DYNAMIC-MODELS FOR HEAT-EXCHANGERS AND HEAT-EXCHANGER NETWORKS

Dynamic models are needed to assess controllability of heat exchangers and heat exchanger networks. A simple model is desirable, but all imp ortant model features must be included. We discriminate between import ant and less important model features by order of magnitude argumentat ion, comparison of controllability measures and dynamic simulations. I mportant model features for single heat exchangers are model order, wa ll capacitance and fluid compressibility, whereas how configuration an d temperature driving force have only a small effect on the dynamics. The most important model feature for heat exchanger networks is reside nce time of the connecting pipes. Simpler models may fail to identify inherent control limitations such as zeros in the right half plane.