Convegni ATI - Accesso riservato soci CTI

Autore: A. Piccolo, G. Pistone, G. Cannistraro, L. Ponterio

Collana: CA - 61 - Perugia 2006

Note:
We present a numerical calculus scheme developed by implementing the simplified linear thermoacoustic theory − the short stack approximation − into a simple energy conservation model through a finite difference methodology. The model allows to enquire on the optimal length of thermoacoustic heat exchangers and on the magnitude of the related heat transfer coefficients between gas and solid walls. The effects of acoustic amplitude, plate spacing, plate thickness and Reynolds number on the heat transfer characteristics are examined. The results clearly indicate that a net heat exchange between the acoustically oscillating gas and the solid boundary takes place only within a limited distance from the stack edges.
This distance is found to be an increasing function of the plate spacing in the range (0 ≤ y0/δκ ≤ 2), becoming constant for y0/δκ≥ 2. The calculated dimensionless convective heat transfer coefficients, the Nusselt numbers, between gas and solid wall are comparable to those evaluated from classical correlations for steady laminar flow revised under the “Time-Average Steady-Flow Equivalent” (TASFE) and “root-mean-square Reynolds number” (RMSRe) models.