Trial and error method starting from common temperature control parameters:
Kc = 2-10 (Reduce overshoot by decreasing)
Ti = 2-10 min (Reduce overshoot by increasing)
Td = 0-5 min (start with 0 especially with a noisy measurement)
(Proportional Band % = 100 / Gain; Gain of 2 = 50 PB%)
PI interaction tuning map: P = Kc, I = Ti, D = 0
Or use the FOPDT model for the scientific approach to tuning (first order plus dead-time model):
Find Kp, Tp, and Өp for your system while in manual mode.
Process Gain - Kp - How Far
Process Time Constant - Tp - How Fast
Dead time - Өp - How Much Delay
Use standard Internal Model Control correlations to arrive at the closed loop time constant, Tc.
Aggressive action: Tc is the larger of 0.1*Tp or 0.8*Өp
Moderate action: Tc is the larger of 1*Tp or 8*Өp
Conservative action: Tc is the larger of 10*Tp or 80*Өp
Plug Tc, Kp, Tp, and Өp into the following tuning parameter equations (setting these up in a spreadsheet will allow adjustments of Tc later).
Proportional: Kc = 1/Kp * (Tp+0.5*Өp)/(Tc+0.5*Өp)
Integral: Ti = Tp + 0.5*Өp
Derivative: Td = Tp*Өp/(2*Tp+Өp)
Enter Kc, Ti, and Td as P, I, and D tuning parameters. Pay attention to units.
PID Control of a heat exchanger