Energy-efficient operation of a complete Chiller-air handing unit system via model predictive control

Abstract Chiller-air handing units (Chiller-AHU) system is widely used in the heating, ventilation and air conditioning (HVAC) system of commercial and residential buildings. An effective control strategy is critical for the Chiller-AHU plant to reduce energy consumption and costs. Past control strategies focus more on leveraging building load flexibility to decrease the cost bill by setting the different room temperatures according to different electricity prices. Neglecting how to achieve the set room temperature with minimized total power consumption. In addition, the Chiller-AHU system is not considered as a whole and the constant coefficient of performance (COP) of the chiller is assumed in some research. All these limitations cause compromised results. In this paper, we build a complete Chiller-AHU model and propose a nonlinear model predictive control (MPC) strategy for the Chiller-AHU system. The MPC can provide the optimal inputs for the system, the minimal total power consumption can be achieved by optimally coordinating the operating from fans, pumps and chiller providing that the room temperature is well maintained. The proposed strategy is evaluated under the energy-saving case and cost-reduction case, a 6.2% total power consumption saving and 12.3% electricity bill reduction is achieved compared to the traditional PI control. The simulation results validate the effectiveness of the proposed strategy.