HEAT TRANSFER AND PRESSURE DROP CHARACTERISTICS FOR AIRFLOW OVER ARRAYS OF RECTANGULAR MODULES

The heat transfer and pressure drop characteristics for an array of rectangular modules on one wall of a flat rectangular duct were examined experimentally with air as the working fluid. The experiments were performed for a generic configuration encountered in the cooling of electronic equipment. There were three major geometrical categories investigated during the course of the experiments. These include: (a) a regular patterned array of modules, (b) arrays with randomly dispersed missing modules, and (c) arrays in which transverse barriers were implanted to enhance heat transfer.;An investigation of the heat transfer coefficient on a per-module basis indicated that the flow was fully developed in the fifth and subsequent rows of the array, and the heat transfer coefficient was independent of position in the fully developed regime. The removal of a single module in the fully developed regime gives rise to enhancement of the heat transfer coefficients at neighboring modules within the realm of influence of the missing module. The greatest enhancement (about forty percent) occurs directly downstream of the missing module.;It was found that barriers served well in their function as heat transfer enhancement devices. The percentage enhancement was greatest for the highest of the barriers tested. The maximum impact of the enhancement (about a factor of two) occurred in the second row downstream of the barrier. Significant enhancements persisted as far as ten rows downstream of the barrier. The largest percentage enhancements, induced either by a barrier or by a missing module, occurred at the lower Reynolds numbers.;Some thermal design guidelines can be concluded. When several modules needing enhanced heat transfer are grouped together, a barrier provides a viable solution. In the case of a single specific module requiring enhanced heat transfer, a missing module directly upstream of the critical module is more efficient because it does not cause a pressure penalty.;Pressure measurements in fully populated arrays with and without barriers identified the excess pressure loss inflicted by the presence of a barrier. The barrier heights investigated yielded incremental pressure losses equivalent to that induced by tens of rows of modules in a barrier-free array.