| The supply of fresh air ensures good indoor air quality. The central fresh air system is used more and more widely. The application of central fresh air system is closely related to its automatic control system. In this paper, the fresh air volume control is analyzed based on air pollutants concentration. The automatic control method and strategy of the central fresh air system are researched to provide reference for the practical application.Firstly, the correlation degree between the indoor pollutants is calculated by using grey correlation degree theory. Pollutants are classified according to the degree of correlation. Pollutants in the underground supermarkets, office buildings,classrooms, hospitals, trains, residential buildings are analyzed and calculated.Through the similar degree among various pollutants, the representative pollutants of different types of buildings are listed, which provides reference for the fresh air system control strategy.Secondly, the defects of the existing demand control ventilation system are analyzed and improved. The fresh air volume is determined by using a variety of pollutants as the control object and a new automatic control strategy is established.The fuzzy PID control is used to control the frequency conversion fan in the central fresh air system. The simulation results show that the fuzzy PID control is better than the traditional PID control.Finally, taking a hospital as the research object, the automatic control system of central fresh air system is designed, including automatic control scheme,communication network, PLC selection, all kinds of pollutant detection equipment and so on. The PLC programming software is used for automatic control system programming. What's more, the monitoring configuration interface is designed for the hospital central fresh air system. |
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