electric heating to achieve the purpose of dehumidification,heating and cooling,and maintain the indoor air at 25 degrees Celsius plus or minus 2 degrees Celsius,the humidity within the range of 60% or less,and remain stable.On the premise of fully guarantee the reliability of communication network,it will communicate Siemens S7-200 with S7-200 PLC by PROFIBUS-DP communication network.Through Ethernet s7-300 plc,the collected information can be transferred to PC upper computer,and the PC upper computer can issue command control to s7-300 plc via Ethernet.Through the research on the control strategy of air conditioning automatic control system,the STEP7 control program was written.The establishment of man-machine interface makes it more convenient for the operator to understand the scene control situation,edit the touch screen Smart700 interface,and communicate directly with PLC controller.Through configuration software WINCC to write the Upper-position computer interface,it will achieve the real-time monitoring of indoor data online,and it will record the operation data of the air conditioning automatic control system and send out the alarm signal when the air-conditioning system fails.The operator can control the PLC controller through the upper computer interface,and can adjust the setting parameters and control the start-stop of the system.