Numerical Simulation And Control Simulation Of The Residential Fresh Air System

A good indoor air quality can not only provide a healthy environment, but also improve human's work efficiency. The paper conducts a reaearch of the application of The Fresh Air System to residential buildings in cold regions, analyzes the impact of the fresh air volume on the indoor environment, and puts forward a controlling strategy of fresh air with the change of air pollutant concentration.The buildings in such area use The Fresh Air System combined with The Floor Heating System. Three different conditions based on the different fresh air volume are assumed. Firstly, the K-? Two-equation Turbulence Models are adopted using Airpak software, the indoor air flow is measured by SIMPLE algorithm for analyzing the indoor velocity field, temperature field, and so on. Secondly, considering the contradiction of the fresh air volume, energy consumption and indoor air quality, I have chosen the indoor air quality as our No.1 priority about controlling ventilation. The fresh air volume of the fresh air system is regulated by the fuzzy PID controller. Furthermore, MALTAB simulation has been applied to contribute a control simulation curve.According to the Computational Fluid Dynamics and the simulation, the results follow by:(1) Basing on the Airpak, the air velocity of the main indoor active regions remains less than 0.2 m/s. When the air velocity has become faster than 0.5 m/s, people start to have the feeling of draft sensation. When the air velocity has dropped significantly, it cannot satisfy the requirement of breathing.(2) The temperature of the comfort zones remains mainly between 17 to 22?; the surface temperature of the radiation is mainly at 25~27?; the indoor temperature difference in the vertical direction is less than 3?, which satisfies the needs of the human. The higher the blowing rate, the more areas with the surface temperature lower than 24?. However, the temperature gradient become larger when the blowing rate is too small, which might cause a lower temperature near the vent.(3) The blowing of fresh air can effectively ameliorate the sense of thermal. Moreover, the greater of the fresh air volume is, the more comfortable people might feel. In contrast, when the Air volume is too large, people would have the sense of draft which would also lead to the increasing dissatisfaction.(4) The simulation curve barely has overshoot. Also, the response time is short.