The Efficiency of Heat Transfer in Heat-Transfer Apparatuses with Interacting Swirled and Transit Flows

Resumo

The efficiency of power units designed for different applications is determined by their power density, weight, dimensions, and reliability, and it can be increased by introducing new engineering solutions to increase heat transfer rate on heat-release surfaces in heat-transfer apparatuses (HTA). Heat transfer is often enhanced through the use of interacting swirled flows. The heat-transfer enhancement is achieved due to interaction of swirled and transit (with a pitch equal to infinity) flows along a convex heat-release surface. The efficiency is estimated of HTAs with convex and concave heat-release surfaces on which precisely this method of heat-transfer enhancement is used. An annular channel is selected as the basic HTA. This selection is due to the fact that the channel elements (i.e., the outer pipe has a concave heat-release surface, and the inner rod has a convex release surface) are components of various heat exchangers and nuclear power installations. In evaluating the efficiency of HTAs, the known correlations for heat transfer and hydraulic resistance in smooth annular channels and the relationships for heat transfer coefficient on convex and concave surfaces of annular channels with swirled and transit flows obtained by the author were used. It is demonstrated that an increase in the heat transfer is greater than a rise in the hydraulic resistance with the interaction of swirled and transit flows at heat-transfer surfaces in a certain range of flow conditions and geometries. Evaluation of the HTA’s effectiveness based on the known criteria has revealed that the heat-transfer enhancement method using interacting swirled and transit flows is comparable in terms of its effectiveness with other known methods of heat-transfer augmentation.