Question 1

An engineer uses a temperature sensor mounted in a thermowell to

measure the temperature in a CSTR. The temperature sensor behaves as

a first-order process with a time constant of 3 seconds, and the

thermowell behaves as a first order process with a time constant of 9

seconds.

Using Matlab:

(a) Plot the open-loop response of the system to a step-change in the

CSTR temperature. Comment on whether the response in under or

over damped

(b) Plot the closed-loop response of the system for proportional only

control with a controller gain of unity.

(c) The engineer notes that the measured temperature has been

varying sinusoidally between 180 and 186°C with a period of 20

seconds for at least 10 minutes. Determine the likely temperature

fluctuation in the CSTR contents to the nearest degree.