Unity Mach number axial dispersion model for heat exchanger design

• Published in: Journal of physics. Conference series Vol. 395; no. 1; pp. 12052 - 9
• Main Authors: Ranong, C Na, Roetzel, W
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.01.2012
• Subjects: Cold flow; Dispersion; Dispersions; Exact solutions; Frequency domain analysis; Frequency domains; Heat exchangers; Laplace transforms; Mach number; Mathematical analysis; Mathematical models; Peclet number; Physics; Plug flow; Thermal design; Unity
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/395/1/012052

Recently a new axial dispersion model for the thermal design of heat exchangers with deviations from plug flow has been developed by considering the limiting case of unity dispersive Mach number of the hyperbolic dispersion model. The main advantage of the new dispersion model is that known and proved design charts and formulae for plug flow can further be applied. Only the numbers of transfer units have to be corrected. The corrections are simple functions of the dispersive Peclet numbers of the hot and the cold flow stream. In this paper a method for the determination of the dispersive Peclet numbers by transient tracer experiments is presented. The experimental inlet signals and outlet responses are evaluated in the frequency domain using Laplace transforms. Together with the analytical solution of the model equations the dispersive Peclet numbers are obtained. For comparison the evaluation procedure in the frequency domain is also applied to the parabolic dispersion model and the model of stirred tanks in series.