Liquid-level Control System: (30 Points) A liquid level control system (refer to Fig 11.15 and Example 11.2 in the Book) uses a computer controller with inputs and outputs in terms of the full range (0 to 100%). The tank is 1.5 meters in diameter, with a control valve resistance [R] of 12 min/m^2. The level transmitter has a span of 2.0 meters [0 to 100% range]. The valve characteristic is given by: f = (25)^-1, where L is the fraction of lift. When the control valve is fully open [L = 1], the flow rate through the valve is 0.35 m^3/min. The air-to-open control valve receives a 3 to 15 psi signal from an I/P transducer, which receives a 0 to 100% signal from a proportional-only controller. At nominal operating conditions, the control valve is partially open (L = 0.4).
Using an appropriate dynamic model, calculate the closed-loop response to a step change in the set point of 0.5 meters, for the following controller gain: K = 10.