Control of an Evaporative Cooling Process 

A.S. White [1]

  School of Engineering and Information Sciences Middlesex University The Burroughs, Hendon, London NW4 4BT. Email:
[1] Corresponding author;
A simplified model of the thermofluid behaviour of a water evaporation heat exchanger design is described. The simple one dimensional model developed using normal heat transfer analysis is compared to a sophisticated three dimensional multi-phase numerical computer model, with fair results. Control of the waste heat rejection process by Pulse-Width-Modulation of the control valve is evaluated for a PI controller and a Pseudo-Derivative Feedback Plus (PDF+) controller invented by Phelan. These show clearly that both the PDF+ controller and the PI controller when ramp disturbances are introduced are well able to keep the error in temperature to less than the permitted maximum of 1oC.
heat exchanger, evaporative cooler, PI control, PDF+ control, Simulink, disturbance control

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