MIMO fuzzy logic controller design for temperature regulation of HVAC systems in cooling mode subjected to time-varying natural ventilation loads

• Published in: Sadhana (Bangalore) 2024-04, Vol.49 (2), Article 149
• Main Authors: Sandal, Baris, Hacioglu, Yuksel, Yagiz, Nurkan
• Format: Article
• Language: English
• Subjects: Engineering
• ISSN: 0973-7677; 0973-7677
• DOI: 10.1007/s12046-024-02508-w

A fuzzy logic control strategy for temperature and relative humidity control of air-handling unit in heating, ventilating, and air-conditioning systems is proposed. Those systems operating in the cooling process are multi-variable and nonlinear systems and their control is very difficult. The dynamics of all elements of the system are presented and the case of an unknown external disturbance is also considered. The zone temperature is regulated by controlling the flow rate of cold water passing through the cooling coil. The numerical results for the uncontrolled, On–Off controlled, and Proportional-Integral-Derivative (PID) controlled systems are compared with the proposed fuzzy logic controlled system under the weather conditions of Istanbul, Turkey in summer season. From the numerical results, it was observed that for the zone temperature the 78 min settling time of the uncontrolled case was reduced to the 26 min by the proposed fuzzy logic controller, which yielded the best result among the other controllers. The PID and fuzzy logic controllers provided smoother control signals when compared to the fluctuating control signal of the On–Off controller for the flow rate of cold water. The energy consumptions of the controllers, normalized with respect to the uncontrolled case, were also compared to show the expense of achieving fast time response. The increase is only between 2.5–7.4% and the proposed fuzzy logic controller used less energy than the PID controller.