Design Of PLC Control System For Dehumidification Heat Pump

In the production,processing and storage of food,timber,medicine and other industry areas,the air temperature and relative humidity will have a great impact on yield,quality,and appearance.Drying is one of the main methods in food and agricultural product storage and deep processing.Owing to many types of materials,drying methods also vary widely.The problems to accelerate the dehumidification drying speed,shorten the drying time,improve the quality of the dried product and energy saving drying are the main research projects.Dehumidification heat pump PLC control system is designed.By setting the bias,the control precision is increased.In order to meet the needs of different control and cooling system,two operation modes of "value" and "curve" are designed.Using cooling technique,wet air in the drying chamber is cooled and dehumidified,at the same time,latent heat of condensation water is recycled through the heat pump principle,so the purpose of heating the dried material and energy saving can be achieved.The main work is as follows.(1)The dynamic dehumidification heat pump technology at home and abroad is introduced,dehumidification drying characteristics and trends are highlighted.(2)The principle and process of dehumidification heat pump PLC control system is analized.Scheme and control process according to the control requirements are designed.Various hardwares are selected.(3)According to the control requirements,the control system is designed,including PLC control program design and touch screen programming.PLC program includes analog conversion,each execution unit running,setting running and curve running and alarm reset procedures.Touchscreen interfaces include screen interface,curve interface,operation monitoring,parameter set,temperature and humidity records and failure information components.Touchscreen r monitors and displays temperature,humidity in realtime.After installation,the PLC system runs successfully in the enterprise.It can achieve reliable,accurate control of the temperature and humidity,realize dehumidification drying effect.