Effect of interbaffle spacing on heat transfer and pressure drop in a shell-and-tube heat exchanger

Experiments have been performed to determine the response of the heat (mass) transfer and pressure drop on the shell side of a shell-and-tube heat exchanger to changes in the interbaffle spacing. Per-tube, per-row and per-compartment heat (mass) transfer coefficients were obtained by means of the naphthalene sublimation technique, all for the fully developed regime. Pressure distribution measurements were made throughout the heat exchanger, and the pattern of fluid flow was visualized with the aid of the oil-lampblack technique. The greatest sensitivity of the per-tube heat transfer coefficient to the interbaffle spacing occurred at the tubes situated in the inflow window of a compartment, where higher coefficients (by about 15%) were encountered for larger interbaffle spacings. In the crossflow zone, the per-tube transfer coefficients corresponding to the smaller interbaffle spacing exceeded those for the larger interbaffle spacing by about 5%, and similarly in the baffle-adjacent row in the outflow window of the compartment. The other rows in the outflow window were ambivalent about the effects of interbaffle spacing. Owing to cancellations among the aforementioned per-tube responses, the compartment-average transfer coefficients were virtually unaffected by the spacing. The per-compartment pressure drop decreased as the interbaffle spacing decreased, but for a fixed streamwise length, the pressure drop was slightly larger for smaller spacings. The experimental results were compared with the predictions of the Tinker and Delaware Project design methods.