HEAT TRANSFER ENHANCEMENT IN A TUBE BUNDLE PLACED IN CROSS FLOW WITH COUNTER-FLOW LOW-FREQUENCY ASYMMETRIC PULSATIONS

Abstract

he article presents the results from mathematical modeling of heat transfer in an in-line tube bundle under the conditions of low-frequency asymmetric pulsations. The importance of heat transfer enhancement and the problem of modeling asymmetric pulsations are considered. The basic design of a system for setting up counter-flow low-frequency asymmetric pulsations in heat transfer equipment is presented. The Ansys Fluent 14.0 software package was used for simulating heat transfer. The calculations were carried out for a 2D statement of the problem without taking into account the gravity forces. The Spalart–Allmaras model with correction for the flow line curvature (SARC) was chosen as the turbulence model. The simulated area included a rectangular channel with a tube bundle. Based on the numerical simulation results, a positive influence of the pulsating flows on the heat transfer coefficient was revealed. It is shown that with increasing the frequency f and the amplitude A of pulsations, the heat transfer intensity is enhanced irrespectively of Re numbers. A comparison of the numerical results with experimental data was made with the experimental measurements error not more than 15%. The factors leading to heat transfer enhancement in pulsating flows are pointed out. It is shown, that among the factors affecting the growth of heat transfer intensity δNu in unsteady flow as compared with steady flow averaged over the entire studied region, it was noticed that the most intensive influence on the augmentation of heat transfer intensity δNu is due to increasing the convective transfer fluid velocity.