NUMERICAL AND EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER COEFFICIENT AND FRICTION FACTOR IN INTERNAL CHANNELS WITH FINS

Surface heat transfer enhancement is widely used in a wide range of industrial applications. The turbulence created by the enhancement has significant effects on increasing the heat transfer. On the other hand, the surface enhancement usually causes a larger friction that leads to a larger pressure drop. In this study, an experimental investigation with computational verification of the wall heat transfer and the friction characteristics of a fully-developed turbulent air flow in a square channel with circular micro-fins was reported. The protuberances of 6.35x10(-3) m diameter and 6.35x10(-3) m height were placed in three different configurations. Tests were performed for the Reynolds numbers ranging from 27,000 to 96,000. The fin height-to-channel hydraulic diameter ratio, e/Dh, was kept at 0.125. The channel length-to-hydraulic diameter ratio, L/Dh, was 20. The heat transfer was enhanced using micro-fins as turbulence promoters. The computational analysis was also performed and found in close agreement with the experimental results. The simulations can be used in predicting local turbulence characteristics, thus the turbulence heat transfer relationship. The simulation results can also predict the local heat and friction characteristics and in locating high temperature regions, or "hot spots," which is beyond the potential of the experimental setup. This investigation could be helpful in applications concerning internal channel turbulent flows and involving micro-fins to boost heat transfer. Heat Exchangers, Air Compressors, Turbines are some of equipment where the results of this study can be utilized.