Air Handling Unit Of Air Conditioning Control Research

With the development of people’s living standards, the air conditioning becomes more popular, which improves the comfort. The high energy consumption of the air conditioning system has also become an urgent problem. The cooling coils is a device for realizing the heat and moisture exchange between chilled water and air, which is the core component of the air handling unit, and its performance directly affects the energy consumption of the air conditioning system. Therefore, the research on the modeling and control method of the cooling coils has always been a hot topic in the field of air conditioning.Firstly, after reading a large number of domestic and foreign references, this thesis summarize the variable research status of VAV air conditioning system, and output regulation problem of air handling unit situation. It is found that the complexity of the working condition affects the accuracy of the modeling, therefore, the control effect is not ideal. This thesis focuses on dealing with the difference of the cooling coils model under different conditions, to improve the control precision.Secondly, the central air conditioning system, especially the core part of the air handling system, is studied, and the changes of the model under different working conditions are studied. It is found that the change of heat transfer coefficient affects the established model of the cooling coils. In the previous literature the sensible heat ratio changes is considered, and the influence of changes on the cooling coils model of the heat transfer coefficient is ignored. This thesis also considers the influence of the outlet air temperature regulation changes in SHR and the heat transfer coefficient under different conditions.Then, aiming at the problem of regulating the outlet air temperature in the cooling coils, the uncertainty state space model is established for the cooling coils in which the heat transfer coefficient is taken as the parameter perturbation. The heat transfer coefficient varies with different working conditions. In order to overcome the influence of the model uncertainties, according to the range of the perturbation parameters, robust controller is designed to ensure that the system has good robustness under different working conditions and an analytical expression of the robust controller and its theoretical proof are given.Finally, the control system is simulated in the MATLAB environment. The simulation results show that the robust controller overcomes the influence of the uncertainty of the model and the tracking control is realized with the performs of fast response, no overshoot, and no oscillation.