Cascaded PID temperature controller for FOPDT model of shell-and-tube heat exchanger based on Matlab/Simulink

Cascade control is one of the most successful methods for improving single loop control performance. This control can stabilize the system, minimalize both of oscillation and integral error of interference in manipulation variables. Cascade control structure consists of two controllers where loop feedback in the loop feedback. This research takes a case on original shell-and-tube heat exchanger and simulated using Matlab/Simulink. Cascade control is used to stabilize outlet temperature even there is interference. Shell-and-tube heat exchanger is modeled using first order plus delay time (FOPDT). The type of controller is used PID standard with Ziegler-Nichols tuning method. Performance of cascade control is tested by providing inlet fluid flow disturbance. The experiment got the best performance on PI control (secondary controller) with parameter of Kp and Ti worth 1.375 and 2. PI control produces smallest IAE amount 34.57. Test control of cascade (primary controller) obtained a result that control of PID produces the best response. PID control with parameter values Kp, Ti, and Td of 2.85, 53.06 and 13.265 gave the smallest IAE of 601.54 and the fastest rise time of 121.5 seconds. From this research, it is concluded that the shell-and-tube heat exchanger system can use cascade control to regulate the temperature stably even with an unstable fluid flow.