Investigation of coupled systems consisting of fluid movers and heat-exchange devices

ABSTRACT

A heat exchanger and the fluid mover that delivers a working fluid to the exchanger inlet may experience profound interactions, which argues against treating them as separate entities. On the other hand, the design practice commonly assumes that the fluid delivered to the heat exchanger inlet is specifiable without consideration of any possible influence of the exchanger. The magnitude of the flow rate arriving at the exchanger inlet is generally based on the pressure rise—flow rate (P-Q) curve supplied by the manufacturer of the fan and coupled with the assumption that that flow is uniformly distributed across the exchanger inlet. It was found that the complexity of the fluid flow delivered by the rotating fan gives rise to a large fluid resistance within the pin-fin array, such that the delivered air flow rate was only about 37% of that for the P-Q case. On the other hand, the corresponding reduction in the rate of heat transfer was, at most, 27%.