Research On Indoor Temperature And Humidity Control Of VAV Air-Conditioning System Based On Absolute Humidity Control

Summer is the most prominent season of energy demand for air-conditioning system,the main reason lies in the rise of the environmental humidity and temperature.Humidity mainly affects the human body's thermal metabolism and water salt metabolism.With the improvement of people's comfort requirements,the control of temperature and humidity has become the key of summer air-conditioning.It is a hot topic of domestic and foreign scholars.In order to make the air-conditioning room maintain appropriate temperature and humidity,dehumidification is necessary.There is a coupling between relative humidity and temperature,but there is non-coupling between absolute humidity and temperature.In this case,the absolute humidity is introduced and the dew point dehumidification control is studied.The domestic and foreign scholars have conducted a lot of research on the temperature and humidity control strategy,decoupling method and terminal device.However,the humidity control based on absolute humidity and end control has not been seen.Through the theoretical analysis of the relationship between the absolute humidity and the indoor temperature and humidity and the control of the terminal circuit,an indoor temperature and humidity control method of VAV air-conditioning system combining humidity control of absolute humidity with terminal circuit is presented in this paper.Firstly,the relationship between absolute humidity and relative humidity was analysed.The indoor temperature and humidity control scheme of VAV air-conditioning system-control method of indoor temperature and humidity combining cascade double closed loop-is presented.Secondly,the classical system identification method is used to model the necessary control loop of the air-conditioning system.According to the closed characteristics of the end loop,the closed loop identification method is used to room air capacity and room temperature model.Finally,the correction coefficient is introduced in the room temperature and humidity control loop to remove the coupling between temperature and humidity.In addition,an incremental PID controller based on Z-N tuning method and an incremental PID controller based on simplex method and single neuron adaptive PID controller are studied for air supply temperature control loop,an incremental PID controller based on simplex method and single neuron adaptive PID controller are studied for the room humidity and room temperature control loop.In the MATLAB simulation,the simulation results are analyzed and the controller with better control effect is selected.Finally,the control algorithm is applied to the actual air conditioning system,and the control of room humidity and temperature is basically stable.After adding the correction factor 802 S,the system runs stable.The control of room temperature and humidity accelerate the response speed and shorten the adjustment time,temperature and humidity combined control of the overall control effect has been significantly improved The results show that the indoor humidity and temperature control scheme based on absolute humidity control is feasible,It provides a reference for engineering application.