Study On VAV Air Supply System Based On Ventilation Network

With the improvement of the people's life, the air—conditioning systems (VAV) play a vital role in people's 1ife.Because of the wide using of the air—conditioning systems, the energy waste of VAV system became an importance problem. Nowadays, VAV air-conditioning system has gradually become most popular in China and abroad because of it's significantly energy saving. However, since VAV system is multivariable, strongly coupled, nonlinear and time variant. its design,performance and management are difficult, It's an important reason that limits the VAV system for a greater use. And stable control of the entire VAV system is focused unparticular.The independent regulations of the control links in VAV air supply system will affect the distribution of air volume seriously in each room, Thereby, the affecting the effect of VAV air-conditioning. That whether the structure of the VAV air supply system is rational, will seriously affects the stability of the control system. In order to make the control system coordinated, in this paper, the Predictive Control module based on Ventilation Network is used to predict the structure of air system in form of feed-forward control. In order to make the structure of air supply system is in a flexible, stable and reliable state, in this paper, the Prediction Control Model will regulate the resistance of all the ducts in the system except the trunk duct. In addition, the resistance of to be adjusted will be shared by the VAV-Box and the valve in the duct which the VAV-Box is in. And the predictive module projects the valve's reasonably. And according to this value, the valve does not have to adjust frequently.In this paper, the VAV air conditioning system mode is established based on the TRNSYS platform. The distribution of air volume by VAV air system is simulated. Simulation tests show that the structure of VAV air system which is controlled by this control strategy is very stable and flexible, and control system has good performance. As the experimental results show, in the working periods, the relative deviation of air volumes in all the rooms are less than 10%, the average regulation time is 22min; The trends of energy consumption in ventilation network is almost the some as the total amount of air volume in VAV air supply system. Therefore, the model predictive control can insure the distribution of air system timely and accurate, while saving the energy of air supply system effectively.