In this paper the structural controllability and observability of heat exchanger networks are determined from qualitative information about the heat exchangers and their network topology. The heat exchanger network is modelled as a time-varying linear system based on first engineering principles where the effect of the flowrate variations is described by unknown time-varying parameters, inlet temperature variations are regarded as disturbances and external heaters/coolers are considered as input variables. Necessary and sufficient conditions for structural controllability and observability of heat exchanger networks are derived, based on an extended Kalman-type rank criterion for linear systems with time-varying parameters. Determining the structural controllability and observability of heat exchanger networks needs only checks for the input and output connectability of the network in both constant and time-varying parameter cases. The results are extended to the more-practical case where bypass ratios are also used as control variables and where more than one time-varying parameter enters into the state-space matrices.
ASJC Scopus subject areas
- Control and Systems Engineering
- Computer Science Applications
- Electrical and Electronic Engineering
- Applied Mathematics