In recent years, many multi-type package air conditioning systems for buildings have become widespread in office buildings in Japan, and there are many cases where one air conditioning space is shared by using several indoor air conditioning units. The advantages of multi-type package air conditioning system are that it is possible to operate and control individually for each indoor unit, and that the user can arbitrarily change the temperature setting of the indoor unit. On the other hand, these advantages cause air conditioning control problems such as air quality deterioration and mutual interference between adjacent indoor units. Therefore, this study aims at developing a new air conditioning control method that reduces air quality deterioration and influence of mutual interference by using model predictive control (hereinafter MPC) when sharing one air conditioning space with multiple air conditioning indoor units. In this paper, we carried out CFD (Computational Fluid Dynamics) analysis incorporating multiple-input multiple-output (hereinafter MIMO) MPC that controls each zone while considering the thermal environment between adjacent zones in an office where the set temperature differs between zones. Furthermore, we showed the effectiveness of this method (MIMO MPC) by comparing the single-input single-output (hereinafter SISO) MPC.
The following results were obtained: 1) when comparing the outlet air temperature, SISO MPC had a large fluctuation range of the outlet air temperature in the zone where the set temperature was 26 degree, but MIMO MPC was small. 2) The averaged room air temperature in the zone where the set temperature was 27 degree showed almost the same behavior in both control methods, but comparing the behavior of room air temperature at each point, the temperature fluctuation of SISO MPC was large, and the MIMO MPC was small. The reason for this is presumed that the fluctuation range of the room air temperature was suppressed in MIMO MPC in accordance with the difference in the behavior of the outlet air temperature in the adjacent zone. From the results of 1) and 2), the improvement of control performance and the reduction effect of mutual interference were confirmed by the introduction of MIMO MPC for the office with different set temperatures among each zone.