An energy-saving oriented air balancing method for demand controlled ventilation systems with branch and black-box model

Abstract

This paper proposes an energy-saving oriented air balancing method based on a branch and black-box (B2) model for multi-zone demand controlled ventilation (DCV) systems. The proposed method can achieve accurate air flow control in each zone, which avoids unnecessary energy consumption caused by over-ventilation. The operating procedures of the proposed method are as follows: Building the B2 model for the DCV system → Predicting the terminal static pressures under the given zone design flow values → Determining the damper angles of each zone based on the static pressure predictions. In the proposed air balancing method, the basic modelling unit is the duct branch, instead of the internal fittings in the previous model-based air balancing method. Therefore, the proposed method does not need to know the complicated fitting information (e.g., elbows, transitions, dampers, etc.,) in its modelling process and therefore becomes much simpler. In addition, the complexity of the proposed B2 model is also greatly reduced since it is independent with the fitting numbers and does not need to calculate the fitting loss coefficients. Furthermore, the radial basis function (RBF) kernel is also utilized in the proposed method to guarantee the air balancing accuracy. Compared with the existing air balancing methods, the proposed method is more efficient and effective in practice. In the lab, the proposed air balancing method was validated on a real DCV system of 5 zones under various design flow conditions. The experimental results verified the effectiveness of the proposed method on both the air balancing control accuracy and the energy saving ability.