Fuzzy control of temperature in gas flow control system based on mixed cold and hot gases

This study proposes a novel high-temperature gas flow temperature simulation system based on the mixing of cold and hot gas flow. The outlet gas flow temperature is controlled by adjusting the flow rate of the cold gas flow. To achieve consistent control of high-precision and wide-range temperature control of the system. The system mathematical model was constructed and the system characteristics were analyzed. However, traditional PID control suffers from inconsistencies in control performance at high and low temperatures, as well as inconsistent responses during temperature increasing and decreasing processes. To address these issues, fuzzy PID control was introduced, but its parameter tuning proved challenging, resulting in poor consistency of control performance. To expand the adaptability of fuzzy control, a function-based and fuzzy inference-based variable universe fuzzy PID controller was proposed. Experimental and simulation results demonstrate that the fuzzy inference-based variable universe fuzzy PID controller exhibits good dynamic and static performance under different operating conditions. The max settling time and static error are 16.5 s and +/- 4 K, respectively. Compared with PID controller, the settling time and static error are reduced by 56.2% and 67.5% respectively. The fuzzy inference-based variable universe fuzzy PID controller overcomes the performance discrepancies during temperature increasing and decreasing processes, different operate temperatures, and various step amplitudes. Consequently, highly accurate simulation of system outlet gas flow temperature is realized. This methodology can be widely applied to control systems with strong nonlinearity and asymmetry, improving the consistency of the system control performance.