S-SS-3-14 CFD Study of NTIW Bundles

K. J. Farrell

The thermal hydraulic performance of a gas-gas no-tubes-in-window (NTIW) field exchanger was studied parametrically using computational fluid dynamics (CFD). The tubes were modeled using porous media with velocity-dependent volumetric heat generation. An important performance indicator among the design variants was the ratio of the window velocity to the crossflow velocity. When a single central crosspass was used in the design, the exchangers were more efficient for Vwind/Vcross £ 4. Among the range of variables studied, the largest baffle spacing (Lbc/Ds = 1.98) and intermediate baffle cut (20.5 percent) performed best. Support plates are nearly ideal remedies for tube vibration problems; they have little effect on heat transfer or pressure drop. The CFD results reported herein quantify anecdotal rules of thumb and provide important design guidelines for NTIW exchangers.