S-SS-3-21 Disk-and-Doughnut Baffled Heat Exchangers: CFD Simulations and Methods
Disk-and-doughnut baffled heat exchangers can generate more heat transfer with less pressure drop than conventional segmental exchangers in certain industrial applications. Unfortunately, little information is available on these units in service. This report introduces new methods for analyzing and rating a disk-and-doughnut baffled heat exchanger. Using three-dimensional computational fluid dynamics (CFD) simulations, we describe the exchanger’s thermal-hydraulic performance in detail. Validated CFD results enable us to perform a high-resolution stream analysis through the exchanger that includes tube-to-baffle, bundle-to-shell, and baffle-to-shell leakage flows. Computed shellside crossflow and window velocities as well as flow fractions are compared between our CFD simulations and Xist® ratings. Using existing Xist single-segmental and double-segmental baffle options, we calculate pressure drop and heat transfer with quantifiable error estimates. The report concludes with new hand-rating calculations of pressure drop and shellside heat transfer coefficients that are more accurate than formulations previously proposed by HTRI.