Conservation of available work (exergy) by using promoters of swirl flow in forced convection heat transfer

Abstract

We examine the potential of heat-transfer augmentation techniques to reduce irreversibility (entropy generation, destruction of available work) in equipment for heat exchange. A number of popular swirl flow-promoting techniques is investigated in detail. It is shown that the irreversibility reduction induced by each technique depends strongly on the operating parameters of the apparatus in which heat transfer is to be augmented. An important operating parameter is the ratio of fluid-friction irreversibility divided by heat-transfer irreversibility, φ 0. It is shown that φ 0 must lie below a critical value in order for a proposed augmentation technique to yield savings in available work. The paper illustrates the use of entropy generation in assessing the relative merit of competing heat-transfer augmentation techniques. The geometric features of a proposed augmentation technique can be optimally selected in order to yield the maximum reduction in heat exchanger duct irreversibility.