Comparative Three Dimensional CFD Study for Inline Cross Flow Plate Finned Tube Heat Exchanger

Abstract

In this paper, three dimensional study has been investigated on finned-tubes cross flow heat exchanger. The investigation takes into account the outer cold fluid flow (air). The inner hot fluid flow (water) and the conjugated solid domain. The hot water flowing inside the tube is considered laminar while the air flowing outside the tubes inside the fin passages is treated as turbulent. All heat transfer and fluid flow parameters have been studied at different velocities for air in the range between 1-to-6 m/s with fixed Re =1200 for inner water flow. In this study, the heat transfer coefficients and pressure drops on both sides of fluids are calculated numerically for both the conventional size and the selected micro size heat exchangers with plain-tube and finned-tubes arrangements. The results declare that the micro tube has higher performance with controllable pressure drop as the heat flux ratio is increased by 20% whereas, the heat per unit volume ratio is increased by 800-1200% with the increase of air velocity from the given lower to the higher one. It is found that the effects of using fins are profitable only for the conventional exchanger but not for the micro size exchanger. The most interesting results obtained from this study is the superiority of the micro tube heat exchangers over the typically conventional one in regards of the heat transfer rate per unit volume.