Simulation Study on Flow and Heat Transfer of Cross-Arrangement Tube Bundle

The air precooler of SABRE engine (Synergetic Air-Breathing Rocket Engine) is a tube bundle type of heat exchanger consisting of thousands of small tubes. The cold helium gas flows in the small tube bundle, and the high-speed hot air circulates outside the tubes and exchanges heat with the helium in the tubes. In this study, the cross-arrangement tube bundle consisting of small tubes with outer diameter of 1mm was taken as the research object. The system simulation calculation and data sorting were carried out. It is found that the empirical correlation of the conventional tube bundle is no longer applicable to the small tube and the reasons for inapplicability are explained by analysis of flow field. In addition, the results show that the average heat transfer coefficient of cross small/micro tube bundle isn't affected by heat flux, but increases with the increase of Reynolds number, increases with the increase of transverse spacing, and decreases with the increase of longitudinal spacing. The flow resistance coefficient isn't affected by heat flux and longitudinal spacing, but decreases with the increase of Reynolds number, and decreases with the increase of transverse spacing.