Control of Temperature Profile in Counter Flow Heat Exchanger using Quantitative Feedback Theory

A heat exchanger is an essential component in heavy industry in terms of its distinct heating and cooling properties. The availability of a robust controller suitable for performing multiple tasks can aid this process in being executed in an efficient manner. In this context, a sequential multivariable quantitative feedback theory (QFT) based methodology has been followed to design the temperature control law. A unique cost function has been optimised to enhance the diagonal dominance of the compensated plant. Robustness has been checked irrespective of uncertainty by using frequency domain as well as time domain analysis. Finally, robust stability has been verified for all possibilities through the generalised Nyquist plot and corresponding computation of Gershgorin bands.