Natural Ventilation System for Office Buildings with Perforated Metal Ducts on Ceiling

In order to distribute the cool outdoor air evenly in the large office room Perforated Metal Duct on Ceiling (PMDC) are proposed as Natural Ventilation system for large office buildings. The bottoms of the ducts are composed of perforated metal plates and outside air should be designed to make the velocity distribution uniform. The authors developed the duct airflow model to predict supply air flow rate distribution and its results were compared with CFD for validation. From the comparison between them, the pressure loss coefficient of the duct surface was identified, and the distribution of opening ratio of PMDC was obtained by means of duct airflow. In addition, the result was compared with the CFD result for validation. At last, the authors proposed to adopt PMDC with two vertical ventilation shafts in a high-rise office building. The waste heat from cogeneration system is generated in the ventilation shafts in order to enhance buoyancy-driven ventilation. To estimate this effect, the overall flow network model for the whole building was resolved by Gauss-Seidel iteration method, and an appropriate distribution ratio of waste heat in the ventilation ducts were made clear using this overall network model.