Transfer function-based analysis of the frequency-domain properties of a double pipe heat exchanger

This paper discusses irrational transfer function representation for a typical thick-walled double pipe heat exchanger. Closed-form analytical expressions for the individual elements of 2 x 2 transfer function matrix are derived both for the parallel- and the counter-flow configurations using the Laplace transform method. Based on the transfer function representation, its frequency responses are demonstrated both in the form of three-dimensional graphs as well as classical, two-dimensional Bode and Nyquist plots. Finally, steady-state temperature profiles are presented and compared for both flow arrangements considered.