S-SS-3-27 A Review of the A-stream Model of the Stream Analysis Method

K. J. Farrell

After a brief overview of the evolution of the Stream Analysis Method, we use CFD simulation results to compare A-stream, tube-to-baffle leakage flow geometry and pressure drop models. We propose a modified A-stream pressure drop model for the refactored software that, contrary to current usage in HTRI Xchanger Suite 7, calculates the friction factor using an effective length scale, which is less than the hydraulic diameter of the annulus and is continuous over the entire Reynolds number range. Furthermore, the momentum changes incurred at the sudden contraction and expansion of the A-stream leakage flow are modeled using an empirical fit of Idelchik’s values for various area ratios versus a Reynolds number. While the resistance coefficients predicted with the proposed method are marginally better, they exhibit realistic behavior with variations in Reynolds number, are more numerically robust, and have other potential applications within a shell-and-tube exchanger.