Abstract
The aim of the present work is to study the static and the dynamic behaviors of a lumped parameter heat exchanger controlled by manipulation of the flow rate. It is shown that a PI-feedback control system has a unique steady state and that a P-control system is always stable, but that a PI-control system has an unstable region in which the limit cycle is caused by the nonlinearity of the manipulation of the flow rate rather than by valve saturation. The amplitude and the period of the limit cycle can be determined by approximate calculation. Experimental results verify the existence of the limit cycle and agree well with the theoretical calculation.
